U.S. patent application number 12/078013 was filed with the patent office on 2008-07-31 for liquid crystal display device.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Shusuke Endo, Shunsuke Morishita.
Application Number | 20080180601 12/078013 |
Document ID | / |
Family ID | 17602947 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080180601 |
Kind Code |
A1 |
Morishita; Shunsuke ; et
al. |
July 31, 2008 |
Liquid crystal display device
Abstract
The object of the present invention is to make parts and kinds
of liquid crystal display devices in common for cope stably and
flexibly with commercial products of computer makers and television
makers which have been promoted in various kinds, for simplifying
maintenance of a liquid crystal display unit mounted on computers,
display monitors therefor or televisions, and preferably for
enabling to omit positional adjustment of a light source unit and a
liquid crystal display panel during the maintenance of the liquid
crystal display device. For this object, the invention provides a
liquid crystal display device comprising first, second, and third
housings, a liquid crystal display panel fixed between the first
and second housings, a light source (cold-cathode fluorescent
tubes) fixed to the third housing, the second and third housings
being detachable to one another, being constructed by overlapping
the first, second and third housings with each other, wherein a
timing-converter board fixed to an opposite side surface of the
third housing to a side surface to which the light source is fixed,
and protrusions formed on the opposite side surface so as to
determine a maximum thickness of the liquid crystal display
device.
Inventors: |
Morishita; Shunsuke;
(Mobara, JP) ; Endo; Shusuke; (Mobara,
JP) |
Correspondence
Address: |
Stanley P. Fisher;Reed Smith Hazel & Thomas LLP
Suite 1400, 3110 Fairview Park Drive
Falls Church
VA
22042-4503
US
|
Assignee: |
Hitachi, Ltd.
|
Family ID: |
17602947 |
Appl. No.: |
12/078013 |
Filed: |
March 26, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11252848 |
Oct 19, 2005 |
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12078013 |
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09671429 |
Sep 27, 2000 |
6992734 |
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11252848 |
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Current U.S.
Class: |
349/70 |
Current CPC
Class: |
G02F 1/133608 20130101;
G02F 1/133308 20130101; G02F 1/133604 20130101 |
Class at
Publication: |
349/70 |
International
Class: |
G02F 1/1335 20060101
G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 1999 |
JP |
11-278844 |
Claims
1. A liquid crystal display device comprising: a liquid crystal
display panel comprising a pair of linger sides, a first shorter
side, and a second shorter side; a housing comprising a first
surface and a second surface opposed to the first surface; a
plurality of fluorescent tubes disposed between the liquid crystal
display panel and the first surface of the housing, and arranged in
parallel with the pair of longer sides; a light source control
circuit mounted on the second surface of the housing, and disposed
adjacent to the first shorter side; and a first frame disposed
adjacent to the first shorter side and a second frame disposed
adjacent to the second shorter side, wherein the plurality of
fluorescent tubes comprise first ends adjacent to the first shorter
side and second ends adjacent to the second shorter side, wherein
the first frame comprises first grooves, and the first ends of the
plurality of fluorescent tubes are fitted into the first grooves
and fixed by first rubber bushes, and wherein the second frame
comprises second grooves, and the second ends of the plurality of
fluorescent tubes are fitted into the second grooves and fixed by
second rubber bushes.
2. A liquid crystal display device according to claim 1, wherein
the first rubber bushes are inserted into the first grooves, and
the second rubber bushes are inserted into the second grooves.
3. A liquid crystal display device according to claim 1, wherein
the first frame and the second frame are fixed to the housing.
4. A liquid crystal display device according to claim 1, wherein
the plurality of fluorescent tubes comprises first terminals at the
first ends, the first terminals are connected to separated leads,
and each pair of the separated leads is connected to each of
connectors, and wherein the connectors are connected to the light
source control circuit.
5. A liquid crystal display device according to claim 4, wherein
the separated leads are same length.
6. A liquid crystal display device according to claim 1, wherein
the light source control circuit comprises a plurality of voltage
transformation elements disposed along the first ends of the
plurality of fluorescent tubes.
7. A liquid crystal display device according to claim 6, wherein
number of the plurality of voltage transformation elements and
number of the plurality of fluorescent tubes are same.
8. A liquid crystal display device according to claim 6, wherein
the plurality of fluorescent tubes comprises first terminals at the
first ends, and second terminals at the second ends, the first
terminals are connected to separated leads, and the second terminal
are connected in common.
9. A liquid crystal display device according to claim 8, wherein
the second terminals are connected to the light source control
circuit by a cable.
10. A liquid crystal display device according to claim 9, wherein
each pair of the separated leads is connected to each of
connectors, and the connectors are connected to the light source
control circuit.
11. A liquid crystal display device according to claim 9, wherein
the cable is longer than the separated leads.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a Continuation of U.S.
application Ser. No. 11/252,848 filed on Oct. 19, 2005, which is a
Continuation of U.S. application Ser. No. 09/671,429 filed on Sep.
27, 2000, and claims priority from U.S. application Ser. No.
11/252,848 filed on Oct. 19, 2005, which claims priority from U.S.
application Ser. No. 09/671,429 filed on Sep. 27, 2000, which
claims the priority of Japanese Patent Application 11-278811 filed
on Sep. 30, 1999, the contents of which are hereby incorporated by
reference into this application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a liquid crystal display device
used for a monitor for laptop personal computers, desktop computers
or the like, and a liquid crystal display monitor using the
same.
[0004] 2. Description of the Related Art
[0005] Liquid crystal display devices have become widespread as
monitors for laptop personal computers and desktop computers.
[0006] In such products, a liquid crystal display device is mounted
as a liquid crystal display module including in combination a
liquid crystal display panel and a light source. A configuration of
such liquid crystal display device is described in, for example,
Japanese Patent Laid-Open No. 264991/1993 and Japanese Patent
Laid-Open No. 218914/1995.
SUMMARY OF THE INVENTION
[0007] In recent years, commercial products have been diversified
in such products as laptop personal computers and desktop
computers.
[0008] More specifically, under circumstances, in which these
commercial products are produced in various kinds and small
quantity, liquid crystal display devices cannot but be diversified
in configuration.
[0009] Meanwhile, reduction of kinds of parts for liquid crystal
display devices has become a task in order to supply liquid crystal
display devices stably (first task).
[0010] Also, under circumstances in which time taken in using
monitors of laptop personal computers, desktop computers has been
increasing, it has been demanded to reduce burdens related to
maintenance of these commercial products (second task). More
specifically, an increase in time taken in using the
above-mentioned computer products in use in offices and personal
use has increased burdens on light source units, in particular,
cold-cathode fluorescent tubes used therefor, of liquid crystal
display devices to cause unexpected deterioration of these
parts.
[0011] Further, under circumstances, in which computer manufactures
have increased, it has become important to efficiently supply the
above mentioned liquid crystal display devices to these
manufactures. Under such circumstances, it is essential to reduce
probability of breakage of liquid crystal display devices as much
as possible during conveyance of the devices to computer
manufactures.
[0012] However, under circumstances, in which it is promoted to
make liquid crystal display devices thin and to make control
devices therefor high in performance, it has become difficult year
after year to reduce the above-mentioned breakage. Also, under
circumstances, in which production of liquid crystal display
devices tends to be done in various kinds and small quantity, there
has been increased the possibility that supplying of liquid crystal
display devices of particular types cannot but be stopped due to
problems of the above-mentioned breakage and so on.
[0013] It is a first object of the invention to use types of parts
for liquid crystal display devices in common to stably and flexibly
cope with commercial products of manufactures of computers and
televisions which get various in kind.
[0014] It is a second object of the intention to simplify
maintenance of liquid crystal display devices mounted in computers,
display monitors therefor, and televisions, and to omit positional
adjustment of a light source unit and a liquid crystal display
panel at the time of maintenance or to prevent particles such as
dusts from entering a gap between a liquid crystal display panel
and an optical sheet adjacent thereto.
[0015] To solve the above-mentioned problems in a liquid crystal
display device comprising first, second and third housings the
second and third housings of which are detachable from one another,
a liquid crystal display panel fixed between the first and second
housings, and a light source fixed to the third housing, being
assembled by overlapping the first, second and third housings with
one another, the present invention fixes a timing-converter board
fixed to a surface of the third housing opposite to another surface
thereof the light source is fixed to, and provides protrusions
being formed on the opposite surface for determining a maximum
thickness of the liquid crystal display device. The protrusions
protect parts of the time-converter board against breakage due to
external forces applied to the liquid crystal display device.
[0016] Also, the protrusions are formed inside a peripheral edge of
the liquid crystal display device.
[0017] Also, a light source control circuit is arranged on the
opposite side surface.
[0018] Also, a first fixing means for fixing the first and second
housings, and a second fixing means for fixing the second and third
housings are provided, and the first fixing means does not fix the
third housing.
[0019] Further, a liquid crystal display monitor uses the liquid
crystal display device, and the first fixing means is used to fix
either of a housing of the liquid crystal display device, and the
first or second housings.
[0020] The above-mentioned first, second and third housings contain
first members (principal plane member, plate) along a principal
plane of, for example, a substrate (for example, a member called a
liquid crystal display substrate, or a transparent substrate
corresponds thereto) contained in the above-mentioned liquid
crystal display panel. In the case where a peripheral edge of an
image display area of a liquid crystal display device is made
small, the first members of the first and second housings are
occupied at their surfaces by openings, through which a liquid
crystal display panel is exposed, to assume a configuration of a
so-called picture frame. Profiles of these first members are
changed in area in the order of, for example the first, second and
third housings, and the liquid crystal display device is assembled
in such a manner that the profile of the first member of one of the
housings receives therein the profile of the first member of the
other of the housings in overlapping manner. Also, at least one of
the first, second and third housings comprises a second member
(side surface member, side) projecting from one of surfaces of or a
peripheral edge of the first member in a thickness direction of the
substrate. In accordance with use of the liquid crystal display
device, the second member is in some cases formed integrally in
such a manner to surround at least a part of the one of surfaces of
the first member and interrupting portions such as notches are in
some cases provided on at least the part. The second member also
serves as a guide when two of the first to third housings are
overlapped on one another.
[0021] "A thickness (maximum thickness)" of the liquid crystal
display device in the invention is defined as a dimension in a
thickness direction of the substrate (direction, in which the
second member protrudes). A height of the protrusions is defined as
a dimension in a thickness direction of the substrate. The
definition of this configuration will be explained later with
reference to the drawings. In addition, the plurality of
protrusions may be provided on the third member to be spaced from
one another, or walls formed as the protrusions may be formed on
the third member to surround a portion (for example, a portion, on
which the above-mentioned parts are mounted) of the first member of
the third housing.
[0022] The invention makes parts of and types of liquid crystal
display devices common to enable stably and flexibly coping with
commercial products of computer makers and televisions makers,
which have been increased in kinds. Also, it is possible to
simplify maintenance of liquid crystal display devices mounted on
computers, display monitors therefor, and televisions, and to omit
positional adjustment of a light source unit and a liquid crystal
display panel at the time of maintenance. Alternatively, in the
case where an optical sheet is provided on the second housing to be
adjacent a liquid crystal display panel, the liquid crystal display
device can be prevented from being deteriorated in optical
characteristics due to entering of dust between the liquid crystal
display panel and the optical sheet, because there is no need to
separate the first housing and the second housing.
[0023] These and other objects, features and advantages of the
present invention will become more apparent from the following
description when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is an exploded, perspective view showing a liquid
crystal display device according to the invention (a view as seen
from a side of a liquid crystal display panel);
[0025] FIG. 2 is an exploded, perspective view showing the liquid
crystal display device according to the invention (a view as seen
from a back side of the liquid crystal display device, that is, a
view as seen from a side opposite to the side of FIG. 1);
[0026] FIGS. 3A-3I include assembly drawings FIGS. 3A to 3G, a
perspective view FIG. 3H, and a sketch drawing FIG. 3I of the
liquid crystal display device according to the invention, as viewed
from a right side surface (III direction) of FIG. 1.
[0027] FIG. 4 is a perspective view showing the liquid crystal
display device according to the invention, as viewed from a left
side surface (IV direction) of FIG. 1;
[0028] FIGS. 5A-5D include assembly drawings FIGS. 5A to 5C, a
perspective view FIG. 5D of the liquid crystal display device
according to the invention, as viewed from a front side (V
direction of FIG. 1;
[0029] FIG. 6 is a sketch drawing of the liquid crystal display
device according to the invention, as viewed from a top surface (or
the back side of the liquid crystal display device) of FIG. 2;
[0030] FIGS. 7A and 7B are illustrations of a first constitution
according to the invention. FIG. 7A shows the case where a light
source drive circuit is provided on the liquid crystal display
device and FIG. 7B shows the case where no light source drive
circuit is provided;
[0031] FIG. 8 illustrates a state, in which the liquid crystal
display device is packed up at the time of shipping;
[0032] FIGS. 9A and 9B are illustrations of a second constitution
according to the invention, FIG. 9A shows the case where a light
source drive circuit is removed from the liquid crystal display
device and FIG. 9B shows in enlarged scale a construction shown by
a circle of FIG. 9A;
[0033] FIGS. 10A-10C shows an example of a monitor making use of
the liquid crystal display device according to the invention, FIG.
10A is a side view, FIG. 10B is a front view (a view seen from the
monitor, that is, from a user's side), and FIG. 10C is a side view
showing a state, in which the light source unit is removed in the
monitor; and
[0034] FIG. 11 is a circuit diagram containing a matrix portion and
its surroundings of the liquid crystal display device.
DETAILED DESCRIPTION
[0035] An explanation will be given below to an embodiment of the
invention with reference to the drawings. In addition, parts having
the same function are designated by the same characters in the
drawings illustrated below, and reiteration of the explanation is
omitted.
[0036] (Entire Constitution of an Liquid Crystal Display
Device)
[0037] FIGS. 1 and 2 are exploded, perspective views showing a
liquid crystal display device according to the invention.
[0038] FIG. 1 is a perspective view from a side of a liquid crystal
display panel (a front side of the liquid crystal display device
relative to a user's visual field), and FIG. 2 is a perspective
view from a side opposite to FIG. 1 (aback side of the liquid
crystal display device relative to a user's visual field).
[0039] In FIG. 1, the reference numeral 1 designates a first
housing, 2 second housing 2,3 a third housing, 4 a liquid crystal
display panel, 5 an optical sheet (a diffusion film on an optical
source side, and a prism film on a display panel side), 61
cold-cathode fluorescent tubes, 7 a timing-converter board, 8 a
light source control circuit board constituting a light source
control circuit, 11 an opening (liquid crystal display window) of
the first housing 1, 21 an opening of the second housing 13 a hole
in the first housing 1, 23 holes in the second housing 2, 14
notches (notches bent and fixed) on the first housing 1, 24
projections on the second housing, 2, 22 a terrace on the second
housing 2, 64, 65 frames, 641, 651 rubbers bushes, 43 a flexible
printed circuit board, 62 connectors (high voltage side), 63
connectors (low voltage side), 41 a gate drive IC, and 42 a drain
drive IC.
[0040] In FIG. 2, the reference numeral 31 designates a protrusions
provided on the third housing 3 for protection of parts on the
time-converter board 7, 32 a surface of the terrace, 321, 331
aprons, 33 an upper surface, 34 side surfaces, 341 openings for
provision of aprons 331, and 335 an opening for monitoring of
brightness of a light source.
[0041] The liquid crystal display device is assembled by fixing the
liquid crystal display panel 4 between the first housing 1 and the
second housing 2, and fixing to the second housing 2 and the third
housing 3, to which a light source containing the cold-cathode
fluorescent tubes 61 (or discharge tubes) is fixed. The second
housing 2 and the third housing 3 are detachable. The first housing
1, the second housing 2 and the third housing 3 are superposed on
one another to constitute the liquid crystal display device.
[0042] FIGS. 3A 3I include detailed assembly drawings of the
above-mentioned liquid crystal display device as viewed from a III
direction of FIG. 1 and views after assembly, FIG. 4 is a detailed,
perspective view showing the liquid crystal display device after
assembly as viewed from a IV direction of FIG. 1 and FIG. 5A-5D
include conceptional assembly drawings and a view, after assembly,
of the liquid crystal display device as viewed from a V direction
of FIG. 1. Also, FIG. 6 is an overhead view of FIG. 2 (a back view
of the liquid crystal display relative to a user's visual field)
after assembly. In addition, it is to be understood that relative
to FIGS. 1 and 2, constitutions in FIGS. 3 to 6 are partly deformed
for the purpose of explanation. For example, ten cold-cathode
fluorescent tubes 61 in FIGS. 1 and 2 are shown as nine in FIGS. 3
to 6.
[0043] In FIG. 3A, the reference numeral 12 designates an upper
surface of the first housing 1, 15 designates a terrace on the
first housing 1, and 16 designates an underside of the first
housing 1.
[0044] In FIG. 3B, the reference numerals 411, 421 designate
printed circuit boards, and 441, 442 designate LCD substrates.
[0045] In FIG. 3C, the reference numeral 25 designates an upper
surface (support of the LCD substrates) of the second housing 2, 26
designates protrusions, 261 designates openings for receiving the
protrusions, and 221 designates a terrace.
[0046] In FIG. 3E, the reference numeral 642 designates grooves
provided on a frame 64 for holding the cold-cathode fluorescent
tubes 61, and 643 designates screws.
[0047] In FIG. 3F, the reference numeral 333 designates a
hanger.
[0048] In FIG. 3G, the reference numeral 71 designates a
timing-converter LSI, 72 designates a voltage transformation
element (ferrite core), and 73 designates a connector (port).
[0049] In FIG. 3H, the reference numeral 631 designates a length of
cable (low voltage side).
[0050] In FIG. 3I, MDL designates a liquid crystal display
module.
[0051] In FIG. 4, the reference numeral 81 designates a voltage
transformation element (ferrite core).
[0052] In FIGS. 5A-5D, the reference numeral 74 designates screws
for fixing the timing-converter board 7 to an outside surface of
the third housing 3, 82 designates screws for fixing the light
source control circuit board 8 to an outside surface of the third
housing 3, and 334 designates screws.
[0053] (Liquid Crystal Display Panel 4)
[0054] The liquid crystal display panel 1 comprises, as showing in
FIG. 3B, the paid of substrates 441, 442, a body containing liquid
crystal compounds sealed between the substrates, and the drive ICs
(integrated circuit elements) 41, 42 for applying electric field to
the liquid crystal compounds to change optical transmissivity in a
direction through the substrates. These drive ICs are arranged on
the printed circuit boards 411, 421, which in turn are mounted on a
peripheral edge of one 112 of the pair of substrates. The liquid
crystal compounds sealed between the pair of substrates 441, 442
constitute a so-called liquid crystal layer between the substrates,
and as the layer is negligibly thin in thickness as compared with
the both substrates, it is not shown.
[0055] FIG. 11 is a schematic view showing the liquid crystal
display device, that is, a connection diagram containing an
equivalent network for a display matrix portion and its surrounding
network.
[0056] Tcon designates a timing-converter circuit, SC designates an
image display region, PX designates a pixel, C.sub.lc designates a
capacitance of a liquid crystal layer (cell), C.sub.s designates an
additional capacitance of an pixel, GATE DRV designates a gate
signal drive circuit, GL designates gate signal lines (scanning
signal lines), DATA-DRV designates a data signal drive circuit, DL
designates data signal lines (picture signal lines), Vcom
designates a common (counter) voltage power source and CL
designates a common (Counter) voltage signal line.
[0057] The liquid crystal display panel 4 shown in the embodiment
is a liquid crystal display device called an active matrix type,
and is known as one having, for example, an equivalent network
shown in FIG. 11. As shown in FIG. 11, the liquid crystal display
device of this type have switching elements TFT on respective
pixels PX (one of which is shown in an area enclosed by broken
lines) arranged two-dimensionally in an image display area (a
so-called screen) SC, and at least a pair of electrodes (forming of
capacitance C.sub.LC with the liquid crystal layer therebetween)
for application of electric field to the liquid crystal layer. In
the liquid crystal display device according to the embodiment, the
above-mentioned switching elements TFT are represented by symbols
for field-effect transistors, and may be replaced by diodes or the
like.
[0058] The gate signal lines GL are connected to gate electrodes of
symbols for field-effect transistors, to which signals from the
gate signal drive circuit GATE-DRV are supplied. The gate signal
lines GL are arranged in plural in parallel (on, for example, the
substrate 112 and connected to gate electrodes of the switching
elements TFT for the respective pixels PX arranged along the
respective gate signal lines GL.
[0059] Meanwhile, each of electric paths opened and closed by the
switching elements TFT is connected at one end thereof to one of a
pair of electrodes (called pixel electrodes), for which form
capacitance C.sub.LC with the above-mentioned liquid crystal layer
therebetween, and connected at the other end thereof to the data
signal lines DL. The data signal lines DL are arranged in plural in
parallel on, for example, the substrate 442, and connected to the
above mentioned other ends of the switching elements TFT for the
respective pixels PX arranged along the respective data signal
lines DL. At the above-mentioned other ends of the switching
elements TFT are supplied with signals from the data signal drive
circuit DATA-DRV. The above-mentioned one, ends of the switching
elements TFT may be conveniently called source electrodes, and the
other ends called drain electrodes, irrespective of functions
thereof. Therefore, the data signal drive circuit DATA-DRV is
called "drain signal drive circuit".
[0060] The data signal lines DL and the gate signal lines GL extend
in directions, in which they intersect each other, and are
electrically separated from each other above and below an
insulating film (for example, a gate insulating film of the
above-mentioned field-effect transistors) on the substrate 442.
[0061] In the respective pixels PX shown in FIG. 11, the other
(called counter electrode or common electrode) of the pair of
electrodes, which form capacitance C.sub.LC with the liquid crystal
layer therebetween, is applied with a predetermined voltage through
the counter voltage sign line CL from the voltage power source
Vcom. Also, the additional capacitance C.sub.s is formed in order
to suppress fluctuation of potential difference between the
electrodes, which form capacitance C.sub.LC with the liquid crystal
layer therebetween, while the switching elements TFT are closed.
The additional capacitance C.sub.s is constituted by, for example,
having the above-mentioned pixel electrode and the counter
electrode facing each other with a dielectric (the above-mentioned
gate insulating film or the like) except the liquid crystal layer.
With ones called a TN type (twisted nematic) among liquid crystal
display devices, the pixel electrode and the counter electrode are
frequently arranged to face each other with the liquid crystal
layer interposed therebetween, and with ones called a IPS type
(enplane switching type) or a FFS type (fringe field type), the
pixel electrode and the counter electrode are frequently arranged
on the same substrate. With the TN type, pixel electrodes are
provided separately every pixel PX on, for example, the substrate
442, while counter electrodes are in some case provided, which is
large to face pixel electrodes of a plurality of pixels PX disposed
in the image display area SC on the substrate 441.
[0062] With a liquid crystal display device of active matrix type,
switching elements TFT of a plurality of pixels PX along the
respective gate signal lines GL are selectively opened every gate
signal line GL to supply data signals to the pixels disposed along
the respective gate signal lines GL in a time-divisional manner. A
circuit for controlling this is called the timing-converter circuit
Tcon. Such timing-converter circuit Tcon generates clock signals
for e.g. the above-mentioned time-divisional control, and supplies
a liquid crystal drive voltage applied to the liquid crystal layer,
which corresponds to individual pixels PX. A circuit having a
function similar to this is used in passive matrix type liquid
crystal display devices (typified by STN (super twisted nematic).
Accordingly, the time-converter circuit Tcon is estimated as a
liquid crystal drive control and power source circuit.
[0063] The timing-converter circuit Tcon is formed on the
timing-converter board 7 (printed board) shown in FIGS. 1 to 6 to
be disposed on a back surface (an upper surface 33 shown in FIG. 2)
of the third housing 3 as viewed from a user of the liquid crystal
display device. As shown in FIGS. 3 and 6, the timing-converter
board 7 mounts thereon the voltage transformation element 72 made
of ferrite core or the like in addition to the timing-converter LSI
71. While other elements are formed on the timing-converter board
7, they are omitted from the drawings for the simplicity of
explanation.
[0064] As described above, the timing-converter circuit Tcon not
only generates signals for image display control, but also supplies
data signal voltage applied to the liquid crystal layer. The liquid
crystal display device is supplied with a power source voltage of,
for example, 12 V (even when AC voltage of 100 V is supplied from
an external power source, it is once converted in a predetermined
power source voltage value). In contrast, the drive ICs connected
to the gate signal lines GL and the data signal lines DL have
voltage of 3 V to 5 V. On the other hand, voltage applied to the
liquid crystal layer by the pixel electrodes in the individual
pixels PX ranges, for example, from 5 V to 10 V depending upon the
kind of liquid crystal compounds used. Further, to avoid
polarization of the liquid crystal layer during control thereof, it
is necessary to reverse polarity relatives to electric potential of
the counter electrodes. Accordingly, it is requested that supplying
of voltage to the pixel electrodes realize voltage fluctuation in
the range of two times voltage applied the liquid crystal layer,
for example, 10 V to 20 V. Therefore, it is essential to mount the
voltage transformation element 72 on the timing-converter board 7
in order to general voltage signals, which are different in width
of fluctuation by uses, from a predetermined voltage supplied to
the timing-converter substrate. Such request is the same with a
liquid crystal drive control and power source circuit in passive
matrix type liquid crystal display devices
[0065] In a liquid crystal display device of active matrix type,
the gate signal drive circuit GATE-DRV shown in FIG. 11 contains
the plurality of gate drive ICs 41 (shown in FIGS. 1, 3 and 4. The
timing-converter board 7 and these groups of drive IC's are
connected to each other by the flexible printed circuit board 43. A
circuit pattern generated on the flexible printed circuit board 43
is connected at one end thereof to a circuit pattern generated on
one end of a printed circuit board 412 mounting the data drive IC's
42, and a terminal provided on the other end thereof is inserted
into the connector (port) 73 provided on the timing-converter board
7 to connect the both circuit patterns to each other.
[0066] The timing-converter board 7 supplies, through the flexible
printed circuit board 43, clock signals, drive voltage of the date
drive IC's 41 and so on to the gate signal drive circuit GATE-DRV,
and supplies clock signals, drive voltage of the data drive IC's
42, voltage applied to the liquid crystal layer and so on to the
data signal drive circuit DATA-DRV. The gate drive IC's 41
constituting the gate signal drive circuit GATE-DRV are mounted on
a printed circuit board 411, and receive voltages and signals from
the timing-converter board 7 owing to connection of the both
circuit patterns to each other by means of joiners (not shown)
provided between the printed circuit board 411 and the printed
circuit board 412. An arrangement similar to the above one is found
in passive matrix type 1 liquid crystal display devices, so, for
example, the gate drive ICs 41 are replaced by common electrode
drive IC's, and the data drive ICs 42 are replaced by segment drive
ICs).
[0067] (Storage of the Liquid Crystal Display Panel 4)
[0068] The above-mentioned liquid crystal display panel 4 is
contained between the first housing 1 and the second housing 2
shown in FIGS. 1 to 3.
[0069] The image display are SC not shown but diagrammatically
shown in FIG. 11 is formed on an upper surface of the liquid
crystal display panel 4 shown in FIG. 1. The first housing 1 has
the opening 11 contacting with the upper surface, through which
opening a user of the liquid crystal display device sees the image
display area SC. A surface of the first housing 1 having therein
the opening 11 is formed by a sheet material of, for example, metal
or the like, which has the upper surface 12 facing a side of a user
of the liquid crystal display devices and the surface (underside)
16 to opposite to the upper surface, as shown in FIG. 3A. The
liquid crystal display panel 4 shown in FIG. 1 is fixed to the
first housing 1 with a peripheral edge of its upper surface
contacting with the underside 16.
[0070] The underside (upper surface in FIG. 2) of the liquid
crystal display panel 4 shown in FIG. 1 is fixed such that its
peripheral edge contacts with a recess 25 on the upper surface of
the second housing 2 shown in FIG. 3C. Although not shown in FIG.
3C, the recess 25 on the upper surface is provided with an opening,
which corresponds to the image display area SC in the liquid
crystal display panel 4.
[0071] In this manner, the first housing 1 and the second housing 2
are fixed in a state, in which the peripheral portions on the upper
surface of and on the underside of the liquid crystal display panel
4 are contacted with the first housing 1 and the second housing 2,
respectively. Either of the first housing 1 and the second housing
2 is formed with a side surface, which extends in a direction,
along which its peripheral edge intersects the upper surface or the
underside of the liquid crystal display panel 4. As shown in FIGS.
1 and 3A, rectangular-shaped notches 14 are formed on lower
portions of side surfaces of the first housing 1. Also, holes are
provided at two locations on III- and V-sides, respectively, of
these side surfaces in FIG. 1. Meanwhile, as shown in FIGS. 1 and
3B, protrusions 24 are formed on lower portions of side surfaces of
the second housing 2. Also, holes 23 are provided at two locations
on III- and V-sides, respectively, of these side surfaces in FIG.
1.
[0072] The liquid crystal display panel 1 is received between the
first housing and the second housing 2 in a state, in which the
second housing 2 is covered by side surfaces of the first housing 1
when the both housings are put together. The holes 13 in the first
housing 1 and the holes 23 in the second housing 2 are formed so as
to be substantially aligned in position when the liquid crystal
display panel 4 is held between these housings. Threads are formed
on inner walls of at least one of the holes 13 and the holes 23.
First, screws are passed through the corresponding holes 23 from
the four holes 13 (two on the III-side and two on the V-side in
FIG. 1) on the side surfaces of the first housing 1 to loosely fix
the first housing 1 and the second housing 2 to each other.
[0073] At this time, the notches 14 on the side surfaces of the
first housing 1 come near the protrusions 24 provided on the lower
portions of the side surfaces of the second housing 2 (see FIGS. 1,
3C and 5B). The respective notches 14 are pushed and bent below the
side surfaces of the second housing 2 (in other words, inside the
first housing 1) in such a manner as to have rectangular, upper
sides of the notches 14 (see FIGS. 1, 3A and 5A) abutting against
the lower portions (on which the protrusions are not formed) of the
protrusions 24 on the side surfaces of the second housing 2.
Thereby, the first housing 1 and the second housing 2 are fixed to
each other. FIG. 6 shows the first housing 1 as being positioned
outermost as a profile 1 of its side surfaces and the second
housing 2 as being positioned adjacent to the profile 1 of the
first housing 1 as a profile 2 (a portion thereof partly covered by
the terrace on the first housing 1 (described later) in an upper
area of the drawing being indicated by broken line) of its side
surfaces. As shown in FIG. 6, the notches 14 are bent whereby the
first housing 1 assumes such a configuration that the notches hold
undersides of the side surfaces of the second housing 2. In this
manner, for example, Japanese Patient Laid-Open No. 199180/1995
discloses a configuration, in which notches 14 (or pawls) are
formed on side surfaces of one of housings and are pushed into
recesses formed on those side surfaces of the other of the
housings, which contact with the side surfaces of the one of the
housings, to fix the two housings. Of course, the notches 14 on the
side surfaces of the first housing 1 may be replaced by holes and
the side surfaces of the second housing 2 may be extended downward
to permit threaded holes to be formed on the side surfaces to be
conformed to the holes on the side surfaces of the first
housing.
[0074] As shown in FIGS. 1, 3C and 5B, upwardly extending
protrusions 26 are formed on upper portions of the side surfaces of
the second housing 2. The protrusions 26 are provided by forming
cuts partially on the sheet material on the side surfaces and
bending the same upward. Accordingly, openings 261 appear on the
upper portions of the side surfaces corresponding to the
protrusions 26. The protrusions 26 serve as a guide when the second
housing 2 is inserted into a space defined by the side surfaces of
the first housing 1, and are formed so as to contact with the
underside 16 of the first housing 1 (see FIGS. 3A and 5A) at the
time when the liquid crystal display panel 4 is received between
the housings. Therefore, even if forces tending to push the
housings toward each other were applied, they would be buffered by
the protrusions 26 and the underside 16 of the first housing 1
before being applied to the liquid crystal display panel 4, whereby
in particular, the glass substrate of the liquid crystal display
panel is prevented from being broken.
[0075] As shown in FIGS. 3C and 5B, the second housing 2 is formed
with terraces 22, 221, which extend inside from the side surfaces,
as well as with the upper surface 25 having the recess holding the
liquid crystal display panel 4. The terrace 22 hides below the
upper surface 25 of the second housing 2 in FIG. 1 but can be seen
in FIG. 2. Also, as shown in FIG. 5B, the terrace 22 is formed on
that portion of the side along the data drive ICs 42, on which the
protrusions 24 are formed. Formed between the terraces 22, 221 and
the underside (back surface) of the upper surface 25 is a gap, into
which an end of the optical sheet 5 shown in FIG. 3D is inserted to
be fixed. The optical sheet 5 is fixed in the order of, for
example, the prism sheet and diffusion sheet from a side of the
liquid crystal display panel 4. The diffusion sheet may be replaced
by a diffusion plate, which is provided by applying dot printing to
an acrylic plate, in which case the recess portion on the upper
surface 25 is preferably formed by a separate member and an edge of
the upper surface 25 surrounding the recess is fitted onto a
peripheral edge of the member. With such arrangement, the diffusion
plate is surely fixed to the second housing 2 upon securing of the
first housing 1 and the second housing 2. The optical sheet may be
replaced by a constitution composed of a first prism sheet, a first
diffusion sheet, a second diffusion sheet, and a second prism sheet
for the liquid crystal display panel 4 in accordance with use of
the liquid crystal display device and specifications of an optical
source unit described later.
[0076] <Assembly of the Optical Unit (Securing Manner Thereof to
the Third Housing 3)>
[0077] As shown in FIGS. 1, 2 and 3E, the third housing 3 is
composed of the upper surface 33 projecting on a back side as
viewed from a user of the liquid crystal display device, side
surfaces 34 joined to two opposite sides at ends of the upper
surface, and terraces 32 joined to ends of the respective side
surfaces to extend on a plane along the upper surface 33. As shown
in FIGS. 3A-3I, assuming that a side of a user of the liquid
crystal display device is disposed on an upper portion of the
drawing, the third housing 3 has a cross sectional shape
"downwardly concave". Also, as apparent from FIGS. 1 and 5C, the
downwardly concave, cross sectional shape appears along a
direction, in which the gate drive ICs 41 are arranged, but does
not appear along a direction, in which the gate drive ICs 42 are
arranged.
[0078] In this embodiment, the downwardly concave shape of the
third housing 3 is made use of to fix the plurality of cold-cathode
fluorescent tubes 61, which constitute light source units of the
liquid crystal display device. Supplied at one ends with a higher
voltage than at the other ends, the cold-cathode fluorescent tubes
61 is lit. The one ends of the cold-cathode fluorescent tubes 61
are called high voltage sides (hot sides), and the other ends are
called low voltage sides (cold sides). In FIG. 1, portions near the
high voltage ends of the cold cathode fluorescent tubes 61 are
fitted into grooves 652 provided on the frame 65, and rubber bushes
651 are inserted into the grooves 652 to be fixed to the frame 65.
Likewise, portions near the low voltage ends of the cold-cathode
fluorescent tubes 61 are fitted into the grooves, 642 provided on
the frame 64, and rubber bushes 641 are inserted into the grooves
to be fixed to the frame 64. The frames 64, 65 fixing thereto the
both ends of the cold-cathode fluorescent tubes 61 are fixed to and
contacted with the upper surface 33 and side surfaces 34 on the
third housing 3 FIG. 3E is a view illustrating assembly as viewed
from the low voltage sides of the cold-cathode fluorescent tubes
61. screws 643 are passed through holes (not shown) formed on both
ends of the frame 64, and tip ends of the screws are inserted into
and fixed to screw holes (not shown) provided on the upper surface
33 shown in FIG. 3F (back side of the upper surface 33 as viewed
from FIG. 2). The frame 65 on the high voltage sides of the
cold-cathode fluorescent tubes 61 is fixed to the third housing 3
by way of similar screws, but an illustration thereof is omitted.
The low voltage terminals of the cold-cathode fluorescent tubes 61
project from the frame 64, and the high voltage terminals project
from the frame 65. Connectors 63 are connected to the low voltage
terminals, and connectors 62 are connected to the high voltage
terminals. In the present embodiment, the connectors 63 connecting
in parallel to the plurality of terminals of the cold cathode
fluorescent tubes 61 are used in order that a terminal voltage on
the low voltage side be made a reference voltage in the third
housing 3 (ground voltage in the case where the third housing 3
itself is to be kept at ground potential). FIG. 3H is a perspective
view after assembly of the first to third housings, which shows a
parallel connection to lengths of cable (lead) 631 passing through
central portions of the connectors 63 in the form of frame shown by
broken lines. Meanwhile, the connectors 62 having separate leads
for every terminal are used for the high voltage terminals of the
cold-cathode fluorescent tubes 61. As shown in FIG. 1 and
perspective views as viewed in a IV direction after assembly of the
first to third housings, four of the connectors 62 present such an
external appearance that they were connected to two of the
cold-cathode fluorescent tubes 61. However, internal wiring is not
one for conduction between two of the cold-cathode fluorescent
tubes 61. This is because of consideration in making lengths of
voltage supply paths between the high voltage terminals of the
respective cold-cathode fluorescent tubes 61 and voltage
transformation elements 81, described later, for supplying of
voltage to the respective terminals, uniform. The above-mentioned
connection of the connectors 62, 63 leads to completion of a light
source unit of the so-called type built-in, immediately below a
backlight panel, in which the plurality of the cold-cathode
fluorescent tubes 61 are arranged opposite to the liquid crystal
display panel 4. In addition, reflective sheets (not shown) are
applied on surfaces on those sides of upper surface 33 and the side
surfaces 34 of the third housing 3, to which the built-in frames
64, 65 are fixed, whereby light radiated on the surfaces from the
respective cold-cathode fluorescent tubes 61 is reflected on the
liquid crystal display panel 4 to enhance luminance of the image
display area SC.
[0079] The timing-converter board 7 shown in FIGS. 1 and 3G and the
light source control circuit board 8 (printed circuit board) shown
in FIG. 1 are mounted on the upper surface 33 (a side opposite to
that side, on which the built-in frames 64, 65 for the cold-cathode
fluorescent tubes 61 are fixed) of the third housing 3. These
boards are formed by cutting portions of a sheet material, which
constitutes the upper surface 33, raising the same above the upper
surface 33 (back side as viewed from a user of the liquid crystal
display device), and further securely fitting peripheral edges of
the same onto hangers 333, which are formed in an angle fashion.
The timing-converter board 7 are required to be disposed at corners
of the upper surface 33 for the purpose of supplying signals and
voltage to the gate drive ICs 41 and the gate drive IC's 42.
Therefore, as shown in FIGS. 2, 3F and 6, portions of the side
surfaces 34 of the third housing 3 are cut from the upper surface
33 side to form aprons 331 conformed to a height of the upper
surface 33. The timing-converter board 7 is fixed to screw holes
334 provided on the aprons by means of screws 74. Meanwhile, the
light source control circuit board 8 is also fixed to the upper
surface 33 by means of screws 82.
[0080] The light source control circuit board 8 in this embodiment
is formed with an inverter circuit (dinner circuit) for controlling
lighting of the cold-cathode fluorescent tubes 61, and a power
source circuit, which is controlled by the former to supply voltage
to the high voltage terminals of the respective cold-cathode
fluorescent tubes 61. As the technique for using an inverter
circuit to stabilize lighting of the cold-cathode fluorescent tubes
61 has already become widespread, a detailed explanation thereof is
omitted herein. Voltage supplied to the high voltage terminals of
the respective cold-cathode fluorescent tubes 61 is high, for
example, 600 V, 6 mA relative to drive voltages for not only the
inverter circuit but also the dinner circuit. In contrast, power
source voltage supplied to light source control circuit board 8 is
low like that on the timing converter board 7. Also, it is desired
that voltage supply paths for supplying such high voltage to the
high voltage terminals of the respective cold-cathode fluorescent
tubes 61 be made smaller, and it is requested in giving uniform
brightness to the image display area SC in the liquid crystal
display panel 4 that voltage supply paths between the cold-cathode
fluorescent tubes 61 be made uniform in length especially in a
light source unit, which uses the plurality of cold-cathode
fluorescent tubes 61. Therefore, the voltage transformation
elements 81 for supplying voltage to the high voltage terminals of
the respective cold-cathode fluorescent tubes 61 are mounted on the
light source control circuit board 8 disposed on the upper surface
of the third housing 3, and in the case where the plurality of
cold-cathode fluorescent tubes 61 are provided in parallel as in
the embodiment, the voltage transformation elements 81 will be
disposed along the arrangement of the cold-cathode fluorescent
tubes 61.
[0081] Such request for the specification of the light source
control circuit board 8 is the same not only for a light source
unit of the above-mentioned type built-in immediately below a
backlight panel, but also for a configuration (light-transmission
plate type light source unit), in which discharge tubes such as the
cold-cathode fluorescent tubes 61 are arranged in a position offset
from a lower portion of the image display area SC in the liquid
crystal display panel 4, and a light-transmission plate for
transmitting light is disposed in the lower portion of the image
display area SC so that light from the discharge tubes is conducted
via the light transmission plate to the image display area SC in
the liquid crystal display panel 4. The reason for this is that in
this configuration high voltage as compared with that for the
above-mentioned other drive circuits must be supplied to one ends
of the discharge tubes.
[0082] Accordingly, configurations of a circuit pattern in the
light source control circuit board 8 and of the connectors 62 on
the high voltage side, connected to the board are designed taking
account of these requests.
[0083] In contrast to that wiring on the high voltage side of the
cold-cathode fluorescent tubes 61, which is restricted with respect
to lengths of the voltage supply paths, wiring on the low voltage
side has freedom in configuration. For example, as shown in FIG. 6,
the cable 631 may be extended to the light source control circuit
board 8 across the upper surface 33 of the third housing 3 from the
low voltage terminals of the cold-cathode fluorescent tubes.
[0084] In addition, as shown in FIG. 6, the upper surface 33 of the
third housing 3 contains a so-called vacant space where the
timing-converter board 7 and the light source control circuit board
8 are not disposed. Such vacant space is suitable for mounting of
optional circuits by makers, which incorporate liquid crystal
display devices into set products such as personal computers,
liquid crystal display monitors or televisions. Also, an opening
335 formed centrally of the upper surface 33 serves as a
measurement window of a light receiving element for measuring
luminance of the cold-cathode fluorescent tubes. In the case where
a luminance monitor circuit of the light source unit is mounted in
the vacant space on the upper surface 33 of the third housing 3,
the liquid crystal display panel can be stably maintained in
brightness by measuring emission luminance of the light source unit
through the opening 335, and performing feed-back of the result to
a control circuit on the light source control circuit board 8.
(Assembly of the Liquid Crystal Display Device (fixing of the third
housing 3 to the second housing 2)) As described above, the third
housing 3, into which the light source unit is assembled and to
which the timing converter board 7 and the light source control
circuit board 8 are fixed, is fixed to the second housing 2. Such
fixed configuration is shown in FIG. 3(h), which is a perspective
view as viewed from a III direction of FIG. 1, and shown in FIG. 4,
which is a perspective view as viewed from a IV direction of FIG.
1, and further shown in FIG. 5D, which is a perspective view as
viewed from a V direction of FIG. 1.
[0085] As shown at a left end of FIG. 3H, the terrace 32 formed at
one end of the third housing 3 and the terrace 22 extended from
inside the side surface of the second housing 2 are fixed to each
other by screws 322. Locations for such fixing are three as shown
in FIGS. 5A-5D. The screws 322 are set in length so as not to
extend through the terrace 22 to project much from the upper
surface thereof.
[0086] Meanwhile, as shown on a right side of FIG. 3H, the terrace
221 extended from inside the side surface of the second housing 2
and the terrace 15 extended from inside the side surface of the
first housing 1 define a recess. Fitted into this recess is the
terrace 32 formed at the other end of the third housing 3. The
third housing 3 is fixed to the second housing 2 by first fitting
the terrace 32 formed at the other end of the third housing 3 into
the recess, then putting the terrace 32 formed at the one end of
the third housing 3 and the terrace 22 of the second housing 2
together to fix them by the screws 3.2.2.
[0087] Instead of forming the recess by the terrace 15 on the right
side of FIG. 3H, screw holes may be provided in the terrace 221 of
the second housing and the terrace 32 at the other end of the third
housing 3 may be fixed by screws. This configuration makes the
first housing simple in design.
[0088] Meanwhile, in the case of screwing the terrace 32 to the
terraces 22, 221, the following should be taken care of. In the
case where an optical sheet is somewhat large in size, tip ends of
the screws projected from upper surfaces of the terraces 22, 221
press ends of the optical sheet. Such pressing causes the
possibility of imparting an unexpected polarized component to light
incident on the liquid crystal display panel 4 from the light
source unit. To avoid this, there is recommended a configuration,
in which the terrace 32 formed at the other end of the third
housing 3 is fitted into the recess. Also, in the embodiment, a
position where the terrace 32 at the one end of the third housing 3
is screwed to the terrace 22 of the second housing 2 is set near an
inner wall on the side surface of the second housing 2 distant from
the image display area SC in the liquid crystal display panel 4.
Further, the position of screwing is provided on a side where the
gate drive ICs 42 are arranged. The reason for this is that a
position, which meets at least one of these conditions, makes a
dead space (there is no possibility that the optical sheet is
extended to this position) relative to the position of the optical
sheet even taking account of errors in design. Meanwhile, in the
embodiment, as shown in FIGS. 5A and 5B, the protrusions 24 are
provided on the lower portion of the side surface of the second
housing 2, and notches 14 formed on the lower portion of the side
surface of the second housing 2, and notches formed on the lower
portion of the side surface of the first housing 1 are fitted right
and left of the protrusions. Therefore, the terrace 32 cannot be
screwed to the terrace 22 in a position near the side surface of
the second housing 2 where the notches 14 are fitted. Hereupon, as
shown in a lower portion of FIG. 6, the terrace 22, on an end of
which the protrusions 24 are formed, is used for screwing. This is
because the notches 14 are not fitted on the underside of the
terrace 22. Also, the entire terrace 32 of the third housing 3 is
not extended to the inner wall on the side surface of the second
housing 2, but a portion used for the above-mentioned screwing is
extended as the terrace 321 to the inner wall on the side surface
of the second housing 2 and ends thereof are used for screwing as
shown in FIGS. 2 and 6.
[0089] In addition to the above-mentioned screwing and fitting into
the recess, the terrace 32 of the third housing 3 and the terraces
22, 221 of the second housing 2 may be fixed to one another by
providing clips (not shown) on, for example, the terrace 22 of the
second housing 2 and having them interposing therebetween the
aprons 321, which project from the terrace 32 of the third housing
3. The clips may be installed by fixing elastic clip members to the
terrace 22 by way of screws, soldering or welding, but in the case
where the second housing 2 is formed from elastic metals, resins or
the like, it may be partially formed with notches and portions
thereof may be raised toward the contact surfaces of the aprons
321. In this case, the aprons 321 are fixed by the use of righting
forces of the notch portions of the terrace 22.
[0090] The third housing 3 is fixed to the second housing 2 to
complete the liquid crystal display device according to the
embodiment. FIG. 31 shows an external appearance of a liquid
crystal display module MDL as viewed from a III direction of FIG.
1. As compared with the perspective view shown in FIG. 3H, the
external appearance becomes neat and clear. These liquid crystal
display devices are also called a liquid crystal display module,
and are actually incorporated into housings of personal computers,
liquid crystal display monitors or televisions to be sold to
consumers. (Setting of the Protrusions 31 on the Upper Surface of
the Third Housing 3)
[0091] Although not conspicuous in the external appearance shown in
FIG. 31, an upper end of the voltage transformation element 2
mounted on the timing-converter board 7 actually projects in many
cases from the underside of the side surface of the first housing
1. Also, when seen in the IV direction in FIG. 1, that is, from a
side where the light source control circuit board 8 is mounted,
upper ends of the voltage transformation elements 81 mounted on the
light source control circuit board 8 project from the first side
surface as shown in the perspective view shown in FIG. 4.
[0092] When elements fixed to the housings assembled in this manner
project, there is caused the possibility that these elements may be
broken at the time of mounting of the liquid crystal display
devices onto set products such as personal computers, liquid
crystal display monitors or televisions. Also, there is caused a
similar possibility at the time of shipment of the liquid crystal
display devices to makers of the above-mentioned set products.
[0093] In the present invention, the protrusions 31 are provided on
the upper surface 33 (back side as viewed from a user of the liquid
crystal display device) of the third housing 3 in order to protect
elements (electronic parts and so on) fixed to the housings, which
constitute the liquid crystal display device, from the
above-mentioned breakage. The reason for provision of the
protrusions 31 on the third housing 3 is as follows.
[0094] As described above, the third housing 3 is provided with the
light source unit. Meanwhile, the first housing 1 and the second
housing 2 grasp the liquid crystal display panel 4 by peripheral
edges of the upper and lower surfaces thereof to receive the liquid
crystal display panel 4 therebetween as described above. One of the
upper and lower surfaces of the liquid crystal display panel 4
therebetween as described above. One of the upper and lower
surfaces of the liquid crystal display panel 4 must have light from
the light source unit being incident upon a liquid crystal layer
provided therein, and the other of the upper and lower surfaces
must display an image, which is generated by modulation of the
light at the liquid crystal layer, to a user of the liquid crystal
display device. Because of this, the first housing 1 and the second
housing 2 are formed with openings (for example, the opening 11 of
the first housing 1 shown in FIG. 3A) along the surface (the main
surface of one of the substrates 441, 442 contained in the panel)
of the liquid crystal display panel 4. In contrast, it is not
necessary to form any opening on a member (an upper portion of the
upper surface 33 in FIG. 31) of the third housing 3, which holds
the light source unit. Therefore, mounting of the timing-converter
board 7 and the light source control circuit board 8 on the member
is desired in stably fixing these boards to the liquid crystal
display device. Accordingly, electric circuit elements being
protected by the protrusions 31 are fixed to the timing-converter
board 7 and the light source control circuit board 8, so that they
are naturally disposed on the upper surface 33 of the third housing
3.
[0095] Also, since the first housing 1 and the second housing 2
protect a peripheral edge of the liquid crystal display panel as
well as the drive ICs, they become large in area along the surfaces
of the liquid crystal display panel 4. In contrast, the light
source unit suffices to supply light to the image display area SC
in the liquid crystal display panel 4, and so its area along the
surfaces of the liquid crystal display panel 4 may suffice to
correspond to the image display area SC or enlarge the surrounding
a little (needs not be enlarged to a side of the drive ECs). As
apparent from this, the first housing 1 and the second housing 2
are formed to be larger than the third housing 3 as viewed in a
direction (for example, from a viewpoint in FIG. 6) perpendicular
to the surface of the liquid crystal display panel 4. In other
words, the upper surface 33, the side surfaces 34 and the terrace
32, which constitute the third housing 3, are contained in the
respective outer frames of the first housing 1 and the second
housing 2.
[0096] Therefore, the provision of the protrusions 31 or their
equivalent on the third housing 3 rather than on the first housing
1 and the second housing 2 is effective in protecting the
above-mentioned electric circuit elements arranged on the upper
surface 33 of the third housing 3.
[0097] FIGS. 7A and 7B are illustrations of a first constitution
according to the invention, FIG. 7A showing the case where the
liquid crystal display device shown in FIG. 5D is reversed up and
down. In the following explanation, a dimension of the liquid
crystal display device along a vertical direction in FIG. 7 is
represented as "thickness" or "height," and a dimension of the
liquid crystal display device along a direction laterally across
FIG. 7 is represented as "width" or "area".
[0098] Seeing FIG. 7A on the assumption that the protrusions 31 are
not present on the upper surface 33 of the third housing 3, it is
focused that a thickness h.sub.1 of the liquid crystal display
device is determined by the voltage transformation elements 81 on
the light source control circuit board 8. In the case where the
timing-converter board 7 and the light source control circuit board
8 are not provided on the upper surface 33 of the third housing 3,
the thickness of the liquid crystal display device is determined by
a difference h.sub.1 in level between the upper surface 12 of the
first housing 1 (see FIG. 3A) and the upper surface 22 of the third
housing 3 (see FIG. 3F) (the hangers 333 are neglected). Therefore,
the protrusions 31 are provided on the upper surface 33 of the
third housing 3, and their height h.sub.6 is determined so as to
satisfy the relationship h.sub.6>(h.sub.1 h.sub.2). As a result,
although the thickness (maximum thickness) of the liquid crystal
display device is increased to h.sub.1 (however,
h.sub.1>h.sub.1), a work of mounting the liquid crystal display
device on set products is not adversely affected because a position
where the protrusions 33 are formed is set back from the peripheral
edge of the liquid crystal display device.
[0099] In some cases, makers of set products provide light source
drive circuits on bodies of such set products as personal computers
and the like to make use of a liquid crystal display device in a
state, in which the light source control circuit board 8 is not
mounted on the liquid crystal display device. In this case, as
apparent from FIG. 7A, from which the light source control circuit
board 8 and all elements mounted on the board are all removed, the
thickness h.sub.2 of the liquid crystal display device except for
the protrusions 31 is determined by the voltage transformation
element 72 on the timing-converter board 7. As apparent from FIG.
7A, the protrusions 31 having a thickness of h.sub.6 is higher than
necessary to protect the electric circuit elements on the
timing-converter board 7, and rather causes the possibility of
interfering with a work, in which the liquid crystal display device
is assembled into set products.
[0100] In this case, only a member of the third housing 3 is
prepared which is different from that shown in FIG. 7A. The third
housing 3 shown in FIG. 7B is such that the protrusions 31 have a
thickness h.sub.62 (however, h.sub.62>(h.sub.2-h.sub.2) is met).
Therefore, the entire liquid crystal display device, on which the
light source control circuit board 8 is not mounted, has a
thickness h.sub.2 (maximum thickness) smaller than h.sub.1.
[0101] As apparent from the above explanation, there is involved
the possibility that depending upon whether a light source control
circuit is mounted on a liquid crystal display device mounting
thereon a liquid crystal display panel 4 having the same dimension,
a housing of the device is substantially varied in size. In the
invention, the third housing 3 having the protrusions 31, which are
different only in height, is prepared to accommodate variation of
the liquid crystal display device, but the following problems arise
in the case where protrusions or the like are provided on the side
surfaces of the first housing 1 and the second housing 2 to protect
the above-mentioned electric circuit elements.
[0102] One of the problems is that lines for manufacture of two
kinds of liquid crystal display device products, which are
different from each other only with respect to the presence of a
light source control circuit, must be provided separately from
mounting of a liquid crystal display panel 4. Since the first
housing 1 and the second housing 2 are both members serving to
grasp the liquid crystal display panel 4, assembly on the same line
is complex to lower productive efficiency in the case where either
of the housing is varied in configuration.
[0103] Another one of the problems is that in the case where
assembly of the first housing 1 and the second housing 2 of one of
the two kinds of liquid crystal display device products is delayed,
or failure generates, production itself of that kind of liquid
crystal display device products will be delayed.
[0104] A configuration of the third housing 3 copes with
manufacture of two kinds of liquid crystal display device products
as in the invention, and then the process of grasping of the liquid
crystal display panel 4 with the first housing 1 and the second
housing 2 and the intermediate products in the process are made
common to the two kinds of liquid crystal display device
products.
[0105] Further, the invention has the following advantages in
conveyance of liquid crystal display device products.
[0106] These will be explained using an illustration of FIG. 8
showing a condition of packaging at the time of shipment of liquid
crystal display devices (also, called a liquid crystal display
module).
[0107] In FIG. 8, BX denotes a cardboard box for conveyance (for
example, decorative box), PKG denotes a packing (cushioning)
material, VYN denotes vinyl bags, and MDL denotes liquid crystal
display modules (the above-mentioned liquid crystal display device
products). The liquid crystal display modules MDL shown employ the
invention in which the protrusions 31 for protection of circuit
elements are provided on the third housing 3 (a plurality of the
liquid crystal display device shown in FIG. 7A are shown in FIG. 8
while being reduced in size and turned 90 degrees.
[0108] A cushioning material such as urethane foam or the like is
used as the packing material PKG on inner walls of the cardboard
box BX for conveyance. Every one of the liquid crystal display
modules MDL is contained in the vinyl bag VYN to be received in the
cardboard box for conveyance BX. The packing material PKG is also
inserted between the liquid crystal display modules MDL, but
cardboard for cardboard boxes is frequently used in place of the
packing material.
[0109] In such packaging configuration, the protrusions 31 formed
on the respective liquid crystal display modules MDL (or the third
housing 3) inhibit flexure of the packing material PKG inserted
therebetween to prevent the flexed packing material PKG from
pressing and breaking electric circuit elements mounted on the
respective liquid crystal display modules MDL.
[0110] As described above, an area of the third housing 3 extending
along the main surfaces of the substrates 441, 442 (also, called a
liquid crystal display board) contained in the liquid crystal
display panel 4 is smaller than those of the first housing 1 and
the second housing 2. Therefore, the provision of the protrusions
31 on the third housing 3 presents an advantage that the
protrusions 31 were provided on the first housing 1 and the second
housing 2, location of the protrusions 31 would be distant from the
electric circuit elements. The packing material PKG would flex by
an amount of the distance between the protrusions 31 and the
electric circuit elements. In view of this, it is apparent that
possible breakage of the electric circuit elements can be surely
prevented by the provision of the protrusions 31 on the third
housing 3.
[0111] In addition, the voltage transformation elements 72, 81
mounted on the timing-converter board 7 and the light source
control circuit board 8 are constituted to include parts such as
ferrite core and so on. While depending upon function of the
voltage transformation, the voltage transformation elements are
highest among elements mounted on the timing-converter board 7 and
the light source control circuit board 8 in many cases. Also, these
voltage transformation elements are said to be susceptible of
mechanical shocks as compared with semiconductor ICs (integrated
circuit elements), which are molded with a resin (resin material).
It has been described that the protrusions 31 had better be set to
be higher than a top end of that element (in other words, a highest
element relative to the upper surface 33 of the third housing 3),
which determines the height of the liquid crystal display device
except the protrusions. However, directing attention only to
breakage of elements at the time of conveyance, the protrusions 31
may be set higher (for example, even lower than other semiconductor
ICs) than an upper end of a highest one among elements mounted on
the upper surface 33 of the third housing 3. Such setting of the
protrusions 31 may be altered in its standard in accordance with
the specifications of the respective liquid crystal display devices
(variation of electric circuit elements as mounted).
[0112] In the above description, the protrusions 31 are formed on
the upper surface 33 of the third housing 3 but they may be cut
partially at their side surfaces 34 to have one ends of cut
portions bent to a higher position than the upper surface 33 (in a
layout shown in FIGS. 7A and 7B) or may be provided on the aprons
32 (may be suitably changed in position depending upon layouts of
the timing-converter board 7 and the light source control circuit
board 8).
[0113] (Maintenance of the Light Source Unit)
[0114] Having been described with respect to assembly of the liquid
crystal display device (fixing of the third housing 3 to the second
housing 2) with a second constitution of the invention, securing of
the third housing 3 and the second housing 2 is effected separately
from securing of the first housing 1 and the second housing 2. This
constitution is effective in reducing a burden in maintenance of
the light source unit in the liquid crystal display device products
(liquid crystal display modules).
[0115] FIGS. 9A and 9B are illustrations of a second constitution
according to the invention, FIG. 9A showing the case were a light
source unit (the third housing 3, on which the unit is installed)
is removed from the liquid crystal display device and FIG. 9B
showing in enlarged scale a construction shown by a circle of FIG.
9A. FIG. 9A is equivalent to a construction obtained when FIGS. 3H
and 31 are reversed up and down.
[0116] As described above, the terrace 32 at the other end
(peripheral edge, on which the data drive ICs are not arranged) of
the third housing 3 is fitted into the recess defined by the
terrace 15 on the first housing 1 and the terrace 221 on the second
housing 2. When the screws 322 for securing one end (peripheral
edge, on which the data drive ICs are arranged) of the third
housing 3 to the terrace 22 on the second housing 2 are disengaged,
the one end of the third housing 3 is lifted as shown in FIG. 9A.
The terrace 32 at the other end of the third housing 3 is small in
a distance between the side surface 34 and an end thereof as
compared with the terrace at the one end, and so can be moved in
the recess upon lifting of the one end of the third housing 3. The
third housing 3 can be disengaged from the second housing 2 (the
liquid crystal display module body MDL) in a stage, in which its
one end is lifted to some extent.
[0117] The third housing 3 having been disengaged from the liquid
crystal display module body MDL is placed with the upper surface 33
(surface, on which the timing-converter board 7 and the like are
mounted) facing downward, and maintenance and part replacement of
the light source unit are carried out. For example, those
cold-cathode fluorescent tubes 61 having been degraded in lighting
performance are replaced by new ones. The third housing 3 shown in
the drawings has the above mentioned protrusions 31 according to
the first constitution of the invention, but when such protrusions
are not provided, a jig for grasping, for example, the terraces 32
on the both ends of the third housing is prepared so that parts of
the timing-converter circuit and the light source control circuit,
which are installed on the upper surface 33 of the third housing 3,
are prevented from striking against working tables and desks.
[0118] As apparent from FIGS. 9A and 9B, other parts, such as the
liquid crystal display panel 4 and the optical sheet 5, than parts
relating to maintenance of the light source unit can be subjected
to the maintenance work while being fixed to the liquid crystal
display module body MDL. If the first housing 1 and the second
housing 2 were separated in maintenance of the light source unit,
it would take enormous time for engagement and disengagement of the
liquid crystal display panel 4 and the optical sheet 5, in
particular, for positional registering after maintenance. As
regards the optical sheet 5, while depending upon its
specification, a displayed image is greatly affected in quality by
positioning of the optical sheet relative to the liquid crystal
display panel 4 and by dust entering between the optical sheet and
the liquid crystal display panel during the positioning work. The
second constitution according to the invention reduces a burden on
maintenance and examination of set products, such as personal
computers, liquid crystal display monitors or televisions, by users
or maintenance engineers for the products, even in a state, in
which the liquid crystal display module MDL is mounted on the set
product.
[0119] FIGS. 10A-10C show an example of a monitor making use of the
liquid crystal display device embodying the second constitution
according to the invention. FIG. 10A is a side view, FIG. 10B being
a front view (a view seen from the monitor, that is, from a user's
side), and FIG. 10C being a side view showing a state, in which the
light source unit is removed in the monitor.
[0120] A liquid crystal display monitor 9 is composed of an image
display unit 91 and a liquid crystal display unit support 92, the
former further comprising an image display unit front box 911 and
an image display unit rear box 912. Mounted on the liquid crystal
display unit support are a power source unit (not shown) for
converting electric power (for example, 100V) supplied from outside
into a common voltage (for example, 12 V) in the liquid crystal
display monitor, and an interface circuit for reception of signals
from an external computer.
[0121] The liquid crystal display module MDL (profile of the liquid
crystal display module MDL is shown by broken lines in FIG. 10B) is
fixed inside the image display unit front box 911 by means of
screws 910. The screws 910 are used to have a length not reaching
the third housing 3 of the liquid crystal display module MDL or
contrivance is performed to partially recess the third housing 3 at
locations where the screws 910 reach. This is because of preventing
the screws 910 from making it impossible to disengage the third
housing 3 from the second housing 2.
[0122] As shown in FIG. 10C, maintenance of the light source unit
of the liquid crystal display module on the liquid crystal display
monitor can be performed by opening the image display unit front
box 911 from the image display unit rear box 912 fixed to the
liquid crystal display unit support 92, taking out the back surface
of the liquid crystal display module MDL (upper surface side of the
third housing 3), and then in the same manner as described above
with reference to FIGS. 9A and 9B.
[0123] While the embodiments of the invention have been concretely
described above, the invention is not limited to the
above-mentioned embodiments and of course can be modified in
various manners within the scope not departing from the gist of the
invention.
[0124] As described above, the invention makes parts and kinds of
liquid crystal display devices common to be capable of stably and
flexibly coping with commercial products of computer makers and
television makers, which have been promoted in various kinds. Also,
it is possible to simplify maintenance of a liquid crystal display
unit mounted on computers, display monitors therefor or
televisions, and to omit positional adjustment of a light source
unit and a liquid crystal display panel at the time of
maintenance.
[0125] While we have shown and described several embodiments in
accordance with the present invention, it is understood that the
same is not limited thereto but is susceptible of numerous changes
and modifications as known to those skilled in the art, and we
therefore do not wish to be limited to the details shown and
described therein but intend to cover all such changes and
modifications as are encompassed by the scope of the appended
claims.
* * * * *