JPS60166924A - Image forming device - Google Patents

Abstract

PURPOSE:To solve the problem of uneven illuminance on a display surface and installation position of an image generating device by providing the image generating body in the midway of an optical path which directs the light from a light source to the display surface at a uniform luminous flux density with a light control device. CONSTITUTION:An image generating device G is provided in the course of the light which is emitted from a light source L and is reflected by a light control device C formed as a reflection mirror and is directed toward a display surface D. The device G has elements parts for changing the quantity of transmitted light corresponding to the respective picture elements of an image. If an image signal is inputted to each transparent electrode 5 by a video scanning signal input device 8 or the like in the case of, for example, a liquid crystal type image generating device, the image is generated in the liquid crystal device and the image is produced on the display surface D by the light from the device C and therefore the image formed on the surface D is visible from the side opposite from the device G.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to display devices, televisions, and other image forming devices.

This type of image forming apparatus includes one in which a light source is placed behind a translucent display surface, and an image generating device is interposed between the light source and the display surface in contact with the display surface, and one in which the display surface is a screen; There is one in which light from a light source is projected onto this screen, and an image generating device is interposed between the screen and the light source in the vicinity of the light source.

An example of the former is a liquid crystal television, and an example of the latter is a projection television. However, such conventional image forming apparatuses have the following problems.

That is, in the former case, illuminance unevenness occurs on the display surface because the light source behind the display surface is a point light source or a line light source. This illuminance unevenness cannot be completely eliminated even if the number of light sources is increased depending on the size of the display surface. This uneven illumination can make LCD televisions difficult to watch, especially if they are color televisions, in which the three primary colors are superimposed, whether color sequential or additive. This is extremely undesirable since it affects the resulting white body.

On the other hand, in the latter case, the light source must be installed facing almost the center of the screen, and therefore the image generating device must also be installed facing almost the center of the screen because it is installed between the light source and the screen. Therefore, there is a problem in that the projector body is located in the center of the space facing the screen and obstructs the visual field, and, like the former, uneven illuminance also occurs. Also, when this latter method is used for color image formation, concentrating the same pixels of the image projected onto the screen via the image generator for each of the three primary colors is
This is theoretically impossible unless there is a control means that detects the deviation and provides feedback.

In other words, it is usually impossible to obtain color convergence. Particularly when conventional lenses are used in optical systems, all aberrations occur around the optical axis, but with this method, which requires projection onto a screen using separate optical axes for the three primary colors, the accuracy of each part is improved. No matter how high you raise it, you won't be able to achieve three-color convergence due to aberrations.

The present invention has been made in view of the above-mentioned problems, and its main purpose is to provide an image forming apparatus that can mainly solve the problems of uneven illuminance on a display surface and the installation position of an image generating apparatus.

Furthermore, the combined invention aims to provide an image forming apparatus that can also solve the above-mentioned problems regarding the formation of color images.

Next, the present invention will be described in detail with reference to the drawings.

1 and 2 show the simplest example of an image forming apparatus according to the present invention. In the figure, D is the display surface that forms the image, L is the light source, C is the light control device for the light source, and G
indicate image generating devices, respectively. In the illustrated example, the light source 1 is a point light source, and the light from this light source 1 is reflected by a light control device C formed as a reflecting mirror and directed toward the display surface. An image generating device G is provided on the path of light from the light control device C toward the display surface, so that only the light that has passed through the image generating device G reaches the display surface.

The image generating device G has a transmitted light amount changing element portion corresponding to each pixel of the image, and if only a specific element portion is open to allow light to pass through, it is configured by the open element portion. An image corresponding to the pattern is formed on the display surface by the light reaching the display surface.

In its most basic form, the element part is an opening/closing window. Note that the image formed on the display surface is viewed from the side opposite to the image generating device G. Any pattern can be easily formed on the display surface by opening and closing the element portion using operation signals. According to the invention, a light control device C for sending light to the display surface to form an image on the display surface controls the light from the light source to reach the display surface with a substantially uniform luminous flux density. It is formed in such a way that it

In other words, assuming that the image generating device G is not interposed, the light control device C is configured so that the illuminance distribution on the display surface is uniform. Details of the light control device C will be described later.

The most practical example of the image generator G is a liquid crystal (LC) type image generator, but an electrochromic display image generator (ECD) can also be used. The principle of the liquid crystal image generator G is as shown in Fig. 3, in which 2 is a liquid crystal, 3 is a molecular alignment layer, 4 and 5 are transparent electrodes, 6 is a lath substrate, and 7 is a sealing material. shows. Polarizers and the like are not shown. The - side transparent electrodes 5 are microelectrodes arranged in a grid over the entire surface of the image generating device G, and the voltage between each electrode 4 can be arbitrarily changed. The area of each transparent electrode 5 constitutes each transmission scene changing enement portion E. As is well known, the amount of light transmitted through the liquid crystal belonging to the element portion E belonging to the transparent electrode 5 changes depending on the value of the voltage between a particular transparent electrode 5 and the opposing electrode 4. Therefore, if a video signal is input to each transparent electrode 5 using the video scanning signal input device 8 shown in FIG. appear. Images can of course appear as moving images or still images.

The light control device C can take various configurations.

An example in which the light control device C is formed as a reflection mirror 10 is shown in the first example.
2 and 4. The reflecting mirror 10 reflects a light flux emitted from a point light source toward the display surface, and the shape of the mirror surface is designed so that the reflected light flux reaches the display surface with uniform density.

The illustrated mirror surface has a shape that spreads the reflected light flux in the vertical and horizontal directions. The three-dimensional shape of such a mirror surface can be accurately determined by a computer by determining the light source, the reflection surface 7-io, the relative position and dimensions of the display surface, and the light distribution characteristics. The constant determined when designing the shape of the mirror surface is, for example, h s d Sa 5shf? shown in Figure FA2. is the value of Note that, as shown in FIG. 4, a light shielding plate 11 is provided to prevent the light from the light source from directly reaching the display surface.

The light control device C can also be formed by a 7-Renel plate 12 as shown in FIG. 5 instead of the reflecting mirror. 7. The Renel board 12 is made of a transparent plate having sawtooth projections on one or both sides, and by selecting the spacing and inclination angle of the sawtooth projections, it is possible to make light reach the display surface with uniform luminous flux density. . In addition, when using the 7-Renel plate 12, it is preferable that the light source be a linear light source in a direction perpendicular to the plane of the paper.

FIG. 6 shows another example of the light control device C. In this example, a specially shaped lens 13 is straddled in contact with the light source.

This lens 13 has a cross-sectional shape in which the front center portion 14 is four-sided and the portion near the outer periphery is curved. This shape can also be determined accurately by a computer.

In the light control device C shown in FIG. 7, a reflecting mirror 10 and a specially shaped lens 7:13 are used together. The reflecting mirror 10 reflects the light emitted from the light mL toward the display surface with uniform luminous flux density on the side opposite to the display surface, and the lens 13 reflects the light emitted from the light source toward the display surface on the side facing the display surface. Sends uniform luminous flux density to the surface. In this example, the light from the light source is utilized very efficiently.

The embodiment described below is an apparatus used for forming monochrome images. There have been monochrome image forming devices (for example, monochrome liquid crystal televisions) in which an image generating device (for example, a liquid crystal image generating device) is interposed between a light source and a display surface, but in this conventional image forming device, The light reaching the display surface from the light source does not have a perfectly controlled and uniform luminous flux density. Of course, we try to make the light reach the display surface with as uniform illuminance as possible, but the illuminance is still the brightest at the point closest to the light source and the darkest at the farthest point. This tendency becomes stronger as the display surface becomes larger, and fIv does not disappear even if the number of light sources is increased. According to the present invention, such problems are solved.

The features of the present invention are even more effective in the case of a color image forming apparatus. An example of a color image forming apparatus will be described below.

In FIG. 8, D and G respectively indicate a display surface and an image generating device, as in the case of FIG. The image generating device G is typically a monochrome liquid crystal image generating device,
It has the same structure and operation as that shown in Fig. fjS3. The display surface is a light diffusion plate or a light diffusion layer as in the case of FIG. In this embodiment, three light sources 3, R2, and R3 corresponding to the three primary colors of red, green, and blue are used to form a color image, and three light control devices C1, C2, and C3 are attached to them, respectively. be done. The light from each of the light sources L1, R2 or the light control device C1,
The image generator G is followed under the control of C7 or C3 to reach the display surface. Of course, any of the types mentioned above can be used as the light control device, but in the illustrated example, a reflecting mirror is shown. Each light control device CI, C7, C3 causes the light from each light source L1, I-2, R3 to reach the display surface with uniform luminous flux density.

In this embodiment, three primary color switching devices R1, R2, and R9 are provided in the paths of the light beams from the respective light control devices C1, C2, and C3. Each of the elements R2, R2, and R5 of this switching device is a type of light shutter device, and each element can be independently switched to either a light transmitting state or a light blocking state.

In principle, each of the elements R1, R2, and R3 may be an ordinary mechanical shutter, but in reality, it is preferable to use a liquid crystal shutter.

An example of this is shown in Figure tjS9.

The liquid crystal shutter R shown in the same figure is similar in principle to the liquid crystal device shown in FIG. Transparent electrodes 4a, 5a are placed on the outer surfaces of the molecular orientation layers 3a, 3a.
is arranged, and the outside thereof is sandwiched between glass substrates 6a, 6a. Moreover, a polarizer 20.20 is provided on the outside thereof.

Moreover, with this configuration, when a voltage is applied between both electrodes 4a and Sa, the liquid crystal shutter R opens and light is allowed to pass from one side to the other side, and when the voltage disappears, the liquid crystal shutter R opens.
is closed and light is blocked.

The light sources L1, R2, and R3 shown in Fig. 8 are light sources corresponding to each of the three primary colors, but in reality, instead of assigning a color to each light source, each light source is colored as shown in Fig. 10. It is desirable to send the light to the light control device C via an infrared ray removal filter 22 for removing heat rays, a lens 23, and a color filter 24 for primary colors. The color filter 24 is, of course, colored red, green, or blue.

As shown in FIG. 8, a video scanning signal input device 28 is connected to the liquid crystal image generating device G. This signal input device 28
From there, video scanning signals of the three primary colors of red, green, and evening are sent to the liquid crystal image generator G in a color sequential manner. The input signal from the signal input device 28 is also sent to the three primary color switching devices R, , R2, and R3, and one of the liquid crystal shutter devices, which are elements thereof, is sequentially opened and the other two are closed. That is, assuming that L, 1-z, and I-3 are red, green, and blue light sources, respectively, as described above, when a red video scanning signal is input to the liquid crystal image generator G, the red A voltage is applied to the shutter device R1 to open the shutter device R1, and the red light is transmitted through the liquid crystal image generator aG and sent to the display surface.

This is done similarly for green and blue.

In this way, the operation of the three primary color switching device and the operation of the video signal input device are synchronized.

Thus, images of the three primary colors appear on the display surface in a color sequential manner, resulting in the formation of a color image.

The use of shutter devices R3, R2, R3 is based on the light source.
This is advantageous in that blinking of R2 and I- is not required. In other words, the light source only needs to emit light continuously, which is preferable in terms of lifespan.

The color image forming method with the above configuration achieves excellent effects that could not be obtained in the past due to the light control devices C1, C2, and C3 that can create a substantially or completely uniform luminous flux distribution at will. It is.

When images of three primary colors are sequentially formed on a display surface using a conventional method in which a completely uniform luminous flux distribution cannot be obtained on the display surface, the illuminance on the display surface becomes uneven for each primary color image. The color itself of the color image created by combining the images of the three primary colors will be different from the original combined color. This deficiency 5α is further exacerbated because the light sources L1, R2, and R3 of the three primary colors are installed at different positions with respect to the display surface, as shown in FIG. In other words, regarding the side of Figure 8, the light source
In the case of a conventional light source that does not use the light control device C0, the red light from the display surface has a large illuminance on the left side and a low illuminance on the right side, so that the red color becomes stronger on the left side. Blue light from a light source has a high illuminance on the right side and a low illuminance on the left side, making the blue color stronger on the right side. This state cannot be resolved by conventional light control using a reflector or the like, and it is impossible to generate a correct composite color.

In order to eliminate this drawback, it is possible to install light sources of the three primary colors on the same optical axis (using one light source and rotating the color filters of the three primary colors in front of the light source), but is this a force?
- It is undesirable because it requires rotation-like grooves in the filter, and still leaves a non-uniform illuminance distribution on the display surface.

In contrast, in the present invention, no matter where the light sources Ll, L2, and R3 are placed with respect to the display surface D1, the luminous flux distribution of the light from each light source is made completely uniform on the display surface. By designing, nII
The above problem will be resolved.

This embodiment of the present invention is advantageous in that a monochrome liquid crystal image generating device G can be used even though it is a color image generating device. Color liquid crystal image generating devices are extremely complex and expensive because they must be provided with minute slurry filters for the three primary colors in the portion corresponding to each pixel. However, this embodiment of the present invention is a relatively inexpensive monochrome image generating device. Since it is sufficient to use a liquid crystal generator, the overall manufacturing cost can be reduced.

Furthermore, the advantage of this embodiment is that the opening time of each shutter of the three primary color switching device, that is, the ratio of the appearance time of each color, can be freely controlled, thereby controlling the spectral characteristics and visibility characteristics of the light source and color filter. It is possible to perform matching.

As described above, this embodiment provides a color liquid crystal television that is as simple as a slightly modified monochrome liquid crystal television and has excellent resolution and brightness.

FIG. 11 shows how to freely change the positions of three light sources L1, R2, R3, light control devices C1, C2, C3, and shutter devices R1, R2, R3 of the three primary color switching devices with respect to the display surface. It shows that it is possible. Regardless of the position of the light source R2, R3, the light control device C3
, C2, and C3 allow uniformly distributed light beams to reach the display surface. In this example, in particular, a reflecting mirror C2 serving as a light control device receives the light beam from the light source L2 and reflects it in a crossed state. As described above, various aspects can be considered for the design of the light control device. Similarly, the light control device C shown in FIG. 10 also causes the reflected light beams to intersect. This design is advantageous in that the area of the shutter device R can be reduced.

As described above, the use of a light control device provides various degrees of freedom in design.

FIG. 12 shows the simplest example of a projection type image forming apparatus according to the present invention. In the figure, D is a display surface, L is a light source, C is a light control device, G is an image generation device, and 8 is a video signal input device.
is not in contact with the display surface. The light from the light source is controlled by a light control device C such as a reflecting mirror and reaches the display surface with a uniform luminous flux distribution. Then, the light from the light control device C is transmitted through the image generation device G and projected, thereby forming an image on the display surface. This image also appears on the front side of the display surface.
Also, depending on the type of display surface, 1! It can also be seen from the rear. As the image generating device G, the same device as described in the previous embodiments can be used, but typically a monocolor (or color) liquid crystal image generating device as shown in FIG. 3 is used. In addition, the light control device C
As shown in FIGS. 4 to 7, the same ones as shown in FIGS. 4 to 7 are used.

The effects of this embodiment are the same as those described for the embodiment of FIG. Benefits include being able to freely design the device (light source, light control device, image generation device) on the premise that it is placed in a position where it does not interfere with vision.

FIG. 13 shows an embodiment in which the principle of FIG. 12 is used to form a color image. In the same figure, D is the display surface, and three primary color light sources Ll and L are used to project light onto the display surface.
2, L3 are provided, which are for example red, green and blue light sources from left to right. Each light source is, for example, a 10th light source.
As shown in the figure, the light source, infrared removal filter, lens,
It can be configured with primary color filters. Behind each light source L1, L2, L3 is a light control device ClSC2,
C5 is provided. As the light control device, any of the above-mentioned types can be used. The light control devices C1, C2, and C1 each send light toward the display surface with a uniform luminous flux distribution, and the image generating device G is placed in the path of the luminous flux.
1, G2, and G3 are provided, respectively. Each image generating device is a more color image generating device, and is formed by, for example, a liquid crystal image generating device. And image generator G1, G
2. G3 is equipped with a video signal input device that inputs the video signals of the three primary colors separately and in synchronization. 130 is connected. The primary color images from the three image generators are overlapped on the display surface to form a color image by additive color mixing.

By the way, when an image is formed on the screen surface using the additive color mixing method as described above, a convergence scan is required. That is, each pixel of all the primary color images had to be concentrated at one point on the screen surface, which was the most complicated and time-consuming aspect.

In the conventional method, it was theoretically impossible to obtain complete convergence unless there was a means to analyze and feed back the positional deviation.

Especially when using conventional lenses in the optical system, all aberrations occur around the optical axis, so especially when projecting multiple primary color images on a screen that do not have the same optical axis,
No matter how much you improve the precision of each part, convergence basically cannot be achieved. The misalignment between each image will further increase if the screen surface is enlarged or the distance from the screen is reduced.

This embodiment of the invention fundamentally solves the above-mentioned problems and provides a simple configuration that does not require m'J, correction.

In this regard, the display surface (screen surface) D
The first correlation between the above image and the image of image generator G is
Considering Figure 4, the point wxyz on the display surface
, the point W'X'Y'Z' of the image generator, and the point W '' X '' Y '' Z of the reflecting mirror of the light control device C.
”)-wo&'i R line w w' w, x x'X”
, Y Y'Y" , Z Z'Z" (7) The extensions of each line are concentrated at one point O, and wxyz and w'x'
In conventional projection devices, both images are similar only when y'Z' are parallel. However, such a relationship is not necessarily required when using a light control device as in the present invention. For example, if the light from the light control device is made to converge and intersect in the middle, the similarity and relationship will be completely destroyed. Nevertheless, there is a clear correlation between each point of the image on the display surface and each point of the image of the image generator (transmitted light amount changing element portion E). This is determined by the light flux control analytical function of the light control device.

Considering the case of the present invention with respect to FIG. 13, since the distance between the light control device and the image generation device and the orientation of the image generation device are different, in order to obtain complete convergence, it is necessary to A generator is required. Although it may seem complicated to require three separate image generators, since the dot placement is uniquely determined by the light flux control analysis function, the dot placement can be determined using a computer. It is extremely easy to set up.

As described above, according to the feature of the present invention, the dot (transmitted light amount changing element portion) of the image generating device is adjusted for each primary color.
The light flux control analytical relationship is all folded into the pattern of the dot pattern and the shape of the light control device, and as a result, there is no similarity between the image on the display surface and the dot pattern of the image generator.

In the conventional method, convergence was considered after creating an image similar to the image to be formed on the display surface using an image generator, but in the case of the present invention, convergence can be achieved by designing based on a light flux control analysis function. Obtained naturally.

It should be noted that chromatic aberration occurs when a specially shaped lens as shown in FIG. 6 is used as a light control device, but since each lens is used in monochrome color, almost no problem occurs.

15 and 16 show a modification of the embodiment shown in FIG. 13. In this example, only one light source is provided, and the light from it passes through the infrared ray removal filter 31 and is sent to each light control device C2, C3, and then the light beam distribution is adjusted by each light control device. reaches the display surface through three primary color filters 32, 33, 34 and image generators G1, G2, G3. Note that some members are omitted from illustration in FIG. 15. In this modification, the light beams from the light control devices C1, C0 are directed toward the display surface after converging and intersecting.

In the embodiments described above, the display surface is planar, the image generator G is also planar, and the light control device C is given a shape that distributes the light flux over the surface. However, it is clear that the principles of the present invention can also be applied to the case of a line corresponding to a line whose width in one direction is reduced to the utmost limit. In this case, the light control device is designed to form a bright line with illuminance uniformly distributed in the length direction. At this time, the image generating device G is rod-shaped or plate-shaped with a narrow width. In the examples shown in tIS 4 to 7, the light control device for forming the bright line can be designed to polarize the luminous flux in a direction that makes an angle to the plane of the figure so that it intersects the line on the display surface. good.

Note that although a uniform luminous flux distribution is normally obtained, depending on the shape of the display surface, a non-uniform luminous flux distribution may be intentionally created in order to obtain the most appropriate state.

As described above regarding the embodiments, according to the present invention,
It is possible to obtain an image forming apparatus that has no unevenness in illuminance, is convenient for installation, can produce correct coloring with excellent convergence when forming a color image, and has a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of a monochrome image forming apparatus of the present invention, FIG. 2 is a perspective view of the same, FIG. 3 is an enlarged sectional view of a liquid crystal image generating apparatus, FIGS. 6 and 7 are cross-sectional views showing different examples of light control devices, FIG. 18 is a perspective view of an embodiment of a color image forming apparatus using the principle of the embodiment shown in FIG. 1, and FIG. 59 is a liquid crystal type A sectional view of the shutter device, FIG. 10 is a perspective view showing an example of the primary color light source in the embodiment of FIG. 8, FIG. 11 is a perspective view of a modification of the embodiment of FIG. 8, and FIG. 12 is a perspective view of the present invention. Monocolor image formation 5!
FIG. 13 is a perspective view of the embodiment of the pond at position c; FIG. 13 is a perspective view of a color image forming apparatus using the principle of the embodiment of FIG. 12;
15 is a perspective view of a modification of the embodiment shown in FIG. 13, and FIG. 16 is a side view of the same. D...Display surface, G, G,, G2. G...
Image generating device, c, c, , c2. c, . . . light control device, L IL + fL 2 , L 3 . . . light source, R
, R, , R2, R3... Shutter device (3 primary color switching device, E... Transmitted light amount changing element part, 2...
・Liquid crystal, 4, 5, 4a, 5a...Transparent electrode, 10・
... Reflection mirror, 12...7 Lenel plate, 13... Lens, 22.31 ... Infrared removal filter, 23.
...Lens, 24', 32, 33.34...Color filter, 8,28.30...Video signal input device. Patent Applicant: Masa Negishi Indication of the case Patent application 2 filed on February 10, 1980, Title of the invention Kzo Kaisei Soute image forming device 3, Person making the amendment Relationship to the case Patent applicant postal code 336 4. Number of inventions increased by the amendment 0 5. Application subject to amendment, specification and drawings 6. Contents of amendment

Claims (10)

[Claims] (1) A display surface, a light source located at a distance from the display surface, and a light provided in the light path so as to control the light from the light source so that the light reaches the display surface with substantially uniform luminous flux density. The image generating device includes a control device and an image generation device interposed between the light control device and the display surface, and the image generation device has a transmitted light amount changing element portion corresponding to each pixel of an image to be formed, and each element portion has a Signal T! ) An image forming apparatus configured to provide separate transmission view control. (2) The image forming device according to claim fISi, wherein the image generating device is a liquid crystal image generating device, and the display surface is a light diffusing surface formed on a side of the image generating device opposite to the light reaching side. . (3) The image forming apparatus according to claim Pt51, wherein the light control device includes a mirror that reflects light from the light source. (4) The image forming apparatus according to claim ttSi, wherein the light control device includes a 7-Renel plate that transmits light from the light source. (5) The image forming apparatus according to claim 1, wherein the light control device includes a lens that transmits light from a light source. (6) The display surface, three light sources of the 3Jg colors of red, red, and black located at a distance from the display surface, and the light from each light source is controlled to provide light with substantially uniform luminous flux density to the display surface. A light control device is provided in the path of light from each light source, and an image generation device is provided adjacent to the light source side of the display surface, and the image generation device controls each pixel of the image to be formed. a three primary color switching device which sequentially sends light from the light source of the three primary colors to the image generating device with a time difference; An image forming apparatus further comprising: a video signal input device for controlling the amount of light transmitted through an element portion; and a synchronization device for synchronizing the three primary color switching device and the video signal input device with respect to color. (7) The image forming apparatus according to claim 6, wherein the image generating device is a liquid crystal image generating device. (8) The image forming apparatus according to claim 6, wherein the three primary color switching device comprises a liquid crystal shutter device. (9) Three light sources of the three primary colors of red, green, and blue are located away from the display surface and the die blade surface, and the light from each light source is controlled to provide light with substantially uniform luminous flux density to the display surface. A light control device is provided in the path of light from each light source so that the light reaches has a transmitted light amount changing element portion corresponding to each pixel, and images generated by the three image generating devices are overlapped on the display surface,
An image forming apparatus in which each image generating device is connected to a video signal input device that separately inputs video signals of three primary colors in synchronization. (10) The image forming apparatus according to claim 9, wherein the image generating device is a liquid crystal image generating device.