JP3007008B2 - Image display / input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display / input device having two functions, an image display function and an image input function.

[0002]

2. Description of the Related Art Conventionally, as an image display / input panel having two functions of an image display function and an image input function, Japanese Patent Publication No. 5-40927, "Image Input / Output Device" (Hitachi Microcomputer), JP-A-63-163886 "Liquid crystal panel for display and input" (Alps Electric)
Some proposals have been made, as typified by JP-89230-A "Image reading / display device" (Fuji Xerox) and JP-B-60-1646-A "Display and input device" (Nippon Telegraph and Telephone).

In the image input / output device disclosed in Japanese Patent Publication No. 5-40927, an image input / output panel is formed by arranging a plurality of pairs of light emitting elements and light receiving elements in a matrix on a plane. When operating the image input / output panel as an image display device, the light emitting element is driven based on image data. On the other hand, when operating the image input / output panel as an image input device, a sheet on which density information such as characters is written is overlapped so that the information writing surface faces the image input / output panel. Then, in this state, the light emitting element emits light to shine light on the paper, and the reflected light from the paper is received by the light receiving element paired with the light emitting element.

In the above-mentioned Japanese Patent Application Laid-Open No. 63-163886, entitled "Liquid Crystal Panel for Display and Input", a light receiving element is formed in a pixel of the liquid crystal panel. When the liquid crystal panel is operated as an image input device, light is radiated from the outside onto the paper, and the reflected light or transmitted light is incident on the liquid crystal panel. To detect.

Also, in the above-mentioned Japanese Patent Application Laid-Open No. 5-89230, "image reading / display device", a light receiving element is incorporated in a simple matrix liquid crystal panel. Then, image information is input in the same manner as in the case of the above-mentioned Japanese Patent Application Laid-Open No. 63-163886 "liquid crystal panel for both display and input".

In Japanese Patent Publication No. Sho 60-1646, "display / input device", a display driving unit and a light receiving driving unit are arranged in one pixel of a panel. Then, at the time of input, the light incident on the panel is blocked by a finger or other object, thereby turning off the light-receiving transistor of the light-receiving drive unit and detecting the input coordinates.

[0007] In any of the above-mentioned image display / input panels, when operating as an image input device, the display element is used as a light emitting element. Then, light emitted from the display element (light emitting element) and reflected by a document or the like is received by a light receiving element formed in a pair with the display element. Hereinafter, the above-mentioned Japanese Patent Publication No. 5-40927
The basic operation of the prior art will be described with reference to the publication "Image Input / Output Device" as an example.

FIG. 15 is a perspective view of an image input / output panel as a conventional image display / input panel. FIG. 16 is a partially enlarged perspective view showing a specific structure of the image input / output panel. FIG. 17 is an operation explanatory diagram of a case where the image input / output panel functions as an image display device and a case where it functions as an image input device.

As shown in FIG. 15, the image input / output panel is formed by arranging pixels 2 in a (n × m) matrix on a single rectangular substrate 1. As shown in FIG. 16, each of the pixels 2 has one display element 2a.
And one input element 2b. Here, for example, a light emitting element such as a light emitting diode is used as the display element 2a, while a light receiving element such as a phototransistor is used as the input element 2b. The display element 2a and the input element 2b are arranged adjacent to each other in such a manner that the respective light emitting surfaces or light receiving surfaces face upward.

When the image input / output panel configured as described above operates as an image display device, for example, as shown in FIG. The display device 2a of each pixel 2 corresponding to a dot is turned on or off based on image data to display a two-dimensional figure, character, or the like, operating in the same manner as a display device having a matrix configuration.

In order to operate the image input / output panel as an image input device, as shown in FIG.
The display device 2a of each pixel 2 is sequentially driven to emit light, and the intensity of the reflected light from the document 3 is detected by the input device 2b. Then, weak reflected light reflected on the surface of the original having a low reflectivity to which the ink 4 for drawing a pattern adheres, or strong reflected light reflected on the surface of the original having a high reflectivity to which the ink 4 does not adhere is applied to the input element 2b. Incident. As a result, by binarizing the electric signal read by the input element 2b, it is possible to obtain image data representing a shading pattern on the document 3.

The above-described conventional image display / input panel has been described with reference to Japanese Patent Publication No. 5-40927, entitled "Image Input / Output Device".
Japanese Patent Application Laid-Open No. 5-89, "Display / input combined liquid crystal panel"
In the case of Japanese Patent Publication No. 230 "image reading / display device", a light receiving element is incorporated in a pixel of a liquid crystal panel and operated in the same manner as in the case of Japanese Patent Publication No. 5-40927 "image input / output device". .

FIG. 18 shows an example in which a light receiving element is incorporated in a pixel of the liquid crystal panel.
1 shows a schematic configuration of a liquid crystal panel in JP-A-163886, “Display / input liquid crystal panel”.

A gate line 6, a source line 7 and a signal line 8 are arranged in a grid on the inner surface of the substrate on which the pixel electrode 5 of the liquid crystal cell is formed. Near the intersection of the gate line 6 and the source line 7, a thin film transistor A forming a switching element is formed. The source line 7 is connected to the source electrode of the thin film transistor A, the gate line 6 is connected to the gate electrode of the thin film transistor A, and the drain electrode 9 of the thin film transistor A is connected to the pixel electrode 5.

On the other hand, the gate line 6 and the signal line 8
A thin-film optical sensor B constituting a light receiving element is formed in the vicinity of the intersection with. A gate line 6 is connected to one end of the thin-film optical sensor B, and a signal line 8 is connected to the other end of the thin-film optical sensor B.

In the liquid crystal panel having the above structure, when a predetermined voltage corresponding to image data is applied to the gate line 6 and the source line 7, the thin film transistor A is turned on, a voltage is applied to the pixel electrode 5, and the liquid crystal cell is turned on. It is driven to display an image. When a predetermined voltage is applied to the gate line 6, the gate line 6 connected to the one end of the thin-film optical sensor B via the thin-film optical sensor B on which light is incident.
From the signal line 8 connected to the other end,
The intensity of light is converted into an electric signal.

Hereinafter, the structure and operation of the thin film transistor A and the thin film optical sensor B will be described in more detail. FIG. 19 is a detailed cross-sectional view of the vicinity of the substrate in the liquid crystal panel shown in FIG. A thin film transistor A as a switching element and a thin film optical sensor B as a light receiving element are formed inside one substrate 11 of the liquid crystal cell.

The thin film transistor A is formed as follows. That is, on the substrate 11, the gate electrode 12a, the gate insulating layer 13, the semiconductor layer 14, and the highly doped layer 15 which are drawn from the gate line 6 are formed. The source line 7 is connected to the semiconductor layer 14 via the highly doped layer 15, while the drain electrode 9 is also connected to the semiconductor layer 14 via the highly doped layer 15. A channel portion is formed between the source line 7 and the drain electrode 9, and a light-shielding film 16 is formed above the channel portion. Further, the drain electrode 9 is connected to the transparent pixel electrode 5.

The thin-film optical sensor B is formed as follows. That is, the gate electrode 12 b drawn from the gate line 6 and the signal line 8 are formed on the substrate 11. The gate electrode 12
b and the signal line 8 are connected via the diode 17 and the thin-film optical sensor B. The diode 17
Is formed by sequentially laminating a light shielding film 18, an insulating film 19, a semiconductor layer 20, a highly doped layer 21, and metal layers 22 and 23. Then, the gate electrode 12b and the semiconductor layer 20
Are connected via a metal layer 22, and the metal layer 23 and the semiconductor layer 20 are connected via a highly doped layer 21. Further, a light shielding film 24 is formed above the semiconductor layer 20.

On the other hand, the thin-film optical sensor B comprises a light-shielding film 2
5, an insulating layer 26, a photoconductive semiconductor layer 27, a highly doped layer 28, and metal layers 23 and 29 are sequentially laminated. Then, the diode 17 and the thin film optical sensor B are connected via the metal layer 23, and the thin film optical sensor B
Is connected to the signal line 8.

In the thin film transistor A and the thin film optical sensor B having the above-described structures, when a voltage is applied to the gate line 6, a voltage is applied to the gate electrode 12a of the thin film transistor A, and the thin film transistor A and the thin film optical sensor B approach the gate electrode 12a in the semiconductor layer 14. A carrier is formed in the channel portion. When a voltage is applied to the source line 7 in this state, the source line 7
Then, a current flows to the drain electrode 9 to apply a drive voltage to the pixel electrode 5. Thus, by selecting the gate line 6 and the source line 7 to which a voltage is applied, a desired liquid crystal cell is driven and an image is displayed. The light-shielding film 16 is for preventing the semiconductor layer 14 from being irradiated with external light and causing malfunction due to photoconductivity.

Next, when a voltage is applied to the gate line 6, a voltage is applied to the gate electrode 12b of the diode 17. When light is applied to the thin film optical sensor B from the outside in this state, the semiconductor layer 27 has conductivity and the gate electrode 12b causes the metal layer 22, the semiconductor layer 20, the highly doped layer 21, the metal layer 23, A current flows through the signal line 8 through the doping layer 28, the semiconductor layer 27, and the metal layer 29. Therefore, which thin film optical sensor B connected to the gate line 6 to which the voltage is applied is irradiated with the light can be detected by the signal line 8 through which the current flows, and can be taken out as an output. Thus, two-dimensional optical information can be converted into an electric signal by sequentially applying a voltage to each gate line 6 and detecting a current appearing on the signal line 8. The diode 17 is
Not selected (i.e., no voltage applied)
This is for preventing a current from flowing from the signal line 8 to the gate line 6.

That is, the above-mentioned Japanese Patent Publication No. 5-409.
No. 27, "Image input / output device" (hereinafter referred to as a first conventional example) uses a light emitting diode as a light emitting element constituting the display element 2a. On the other hand, in Japanese Patent Laid-Open Publication No. 63-163886 described later, "Liquid Crystal Panel for Display and Input" (hereinafter referred to as a second conventional example), a liquid crystal panel itself or a pair of a liquid crystal panel and a backlight is used. The on / off control is performed for each pixel, and the pixel is used as a light emitting element. In the case of the second conventional example, similarly to the case of the first conventional example, the liquid crystal panel and the backlight pair are sequentially turned on / off for each pixel to irradiate the original, and the reflected light from the original is thinned. The light / dark pattern on the document is read by receiving light with the optical sensor B and performing photoelectric conversion.

[0024]

However, in the first conventional example, when operating as an image input device, the display element is used as a light emitting element, and the light is emitted from the light emitting element (display element) and the surface of an original or the like is illuminated. The light reflected by the light-emitting element is received by the light-receiving element formed as a pair with the light-emitting element. Therefore, there is a problem that sufficient resolution cannot be obtained at the time of image input due to the directional characteristics of the light from the light-emitting element. . Further, in the above-mentioned second conventional example in which a pair of a liquid crystal panel and a backlight is used as a light emitting element, the light emitting directivity characteristic of light emitted from a liquid crystal cell is a very characteristic characteristic, so that there is a specific problem. Occurs.

Hereinafter, the reason why the above problem occurs will be described. (1) Problems Related to Resolution in the First Conventional Example FIG. 20 shows a state in which a pattern actually drawn on the original 3 is input in the first conventional example. The light emitted from the light emitting element (display element) 2a constituting the pixel 2 and reflected at the point d on the back surface of the document 3 forms a pair with the light emitting element 2a and enters the light receiving element 2b constituting the pixel 2 And is photoelectrically converted. At this time, if the light path of the light incident on a certain light receiving element 2b is only the light path a from the light emitting element 2a forming a pair, the reflected light having the intensity corresponding to the shading of only the point d of the document 3 is reflected on the light receiving element 2b. , The image input / output panel in the first conventional example operates well.

However, in general, the light emitting element 2a does not emit light only in the direction of the light path a. For example, as shown in FIG. 21, the light emitting element 2a has a light emitting directivity characteristic that spreads broadly with respect to a perpendicular to a light emitting surface of the light emitting element 2a. Therefore, as shown in FIG. 20, the light path to the light receiving element 2b includes not only the light path a but also the light path b and the light path c from the light emitting elements forming the pixels adjacent to the pixel 2 at the same time. Become.
As a result, the light receiving element 2b is paired with the light emitting element 2a
(Light path a)
), As well as light radiated from the light emitting elements 2a 'and 2a "and reflected at the points e and f on the document 3 (light from the optical path b and the optical path c). The light reflected at a plurality of points on the document 3 reaches one light receiving element 2b at the same time.

As described above, when the light reflected at a plurality of points on the document 3 reaches one light receiving element 2b at the same time,
The density information at a certain point on the original 3 is detected by the plurality of light receiving elements 2b located in the vicinity, and a certain point on the original 3 obtained from the electric signal photoelectrically converted by the image display / input panel. The shading information is blurred. That is, there is a problem that the resolution at the time of image input cannot be sufficiently obtained.

Such a problem is caused by sequentially turning on each pixel on the liquid crystal panel using the liquid crystal panel and its backlight.
In the case of the second conventional example in which the light emitting element 2a in the first conventional example is turned off / off, the same occurs in the second conventional example.

(2) Specific problem in the second conventional example The above-mentioned liquid crystal panel and its backlight are used to sequentially turn on / off each pixel on the liquid crystal panel to achieve the light emitting element of the first conventional example. In the case of substituting, the light radiation directivity characteristic of the light emitted from the liquid crystal cell is a very peculiar characteristic, so that a new peculiar problem occurs. Hereinafter, this will be described.

FIG. 22 shows an example of the light radiation directivity of light emitted from the pixel. When a specific pixel 32 in the liquid crystal panel 31 is turned on, as shown by a solid line, strong light is radiated not only in the vertical direction but also in a direction substantially nearly horizontal to the pixel 32. In addition, even when the pixel 32 is turned off, as shown by the dotted line, strong light emission remains in a direction nearly horizontal. That is, irrespective of the ON / OFF state of the pixels on the liquid crystal panel, there is always strong light emission in a direction nearly horizontal.

This means that in the second conventional example, regardless of the ON / OFF state of the pixel 32, the first state shown in FIG.
As with the light emitting directivity characteristics of the light emitting element 2a in the related art,
One pixel 32 irradiates a plurality of points on the document, and means that reflected light from a plurality of points on the document arrives at one light receiving element at the same time. That is, each pixel 32 is sequentially turned on / off using the liquid crystal panel 31 and its backlight 33.
In the case of turning off, the operation principle itself of irradiating the original with only the turned on pixels 32 is not satisfied. Therefore, not only the problem that the resolution at the time of image input is deteriorated due to the light emission directivity characteristics of the light emitting element, but also a specific problem that the image input operation itself cannot be performed occurs.

Therefore, an object of the present invention is to irradiate a specific narrow portion on an original with only turned-on pixels, thereby enabling image input by a liquid crystal panel and preventing deterioration in resolution at the time of image input. An image display / input device is provided.

[0033]

In order to achieve the above object, an image display / input device according to the present invention comprises a flat plate-shaped backlight which emits light from one side, and a light which is incident from the backlight. A directional plate that receives light from the surface and emits light in the direction perpendicular to the light incident surface from the light emitting surface, and an image display / input panel in which a light receiving element is incorporated in each pixel of the liquid crystal display panel are sequentially laminated, and image display is performed. Sometimes, on / off of each pixel in the image display / input panel is controlled according to the image data to display an image corresponding to the image data, while at the time of image input, the pixels of the image display / input panel are sequentially turned on. An image display / input device having a control circuit for turning on / off and scanning a document, wherein the directional plate has a flat surface on which light from the backlight is incident and a prism-shaped unevenness. It is formed by laminating two prism sheets each having an uneven surface facing each other so that the extending directions of the unevenness are orthogonal to each other. At the time of the image input, the light is emitted from the backlight, turned on the directional plate, and turned on. The light passing through the pixels is reflected by a document placed on the image display / input panel, and is incident on the light receiving element.

Further, according to the image display / input device of the present invention, the apex angle θ of the convex portion on the concave / convex surface of the prism sheet is provided.
Is preferably in the range of 90 degrees to 120 degrees.

Further, in the image display / input device of the present invention, the arrangement interval of the convex portions on one of the two prism sheets constituting the directional plate is x, and the arrangement interval of the convex portions on the other is y. When the pixel pitch of the image display / input panel is z, it is desirable that the relationship x, y = z or x, y≪z be satisfied.

[0036]

When an image is displayed, the light radiated from the backlight and incident on the directional plate from the plane of the incident surface is changed in its traveling direction to a direction perpendicular to the incident surface when passing through the directional plate. It leads to a panel that can also be used for image display and input. The control circuit controls ON / OFF of each pixel in the image display / input panel according to the image data, and displays an image corresponding to the image data on the image display / input panel. On the other hand, at the time of image input, similarly to the case of the image display, light emitted from the backlight and whose traveling direction has been changed by the directional plate to a direction perpendicular to the incident surface reaches the image display / input panel. The control circuit sequentially turns on / off each pixel in the image display / input panel and scans the original placed on the image display / input panel.

As a result, at the time of the image input, the light condensed by the ON pixels of the image display / input panel and emitted in the vertical direction is reflected by the original and incorporated in the ON pixels. The light is received only by the light receiving element. Thus, image input is performed at a high resolution.

Further, in the image display / input panel according to the present invention, the light incident on the directional plate is projected by the convex portion having an apex angle θ of 90 ° to 120 ° on the prismatic uneven surface when passing through the directional plate. The light is refracted and its traveling direction is changed to a direction perpendicular to the incident surface.

Further, the image display / input panel of the present invention includes an arrangement interval x of the projections on one prism sheet constituting the directional plate, an arrangement interval y of the projections on the other prism sheet, and an image display input / output panel. Since the relationship of x, y = z or x, y≪z is established with the pixel pitch z of the input / input panel, the concave and convex portions of the two prism sheets are moire with the image display / input panel. It is prevented from happening.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows a schematic configuration of an image display / input device according to this embodiment.

In FIG. 1, reference numeral 41 denotes an image display / input panel. As shown in FIGS. 18 and 19, one pixel is formed by a liquid crystal display element and a light receiving element, and an image display function and an image input function are formed. It has both functions. Reference numeral 42 denotes a backlight, which functions as a light emitting element together with each pixel of the image display / input panel 41. Reference numeral 43 denotes a directional plate which is an important component of the present embodiment. A control circuit 44 controls the image display / input panel 41 to execute an image display operation and an image input operation. When the image display / input device having the above configuration is operated as an image input device, an original 45 to be image-input is placed on the image display / input panel 41 by printing the printing surface of the document 45 on the image display / input device 4.
It is placed on the image display / input panel 41 toward one side.

As shown in FIG. 2, the backlight 42 comprises a fluorescent lamp 46, a light guide plate 47, a reflection plate 48, and a diffusion plate 49. The light emitted from the fluorescent lamp 46 is reflected by the reflection plate 48 toward the light guide plate 47, propagates through the light guide plate 47, and is emitted from the emission surface C of the light guide plate 47 toward the diffusion plate 49. Thus, the light radiated from the radiation surface C is diffused by the diffusion plate 49, and is emitted as diffused light into space.
At this time, since the radiated light is diffused light, its emission directivity has characteristics as shown in FIG.

FIG. 3 shows a backlight 4 having the above configuration.
2 shows emission directivity characteristics per minute area. In the backlight 42 according to the present embodiment, uniform radiation characteristics can be obtained from the diffusion plate 49 in a substantially hemispherical direction. Since the radiating surface of the backlight 42 is a set of minute areas having such light emitting directivity characteristics, the radiating surface as a whole emits diffused and substantially scattered light rays.

The light radiation directivity diagrams shown in FIGS. 12 and 13 and the light transmission directivity diagrams shown in FIG. 14 all show the characteristics per minute area of the target object. Therefore, the directional characteristics per minute area are gathered to exhibit the directional characteristics of the entire target object.

As shown in FIG. 5, the directional plate 43 is
The prism sheets 55 and 56 are stacked.
As shown in FIG. 4 (represented by the prism sheet 55), one surface of each of the prism sheets 55 and 56 is a smooth flat surface 51.
The other surface is an uneven surface 54 on which a concave portion 52 and a convex portion 53 are formed such that many rod-shaped prisms are arranged in parallel.
It is. When the two prism sheets 55 and 56 are stacked, they are arranged such that the extending directions of the concave portions 52 and the convex portions 53 are orthogonal to each other.

FIGS. 6 to 10 are explanatory diagrams of the operation of the directing plate 43. FIG. First, the operation of one prism sheet 55 will be described with reference to FIGS. As shown in FIG. 6, a large number of concave portions 52 and convex portions 5 are arranged in parallel.
The light g perpendicularly incident on the prism sheet 55 from the plane 51 side along the plane M orthogonal to the extending direction of the third 3 and the light h obliquely incident along the plane M are prism-shaped irregular surfaces on the opposite side. The concave portion 52 or the convex portion 53 at 54 (see FIG. 4)
, And both light are emitted as light substantially perpendicular to the plane 51. As shown in FIG. 7, a light i vertically incident on the plane 51 along a plane L parallel to the extending direction of the concave portion 52 and the convex portion 53 and a light j obliquely incident on the plane L Are not affected by the concave portion 52 or the convex portion 53 on the opposite side, and are both emitted while maintaining the incident direction to the plane 51.

This will be described in more detail with reference to FIGS. As described above, the prism sheet 5
5 and 56 are used by being laminated on the diffusion plate 49 of the backlight 42. In FIGS. 8 and 9, it is assumed that the plane 51 of the prism sheet 55 is in close contact with the diffusion plate 49. 3 shows a light path in the case where light is radiated radially from a point D having a small area of the diffusion plate 49 in accordance with the light emission directivity characteristics shown in FIG.

FIG. 8 shows a cross section when light is incident on the prism sheet 45 from the plane 51 side along the plane M in FIG. In this case, light emitted from a point D having a small area on the diffusion plate 49 is incident on the prism sheet 55 from the flat surface 51 side, is refracted by the concave portion 52 or the convex portion 53, and is substantially perpendicular to the flat surface 51. Recess 5
2 and the projection 53.

Such an operation substantially coincides with the operation of the plano-convex lens 58 as shown in FIG. Therefore, what kind of incident light on the prism sheet 55 is emitted as light substantially perpendicular to the plane 51 depends on the angle θ between the concave portion 52 and the convex portion 53 of the prism sheet 55. Although a detailed description of the method of calculating the angle θ is omitted,
For example, as will be described later, when the pitch of the irregularities of the prism sheet 55 is about 300 microns, the thickness of the prism sheet 55 is about 1 mm, and the material of the prism sheet 55 itself is polyvinyl chloride, ±
In the case of emitting light within 10 degrees, θ may be about 115 degrees.

The angle θ is set such that the material of the prism sheet 55 is a high-density material such as polycarbonate and a material having a refractive index higher than that of acrylic resin, glass or air, and the thickness of the prism sheet 55 is 150 μm to 1 mm. The image display / input panel 41 having a pixel pitch of 200 μm to 350 μm is used, and in consideration of emitting light within ± 5 ° to ± 15 ° with respect to a perpendicular to the plane 51, the angle is set to 90 ° to 120 °. It is preferable to set.

FIG. 9 shows a cross section when light is incident on the prism sheet 55 from the plane 51 along the plane L in FIG. In this case, the light emitted from the point D on the diffusion plate 49 and incident on the prism sheet 55 from the flat surface 51 side is incident substantially parallel to the extending direction of the concave portion 52 or the convex portion 53. The light exits from the uneven surface 54 while maintaining the angle of incidence on the prism sheet 55. Such an operation is the same operation as when light is simply incident on a glass plate, and light simply refracts twice and passes.

The case where light is incident along a plane M perpendicular to the extending direction of the concave portion 52 and the convex portion 53 in the prism sheet 55 and the case where light is incident along a parallel surface L are described above. However, in the present embodiment, as shown in FIG. 10, two prism sheets 55 and 56 are used by being stacked such that the extending directions of the concave portions 52 and the convex portions 53 are orthogonal to each other. At this time, the light k which is incident on the prism sheet 56 located on the diffusion plate 39 side from the plane 57 side perpendicularly to the plane 57 is incident on the prism sheet 56 as shown in FIG.
Since the light g has the same relationship as the light g, the light becomes substantially perpendicular to the plane 57 of the prism sheet 56 and is emitted to reach the plane 51 of the prism sheet 55. Since this light has the same relationship with the prism sheet 55 as the light g in FIG. 6, it is emitted as light that is substantially perpendicular to the plane 51 of the prism sheet 55. That is, the light k that enters the prism sheet 56 from the plane 57 side perpendicularly to the plane 57 passes through the prism sheets 56 and 55 and exits as it is.

The prism sheet 56 has a recess 52
And light 1 obliquely incident along a plane M perpendicular to the extending direction of the projection 53 is incident on the prism sheet 56 as shown in FIG.
Since the light has the same relationship as the light h, the light exits as light substantially perpendicular to the plane 57 of the prism sheet 56 and reaches the plane 51 of the prism sheet 55. Then, since this light has the same relationship with the prism sheet 55 as the light g in FIG.
The light is emitted as light that is substantially perpendicular to the light. That is, the light 1 that is obliquely incident on the prism sheet 56 along the plane M from the plane 57 side is also emitted from the prism sheet 55 substantially parallel to the light k.

On the other hand, the light m obliquely incident on the prism sheet 56 along the plane L parallel to the extending direction of the concave portion 52 and the convex portion 53 is the light m shown in FIG. Because of the same relationship as j, the light passes through the prism sheet 56 as it is and reaches the plane 51 of the prism sheet 45. Then, since this light has the same relationship as the light h in FIG. 6 with respect to the prism sheet 55, the light is emitted as light substantially perpendicular to the plane 51 of the prism sheet 55. That is, the plane 5 is formed on the prism sheet 56.
The light m incident along the plane L from the seventh side is also emitted from the prism sheet 55 substantially parallel to the light k.

As a result, as shown in FIG. 10, a directional plate 43 formed by laminating two prism sheets 55 and 56 such that the extending directions of the concave portions 52 and the convex portions 53 are orthogonal to each other.
Operates as a filter that emits only light that is substantially perpendicular to the plane 57, regardless of the direction from which light enters.

Considering such a function as a kind of filter, as apparent from FIGS. 8 and 11,
When a plano-convex lens 58 as shown in FIG. 11 is used, all light emitted from the focal point is converted into parallel rays by using the focal point as a light source, so that unnecessary light emission in an oblique direction is performed. Can be completely prevented. On the other hand, since the prism sheets 55 and 56 as shown in FIG. 8 have a cross section that does not form an arc or hyperbola but forms a straight line and approximates the lens, the prism sheets 55 and 56
Is merely an approximation of the operation when the above-described plano-convex lens 58 is used. Therefore, it is insufficient compared with the plano-convex lens 58 in that the light emitted from a point having a very small area is converted into a parallel light beam perpendicular to the plane of incidence to prevent the emission of unnecessary light beams in oblique directions.

Nevertheless, the reason for using the prism sheets 55 and 56 in the present embodiment is as follows. First, the first point is that a microlens array is commercially available in which the plano-convex lenses are arranged in a two-dimensional array, but it is extremely expensive because a high curvature accuracy is required to form a curved surface. . Therefore, a large-sized microlens array applied to the image display / input panel 41 of a 10-inch diagonal class becomes very expensive and cannot be mounted on general products. On the other hand, since the cross section of the prism sheet is straight, it can be easily formed with high accuracy, and has an advantage that the price is low.

The second point is that when examining the precision with which rays radiated from the focal point need to be converted into rays in the vertical direction, the approximate level using a prism sheet is sufficient. I understand. Hereinafter, this point will be described. In FIG. 1, the image display / input panel 41 has substantially the same appearance as a normal liquid crystal panel. Therefore, its thickness is about 2 mm.
The light beam emitted from 3 passes through the image display / input panel 41 having a thickness of about 2 mm and irradiates the original 45.
Therefore, it is assumed that the direction of travel of the light is not completely changed by the directing plate 43, and the light beam emitted from the directing plate 43 slightly deviates from the direction perpendicular to the incident surface. In this case, the light 45 deviated from the vertical direction illuminates the original 45 2 mm ahead.

Therefore, the degree of influence when the light emitted from the backlight 42 and deviated from the vertical direction irradiates the original 45 2 mm ahead will be examined. For example, it is assumed that light incident on the 2-mm-thick directional plate 43 is emitted with a shift of 3 degrees from the vertical direction. Then, while passing through the directing plate 43, the incident light is displaced by 2 mm tan (3 degrees) = 100 microns. This means that if the pixel pitch of the image display / input panel 41 is about 300 microns, the position of the original corresponding to the adjacent pixel is shifted by about 1/3 pixel pitch and is irradiated simultaneously. . As described above, the document 45 is irradiated with the light deviated by 3 degrees from the vertical direction, so that the position corresponding to the adjacent pixel is also illuminated by about 1/3, but within a solid angle of 3 degrees. The intensity of the incoming light is (1/3) 3 = 1
Since this is / 27, the level is negligible when compared with the illumination intensity at the irradiation target position.

Since the directional plate 43 is used by being laminated on the image display / input panel 41, the arrangement intervals x and y of the concave and convex portions of the prism sheets 55 and 56 constituting the directional plate 43 may vary. , Image display and input panel 4
In some cases, moire may occur with the image display / input panel 41 depending on the pixel pitch z at 1. Therefore, the arrangement intervals x and y must be at least exactly the same as the pixel pitch z of the image display / input panel 41 or negligible. That is, x, y =
z or x, y≪z.

Generally, the pixel pitch z of the image display / input panel 41 is about 200 to 300 microns. Therefore, the value of the arrangement interval x, y is several tens of microns or 200 to 300 microns. A value that exactly matches the pixel pitch z is desirable.

In this embodiment, the directional plate 4 having the above-described structure is used.
Reference numeral 3 denotes a backlight 42 exhibiting the emission directivity shown in FIG.
It is used by being laminated. As described above, the emission directivity characteristics when the direction plate 43 is stacked on the backlight 42 are as shown in FIG. Note that the dotted line indicates the emission directivity characteristics of the backlight 42. By obtaining such light emission directivity characteristics, as shown in FIG. 12, light emitted from the backlight 42 in all directions is directed to the directing plate 43 (θ = 1).
15 degrees), the light is converged to light having a directivity within ± 10 degrees from the perpendicular to the plane 51 and emitted. Therefore,
The directional characteristics of the light emitted from the directional plate 43 are substantially only in the vertical direction.

As described above, by using the directing plate 43, the light incident from the backlight 42 at any angle is converged within ± 10 degrees from the perpendicular of the plane 57 and emitted. Therefore, the luminance of the backlight 42 alone measured within ± 10 degrees from the perpendicular to the incident surface is less than ± 10 degrees from the perpendicular by stacking the directional plate 43 on the backlight 42.
The brightness measured within degrees is higher. That is, by using the directing plate 43, not only the traveling direction of the light from the backlight 42 is changed to one direction, but also the brightness at the time of reading the image by irradiating the original 45 is increased to obtain a stronger reflected light. Can be made to enter the light receiving element. The backlight 42 and the directional plate 4 as described above
3 is set on the lower surface of the image display / input panel 41.

When an image is displayed by the image display / output device having the above configuration, the image data is applied to the pixel electrode of each pixel of the image display / input panel 41 in the same manner as in the second conventional example. ON by applying voltage according to
By turning on / off, the image display / input panel 41
The image is displayed on. On the other hand, when inputting an image, a voltage is applied only to the pixel electrode of the pixel facing the point to be input on the document 45 to turn it on, and the voltage is applied to the pixel electrodes of the other pixels. Turn off without applying voltage. In this manner, a specific point on the document 45 is irradiated with light from the ON pixel of the image display / input panel 41, and the reflected light at that point is photoelectrically converted by a light receiving element (not shown) incorporated in the pixel. You do it.

At this time, in the present embodiment, as described above, since the directing plate 43 has a light condensing function,
This makes it possible to illuminate the position of a point to be input on the light source 5 more brightly, and to allow strongly reflected light to enter the light receiving element.

Here, conventionally, a backlight having a light emitting directivity characteristic as shown in FIG. 3 is provided with a high light transmittance irrespective of the on / off state of a pixel in a direction close to a horizontal plane, and in a vertical direction when a pixel is on. Since the light transmittance is high and the light transmission directivity is low when the display is off (see FIG. 14), the light emission directivity as shown in FIG.

On the other hand, in this embodiment, the backlight 42 and the directing plate 43 are laminated, and the image display / input panel 41 is further laminated thereon to form an image display / input device. I have. Thus, the backlight 4
By laminating the directivity plate 43 on the light emitting device 2, the light radiation directivity is improved as shown in FIG. 12, and the light radiation in the direction close to the horizontal plane is almost eliminated. As a result, even if the image display / input panel 41 exhibiting the light transmission directional characteristics shown in FIG. 14 is further laminated thereon, as shown in FIG. 13, the pixels of the image display / input panel 41 are turned on / off. Regardless, light emission in a direction close to the horizontal plane disappears, and when the pixel is turned on, light emission is performed only in the vertical direction. Therefore, an image can be input using the image display / input panel 41 having the same light transmission directivity characteristics as the liquid crystal panel. Further, at the time of the image input, it is possible to prevent light reflected and radiated from a pixel adjacent to the light receiving element incorporated in the turned-on pixel of the image display / input combined panel 41 from being incident, thereby improving the resolution at the time of image input. Can be increased.

When the image is displayed, the control circuit 44 controls the image display / input panel 41 according to the image data.
To display an image corresponding to the image data on the image display / input panel 41. At the time of image input, the pixels of the image display / input panel 41 are sequentially turned on / off to scan the original 45, and the original 45 detected by the light receiving element incorporated in the ON pixel based on the reflected light from the original 45. The output current corresponding to the density of the image is processed and extracted as image data.

As described above, in this embodiment, the directional plate 43 is disposed between the image display / input panel 41 and the backlight 42. Then, the two prism sheets 55 and 56 each having a flat surface and a convex and concave surface (θ = 90 ° to 120 °) on the other surface are formed by extending the concave and convex portions of each other. The directional plate 43 is formed by laminating the directional plates 43 so that the directions are orthogonal to each other, and the traveling direction of the light incident on the directional plate 43 is changed within ± 10 degrees with respect to the perpendicular to the incident surface 57 of the directional plate 43. ing. Therefore,
At the time of image input, only one point of the document located in the vertical direction of the turned-on pixel is irradiated, and the density of the point on the document can be detected according to the intensity of the reflected light from that point.

Further, light emission from the off-pixels in the image display / input panel 41 in a direction close to the horizontal plane is eliminated, and the original can be scanned only by the light emission from the on-pixels. Therefore, image input using a liquid crystal panel becomes possible. Further, the directivity plate 43 is provided with the backlight 4.
Light emitted in all directions from 2 is converged and exited within ± 10 degrees with respect to the perpendicular to the incident surface 57, so the brightness of the original irradiation light at the time of image input is enhanced and the S / N ratio is improved. it can.

Although omitted in the above embodiment, it goes without saying that the image display / input panel 41 is used by arranging polarizing plates on the upper and lower sides as in the case of a normal liquid crystal display module.

In the above description, only the directional plate 43 formed by laminating the prism sheets 55 and 56 so that the extending directions of the concave portions 52 and the convex portions 53 are orthogonal to each other is formed. This is because the purpose of the present invention is, as described in the problem to be solved by the invention, to prevent a reduction in image input resolution due to the divergence of document illumination light in all directions. This is for describing the principle of light collection by the prism sheets 55 and 56 used.

In the case where an image display / input panel has been developed in which the document illumination light diverges only in a specific direction, the purpose can be achieved by preventing the divergence only in the specific direction. In this case, it can be seen that one prism sheet that condenses light in one direction may be used. For example, when an image display / input panel is developed in which there is no large light divergence in the horizontal direction and light divergence only in the vertical direction, the extending direction of the concave and convex portions of the prism sheet is horizontal. Only one prism sheet needs to be arranged so as to be in the direction. Conversely, when an image display / input panel is developed in which there is no large light divergence in the vertical direction and light divergence only in the horizontal direction, the extending direction of the concave and convex portions of the prism sheet is Only one prism sheet needs to be arranged in the vertical direction. By doing so, the cost of the directing plate 43 can be reduced.

[0074]

As is apparent from the above description, the image display / input device according to the present invention emits light from the backlight in a direction perpendicular to the plane of incidence by means of a directional plate laminated on the backlight. Sometimes, the control circuit controls the image display / input panel to scan a document placed on the image display / input panel, and reflects the reflected light from the document in the ON pixels of the image display / input panel. Since the light is received by the light receiving element incorporated in the image display device, a specific narrow portion on the document can be irradiated only with the specific pixel in the image display / input panel. Therefore, at the time of the image input, only the reflected light from only one portion on the document can be incident on the light receiving element in one pixel of the image display / input panel, thereby preventing the resolution from deteriorating.

Furthermore, since only parallel light rays in the vertical direction are incident on the image display / input panel, it is possible to improve the light transmission directivity characteristic of the liquid crystal panel, that is, light is emitted in the horizontal direction from pixels in the off state. . Therefore, the original can be scanned only by the light emitted from the ON pixels. That is, according to the present invention, an image can be input using a liquid crystal panel and a backlight as light emitting elements.

Further, the directional plate includes two prism sheets each having a plane on which the light from the backlight is incident and a concave-convex surface having prismatic irregularities and opposing the planar surface. Are laminated so that the extending directions are orthogonal to each other. Therefore, if the directional plate is used, the light from the backlight can be converged in a direction perpendicular to the plane, so that the original illumination brightness at the time of image input can be improved and the S / N ratio can be improved. Further, by configuring the directional plate with the prism sheet, the directional plate can be configured at a lower cost and easily mass-produced as compared with the case where the directional plate is configured with a lens.

Further, in the image display / input device according to the present invention, the apex angle θ of the convex portion in each prism sheet is set to 90 degrees.
Degrees to 120 degrees, it is possible to easily and reliably change the traveling direction of the light incident on the directional plate to a direction perpendicular to the plane.

The image display / input device according to the present invention further comprises an arrangement interval x of the convex portions on one of the prism sheets constituting the directional plate, an arrangement interval y of the convex portions on the other prism sheet, and Since the relationship of x, y = z or x, y≪z is established with the pixel pitch z of the input / input panel, the concave and convex portions of the two prism sheets are moire with the image display / input panel. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an image display / input device according to the present invention.

FIG. 2 is a sectional view of the backlight in FIG. 1;

FIG. 3 is a diagram showing emission directivity characteristics of the backlight shown in FIG. 2;

FIG. 4 is a perspective view of a prism sheet constituting the directional plate in FIG. 1;

FIG. 5 is a perspective view of a directional plate formed by the prism sheet shown in FIG.

FIG. 6 is an explanatory diagram of one operation of the prism sheet shown in FIG.

FIG. 7 is an explanatory diagram of another operation of the prism sheet shown in FIG. 4;

8 is a cross-sectional view of the prism sheet in FIG.

FIG. 9 is a sectional view of the prism sheet in FIG. 7;

FIG. 10 is an explanatory diagram of the operation of the directing plate in FIG.

FIG. 11 is an explanatory diagram of the operation of the plano-convex lens.

FIG. 12 is a diagram illustrating light radiation directivity characteristics of the stacked backlight and the direction plate shown in FIG. 1;

FIG. 13 is a diagram illustrating light radiation directivity characteristics of the stacked backlight, the directional plate, and the image display / input panel shown in FIG. 1;

FIG. 14 is a diagram showing light transmission directivity characteristics of the image display / input panel in FIG. 1;

FIG. 15 is a perspective view of a conventional image display / input panel.

FIG. 16 is a partially enlarged view showing a specific structure of the image display / input panel shown in FIG. 15;

FIG. 17 is a diagram illustrating the operation of the image display / input panel shown in FIG. 15;

FIG. 18 is a diagram illustrating a configuration of a liquid crystal panel in which a light receiving element is incorporated in a pixel.

19 is a cross-sectional view of the vicinity of a substrate in the liquid crystal panel shown in FIG.

20 is an explanatory diagram of a problem of the image display / input panel shown in FIG.

21 is a diagram showing the light emission directivity of the light emitting element in FIG.

FIG. 22 is a light radiation directivity diagram of the liquid crystal panel shown in FIG.

[Explanation of symbols]

41: Image display / input panel, 42: Backlight, 43: Directing plate, 44: Control circuit, 49: Diffusion plate, 51, 57: Flat surface, 52: Concave portion, 53: Convex portion, 54: Concavo-convex surface, 55, 56 ... Prism sheet.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Yamamoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-63-163886 (JP, A) JP-A-5-205 313156 (JP, A) JP-A-58-66142 (JP, A) JP-A-61-101827 (JP, A) JP-A-5-89230 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06T 1/00

Claims (3)

(57) [Claims] 1. A backlight having a flat plate shape and emitting light from one surface, a directing plate receiving light from the backlight on an incident surface and emitting the light from an output surface in a direction perpendicular to the incident surface, An image display / input combined panel in which a light receiving element is incorporated in each pixel of the liquid crystal display panel is sequentially laminated, and at the time of image display, each pixel in the image display / input combined panel is turned on / off according to image data. While controlling to display an image corresponding to the image data, at the time of image input, the pixels of the image display / input combined panel are sequentially turned on / off.
An image display / input device having a control circuit for turning off and scanning a document, wherein the directional plate has a plane on which light from the backlight is incident and a prism-shaped unevenness and faces the plane. It is formed by laminating two prism sheets each having an uneven surface so that the extending directions of the unevenness are orthogonal to each other. When the image is input, the light is emitted from the backlight.
The light passing through the directional plate and the turned-on pixels is
Reflected by the original placed on the display / input panel,
An image display / input device characterized by being incident on a light receiving element . (2) The image display / input device according to claim 1.
At The vertex angle θ of the projection on the uneven surface of the prism sheet is 9
An image characterized by being in the range of 0 to 120 degrees
Display / input device. (3) The image display / input device according to claim 1.
At One of the two prism sheets constituting the directional plate
X is the arrangement interval of the protrusions in one direction, and
The column spacing is y, the pixel pitch of the image display / input panel
Is z, x, y = z or x, y≪z
Image display input characterized by being established
Force combined device.