JPH01182878A - Photo-conductive type display device - Google Patents

Abstract

PURPOSE:To simplify the constitution of an optical shutter by using the optical shutter with dividing into the respective colors of R, G and B. CONSTITUTION:From the panels of respective optical shutter 106-108 corresponding to the three primary colors of R, G and B, a fiber 105 is connected respectively to R, G and B dot trio for each picture element of a display surface. Thus, for example, by using a method to use a light source, to which a color filter is mounted, or to use a light from the light source with separating the light into the respective colors by using a spectral element singly or with being coupled so as to correspond the three primary colors of R, G and B, without providing a fine color filter layer to correspond to the respective picture elements on the panels of the optical shutters 106-108, the title device can correspond to a coloring. Thus, the structure of the optical shutter can be simplified.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light guide type display device.

[Prior art] Conventional light guiding type display devices include U, S, P, 4
As disclosed in Japanese Patent No. 650280, a display screen was constructed by simply stacking blocks of bundled optical fibers. ◇ [Problem to be solved by the invention] However, in the conventional light guide type display device, a light shutter and a display were used. In order to make images correspond almost one-to-one, the length of the optical fiber tends to be long, which poses a problem in that the price of a portion of the fiber becomes high. In addition, the optical shutter needs to be of the same size or higher than the display screen, and because the display area is large, it is required to have a fairly high definition one. Therefore, in the present invention, at least the optical shutter is R2
The purpose of this is to divide it into three or more parts corresponding to O and B colors so that optical fibers, optical shutters, etc. can be easily constructed and provided at low cost.

[Means for Solving the Problems] The light guide type display device of the present invention has a light shutter with R2O, B
It is characterized by being divided into each color and used.

[Example 1] FIG. 1 shows an overall view of a light guiding type display device of the present invention. 10
1 is 1 block that makes up the screen, 102.103.10
4 is the other end face of the fiber 105, R, G.

It shows the input end of an image corresponding to B3 primary colors.

106, 107, and 108 are optical shutters that are image forming means corresponding to the three primary colors R, G, and B, and in this embodiment, a moat crystal display (hereinafter referred to as LCD) was used. Also, 1
09.110.111 are light source devices for each color.

The present invention will be explained in detail below.

The light guide used in the present invention transmits the power of light, and the light guide forms pixels on the output surface. An optical fiber is suitable as such a light guide, and in consideration of weight, price, flexibility, workability, etc., a plastic fiber is more preferable.

FIG. 2 is a perspective view of one block composed of the above-mentioned fibers. By alternately shifting the fiber east 201 bundled every 30 sheets (one sheet consists of 180 fibers) on the output surface side, the arrangement on the output surface was made to be intersected. On the other hand, the fiber on the side of the entrance surface connected to the optical shutter is not shifted and can have a rectangular cross section. The entrance surface with a rectangular cross section corresponds to the display surface of the optical shutter. Therefore, by assuming that the information incident on the fiber from the optical shutter side is shifted in the opposite direction in accordance with the shift of the output end, the displayed information becomes normal. Further, the entrance surface could have a structure in which fibers 301, each end of which was shaped into a rectangle, were laminated in a close-packed manner, as shown in FIG. In reality, the fiber and the optical shutter are in close contact with each other, but in FIG. 3 they are drawn with a gap 303 between them. Each fiber 301 corresponds to a pixel 302 of the optical shutter.

In the configuration of this embodiment, from each optical shutter panel corresponding to the three primary colors R, G, and B, one pixel of R,
One fiber is connected to each of the G and B dot trios. For this reason, in order to correspond to the three primary colors R, G, and B, for example, a light source equipped with a color filter is used, the light from the light source is separated into each color using a spectroscopic element, and only the required wavelength is used. Use a light source that emits light efficiently, or use a light guide optical fiber from the light source to the optical shutter that has a wavelength distribution that easily transmits only the required wavelengths, or use an end face that is output from the optical shutter. This is done by dyeing the fibers up to so that only R, G, and B light can easily pass through.
By using methods such as providing a single color filter layer on the optical shutter substrate alone or in combination, it is possible to support colorization without providing a fine color filter layer corresponding to each pixel on the optical shutter panel. It became possible. For this reason, it was possible to reduce the cost of a portion of the optical shutter, which is a relatively expensive component, and depending on the method, it was also possible to make the light source smaller. When using a liquid crystal display device where the optical switching characteristics of the optical shutter have wavelength dependence, it is not necessary to have good characteristics on average for each wavelength, and it is possible to design optimally for each color. , it becomes easy to improve the performance of the optical shutter, and it also becomes easier to design, making it easier to lower the price. Additionally, when adjusting color balance, etc., each color can be controlled independently, making adjustments easier. Furthermore, even if the number of pixels on the display screen is the same, the density of pixels in the optical shutter is at least ⅓, which not only makes it easier to fabricate the optical shutter, but also facilitates alignment when coupling with fibers. Furthermore, efficient use of light by spectroscopic elements has become possible, allowing for brighter displays. Furthermore, since less strain is applied when fibers are connected to each optical shutter panel, fibers can be connected in shorter lengths, reducing fiber costs.

Furthermore, in this embodiment, the fourth As shown in the figure, at least one fiber 401 for detecting the amount of light and a light amount detector 402 are arranged for each optical shutter unit, and signals from these fibers are used to control the amount of light from the light source or the amount of light transmitted through the optical shutter. By doing so, a configuration was adopted in which the unevenness of the amount of light at the above-mentioned output end face is reduced.

FIG. 5 (al, (bl) is an enlarged view of a part of the display surface. The fiber 50! is held between spacers 502, and the output end surfaces 201 are aligned.
Figure (at is R, G, when spacer 502 is inserted for B fiber tray No. 503, Figure 5 (bl is R,
This is the case when each fiber is inserted into G and B fibers.

To minimize light leakage between fibers, the spacer should absorb the leakage light. For this reason, in this example, dyeing was performed in various colors, and the dyed black gave the most favorable results for each color. Further, by dyeing in this manner, it is also possible to make the gaps for magnification on the display surface less noticeable and to improve the clarity of the image.

The image magnification method using a fiber-based light guiding optical system is as follows.
Methods such as inserting a spacer between fibers and cutting the fibers diagonally are known, and these methods may be applied as appropriate. In this example, the image formed by the optical shutter was enlarged by inserting a spacer in the horizontal direction and using a cutting method in the vertical direction, and then the blocks were stacked as shown in Figure 1 to form the entire screen. . At this time, in order to improve the uniformity of the light emitting surface, it is preferable to perform control processing on the light emitting direction on the entire light emitting surface at once. Although serration processing, matte finish processing, sandblasting processing, etc. are known as control processing for the emission direction, in this embodiment, sandblasting processing is performed all at once to provide a diffusion processing.

Next, the coupling between the optical shutter and the fiber entrance surface will be explained. FIG. 6 is a sectional view of the joining portion between the optical shutter and the fiber. In order to reduce unnecessary reflections caused by the interface between the optical shutter 601 and the fiber input end 602, in this embodiment, the fiber and the optical shutter are connected by an optical coupling material 603 having a refractive index similar to that of the fiber core. They are brought into close contact to increase coupling efficiency. Specifically, silicone resin with a refractive index of 1.49 was used.

FIG. 7 is an enlarged view of the joining part. The LCD used for the optical shutter has an opposing transparent substrate 7 with electrodes from the fiber side.
01, a liquid crystal layer 703, and a transparent substrate 702, and is brought into close contact with the fiber entrance surface by a coupling material 705. 706 is an electrode corresponding to a pixel. Since the opposing transparent substrate is placed between the pixels and the fiber input end, the distance for optical coupling becomes long, and there is a possibility that the light information formed by the pixels will not be transmitted to the fiber in a one-to-one manner.

The possible incident angle θ is determined by N and A of the fiber. - θ of plastic fiber for boat fishing is ±30°
If the direction of illumination light has a spread of 0 or more, crosstalk from neighboring pixels is proportional to the optical length between the pixel and the fiber input end. Furthermore, if the optical length exceeds the pixel length/lan θ, information from peripheral pixels will be mixed, resulting in a decrease in resolution. Therefore, in the example shown in FIG. 7, by setting the opposite transparent substrate as thin as or less than the pixel length, it is possible to reduce crosstalk therebetween. Furthermore, if the optical shutter requires a polarizing plate on the output side, it is made as thin as possible and placed between the transparent substrate and the fiber.

Furthermore, in order to suppress the reduction in resolution due to such crosstalk between pixels as much as possible, the G pixels, which contain the most luminance information, are particularly carefully combined in an effort to reduce crosstalk.

Further, crosstalk reduction can also be achieved by other methods. For example, FIG. 8 shows another example.

The opposing transparent substrate 801 is etched to fit the fiber joining part 802 and is processed to be thinner than the cross-sectional length of the fiber 803, so that the same effect as using a thin transparent substrate can be obtained, and the structure is also strong and strong. It is advantageous in terms of

Optical coupling of this optical shutter and fiber requires accurate positioning, as can be seen in FIGS. 6, 7, and 8.9. It's not easy to do. In addition, as will be described later, if the optical shutter is arranged at an angle with respect to the fiber coupling end, even if one end of the bundled fibers and the pixel of the shutter are aligned two-dimensionally, misalignment will occur. This means that the coupling is not complete, and it becomes even more difficult to adjust the position to the optimum position while taking into account the deviation.

In this embodiment, the following method was used to reduce the difficulty of alignment.

First, marks for alignment were written on the optical shutter. For example, in the case of an optical shutter with a color filter, this mark indicates that the color filter is made to have a different color from other parts by overlapping G and B, R and B, etc. when creating the color filter.
The fiber was made into a size equivalent to a fiber and used. Alternatively, a black mask for preventing light leakage or a surface processed by etching or the like so as to scatter or absorb light may also be used.

The optical fibers to be connected should be connected diagonally in two directions when bundled.
Also bundle more than two fibers unrelated to image formation.
The fibers other than this extra fiber are coupled to the output end. During alignment for optical shutter and fiber coupling,
By injecting reference light into the fiber unrelated to image formation from the end face on the side that is not coupled with the optical shutter, the fiber side corresponding one-to-one to the alignment mark of the optical shutter is applied. It became a shining landmark as a mark for alignment.

While detecting this reference light from the fiber side through the substrate of the optical shutter, alignment was possible without much difficulty by aligning the alignment marks on both the optical shutter and the fiber input end so that they overlapped. At the time of this light detection, positioning has become easier by using a photodetector whose sensitivity is matched to the light that is transmitted or the light that is not transmitted.

By doing the above, the coupling direction and the optical path of the reference light become the same, so it becomes possible to easily align an arbitrary optical shutter with respect to one direction of the fiber.

Another method is to make a depression or depression corresponding to the length of the fiber by etching, pasting, or thick film printing on the side of the optical shutter that is connected to the fiber. There is also a method of aligning one end surface of an optical fiber that has been processed to have a symmetrical concave or protruding surface so that the convex and concave surfaces of each fiber align, and this method also allows for easy alignment. . In this case, it is necessary to accurately determine where to align at the design stage.

Next, the connection between the LCD and the fiber will be explained. FIG. 9 is a cross-sectional view when the LCD is obliquely engaged with the fiber input end. By setting the coupling angle of the optical shutter 901 to the fiber east 903 at an angle other than the right angle, even when using an optical shutter such as an LCD in which the display contrast changes depending on the direction of the incident light 902. , allowing use at angles with maximum contrast. This is Twisted
Nematic (hereinafter abbreviated as TN) mode,
Electrical17 Controlled B
irefringence mode, Guest
This occurs in Ho5t mode, etc., and by making the light source light incident obliquely, the performance of each mode can be maximized. T used in this example
In the case of N mode, there is an optimal switching direction in the pretilt direction of the liquid crystal molecules, and the LCD is tilted and engaged with the fiber so that light is emitted in this direction. - Boat fishing T
In N mode, the LCD has an angle of 0 to 30 with respect to the central angle of the incident light.
It is preferable to have an inclination of approximately 1°.

FIG. 10 is a perspective view of the incident surface when a plurality of LCDs are coupled to a fiber. The fiber input end is divided into a plurality of fiber units 1 (101), and each unit is connected to a small-scale LCD 1002. At this time, the light source is unified to illuminate all the units at once. This can prevent unevenness caused by variations in the light source.

Furthermore, such a configuration has the advantage that the scale of the LCD can be reduced and it is easy to secure a mounting space for the LCD. 1003 indicated by diagonal lines in FIG. 10 is an LCD driver circuit board, which does not affect the display at all by being installed between the unit units.

In this embodiment, in order to handle TV signals, at least 5
Although pixels of about 00 x 50 G are required, the above-mentioned unitization makes it possible to use a small LCD of about 100 x 100 pixels. Further, the LCD has the advantage that it is easier to obtain space for installing a circuit for inputting electrical signals for control, which is essential to the LCD.

Figure 11 shows the LCD used as an optical shutter in this example.
FIG. The basic structure is that a color filter layer 1102 is placed between two transparent substrates 1103 with electrodes, and liquid crystal is sealed between them to form a liquid crystal layer 1104. This color filter layer may not be present depending on the configuration of the fiber, light source, etc. In this example, thin film transistors shown in Table 1 are used.
An active matrix type liquid crystal display (hereinafter abbreviated as TPT-LCD) in which the IITransistorll 101 is used as an active element is used. TPT-L
The general driving method and structure of a CD is described in Nikkei Electronics No. 351 (+981) p. 211. S.I.
D' 83 DG E S T p, +56.

Table 1 Display mode TN mode driving method TPT active matrix pixel number
480X 440 Display effective area 96X88 mm Color RGB dichroic filter
Filter Next, a driving method when a plurality of LCDs are used will be explained with reference to FIGS. 12 to 14. One of the simplest methods is to connect the X and Y lines as if they were a single LCD, as shown in FIG. 1203 is LCD, 1201
1202 is a scanning circuit on the X side of the LCD, and 1202 is a scanning circuit on the Y side of the LCD.

FIG. 13 shows an X-side scanning circuit 1303 and a Y-side scanning circuit 130 for each LCD in order to reduce the number of connection lines between the LCD and external circuits.
4, and the wiring to each LCD is limited to display data 1301 and timing signal 1302 corresponding thereto.

However, by sending the display data in a point-sequential manner as a whole, it is possible to set the duty ratio per pixel of each LCD so that it does not become too high.
It is possible to avoid deterioration of LCD characteristics that would occur if the duty ratio was made too high.

In Fig. 14, display data is sent to each LCD in parallel. Serially transmitted data 1402 is once stored in a display memory 1401, and read out in parallel according to the share of each LCD 1403. This shows how to write it as display data. 1404 is a data bus, and 1405 is a CPU that performs control. With this method, the wiring to the LCD is reduced and at the same time
This has the advantage of increasing the operating duty of the pixel and increasing the selection time per pixel.

In this way, by using a plurality of LCDs, the aspect ratio of the LCD can be determined regardless of the aspect of the displayed image, which has the effect of making it possible to drive the LCD in a region with good electro-optical characteristics. FIG. 15 is an example of this, and is a perspective view of a portion that engages with the fiber. R,G
, an NTSC television signal of 540 x 5401-Rio in terms of B pixel trio is constructed using 27 +80 x 180 pixel T F T -L CD +501. 1502 is a fiber bundle corresponding to - LCDs. - LCD is in charge of I'80x60 in terms of R, G, B pixel trio.

FIG. 16 shows the structure of the coupling portion between the optical shutter and the light source used in this example. Normally, a polarizer is used to limit the plane of polarization of incident light and output light from a liquid crystal panel, but in this example, a polarizing beam splitter is used to limit the polarization of incident light.
1601, an optical shutter was constructed using liquid crystal panels 1602 and 1603, each without an upper polarizing plate, for each light emitted from a polarizing beam splitter that was limited to one polarization plane. 1604 is a fiber bundle.

According to this method, only one polarization plane of the light emitted from the light source is used, and half of the light is absorbed by the polarizer, compared to existing liquid crystal displays, which would otherwise be discarded. This makes it possible to use light more effectively, reducing the number of light sources by about half. For this reason, not only the direct effect is miniaturization of the device and reduction in power consumption, but also the burden of cooling the portion corresponding to the heat generated by the light absorbed by the polarizer is reduced. Therefore, it is no longer impossible to downsize the device due to heat generation, or a large cooling device is required, and there is also an indirect effect that the device can be downsized and power consumption can be reduced.

FIG. 17 shows an example of a sectional view of the light generating portion of the light source of this embodiment. 17 represents a light generating part such as a halogen lamp, cold cathode tube, or fluorescent lamp, and 1702 represents an optical fiber for the light source. For light sources that generate a lot of heat, we focused on heat-resistant fibers, such as those made of quartz glass, and for light sources that generate little heat, we used plastic fibers in consideration of price and weight. Compared to the conventional combinations of a reflector and condenser lens or the combination of a reflector and a fiber, this type of fiber eliminates the need for complex optical design, making it easier to align the optical shutter and light source. Since precision is no longer required for
Manufacturing has become much easier. Additionally, there is no need to consider the reduction in peripheral light intensity that tends to occur with condensing optical systems that keep costs low, resulting in a light source that can provide high-quality, uniform light. The optical fiber for this light source uses a diameter smaller than the size of a pixel on the optical shutter panel surface, and by making multiple light source fibers correspond to one pixel, there is no need for alignment, and each pixel It has become possible to create a light source with less unevenness in the amount of light. Furthermore, when bundling the fibers taken out from the light generating section, the light source fiber 170 in the light generating section 1701
By arranging the positions of 2 to be irregular, it was possible to average out the unevenness in the amount of light depending on the portion of the light generating section and reduce the unevenness in the amount of light.

With the above configuration, the optical shutters are R and G.

By dividing and using the three B colors, it becomes possible to reduce the cost of the optical shutter, easily align it with the fiber, and optimize the light source.

[Embodiment 2] FIG. 18 shows another embodiment of the light guide type display device of the present invention. 1801 is a fiber bundle which is a magnifying optical system; 1802
is the image input end of the other end face of the fiber corresponding to the three primary colors R, G, and B. 1804 is a liquid crystal projection device which is an image forming means. The difference from the first embodiment is that the LCD is not directly installed at the image input end, but the image is input via an imaging optical system.

The details of this embodiment will be explained below.

FIG. 19 is a basic configuration diagram of the liquid crystal projection device used in this example. 1901 is a light source device, 1902 is an LCD,
1903 is a projection optical system, and 1904 is a fiber bundle. Such projection devices include (1) those using a transmission type optical shutter (Appl, Phys, Lett, V
ol, 21392 (19721+, (2) Using a reflective optical shutter (Japanese Patent Laid-Open No. 56-43681),
(3) Using an optical writing type optical shutter (Television Society Technical Report 0PT-216 January 1986), (
4) Using a matrix type optical shutter (Japanese Patent Application Laid-open No. 1983
l-99118) is known. Although the present invention can be used without any problems, here, a color projector using a TPT-LCD shown in FIG. 20 was used. This is 3 due to the dichroic element 200+.
It combines primary colors and has higher light usage efficiency than methods that use color filters, so it can provide a brighter display. Furthermore, matrix type L CD 20
02 onto the entrance surface 2003 of the fiber matrix, accurate pixel positioning is achieved. 2004
2005 is a dichroic mirror for spectroscopy, 2006 is a mirror, and 2007 is a projection optical system. In addition, since the three primary colors can be input into the fiber at once, the number of fibers used can be reduced, which has the effect of reducing the overall fiber length.

Although the configuration of the light guide section in Example 2 was the same as that in Example 1, accurate image formation by the projection device became possible even with a simple laminated light guide.

By coupling the image forming portion by the optical shutter with the fiber through the coupling optical system in this way, a light guide type display device that is bright, has higher resolution, and has excellent display quality can be obtained. Additionally, fiber length can be saved, further reducing costs.

[Effects of the Invention] As described above, according to the present invention, the optical shutter is
, G, and B, the configuration of the optical shutter becomes simple and the connection to the fiber becomes easy. Furthermore, the fiber can be made shorter, which has the effect of reducing costs.

[Brief explanation of the drawing]

FIG. 1 is an overall view of the light guiding type display device of the present invention in Example 1, and FIG. 2 is a perspective view of one block taken out. FIG. 3 is a diagram showing the structure of one end of a rectangular fiber, FIG. 4 is a diagram showing an optical shutter unit, and FIG. 5 is an enlarged view of a part of the display surface. FIG. 6 is a cross-sectional view of the joining portion between the optical shutter and the fiber, FIG. 7 is an enlarged view of the joining portion, and FIG. 8 is a diagram showing the joining portion between the optical shutter and the fiber by another method. Fig. 9 is a cross-sectional view when an LCD is obliquely engaged with the fiber input end, and Fig. 10 is a perspective view of the entrance plane when a plurality of LCDs are engaged with the fiber. 12 is a cross-sectional view of an LCD used as an optical shutter in Example 1. FIGS. 12, 13, and 14 are diagrams showing a driving method when using multiple LCDs, and ,
Diagram when Y is connected like one LCD, 1st
Figure 3 shows a case in which scanning circuits are arranged on both the X and Y sides to reduce the number of connection lines with external circuits, Figure 14 shows a case in which display data is sent to each LCD in parallel, and Figure 15 shows a TPT. -LC
It is a figure showing the case where it is comprised using 12 sheets of D. 16th
The figure shows the structure of the coupling part between the optical shutter and the light source used in Example 1, and FIG. 17 shows a cross-sectional view of the light generating part of the light source of Example 1. FIG. 18 is a diagram showing a light guide type display device in Example 2, and FIG. 19 is a configuration diagram of a liquid crystal projection device used in Example 2. FIG. 20 is a diagram showing a color projector used in Example 2. 101......One block that makes up the screen 102, 103.104...Fiber input end +05
...... Fiber 106, 107.1
08...Optical shutter 109, 110.111...Light source device 201...Fiber East 202...
......Fiber 203...
Fiber input end 301 ...... Fiber 302 ...... Pixel 303 ...... Spacing 401 ...... Light amount detection fiber 40
2......Light amount detector 501...
...... Fiber 502 ...... Spacer 503 ...... R, G, B fiber trio 601 ...... Optical shutter 6
02......Fiber input end 603.
...... Optical coupling material 701...
...... Opposing transparent substrate 702 ......
・Transparent substrate 703...Liquid crystal layer 705...Coupling material 706...
......Electrode 1i01 corresponding to pixel...
...... Opposing transparent substrate 802 ......
Fiber 901......Incoming light 902...Fiber 903...
・・・・・・Optical shutter 1001・・・・・・・・・
・Fiber unit 1002...
・LCD 1003...LCD driver circuit board 1101...Thin film transistor 1102...Color filter layer 11
03......Transparent substrate ■104...
...Liquid crystal layer 1201...X side scanning circuit 1202.
......Y side scanning circuit 1203...
......LCD1301...Display data 1302...Timing signal l
303......LCD X-side scanning circuit 13
D4・・・・・・・・・〃Y side 〃1401・
......Display memory 1402...
...Serial display data 1403...
...LCD 1404... Data bus 1405...
......Control CPU+501...
...TFT-LCD1502...Fiber bundle 1601...Polarizing beam splitter 1602, 1603...Liquid crystal panel 1604... ...Fiber bundle 170!・
......Light generation part l702...
...Optical fiber for light source 1801...
...Fiber bundle 1802......Fiber bundle entrance surface 1804......Liquid crystal projection device 1901...Light source device 1902
・・・・・・・・・・LCD1903・・・・・・・
...Projection optical system 1904...Fiber bundle 2001...Dichroic element 2002...Matrix type LCD 2
003......Incidence surface of fiber matrix 2004...Light source device 2005.
・・・・・・Dichroic mirror 2006...
・・・・・・・・・Q200F・・・・・・・・・Projection optical system and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Tsutomu Mogami (and 1 other person) Figure 2 Figure 4 Figure 5 (α) (a2 Figure 5 (b) Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 13 Figure 14 Figure 15 Figure 16 Figure 18

Claims (1)

[Claims] A light-guiding display device characterized in that a light shutter of the light-guiding display device is divided into R, G, and B colors.