U.S. patent application number 12/519386 was filed with the patent office on 2010-02-04 for lens structure and manufacturing method, and the manufacture of shaped polymer articles.
This patent application is currently assigned to KONINKLIJKE PHILIPS ELECTRONICS N.V.. Invention is credited to Ivar Jacco Boerefijn, Henricus Joseph Cornelus Kuijpers, Raymond Gijsbertus Anthonius Van Agthoven, Hans Zuidema.
Application Number | 20100027114 12/519386 |
Document ID | / |
Family ID | 39365884 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100027114 |
Kind Code |
A1 |
Zuidema; Hans ; et
al. |
February 4, 2010 |
LENS STRUCTURE AND MANUFACTURING METHOD, AND THE MANUFACTURE OF
SHAPED POLYMER ARTICLES
Abstract
A method of manufacturing a shaped polymer device comprises
forming a planar polymer layer over a substrate which has a lower
coefficient of thermal expansion than the polymer layer; and
shaping the polymer layer using a laser ablation process. This
method uses a substrate with low thermal expansion to limit the
expansion of the attached polymer layer when it is being shaped by
a laser ablation process. In addition there is provided a lens
structure for an *autostereoscopic display device comprising a
substantially planar glass substrate and a polymer layer defining a
lenticular arrangement provided over the glass substrate.
Inventors: |
Zuidema; Hans; (Eindhoven,
NL) ; Van Agthoven; Raymond Gijsbertus Anthonius;
(Eindhoven, NL) ; Boerefijn; Ivar Jacco;
(Eindhoven, NL) ; Kuijpers; Henricus Joseph Cornelus;
(Haler, NL) |
Correspondence
Address: |
PHILIPS INTELLECTUAL PROPERTY & STANDARDS
P.O. BOX 3001
BRIARCLIFF MANOR
NY
10510
US
|
Assignee: |
KONINKLIJKE PHILIPS ELECTRONICS
N.V.
EINDHOVEN
NL
|
Family ID: |
39365884 |
Appl. No.: |
12/519386 |
Filed: |
December 13, 2007 |
PCT Filed: |
December 13, 2007 |
PCT NO: |
PCT/IB07/55088 |
371 Date: |
June 16, 2009 |
Current U.S.
Class: |
359/463 ;
156/220; 264/1.37 |
Current CPC
Class: |
G02B 3/0025 20130101;
G02B 3/005 20130101; Y10T 156/1041 20150115; B23K 26/1476 20130101;
B29D 11/00278 20130101; G02B 3/0031 20130101 |
Class at
Publication: |
359/463 ;
156/220; 264/1.37 |
International
Class: |
G02B 27/22 20060101
G02B027/22; G02B 1/12 20060101 G02B001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2006 |
EP |
06126447.9 |
Claims
1. A lens structure for an autostereoscopic display device
comprising: a substantially planar glass substrate (43); and a
polymer layer (44) defining a lenticular arrangement provided over
the glass substrate.
2. A lens structure as claimed in claim 1, wherein the lenticular
arrangement (44) has an area greater than 100 cm.sup.2.
3. A lens structure as claimed in claim 1, wherein the lenticular
arrangement (44) has an area greater than 400 cm.sup.2.
4. A lens structure as claimed in claim 1, wherein the lenticular
arrangement (44) has an area greater than 900 cm.sup.2.
5. A lens structure according to claim 1, wherein the glass
substrate (43) has a thickness at least as great as the maximum
thickness of the polymer layer (44).
6. A lens structure according to claim 1, wherein the polymer layer
(44) has a maximum thickness less than 1 mm.
7. A lens structure according to claim 1, wherein the polymer layer
(44) is bonded to the glass layer using a pressure sensitive
adhesive.
8. A lens structure according to claim 7, wherein the pressure
sensitive adhesive has a thickness less than 0.2 mm.
9. A lens structure according to claim 1, wherein the lenticular
arrangement comprises a lens layer (44) and a replica layer (47)
arranged over the lens layer.
10. An autostereoscopic display device comprising: a display panel
(42) for producing a display; and a lens structure according to
claim 1.
11. A method of manufacturing a shaped polymer device, comprising:
forming a planar polymer layer (44;54) over a substrate (43;52)
which has a lower coefficient of thermal expansion than the polymer
layer (44;54); and shaping the polymer layer using a laser ablation
process.
12. A method as claimed in claim 11, wherein the shaped polymer
layer (44) defines an array of lenticular elements.
13. A method as claimed in claim 12, wherein the substrate (43)
comprises glass.
14. A method as claimed in claim 12, for manufacturing a lenticular
array for an autosteroscopic display device.
15. A method as claimed in claim 11, wherein the shaped polymer
layer (54) defines a mould (50) for use in manufacturing an array
of lenticular elements.
16. A method as claimed in claim 15, wherein the substrate (52)
comprises glass or metal.
17. A method as claimed in claim 15, further comprising using the
mould (50) to manufacture the array of lenticular elements for an
autostereoscopic display device.
18. A method as claimed in claim 11, wherein forming a planar
polymer layer over the substrate comprises using a pressure
sensitive adhesive.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a lens structure and manufacturing
method, for an autostereoscopic display device, and also relates
more generally to the manufacture of shaped polymer articles.
BACKGROUND OF THE INVENTION
[0002] A known autostereoscopic display device is illustrated in
FIG. 1. This known device 1 comprises a two dimensional liquid
crystal display panel 3 having a row and column array of display
pixels 5 acting as a spatial light modulator to produce the
display. For the sake of clarity, only a small number of display
pixels 5 are shown in FIG. 1. In practice, the display panel 3
might comprise about one thousand rows and several thousand columns
of display pixels 5.
[0003] The structure of the liquid crystal display panel 3 is
entirely conventional. In particular, the panel 3 comprises a pair
of spaced transparent glass substrates, between which an aligned
twisted nematic or other liquid crystal material is provided. The
substrates carry patterns of transparent indium tin oxide (ITO)
electrodes on their facing surfaces. Polarising layers are also
provided on the outer surfaces of the substrates.
[0004] Each display pixel 5 is associated with a switching element,
such as a thin film transistor (TFT) or thin film diode (TFD). The
display pixels are operated to produce the display by providing
addressing signals to the switching elements, and suitable
addressing schemes will be known to those skilled in the art.
[0005] The display panel 3 is illuminated by a light source 7
comprising, in this case, a planar backlight extending over the
area of the display pixel array. Light from the light source 7 is
directed through the display panel 3, with the individual display
pixels 5 being driven to modulate the light and produce the
display.
[0006] The display device 1 also comprises a lenticular sheet 9,
arranged over the display side of the display panel 3, which
performs a view forming function. The lenticular sheet 9 comprises
an array of lenticular elements 11 extending parallel to one
another, of which only one is shown with exaggerated dimensions for
the sake of clarity.
[0007] Thus, an array of elongate lenticular elements 11 extending
parallel to one another overlies the display pixel array, and the
display pixels 5 are observed through these lenticular elements
11.
[0008] The lenticular elements 11 act as a light output directing
means to provide different images, or views, from the display panel
3 to the eyes of a user positioned in front of the display device
1. The above described device provides an effective three
dimensional display device (if the image comprises multiple
views).
[0009] In an arrangement in which, for example, each lenticular
element 11 is associated with two columns of display pixels 5, the
display pixels 5 in each column provide a vertical slice of a
respective two dimensional sub-image. The lenticular sheet 9
directs these two slices and corresponding slices from the display
pixel columns associated with the other lenticular elements 11, to
the left and right eyes of a user positioned in front of the sheet,
so that the user observes a single stereoscopic image.
[0010] The lenticulars are mounted in front of the display and need
to be aligned accurately with respect to the pixels in order to
project the correct pixel information. For the same reason the
dimensions of the lens array, such as the pitch and the lens shape,
need to be maintained during thermal cycles. This presents
difficulties in the design and manufacture of the lenticular lens
array.
[0011] Examples of manufacturing techniques for lenticulars are
replication techniques such as UV-replication, in-mould pressing
(compression moulding) and embossing. Direct structuring methods
can also be used, in which a polymer plate is shaped by laser
ablation. Reflow methods are also known in which the lens shapes
are defined by a melting and re-solidification process.
[0012] Compared to glass, the thermal coefficient of expansion of
polymers is high, for example 200-700.times.10.sup.-7/.degree. C.
for plastic and 60-120.times.10.sup.-7/.degree. C. for glass. This
high thermal coefficient of expansion results in unacceptable
dimensional and alignment inaccuracies of the lenticular, resulting
in poor 3D performance.
SUMMARY OF THE INVENTION
[0013] According to the invention, there is provided a lens
structure for an autostereoscopic display device comprising:
[0014] a substantially planar glass substrate; and
[0015] a polymer layer defining a lenticular arrangement provided
over the glass substrate.
[0016] This lens structure has a stable glass substrate on which a
polymer sheet is formed (e.g. laminated). The lens structure when
applied onto a display panel will have lower alignment and
dimensional inaccuracies due to the thermal expansion mismatch
between the panel and lenticular. Thermal stress due to the thermal
expansion mismatch between the panel and lenticular can also be
reduced.
[0017] This lens structure can be used as a substrate to which
laser structuring is applied, with thermal expansion caused by the
laser process being controlled and limited by the glass substrate.
This is particularly suitable for large area lens structures, for
example for lenticular arrangements having an area greater than 100
cm.sup.2, or more preferably greater than 400 cm.sup.2 and even
more preferably greater than 900 cm.sup.2.
[0018] The glass substrate may have a thickness at least as great
as the polymer layer, and the polymer layer preferably has a
maximum thickness (i.e. a thickness before it is shaped) of less
than 1 mm. The polymer layer can be bonded to the glass layer using
a pressure sensitive adhesive, for example with a thickness less
than 0.2 mm.
[0019] The invention also provides an autostereoscopic display
device comprising a display panel for producing a display and a
lens structure of the invention.
[0020] The invention also provides a method of manufacturing a
shaped polymer device, comprising:
[0021] forming a planar polymer layer over a substrate which has a
lower coefficient of thermal expansion than the polymer layer;
and
[0022] shaping the polymer layer using a laser ablation
process.
[0023] This method uses a substrate with low thermal expansion to
limit the expansion of the attached polymer layer when it is being
shaped by a laser ablation process. The invention relates to the
use of a polymer laser ablation process, and this can be used as a
technique for manufacturing lenticulars that can either be used as
a master for use in a replication process, or for the direct
manufacture of the lens component.
[0024] Thus, the shaped polymer layer may define an array of
lenticular elements, and in this case, the substrate is preferably
glass. The method can be for manufacturing a lenticular array for
an autosteroscopic display device. The method then reduces
dimensional inaccuracies which can otherwise arise due to thermal
expansion during laser ablation.
[0025] Instead, the shaped polymer layer can define a mould for use
in manufacturing an array of lenticular elements by a replication
process. In this case, the substrate does not need to be
transparent, and may comprise a metal sheet. The mould can then be
used to manufacture the array of lenticular elements for an
autostereoscopic display device. The method again reduces
dimensional inaccuracies during the lens formation, as there will
be reaction heat of the UV curing process of the replication
method, with resulting thermal expansion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Embodiments of the invention will now be described, purely
by way of example, with reference to the accompanying drawings, in
which:
[0027] FIG. 1 is a schematic perspective view of a known
autostereoscopic display device;
[0028] FIG. 2 is a schematic cross-sectional view of an
autostereoscopic display device having a lens arrangement according
to an embodiment of the invention; and
[0029] FIG. 3 is used to explain a different manufacturing method
of the invention for the lens arrangement of an autostereoscopic
display device.
DETAILED DESCRIPTION OF EMBODIMENTS
[0030] The invention provides methods for manufacturing shaped
polymer articles, such as a lens structure for an autostereoscopic
display device, in which the manufacture involves forming a planar
polymer layer over a substrate which has a lower coefficient of
thermal expansion than the polymer layer, and shaping the polymer
layer using a laser ablation process. The heat generated by the
laser ablation process tends to expand the polymer, but this
expansion is constrained by the underlying substrate. The shaped
polymer can be a lens structure or an inverse for use in a
subsequent replication process.
[0031] FIG. 2 is a schematic cross-sectional view of an
autostereoscopic display device 40 according to an embodiment of
the invention. The autostereoscopic display device 40 comprises a
two dimensional liquid crystal display panel 42 for producing a
display. The structure of the liquid crystal display panel 42 is
entirely conventional.
[0032] In a similar fashion to a known autostereoscopic display
device (as described in the background section of this
application), the display panel 42 is illuminated by a light source
(not shown). Light from the light source (indicated generally by
the arrow labelled "L") is directed through the display panel 42,
with individual display pixels of the display 42 being driven to
modulate the light and produce an image.
[0033] The lens structure in an autostereoscopic display device of
the invention has a planar glass substrate 43 and a polymer layer
44 defining the array of lenticular elements 46. The glass
substrate provides stability, and the lens structure has lower
alignment and dimensional inaccuracies over the display panel 42
due to the thermal expansion mismatch between the panel and
lenticular. Thermal stress due to the thermal expansion mismatch
between the panel and lenticular can also be reduced.
[0034] The lens structure shown in FIG. 2 can be shaped by a laser
ablation process, applied to the layer 44 while supported by the
underlying substrate. Thus, laser structuring is applied directly
to the lens structure, and thermal expansion caused by the laser
process is controlled and limited by the glass substrate. This is
particularly suitable for large area lens structures, for example
the invention can be used for lenticular arrays for 42 inch (105
cm) diagonal displays.
[0035] In the configuration of FIG. 2, the glass substrate may have
a thickness at least as great as the thickness of the polymer
layer, for example at least about 0.5 mm and typically
approximately 2 mm, and the polymer layer may have a thickness
before it is shaped of less than 1 mm, for example approximately
0.1 mm. The polymer layer is bonded to the glass layer using a
pressure sensitive adhesive, for example with a thickness of 0.02
mm.
[0036] FIG. 2 also shows an optional replica layer 47 over the lens
layer.
[0037] In the example of FIG. 2, the lens structure is shaped
directly, but a replication process may instead be used, as shown
in FIG. 3.
[0038] The replication mould 50 comprises a substrate 52 of lower
coefficient of thermal expansion than an overlying polymer layer 54
which is shaped by the laser ablation process to define the replica
inverse lenticular shape shown. As also shown in FIG. 3, the
resulting lens structure is formed from a single layer which is
then provided over the display panel 42, or the lens structure may
be provided over a separate substrate.
[0039] The replication process typically involves filling the
replica with a liquid monomer, pressing the liquid into the replica
using a substrate, and using UV photo polymerization to cure the
polymer lens body. The resulting lens array can be removed from the
substrate used to press the mould, or the substrate may form part
of the lens array.
[0040] Thus, the invention can be applied to the lenticular sheet
or the replication mould, and provides a thin polymer sheet
laminated on another substrate instead of using a full polymer
sheet. For direct manufacture of a lenticular sheet, the substrate
material should be optically clear (for example glass) just like
the polymer foil. For a replication mould neither of these needs to
be optically clear, for example a metal (e.g. steel) substrate and
an opaque polymer can be used.
[0041] The manufacturing method comprises lamination of the polymer
foil on the glass or other substrate by using a pressure sensitive
adhesive. The lens or replica shape is then structured into the
polymer surface by laser ablation, and the shaped surface is then
cleaned.
[0042] The effectiveness of the method can be demonstrated by
analysing the relative displacement of the polymer layer compared
to the underlying substrate during heating. For example, the
expansion of the combined glass-polycarbonate structure can be
analysed when heating in a cycle, for example from 20.degree. C. to
60.degree. C. This represents the typical thermal cycle of a
display during operation.
[0043] It has been found by modelling that the relative shift of
the polymer sheet with respect to the glass substrate is such that
an overlay resulting at the edge of the display is much smaller
than the overlay based on free expansion of the polymer.
[0044] The invention can be used in several fields where
stabilization of polymer layers is required for good dimensional
accuracy during processing and application. The text above relates
to the manufacture of a thermally stable lenticular that can be
directly mounted to on a 2D display to make a 3D display or that
can be used as a master lenticular for replication. However, those
skilled in art can well think of different applications.
[0045] The lenticulars are shown as semi-cylindrical lenses, but
other designs are possible, such as discrete circular (or oval)
lenses, or bi-convex lenses.
[0046] Various other modifications will be apparent to those
skilled in the art.
[0047] Summarizing, the invention relates to a method of
manufacturing a shaped polymer device comprises forming a planar
polymer layer over a substrate which has a lower coefficient of
thermal expansion than the polymer layer; and shaping the polymer
layer using a laser ablation process. This method uses a substrate
with low thermal expansion to limit the expansion of the attached
polymer layer when it is being shaped by a laser ablation
process.
[0048] It should be noted that the above-mentioned embodiments
illustrate rather than limit the invention, and at that those
skilled in the art will be able to design many alternative
embodiments without departing from the scope of the appended
claims. In the claims, any reference signs placed between
parentheses shall not be construed as limiting the claim. The word
"comprising" does not exclude the presence of elements or steps
other than those listed in a claim. The word "a" or "an" preceding
an element does not exclude the presence of a plurality of such
elements. In the device claim enumerating several means, several of
these means may be embodied by one and the same item of hardware.
The mere fact that certain measures are recited in mutually
different dependent claims does not indicate that the combination
of these measures cannot be used to advantage.
* * * * *