U.S. patent application number 09/742400 was filed with the patent office on 2001-07-12 for luminescence controlling apparatus, a luminescence apparatus, in image reading.
Invention is credited to Matsuura, Hideki, Takasu, Akira.
Application Number | 20010007411 09/742400 |
Document ID | / |
Family ID | 18530977 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007411 |
Kind Code |
A1 |
Matsuura, Hideki ; et
al. |
July 12, 2001 |
Luminescence controlling apparatus, a luminescence apparatus, in
image reading
Abstract
A luminescence controlling apparatus includes a rare gas pipe
equipped with a pair of electrodes in which rare gas is sealed, a
power supply for impressing voltage to the pair of electrodes and
an electric charge absorption member for absorbing electrons
generated during electric discharge of the rare gas pipe caused by
impressing voltage to the pair of electrodes. The absorption member
is disposed in the rare gas pipe. The luminescence controlling
apparatus further includes a controller for controlling a
luminescence amount of the rare gas pipe by adjusting a quantity of
electrons absorbed by the electric charge absorption member.
Inventors: |
Matsuura, Hideki;
(Osaka-shi, JP) ; Takasu, Akira; (Toyokawa-shi,
JP) |
Correspondence
Address: |
Barry E. Bretschneider
Morrison & Foerster LLP
2000 Morrison & Foester LLP
2000 Pennsylvania Avenue, N.W.
Washington
DC
20006-1888
US
|
Family ID: |
18530977 |
Appl. No.: |
09/742400 |
Filed: |
December 22, 2000 |
Current U.S.
Class: |
315/169.3 ;
315/169.4; 348/E5.035; 348/E5.038 |
Current CPC
Class: |
Y02B 20/00 20130101;
H01J 61/95 20130101; H05B 41/386 20130101; Y02B 20/22 20130101;
H05B 41/2806 20130101; H04N 1/40056 20130101; H04N 5/2351 20130101;
H04N 5/2354 20130101; H04N 1/0287 20130101; H01J 65/046
20130101 |
Class at
Publication: |
315/169.3 ;
315/169.4 |
International
Class: |
G09G 003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2000 |
JP |
2000-1790 |
Claims
What is claimed is:
1. A luminescence controlling apparatus, comprising: a rare gas
pipe in which rare gas is sealed, said rare gas pipe being equipped
with a pair of electrodes; a power supply for impressing voltage to
said pair of electrodes; an electric charge absorption member
disposed in said rare gas pipe to absorb electrons generated during
electric discharge of said rare gas pipe caused by impressing
voltage to said pair of electrodes; and a controller for
controlling a luminescence amount of said rare gas pipe by
adjusting a quantity of said electrons absorbed by said electric
charge absorption member.
2. The luminescence controlling apparatus as recited in claim 1,
wherein said pair of electrodes is an external pair of electrodes
formed at an exterior of said rare gas pipe.
3. The luminescence controlling apparatus as recited claim 1,
wherein said electric charge absorption member is a wire-like
conductive member extending from one end of said rare gas pipe to
the other end thereof.
4. The luminescence controlling apparatus as recited in claim 3,
wherein said wire-like conductive member is made of spirally
twisted wires.
5. A luminescence controlling apparatus, comprising: a rare gas
pipe in which rare gas is sealed; a pair of electrodes formed in
said rare gas pipe; a power supply for impressing voltage to said
pair of electrodes; an electric charge absorption member for
absorbing current which flows through said pair of electrodes when
voltage is impressed by said power supply; and a controller which
controls whether or not said rare gas pipe is made to emit light by
switching whether or not said electric charge absorption member
absorbs current.
6. The luminescence controlling apparatus as recited in claim 5,
wherein said electric charge absorption member includes a plurality
of members disposed at predetermined intervals in an axial
direction of said rare gas pipe.
7. A luminescence apparatus, comprising: a rare gas pipe in which
rare gas is sealed; a pair of external electrodes formed on an
outer peripheral surface of said rare gas pipe; and a conductive
member disposed in said rare gas pipe, wherein said conductive
member is capable of sending electrons out of said rare gas pipe,
said electrons being generated during electric discharge of said
rare gas pipe caused by impressing voltage to said pair of
electrodes.
8. The luminescence apparatus as recited in claim 7, wherein said
conductive member is grounded via a variable resistor provided
outside said rare gas pipe.
9. The luminescence apparatus as recited in claim 7, further
comprising a controller which controls a luminescence amount of
said rare gas pipe by adjusting a quantity of electrons sending
from said conductive member.
10. The luminescence apparatus as recited in claim 9, wherein said
conductive member is grounded via said variable resistor provided
outside said rare gas pipe, and wherein said controller controls a
luminescence amount of said rare gas pipe by controlling a
resistance of said variable resistor.
11. The luminescence apparatus as recited in claim 7, wherein said
conductive member is a wire-like conductive member extending from
one end of said rare gas pipe to the other end thereof.
12. The luminescence apparatus as recited in claim 11, wherein said
wire-like conductive member is made of spirally twisted wires.
13. A luminescence apparatus, comprising: a rare gas pipe in which
rare gas is sealed; a pair of external electrodes formed on an
outer peripheral surface of said rare gas pipe; and a plurality of
conductive members disposed at predetermined intervals in an axial
direction of said rare gas pipe so as to contact said pair of
external electrodes.
14. The luminescence apparatus as recited in claim 13, further
comprising: a switch for switching whether or not said conductive
member is grounded; and a controller for controlling whether or not
said rare gas pipe is made to emit light by switching said
switch.
15. An image reading apparatus for reading an original image,
comprising: a light source for irradiating said original image,
wherein said light source includes a rare gas pipe in which rare
gas is sealed, a pair of external electrodes formed on an outer
peripheral surface of said rare gas pipe and a conductive member
disposed in said rare gas pipe, said conductive member being
capable of sending electrons generated during electric discharge of
said rare gas pipe caused by impressing voltage to said pair of
electrodes out of said rare gas pipe; and a solid image taking
element which obtains image data based on incident light from said
original image.
16. The image reading apparatus as recited in claim 15, further
comprising a controller for controlling a luminescence amount of
said rare gas pipe by adjusting a quantity of electrons sending by
said conductive member.
17. The image reading apparatus as recited in claim 16, wherein
said conductive member is grounded via said variable resistor
provided outside said rare gas pipe, and wherein said controller
controls a luminescence amount of said rare gas pipe by controlling
a resistance of said variable resistor.
18. The image reading apparatus as recited in claim 15, wherein
said conductive member is a wire-like conductive member disposed
extending from one end of said rare gas pipe to the other end
thereof.
19. An image forming apparatus, comprising: a photosensitive
member; and a light source for exposing a photosensitive member
corresponding to an image data, wherein said light source includes
said rare gas pipe in which rare gas is sealed, a pair of external
electrodes formed on an outer peripheral surface of said rare gas
pipe and a plurality of conductive members which contact said pair
of external electrodes and are arranged at predetermined intervals
in an axial direction of said rare gas pipe.
20. The image forming apparatus as recited in claim 19, further
comprising a switch for switching whether or not said conductive
member is grounded, a controller for controlling whether or not
said rare gas pipe is made to emit light by switching said switch.
Description
[0001] This application claims priority to Japanese Patent
Application No. 2000-1790 filed on Jan. 7, 2000, the disclosure of
which is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a luminescence controlling
apparatus, a luminescence apparatus, an image reading apparatus and
an image forming apparatus.
[0004] 2. Description of Related Art
[0005] For example, a Japanese Patent Laid-open Publication No.
[0006] H5-242870 proposes a luminescence control technology in
which a plurality of pairs of electrodes are arranged such that
each pair is disposed on a circumference of a discharge lamp along
the axial direction of the discharge lamp, and the number of
electrodes to which voltage is impressed is selected in order to
control the luminescence amount of the discharge lamp.
[0007] However, the aforementioned luminescence controlling
apparatus has drawbacks such that the structure is complicated
since the apparatus has many electrodes for controlling the
luminescence of the discharge lamp, which results in an increased
manufacturing cost. Furthermore, the luminescence amount can only
be changed stepwise by selecting the number of electrodes.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a
luminescence controlling apparatus and a luminescence apparatus
which are simple in structure and can perform a continuous and fine
luminescence control.
[0009] It is another object of the present invention to provide a
luminescence controlling apparatus and a luminescence apparatus
which has a write-in function to a photosensitive member or the
like by partially performing an ON/OFF luminescence control during
the electric discharge.
[0010] It is still another object of the present invention to
provide an image reading apparatus equipped with a luminescence
apparatus which can perform a continuous and fine luminescence
control as a light source for irradiating an original image.
[0011] It is still yet another object of the present invention to
provide an image forming apparatus equipped with a luminescence
apparatus which can partially perform an ON/OFF luminescence
control during the electric discharge, as a light source for
exposing a photosensitive member.
[0012] According to a first aspect of the present invention, a
luminescence controlling apparatus includes a rare gas pipe in
which rare gas is sealed, the rare gas pipe being equipped with a
pair of electrodes, a power supply for impressing voltage to the
pair of electrodes, an electric charge absorption member disposed
in the rare gas pipe to absorb electrons generated during electric
discharge of the rare gas pipe caused by impressing voltage to the
pair of electrodes, and a controller for controlling a luminescence
amount of the rare gas pipe by adjusting a quantity of the
electrons absorbed by the electric charge absorption member.
[0013] With this luminescence controlling apparatus, electrons
(electric charges) generated during the electric discharge of the
rare gas pipe are absorbed by the charge absorption member like a
grid line disposed in the rare gas pipe. Therefore, by adjusting
the amount of electrons to be absorbed by the electric charge
absorption member, the amount of energy of the electrons colliding
with the rare gas atoms can be adjusted, which in turn enables an
adjustment of the excitation energy of the fluorescent substance
layer formed on the inner peripheral surface of the rare gas pipe.
Consequently, although the apparatus is simple in structure, the
luminescence amount of the rare gas pipe can be finely controlled
in an analog manner.
[0014] According to the second aspect of the present invention, a
luminescence controlling apparatus includes a rare gas pipe in
which rare gas is sealed, a pair of electrodes formed in the rare
gas pipe, a power supply for impressing voltage to the pair of
electrodes, an electric charge absorption member for absorbing
current which flows through the pair of electrodes when voltage is
impressed by the power supply, and a controller which controls
whether or not the rare gas pipe emits light by switching whether
or not the electric charge absorption member absorbs current.
[0015] In this luminescence controlling apparatus, by switching
whether or not the electric charge absorption member absorbs the
current when the rare gas pipe is discharging, the excitation
energy of the fluorescent substance layer is controlled, which in
turn enables an ON/OFF control of the luminescence operation.
[0016] According to the third aspect of the present invention, a
luminescence apparatus includes a rare gas pipe in which rare gas
is sealed, a pair of external electrodes formed on an outer
peripheral surface of the rare gas pipe, and a conductive member
disposed in the rare gas pipe, wherein the conductive member is
capable of sending electrons out of the rare gas pipe, the
electrons being generated during electric discharge of the rare gas
pipe caused by impressing voltage to the pair of electrodes.
[0017] With this luminescence apparatus, the electrons generated at
the time of electric discharge of the rare gas pipe is sent from
the rare gas pipe since the conductive member is disposed in the
rare gas pipe. Therefore, the energy amount of electrons colliding
with the rare gas atoms can be adjusted by adjusting the amount of
electrons sending from the rare gas pipe.
[0018] According to the fourth aspect of the present invention, a
luminescence apparatus includes a rare gas pipe in which rare gas
is sealed, a pair of external electrodes formed on an outer
peripheral surface of the rare gas pipe and a plurality of
conductive members disposed at predetermined intervals in an axial
direction of the rare gas pipe so as to contact the pair of
external electrodes.
[0019] With this luminescence apparatus, it is possible to switch
whether or not current is absorbed at the time of electric
discharge of the rare gas pipe for every plural conductive members
disposed so as to contact the external pair of electrodes, which
enables an ON/OFF control of the luminescence operation.
[0020] According to the fifth aspect of the present invention, an
image reading apparatus for reading an original image includes a
light source for irradiating the original image, wherein the light
source includes a rare gas pipe in which rare gas is sealed, a pair
of external electrodes formed on an outer peripheral surface of the
rare gas pipe and a conductive member disposed in the rare gas
pipe, the conductive member being capable of sending electrons
generated during electric discharge of the rare gas pipe caused by
impressing voltage to the pair of electrodes out of the rare gas
pipe, and a solid image taking element which obtains image data
based on incident light from the original image.
[0021] With this image reading apparatus, a variable control of the
irradiation amount to the original image can be continuously
performed at the time of reading the original image.
[0022] According to the sixth aspect of the present invention, an
image forming apparatus includes a photosensitive member, and a
light source for exposing the photosensitive member corresponding
to an image data, wherein the light source includes the rare gas
pipe in which rare gas is sealed, a pair of external electrodes
formed on an outer peripheral surface of the rare gas pipe and a
plurality of conductive members which contact the pair of external
electrodes and are arranged at predetermined intervals in an axial
direction of the rare gas pipe.
[0023] With this image forming apparatus, a writing to the
photosensitive member can be controlled every interval of the
conductive member corresponding to the image data.
[0024] Other objects and the features of the present invention will
be apparent from the following detailed description of the
invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will be more fully described and
better understood from the following description, taken with the
appended drawings, in which:
[0026] FIG. 1 is a perspective view showing a basic structure of a
luminescence controlling apparatus according to an embodiment of
the present invention;
[0027] FIG. 2 is a schematic structural view showing the image
forming apparatus according to the aforementioned embodiment;
[0028] FIG. 3 is a cross-sectional view showing an image scanner of
the aforementioned image forming apparatus;
[0029] FIG. 4 is a structural view showing a luminescence
controlling apparatus according to the aforementioned
embodiment;
[0030] FIG. 5 is a timing chart for the sequence operations of the
fluorescence lamp of the aforementioned luminescence controlling
apparatus;
[0031] FIG. 6 is a schematic cross-sectional view showing an
operation of the aforementioned luminescence controlling
apparatus;
[0032] FIG. 7 is a characteristic graph showing a relation between
a resistance of a variable resistor and illumination at the time of
emitting light;
[0033] FIG. 8 is a flow chart showing the operation of the
aforementioned luminescence controlling apparatus;
[0034] FIG. 9 is a flow chart showing the processes after the copy
concentration is determined;
[0035] FIG. 10 is a structural view showing a luminescence
controlling apparatus according to another embodiment of the
present invention;
[0036] FIG. 11 is a schematic perspective view showing the
luminescence controlling apparatus as a writing means arranged in
parallel with a photosensitive member;
[0037] FIG. 12 is an explanatory view showing a write-in operation
by the aforementioned luminescence controlling apparatus;
[0038] FIG. 13 is a flow chart showing the operation of the
luminescence controlling apparatus; and
[0039] FIG. 14 is a flow chart showing the processes after the
luminescence of the fluorescence lamp.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] FIG. 1 shows a fundamental structure of a luminescence
controlling apparatus using a fluorescence lamp as a rare gas
tube.
[0041] As shown in FIG. 1, the fluorescent lamp main body 2 of the
fluorescent lamp 1 is a cylindrical glass valve with, for example,
a diameter of about 20 mm and a length of about 240 mm.
[0042] A fluorescent substance layer 3 is formed on approximately
the entire inner peripheral surface of the glass valve 2 except a
part of the circumference thereof, and about 80 Torr of Xenon,
which is rare gas, is sealed in the glass valve 2.
[0043] The reference numeral 4 denotes an optical output portion
which allow the light generated in the fluorescent lamp 1 to pass
through. The optical output portion is formed at the predetermined
circumference portion of the glass valve 2 by not forming a
fluorescent substance layer along approximately the entire length
of the axis of the glass valve 2. The width of the circumferential
direction of the optical output portion 4 is set to about 4 mm.
[0044] On the outer peripheral surface of the glass valve 2 except
the optical output portion 4, a pair of external electrodes 5a and
5b are provided so as to extend along approximately the entire
length of the glass valve 2 with a predetermined gap in the
circumferential direction. The width of the gap in the
circumferential direction is about 2 mm which is narrower than the
width of the aforementioned optical output portion 4. In the
aforementioned gap, an insulating layer 8 for preventing a puncture
between the electrodes 5a and 5b on the outer peripheral surface of
the fluorescent lamp 1 is provided. Moreover, the electrodes 5a and
5b are connected to the power supply 7 for impressing an alternate
voltage via leads 6a and 6b, respectively.
[0045] In the aforementioned structure, when voltage is impressed
between the electrodes 5a and 5b from the power supply 7, the
voltage will be supplied to the Xenon in the fluorescent lamp 1
through the glass valve 2 which is a dielectric to cause electric
discharge. Ultraviolet rays generated at that time excite the
fluorescent substance layer 3 to emit visible rays which are
determined by the fluorescent substance layer 3 through the optical
output portion 4.
[0046] The principle of luminescence will be explained in detail
below.
[0047] Since electric discharge is performed through the glass
valve 2 which is a dielectric, the electric discharge remains as
glow discharge in which the current flow is restricted by the
dielectric, and will not develop into arc discharge. Moreover, the
electric discharge does not concentrate on a specific portion, but
occurs at the whole portion corresponding to the electrodes 5a and
5b on the inner peripheral surface of the glass valve 2. If the
thickness of the glass valve 2 or the like is constant and the
characteristic as a dielectric is uniform, the current density of
the inner peripheral surface of the glass valve 2 corresponding to
the electrodes 5a and Sb becomes uniform. Therefore, the density of
the ultraviolet rays to be generated will also become approximately
uniform. As a result, the generation of the visible rays becomes
approximately uniform, which in turn results in an approximately
uniform luminosity distribution on the surface of the fluorescent
lamp 2.
[0048] Furthermore, the current flows at the nearly zero crossing
immediately after the polarity of impressed voltage is reversed. At
the other timing, electric charges are accumulated on the inner
peripheral surface of the glass valve 2, and the current stops
flowing. In other words, a pulse current flows through the
fluorescent lamp 1.
[0049] In the meantime, when the electric discharge in the glass
valve is observed in detail, it is observed that a number of thin
thread-like electric discharges bridging the electrodes 5a and 5b
are generated at almost constant intervals, which looks like
stripes as a whole. In cases where rare gas is sealed in the glass
valve 2, initially, the rare gas atoms are excited to a resonance
level due to the collision with electrons by the electric
discharge. Since the excited atoms of the resonance level are high
in rare gas pressure, the excited atoms collide with the other rare
gas atoms of unexcited level to form excimer of two atomic
molecules. This excimer emits ultraviolet rays to return to two
rare gas atoms of unexcited level.
[0050] Since the ultraviolet rays emitted by the excimer do not
cause a self-breath like atomic resonance ultraviolet rays, most of
the ultraviolet rays reach the inner peripheral surface of the
glass valve 2 to be converted into visible rays by the fluorescent
substance layer 3. That is, in cases of light emission or
luminescence by the excimer, much more bright light can be
obtained. In cases where Xenon is used as rare gas, a glow
discharge type lamp having electrodes therein emits large amount of
xenon resonance ultraviolet rays of 147 nm, however, the
fluorescent lamp 1 of the aforementioned structure emits mainly
ultraviolet rays emitted by the excimer of about 170 nm. A long
wavelength of ultraviolet rays is advantageous to the luminescence
efficiency and the degradation of the fluorescent substance layer
3.
[0051] FIG. 2 shows an image forming apparatus 100 according to an
embodiment of the present invention.
[0052] As shown in FIG. 2, the image forming apparatus 100 is
equipped with a photosensitive drum 22 at approximately the upper
central portion of the apparatus. This photosensitive drum 22 is
rotatable in the direction of an arrow "a". Around the
photosensitive drum 22, various devices for forming an image by
electronic photograph processes are provided. These devices include
an electrification device 23, a laser scanning optical system 24, a
developing device 25, an image transferring device 26, a paper
separation device 27, a cleaning device 28 of residual toner on the
photosensitive drum and an eraser lamp 29 for removing the residual
electric charge.
[0053] The detailed explanation of the principle of electronic
photograph is omitted since it is a well known technology. An
electric signal is converted into an optical signal by the laser
beam scanning optical system 24 in accordance with the image
information inputted from the image scanner 21 to expose the
charged photosensitive drum 22. In this way, an electrostatic
latent image is formed on the photosensitive drum 22, and an image
is formed on the photosensitive drum 22 by developing the
electrostatic latent image by the developing device 25.
[0054] At the lower part of the image forming apparatus 100, a
plurality of paper cassettes 9 and 10 are arranged. Furthermore,
below the image forming apparatus 100, a paper supplying apparatus
200 is provided. The paper supplying apparatus 200 has a function
which supplies a recording paper to the image forming apparatus 100
one by one.
[0055] A recording paper is selectively supplied by paper supplying
rollers 11, 12, 13, 14 or 15 from the paper cassettes 9', 10' of
the paper supplying apparatus 200 or the paper cassettes 9, 10 of
the image forming apparatus 100, and once stopped by the timing
rollers 16 and then supplied to the image transferring device 26 in
synchronism with the image formed on the photosensitive drum 22.
Then, the image on the photosensitive drum 22 is transferred onto
the recording paper by the image transferring device 26, and the
recording paper is conveyed to the fixing means 18 by the
transferring belt 17 after passing through the paper separation
device 27. The recording paper is discharged to the discharging
tray 20 by the discharging rollers 19 after the heat fixing of the
transferred toner.
[0056] FIG. 3 shows a structure of the image scanner 21 for reading
the original image (manuscript image) in the image forming
apparatus 100.
[0057] In FIG. 3, light is irradiated to the image of the original
(manuscript) 51 placed on the platen (contact glass) 52 by the
fluorescent lamps 1 (1A, 1B) as a light source for lighting the
original. The reflected light from the image is reflected by the
first movable mirror 54A, the second movable mirror 54B and the
third movable mirror 54C to reach the dichroic prism 56 via the
focusing lenses 55, and then split there. The split lights are
inputted into the CCDs 57A, 57B and 57C which are solid image
taking elements.
[0058] Disposed outside the original placing region of the
aforementioned platen 2 are a white reference plate 47 for
performing a shading correction and for grasping a change of the
spectral distribution of the fluorescent lamps 1A and 1B, a black
reference plate 48 for performing a dark current correction of the
CCDs 57A, 57B and 57C, and a reference plate 49 which reflects a
specific color (specific wavelength) used for grasping the spectral
distribution change of the fluorescent lamps 1A and 1B.
[0059] The fluorescent lamps 1A and 1B and the first mirror 54A are
provided at a first carriage 58, and the second mirror 54B and the
third mirror 54C are provided at a second carriage 59. Furthermore,
the second carriage 59 moves at the rate of one half of the first
carriage 58 to keep the optical length from the original 51 to the
CCDs 57A, 57B and 57C constant. The first and second carriages 58
and 59 scan from the right to the left when reading the original
image.
[0060] The reference numeral 60 denotes a carriage driving motor,
and a pulley 61 is fixed to the rotation axis 60a of the carriage
driving motor 60. Around the pulley 61, a carriage driving wire 62
is wound, and the first carriage 58 is connected to the carriage
driving wire 62. Furthermore, the carriage driving wire 62 is also
wound around the running block (not shown) on the second carriage
59.
[0061] In accordance with the forward and reverse rotations of the
aforementioned carriage driving motor 60, the first carriage 58 and
the second carriage 59 move forwards (original reading scan) and
moves backwards (return), and the second carriage 59 travels at the
rate of one half of the first carriages 58. When the first carriage
58 is in its home position, the first carriage 58 is detected by a
home position sensor 39 of a reflected type photosensor. When the
first carriage 58 drives leftwards to go away from the home
position during the exposure scanning, the sensor 39 does not
receive light (carriage non-detection status).
[0062] When the first carriage 58 returns to the home position, the
sensor 39 receives light (carriage detection status), and when it
changes to the light receiving status from the non-light receiving
status, the first carriage 58 stops. The lighting fluorescent lamps
1A and 1B are turned on during the forward movement (original
reading scan) and rearward movement (return).
[0063] FIG. 4 shows a structure of a luminescence controlling
apparatus according to an embodiment of the present invention.
[0064] In FIG. 4, the luminescence controlling apparatus A is
applied to the image scanner 21 in the aforementioned image forming
apparatus 100, and is equipped with a fluorescent lamp 1 as a rare
gas tube, an electric charge absorption member 30 disposed in the
fluorescent lamp 1 (in the rare gas), a luminescence control means
34 for controlling the luminescence amount of the fluorescent lamp
1, and a power supply 7 for impressing an alternate voltage to the
electrodes 5a and 5b (see FIG. 1).
[0065] The fluorescent lamp 1 is equipped with a cylindrical valve
2 which is a lamp main body whose opposite end openings are closed
by sealing side plates 2a and 2b, and a fluorescent substance layer
3 formed on almost the whole inner peripheral surface of the glass
valve 2 except a part of the circumferential direction thereof.
Furthermore, the fluorescent lamp 1 is equipped with a plurality of
pairs of electrodes 5a and 5b disposed on the outer peripheral
surface of the glass valve 2 in the length direction of the glass
valve 2. The portion where the fluorescent substance layer 3 is not
formed on the inner peripheral surface of the glass valve 2
constitutes an optical output portion 4 (see FIG. 1).
[0066] Since other basic structures are the same as those shown in
FIG. 1, the explanation will be omitted.
[0067] The electric charge absorption member 30 is provided so as
to absorb the electric charge generated at the time of electric
discharge of the fluorescent lamp 1, and is comprised of an
aluminum grid line with a diameter of about 2 mm extending from one
end of the axial direction of the glass valve 2 to the other end
thereof. Both ends of the grid line 30 are supported by the sealing
side plates 2a and 2b, respectively, and one end thereof is
extended out of one of the sealing side plates 2a and electrically
connected to an external lead 33.
[0068] The luminescence control unit 34 has the external lead 33
connected to one end of the grid line 30, the variable resistor 32
arranged between the external lead 33 and the grand GND, and a CPU
36 for controlling the variable resistor 32. By changing the
resistance of the variable resistor 32 by the CPU 36, the amount of
current flowing through the grid line 30 can be changed.
[0069] Between the end of the grid line 30 and the variable
resistor 32, an analog input terminal TI which sends a signal
corresponding to the amount of current which flows through the
variable resistor 32 to the CPU 36 is connected electrically.
Furthermore, an analog output terminal TO to which a control signal
for driving the variable resistor is impressed from the CPU 36 is
electrically connected to the movable contact of the variable
resistor 32. The reference numeral 35 is an insulating cover for
covering the external lead 34.
[0070] In the aforementioned structure, when an alternate voltage
is impressed to the electrodes 5a and 5b from the power supply 7,
the fluorescent lamp 1 will repeat the lighting operation as
explained in FIG. 1. When the resistance of the aforementioned
variable resistor 32 is changed by impressing the control signal
from the CPU 36 to the analog output terminal TO, the amount of
current which flows through the variable resistor 32 is converted
into voltage, and the converted voltage is detected. Controlling
the voltage value detection and the resistance of the variable
resistor 32 by the CPU 36 enables a control of luminescence amount,
i.e., a luminescence control of the fluorescence lamp 1.
[0071] Concretely, first, electric discharge occurs as explained in
the luminescence principle. In other words, as shown in FIG. 6,
electric discharge occurs in the fluorescent lamp 1 by impressing
an alternate voltage AC to the electrodes 5a and 5b. Due to the
electric discharge, Xe atoms AT and electrons e collide with each
other, which generates ultraviolet rays UR. The ultraviolet rays UR
are irradiated to the fluorescent substance layer 3 to excite the
fluorescence molecules, which in turn generates visible rays L from
the fluorescent substance layer 3.
[0072] The absorption amount of the electrons e, i.e., the quantity
of atoms e which collide with the Xe atoms AT, at the time of the
electric discharge is changed by the resistance of the variable
resistor 32. For example, by decreasing the resistance, the
luminescence amount of the fluorescent lamp 1 decreases. To the
contrary, by increasing the resistance, the luminescence amount
increases (see FIG. 7). This is because electrons easily flow when
the resistance is small and hardly flow when the resistance is
large.
[0073] By changing the resistance of the variable resistor 32 when
electrons collide with Xe atoms AT, the quantity of electrons e to
be absorbed by the grid line 30 is changed, which adjusts the
quantity of electrons colliding with Xe atoms AT. At that time, a
voltage is calculated by integrating the value of the current
passing through the grid line 30 with the resistance of the
variable resistor. Since the current flowing through the grid line
30 is about 3 .mu.A and the resistance of the variable resistor is
1 M.OMEGA., voltage not more than 3 V occurs. By detecting the
voltage value by the CPU 36, the resistance of the variable
resistor 32 can be variably controlled.
[0074] In the meantime, the CPU 36 controls the variable resistor
32 so that the variable resistor synchronizes with the cycle
changes of the alternate voltage of the power supply 7.
[0075] FIG. 5 is a timing chart of the sequence operation of the
fluorescent lamp 1 (1A, 1B) for irradiating the original
(manuscript) at the time of operation of the image scanner 21.
[0076] When the print button (not shown) of the image forming
apparatus 100 is depressed, as shown in FIGS. 5(D) and (E), the
resistance of the variable resistor 32 is changed in synchronism
with the input of the power supply shown in FIG. 5(c) (by which a
PWM control is performed) inputted into the fluorescent lamp 1. The
changed value of the resistance is converted into a voltage value,
and then outputted to the analog input terminal TI.
[0077] Thereafter, the carriage driving motor 60 is operated in
order to detect the home position as shown in FIGS. 5(A) and (B).
Then, after the detection of the home position, the scanning
operation is repeated depending on the number of the originals.
[0078] With such an simple structure in which an electric charge
absorption member 30 like a grid line is disposed in the
fluorescent lamp 1, some electrons generated when the fluorescent
lamp 1 is discharging are absorbed by the aforementioned electric
charge absorption member 30, enabling an adjustment of the amount
of energy generated by colliding electrons with Xe atoms, which in
turn enables a control of the excitation energy of the fluorescent
substance layer 3. Therefore, although it is simple in structure,
the luminescence amount can be finely controlled in an analog
manner.
[0079] The grid line 30 is not limited to the straight member as
mentioned above, and may be a mesh-shaped member, a bunch of plural
wires or a spiral wire. Especially, using a spiral wire is
advantageous in that electric charge can be absorbed uniformly.
[0080] Moreover, the material of the grid line 30 is not limited to
aluminum, but may be conductive materials such as copper or alloy
which can absorb electrons.
[0081] FIG. 8 is a flow chart which shows a luminescence control
operation by the aforementioned luminescence controlling apparatus
A.
[0082] In the following explanation and drawings, a step is
abbreviated as "S". Moreover, in the drawings, YES and NO are
abbreviated as "Y" and "N", respectively.
[0083] First, in S1, it is judged whether or not the power supply 7
is turned on. If it is turned on (YES in S1), the CPU 36 is
initialized in S2. If the power supply 7 is turned off (NO in S1),
the routine waits until the power supply 7 is turned on.
[0084] Subsequently, in S3, the image of the original (manuscript)
51 is scanned (pre-scanned) by the image scanner 21 with the
fluorescent lamp 1 turned on. By performing this, in S4, the
luminescence amount of the fluorescent lamp 1 is measured through
the CCDs 57a-57c. This luminescence amount uses the last
luminescence amount as it is. Therefore, the luminescence amount of
the fluorescent lamp 1 is adjusted each time.
[0085] In S5, it is judged whether or not the measured luminescence
amount is optimum. When the luminescence amount is not optimum (NO
in S5), it is judged whether or not the luminescence amount exceeds
a predetermined value in S6. When the luminescence amount exceeds
the predetermined value (YES in S6), in S7, the resistance of the
variable resistor 32 is decreased based on the instructions from
the CPU 36 to reduce the luminescence amount.
[0086] Moreover, when the luminescence amount does not exceed the
predetermined value (NO in S6), in S8, the resistance of the
variable resistor 32 is increased based on the instructions from
the CPU 36 to increase the luminescence amount. After performing
these luminescence amount adjustment processing, the fluorescent
lamp 1 is made to emit light again in S3, and the adjustment
processing is repeated until the luminescence amount becomes
optimum. When the luminescence amount is proper or optimum (YES in
S5), in S9, the variable resistance value at the time of this
proper luminescence amount is memorized and held.
[0087] Next, when copying, a user selects the copy concentration.
In S10, it is judged whether or not the copy concentration is
medium. When the copy concentration is not medium (NO in S10), in
S11, it is judged whether or not the copy concentration is high.
When the copy concentration is not high (NO in S11), in S13, it is
judged whether or not the copy concentration is low.
[0088] If the copy mode is set to AUTO, the copy concentration is
set to medium, and the routine proceeds to S15. When the copy
concentration is high (YES in S11), in S12, the CPU 36 adjusts the
variable resistor 32 so as to increase the resistance in order to
increase the luminescence amount of the fluorescent lamp 1. Then,
the routine proceeds to S15. Moreover, when the copy concentration
is low, in S14, the CPU 36 adjusts the variable resistor 32 so as
to decrease the resistance in order to decrease the luminescence
amount of the fluorescent lamp 1. Then, the routine proceeds to
S15. The increased and/or decreased amount of the resistance is
calculated on the basis of the initially determined resistance
value.
[0089] FIG. 9 is a flow chart showing the operation after the copy
concentration is determined.
[0090] After the copy concentration is determined, in S15, a
copying operation starts and a time measurement starts. This time
is measured during the copying operation. In S16, when a
predetermined time passes, the measured value is incremented by
Subsequently, it is judged whether or not the measured value
exceeded 60 seconds in S17. The time measurement is continued when
it does not exceed 60 seconds (NO in S17). When it exceeds 60
seconds (YES in S17), in S18, a shading is performed in order to
adjust the luminescence amount of the lamp. At that time, the
measured time value is returned to "0". In S19, it is judged
whether or not the copying operation is completed. If the copying
operation is completed (YES in S19), the routine terminates. When
the copying operation is not completed (No in S19), the routine
returns to S16 to continue the time measurement until the copying
operation is completed.
[0091] FIG. 10 shows a luminescence controlling apparatus B
according to another embodiment of the present invention.
[0092] In FIG. 10, the same reference is given to the same part as
in the luminescence controlling apparatus A shown in FIG. 4, and
the explanation will be omitted.
[0093] This luminescence controlling apparatus B is equipped with a
fluorescent lamp 71 which has one electric charge absorption member
or 2 sets of electric charge absorption members 73 (73A, 73B)
corresponding to the aforementioned electrodes Sa and 5b,
respectively, as illustrated here and a luminescence control unit
76 which controls whether or not the lamp 1 emits light by
controlling the electric charge absorption by the electric charge
absorption member 73.
[0094] The electric charge absorption members 73A and 73B of each
set comprise a plurality of dot-like aluminum pieces (hereinafter
may be referred to as "dot-like elements"). They are arranged at
every constant pitch (dot pitch) in the axial direction of the
glass valve 2 of the fluorescent lamp 71 in a state that they are
completely or half embedded in the peripheral wall of the glass
valve 2.
[0095] The aforementioned luminescence control unit 76 is provided
with a plurality of control lines 72 (72A, 72B) each connected to
electric charge absorption members 73A and 73B, a plurality of
changing switches each disposed between each electric charge
absorption member 73A, 73B and the ground GND, resistors 75a and
75b each disposed between the electric charge absorption members
73A and 73B and each changing switch 74, and a CPU 77.
[0096] Each exchanging switch 74 is comprised of a movable contact
74a connected to the ground GND, a first fixed contact 74b
electrically connected to one electrode absorbent 73A through the
resistor 75a and a second fixed contact 74c electrically connected
to another electrode absorbent 73B through the resistor 75b. The
driving of the movable contact 74a is controlled by the CPU 77.
[0097] When dots of an image is, for example, 200 dpi, in the axial
full length (210 mm) of the fluorescent lamp 1, each one end of,
for example, 1654 control lines 72A and 72B is electrically
connected to each dot-like element 73A, 73B, and each other end
thereof is electrically connected to the resistors 75a or 75b. With
this structure, whether or not the fluorescent lamp 1 emits light
is controlled per an image dot pitch unit corresponding to the
number of control lines.
[0098] In the aforementioned structure, in order to emit light from
the part corresponding to the dot element 73 of the fluorescent
lamp 71, when the positive half cycle of the alternate voltage of
the power supply 7 is impressed to the electrode Sa, the terminal
74a of the exchanging switch 74 is switched to the contact 74c side
(control line 72B side), and when the positive half cycle of the
alternate voltage of the power supply 7 is impressed to the
electrode Sb, the terminal 74a of the exchanging switch 74 is
switched to the contact 74b side (control line 72A side). As a
result, the fluorescent lamp 71 discharges to emit light.
[0099] On the other hand, when the positive half cycle of the
alternate voltage of the power supply 7 is impressed to the
electrode 5a, the movable contact 74a of the exchanging switch 74
is switched to the contact 74b side (control line 72A side). When
the positive half cycle of the alternate voltage of the power
supply 7 is impressed to the electrode 5b, the terminal 74a of the
exchanging switch 74 is switched to the contact 74c side (control
line 72B side). As a result, the electric charge for electric
discharge is absorbed by the dot elements 73A and 73B. The current
of these dot elements 73A and 73B begins to flow to the grand GND
through the resistors 75a or 75b via the changing switch 74. This
stops the electric discharge of the fluorescence lamp 71. That is,
the excitation energy of the fluorescent substance layer 3 is
absorbed by the dot elements 73A or 73B, and the luminescence
operation is controlled at the portions of these dot elements 73A
and 73B.
[0100] In the meantime, if the high voltage generated when the
large current flows through the aforementioned resistors 75a or 75b
is directly grounded to the ground GND, the power supply 7 will be
damaged. For this reason, the aforementioned resistors 75a and 75b
perform current restrictions in order to prevent the damage of the
power supply 7.
[0101] As mentioned above, by switching the contact 74a of the
exchanging switch 74 to each dot element 73A, 73B, the luminescence
operation and non-luminescence operation of the fluorescent lamp 71
can be controlled for every dot pitch (the number of lines).
[0102] Thus, the fluorescent lamp 71 controlled as mentioned above
can be arranged in parallel with the photosensitive drum 22 as, for
example, a print head for exposing the photosensitive drum 22 in
the aforementioned image forming apparatus 100, as shown in FIG.
11.
[0103] By performing the ON/OFF control of the electric charge
absorption operation of the aforementioned dot elements 73 through
the control lines 72 by the CPU 77, the image by the luminescence
dot WO and the non-luminescence dot WF can be written every image
line V1, V2 . . . in accordance with the rotation of the
photosensitive drum 22 (in the direction of an arrow "a"), as shown
in FIG. 12.
[0104] In the meantime, the number of the dot elements 73 as an
electric charge absorption member may be arbitrarily set. When the
number of the dot element 73 is small, the writing operation may be
performed by moving the fluorescent lamp 71 in the axial direction
relative to the photosensitive drum 22.
[0105] FIG. 13 is a flow chart showing an operation when the
aforementioned luminescence controlling apparatus B is used for a
print head.
[0106] First, in S21, it is judged whether or not the power supply
7 is turned on. When the power supply 7 is turned on (YES in S21),
the CPU 77 is initialized in S22. When it is turned off (NO in
S21), the routine waits until the power supply 7 is turned on.
[0107] Subsequently, in S23, the fluorescent lamp 1 is made to emit
light and the image of the original 51 is scanned by the image
scanner 21. In S24, this read image is transmitted as data from the
scanner 52. In S25, data conversion and compression are performed
so that the ON/OFF information in every dot may be added to the
image of one line to this transmitted image data.
[0108] In S26, a control signal is sent out to the print head from
the CPU 77 so that the data is written in the photosensitive drum
22 for every line. Since the ON/OFF control for every image one dot
is needed at that time, in S27, the electric discharge direction of
the fluorescent lamp 71 is sent into the CPU 77 as information from
the power supply 7 side. This is because the power supply 7 is
short-circuited to cause a damage of the apparatus if the electric
discharge direction (+, -) and the direction for dropping electrons
into the ground GND are reversed.
[0109] In S28, when the information on the image data of one line
is processed by the CPU 77, the fluorescent lamp 71 is made to emit
light, and then the written data processed for every dot is sent
out to the print head from the CPU 77.
[0110] FIG. 14 is a flow chart showing a processing after sending
out the aforementioned written data to the print head.
[0111] In S29, when the written data is sent out to the print head
from the CPU 77, the resistance for the electric charge absorption
of the electric charge absorption member (dot element) 73 which is
an electric charge absorber is changed, and a writing in the
photosensitive drum 22 is performed every line (one Figdot
control). Subsequently, in S30, it is judged whether or not a
sending of the image data by the CPU 77 is completed. When the
sending of the image data is completed (YES in S30), the routine
terminates. When the sending of the image data is not completed (NO
in S.sup.30), the routine returns to S28 (luminescence of the
fluorescent lamp 71).
[0112] The terms and expressions which have been employed herein
are used terms of description and not of limitation, and there is
no intent, in the use of such terms and expressions, of excluding
any of the equivalents of the features shown and described or
portions thereof, but it is recognized that various modifications
are possible within the scope of the invention claimed.
* * * * *