JP2915453B2 - Image input device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device having an edge extraction function of an input image.

[Conventional technology]

A plurality of light receiving elements are two-dimensionally arranged to receive an input image, and a photoelectric conversion output from a plurality of light receiving elements of the light receiving element layer is received and arithmetically processed. 2. Description of the Related Art A parallel image processing system that performs image processing that imitates a visual system of a living body by using an image input device having an arithmetic circuit unit that detects an edge of an input image is known (for example, Japanese Patent Publication No.
No. 34901).

By the way, the retina of a living body has a mechanism for detecting the shape of an object, that is, a contour (edge), and a mechanism for detecting a movement (there is another mechanism for detecting a color, etc.). . High resolution is required to detect the shape of an object, and in the case of ecology, there are cells for that in the center. In addition, in order to detect motion, sufficient sensitivity is required, and it is necessary to perform detection without flash.
Cells for that purpose are relatively concentrated around the visual field.

Therefore, in order to realize an image input / output device having the characteristics of such an ecological visual structure, a photoreceptor having a high resolution is arranged at the center of the photoreceptor element layer of the above-described image input device, and a peripheral portion is provided. A method is conceivable in which a light receiving element having high sensitivity is arranged in the portion to realize the light receiving element.

[Problems to be solved by the invention]

However, in order to specifically realize the above-described image input device, a large number of light receiving elements having different characteristics must be provided in the light receiving element layer, and the structure of the light receiving element layer becomes complicated, There are problems in realization such as the wiring and circuit configuration between the receiving element layer and the arithmetic unit becoming complicated, and it has not been realized as an artificial device.

The present invention has been made in view of the above circumstances, and has a high resolution at the center of the visual field, a high edge extraction capability at the peripheral portion, and an image input having image input characteristics closer to the visual characteristics of a living body. It is intended to provide a device.

[Means for solving the problem]

In order to achieve the above object, an image input device according to the present invention includes a light diffusion member having a diffusion surface for diffusing light received from the front side to the back side, and an input image formed on the diffusion surface. A plurality of light receiving element sets each including an element and a peripheral light receiving element surrounding the periphery of the central light receiving element are arranged one-dimensionally or two-dimensionally, and are arranged on the back side of the light diffusing member. A light receiving element array for receiving the diffused light from the diffusion surface and detecting the input image; a photoelectric conversion output from a central light receiving element provided for each light receiving element set of the light receiving element array; An arithmetic circuit for amplifying the photoelectric conversion output from the element at a predetermined amplification factor and then obtaining a differential output between the two outputs, and obtaining an edge output corresponding to an input image by an output from the arithmetic circuit. The diffusion surface of the light diffusion member Characterized in that it has a curved shape.

[Action]

In the image input device according to the present invention, a light receiving element set including a central light receiving element constituting a light receiving element array and a peripheral light receiving element surrounding the periphery of the central light receiving element functions as one unit of pixel, The power transmission conversion output of the central light receiving element and the photoelectric conversion output of the peripheral light receiving element of each light receiving element set are outputs according to the density of the input image (the intensity of the input light).

Here, the arithmetic circuit amplifies the photoelectric conversion output from the central light receiving element and the photoelectric conversion output from the peripheral light receiving element at a predetermined amplification factor, which are provided for each light receiving element set in the light receiving element row. After that, it is configured to output the differential output of both outputs, and the above amplification factor is adjusted so that the output of the central light receiving element and the peripheral light receiving element has a 1: 1 relationship when uniform light is incident. Accordingly, an edge output corresponding to the contour of the input image (the contour of a picture, a character, an object, or the like, that is, the boundary between the light and shade of the input image) can be obtained from the differential output. .
If the amplification factor on the peripheral light receiving element side is "0", the differential output is only the output of the central light receiving element, and an original image output corresponding to the density of the input image can be obtained.

In addition, the resolution and sensitivity of the light receiving element array depend on the distance between the light receiving surface of the light receiving element array and the diffusion surface of the light diffusing member, and the resolution increases as the distance between the light receiving surface and the diffusion surface decreases. When the distance increases, the crosstalk area between the light receiving element sets expands, and the sensitivity increases.

Therefore, by forming the diffusion surface of the light diffusing member into a curved surface shape, the resolution is high in a portion where the distance between the light receiving surface and the diffusion surface is short, and the sensitivity is high in a portion where the distance between the light receiving surface and the diffusion surface is large.

〔Example〕

Hereinafter, an image input device of the present invention will be described in detail with reference to the drawings.

First, the basic configuration of the image input device of the present invention will be described with reference to FIGS.

In FIG. 4, reference numeral 2 denotes a photographing lens, and a diffusing surface for diffusing light received from the front side to the rear side is provided at the image forming position of the input image 1 of the photographing lens 2 and the diffusing surface is provided with the input image. A light diffusing member 13 on which an image 1 is formed is arranged.

As shown in FIG. 5, a light receiving element set 6 including a central light receiving element 7 and a peripheral light receiving element 8 surrounding the central light receiving element 7 is provided on the back side of the light diffusing member 13. A plurality of light receiving element array layers 4 arranged one-dimensionally or two-dimensionally are arranged, and are configured to receive the diffused light from the diffusion surface and detect the input image. .

The light receiving element set 6 constituting the light receiving element array layer 4 has a central light receiving element 7 having a circular light receiving surface and having a photoelectric conversion function.
And a peripheral light receiving element 8 having an annular light receiving surface surrounding the periphery of the central light receiving element 7 and having a photoelectric conversion function. The central light receiving element 7 and the peripheral light receiving element 8 are: They are connected to the input terminals of the amplifiers 9 and 10, respectively, so that the photoelectric conversion outputs from both elements are amplified and output at predetermined amplification factors, respectively. The output terminals of both amplifiers 9 and 10 are connected to the non-inverting input terminal and the inverting input terminal of differential amplifier 11 at the subsequent stage, respectively, so that differential outputs of the outputs from both amplifiers 9 and 10 can be obtained. It is supposed to be. That is,
The amplifiers 9 and 10 and the differential amplifier 11 are provided for each photoreceptor element set 6 of the photoreceptor element row layer 4, and the photoelectric conversion output from the central photoreceptor 7 and the output from the peripheral photoreceptor 8 are provided. An arithmetic circuit for amplifying the photoelectric conversion output at a predetermined amplification factor and obtaining a differential output of both outputs is configured. The output from the differential amplifier 11 of the arithmetic circuit is input to the parallel image processing device 5 connected at the subsequent stage, and is used for original image detection, edge detection, motion detection, and the like of the input image.

In the image input device having the structure shown in FIGS. 4 and 5, the central light receiving element 7 and the peripheral light receiving element 8 surrounding the central light receiving element 7 constituting the light receiving element array layer 4 are described. And a photoelectric conversion output of the central light receiving element 7 and a photoelectric conversion output of the peripheral light receiving element 8 of each of the light receiving element sets 6 are shades of the input image. (The intensity of the input light).

Here, as described above, the arithmetic circuit is provided for each light receiving element set 6 of the light receiving element row layer 4, that is, for each pixel, and outputs the photoelectric conversion output from the central light receiving element 7 and the peripheral light receiving element. Since the photoelectric conversion output from the element 8 and the photoelectric conversion output from the element 8 are each amplified by a predetermined amplification factor, and the differential output of both outputs is output, the central light receiving element 7 and the peripheral light receiving element 8 when uniform light enters. Amplifiers 9 and 10 so that the outputs of
By adjusting the amplification factor, it is possible to obtain an edge output corresponding to the contour of the input image (the contour of a picture, a character, an object, or the like, that is, the boundary of the light and shade of the input image) from the differential output of the differential amplifier 11. it can.

In addition, the amplification factor of the amplifier 10 on the peripheral light receiving element 8 side is set to “0”.
Then, the differential output from the differential amplifier 11 is only the output of the central light receiving element 7, and an original image output corresponding to the density of the input image is obtained. Further, if the amplifier 10 on the side of the peripheral light receiving element 8 can be switched to an inverting amplifier, the output from this amplifier becomes a negative output, so that the differential amplifier 11
Is the sum with the output of the central light receiving element, which is advantageous when obtaining an original image output corresponding to the density of the input image.

If the switching of the amplification factor of each of the amplifiers 9 and 10 is switched by a signal from the parallel image processing device 5, it is easy to switch between the original image detection and the edge detection of the input image.

By the way, the separation ability and sensitivity of the light receiving element array layer 4 are defined as the light receiving surface 4a of the light receiving element array layer 4 and the diffusion surface of the light diffusing member 13 if the characteristics of each light receiving element set 6 are the same. When the distance between the light receiving surface 4a and the back surface 13b of the diffusion surface is short, the resolution increases, and when the distance increases, the crosstalk region between the photoreceptor element sets 6 expands to increase the sensitivity. Therefore, the resolution and sensitivity of the image input device can be controlled by adjusting the distance between the light receiving surface 4a of the light receiving element array layer 4 and the diffusion surface of the light diffusion member 13, that is, the distance.

Here, FIG. 6 is a diagram showing the above-mentioned verification results,
FIG. 7 shows the relationship between differential output (edge detection output) waveforms when the surface distance d between the back surface of the light diffusing member 13 and the light receiving surface 4a of the light receiving element array layer 4 is changed in three stages. FIG.

6 (a), (b) and (c), the upper diagram is a diagram corresponding to the previous FIG. 5, reference numeral 14 is a light shielding plate for forming an edge, reference numeral 13 is a light diffusing member, Reference numeral 6 denotes a light receiving element set. The numerical values in the figure are relative values, and the radius a1 of the light receiving surface of the central light receiving element 7 of the light receiving element set 6 is 2, the inner radius a2 of the light receiving surface of the peripheral light receiving element 8 is 3, and the same. Outer radius a3
Is a relative value when 5 is set. As an edge detection method, a uniform light is irradiated in a state where the light shielding plate 14 is placed in close contact with the diffusion surface of the light diffusion member 13, and the central light receiving element is gradually displaced in the x direction in the drawing. 7 and peripheral light receiving element 8
Detect the differential output of the outputs. The amplification factors of the amplifiers 9 and 10 are adjusted so that the outputs of the central light receiving element 7 and the peripheral light receiving element 8 have a 1: 1 relationship at the time of uniform light incidence. The differential output (edge output) is when the light-shielding plate 14 is not on the light-receiving surfaces of both light-receiving elements 7 and 8, and when the light-receiving surfaces of both light-receiving elements 7 and 8 are completely covered by the light-shielding plate 14. It becomes “0” when it is.

6 (a), 6 (b), and 6 (c) show that the above-mentioned surface distance d is 2, 10, and 15 in relative values, respectively.
The edge output with respect to the displacement x of the light-shielding plate when the light-shielding plate 14 is displaced in the x direction from the state where the entire surface of the light receiving element set 6 is shielded from light by the light-shielding plate 14 is shown.

Here, as shown in FIG. 6 (a), when the surface distance d is small, the light receiving area of each of the light receiving elements 7, 8 of the light receiving element set 6 is narrow, so that the resolution is relatively high. . However, since the light receiving area of each of the light receiving elements 7 and 8 is narrow, a crosstalk area between the adjacent light receiving element sets is also narrow, and a dead portion may be generated.
There is a possibility that a so-called loop may occur. In addition, as shown in FIG. 6C, when the surface distance d is large, the light receiving areas of the light receiving elements 7 and 8 of the light receiving element set 6 are widened, but the resolution is relatively low. However, since the light receiving area of each of the light receiving elements 7 and 8 is wide, the crosstalk area between the adjacent light receiving element sets is also wide, and the detection of the presence or absence of the edge can be performed without fail. That is, edge detection can be performed with high sensitivity.

As described above, the resolution and sensitivity of the light receiving element array layer 4 are the same as the light receiving surface 4a of the light receiving element array layer 4 and the diffusion surface of the light diffusing member 13 if the characteristics of each light receiving element set 6 are the same. The resolution increases as the surface distance d decreases, which is advantageous for detecting the edge shape, that is, the shape of the contour of a picture, a character, or an object. Further, when the surface distance d is large, the crosstalk region between the light receiving element groups 6 expands, and the sensitivity increases, which is advantageous for detecting the presence or absence of an edge.

As described above, by adjusting the distance between the light receiving surface 4a of the light receiving element array layer 4 and the diffusion surface of the light diffusion member 13, that is, the surface interval, the resolution and sensitivity of the image input device can be controlled. When the diffusion surface of the light diffusion member 13 is a uniform plane as shown in FIGS. 4 to 6, the resolution and sensitivity of edge detection are uniform over the entire visual field, and, as in the visual characteristics of a living body, It is difficult to satisfy both functions at the same time.

Therefore, the image input device according to the present invention has a high resolution in the center of the visual field and a high edge extraction capability in the peripheral portion of the visual field, similarly to the visual characteristics of the living body. The light diffusion member has a curved diffusion surface.

FIGS. 1 and 2 are views showing an embodiment of an image input device according to the present invention, which correspond to FIGS. 4 and 5, respectively, and are shown in FIGS. 4 and 5, respectively. The difference from the device is that the light diffusing surface of the light diffusing member 3 has a curved shape, and the other configuration is the same.

1 and 2, the diffusion surface 3a of the light diffusion member 3 is shown.
Has a concave curved surface shape, and the surface interval between the light receiving surface 4a of the light receiving element array layer 4 and the diffusion surface back surface 3b of the light diffusion member 3 is the light receiving surface facing the vertex on the back surface side of the diffusion surface. It is configured to be small at the center of the element row and large at the periphery. For this reason, the light receiving area of the light receiving element set 6 is narrow at the central portion of the light receiving element row facing the vertex on the back side of the diffusion surface and the resolution is high, and the surface distance between the diffusion surface and the light receiving surface increases toward the peripheral portion. As the distance increases, the light receiving area of the photoreceptor element set becomes wider as it goes to the peripheral portion, and the sensitivity increases instead of lowering the resolution.

As described above, in the image input device having the configuration shown in FIG. 1 and FIG. 2, the light diffusing surface of the light diffusing member 3 is formed into a curved surface, and the light diffusing surface becomes convex with respect to the light receiving surface 4a of the light receiving element array layer 4. In this case, the resolution is high in the central part of the light receiving element array layer 4 and the sensitivity is high in the peripheral part, thereby realizing an image input device having edge detection characteristics close to the visual characteristics of a living body. Can be.

Further, in addition to the above-described configuration, as shown in FIG. 3, a lens array 15 is provided between the light receiving surface of the light receiving element array layer 4 and the diffusion surface of the light diffusing member 3, and The directional characteristics of the central light-receiving element 7 and the peripheral light-receiving element 8 can also be controlled.

In addition, instead of forming the diffusion surface of the light diffusion member 3 as a curved surface as shown in FIGS. 1 to 3, the same effect can be obtained by configuring the light receiving surface side of the light receiving element array layer 4 as a curved surface. However, it is technically difficult to fabricate the light receiving surface side as a curved surface, and the productivity is deteriorated.

〔The invention's effect〕

As described above, in the image input device of the present invention, an original image output and an edge extraction output of an input image can be selectively and easily obtained, and in combination with a subsequent parallel image processing device, an original image output can be obtained. It is possible to realize an image processing device similar to artificial vision, which performs extraction and classification of outlines of pictures and characters, extraction of outlines of photographed objects, motion detection, and the like.

Further, in the image input device of the present invention, relatively high-resolution edge detection is performed at the center of the input image, and relatively high-sensitivity edge detection is performed at the peripheral portion. Capture becomes possible, and it becomes easy to realize an artificial vision device such as a robot eye.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image input device according to the present invention, FIG. 2 is a schematic configuration diagram of main parts of the image input device shown in FIG. 1, and FIG. FIG. 4 is a schematic configuration diagram showing a basic configuration of an image input apparatus according to the present invention, and FIG.
FIG. 6 is a schematic view of a main part of the image input device shown in FIG. 6, and FIG. 6 is a diagram showing a surface interval between a light receiving surface of a light receiving element array layer and a diffusion plate in the image input device having the structure shown in FIG. (A),
It is explanatory drawing which shows the relationship of the edge output waveform with respect to the light-shielding plate displacement at the time of changing to three steps shown to (b) and (c). 1 ... input image, 2 ... photographing lens, 3,13 ... light diffusing member, 4 ... light receiving element array layer, 6 ... light receiving element set, 7 ...
... Central light receiving element, 8 ... Peripheral light receiving element, 9,10 ... Amplifier, 11 ... Differential amplifier, 14 ... Light shield plate, 15 ... Lens array.

Claims (1)

(57) [Claims] A light diffusion member having a diffusion surface for diffusing light received from a front side to a back side, an input image being formed on the diffusion surface, a central light receiving element, and a periphery of the central light receiving element. A plurality of light receiving element sets including a surrounding peripheral light receiving element are arranged one-dimensionally or two-dimensionally, and are arranged on the back side of the light diffusion member to receive diffused light from the diffusion surface. A light receiving element array for detecting the input image, and a photoelectric conversion output from a central light receiving element and a photoelectric conversion output from a peripheral light receiving element provided for each light receiving element set of the light receiving element row are respectively predetermined. And an arithmetic circuit for obtaining a differential output of both outputs after amplification at an amplification factor of, and an edge output corresponding to an input image by an output from the arithmetic circuit, wherein the diffusion surface of the light diffusion member is Image input characterized by having a curved shape Location.