JP2529188B2 - Image input device - Google Patents

Description

The present invention relates to an image input device for displaying a subtracted image between frames or fields, an arithmetic mean image between frames or fields, and the like.

[Conventional technology]

In order to obtain only a moving object in an image input from an image pickup device such as an ITV camera, frame-to-frame subtraction between fields or field-to-field arithmetic addition may be performed for the purpose of reducing noise. In order to perform these processes, a configuration as shown in FIG. 7 has been adopted as a conventional typical image input device.

In this device, an analog signal for one frame output from the ITV camera 1 is converted into digital data by the A / D conversion unit 2 and stored in the frame memory unit 3. Next, the analog signal for one frame output from the ITV camera 1 is converted into digital data by the A / D converter 2, and the digital data and the previous frame data stored in the frame memory 3 are processed. For example, an image is added and averaged by the unit 4, reconverted into an analog signal by the D / A conversion unit 5, and an image that is added and averaged between frames is displayed on the monitor 6. At this time, the current digital data is stored in the frame memory unit 3 at the same time as the data of the previous frame stored in the frame memory unit 3 for the arithmetic mean calculation in this arithmetic processing unit is read. In the same manner, the image of the next frame is arithmetically averaged with the previous image, and the image constantly arithmetically averaged between the frames is displayed on the monitor 6. It goes without saying that the difference image is displayed on the monitor 6 if the function of the arithmetic processing unit takes not the averaging but the absolute value of the difference.

Generally, the image processing unit 8 including the A / D conversion unit 2, the frame memory unit 3, the arithmetic processing unit 4, and the D / A conversion unit 5 of this image input device is integrated into one device and is commercially available as an image processing device. It has been used and often used.

[Problems to be solved by the invention]

In the conventional image input device having the above configuration, the image processing unit 8
Special hardware is required, and even if other configurations are used, at least the frame memory unit 3
The hardware for storing the image information as described above and the hardware for performing the arithmetic operation such as the arithmetic processing unit 4 are indispensable, and the cost becomes expensive.

The present invention takes advantage of the non-destructive read-out feature of a static induction transistor (SIT) imager and allows for frame-to-frame or frame-to-frame resolution without the need for expensive specialized image processing hardware. An object of the present invention is to provide a compact and inexpensive image input device capable of displaying a subtracted image between fields and an averaged image between frames or fields.

[Means for solving problems]

In the present invention, as the image pickup device, nondestructive readable light receiving elements such as SIT (static induction transistor) light receiving elements are arranged in a matrix, and two adjacent light receiving elements are paired to form one pixel. , Configuring each pixel 2
One of the two light receiving elements is used for the odd field, and the other is used for the even field. Using an imaging device configured to be selectively connectable to the odd field output terminal and the even field output terminal respectively, the two output terminals simultaneously output. The odd field output signal and the even field output signal are processed by the signal processing means to generate an arithmetic mean image signal, a differential image signal and the like.

[Work]

According to the above-described image input device of the present invention, since the odd and even field output signals are simultaneously supplied from the image pickup device, it is possible to provide a frame memory unlike the prior art.
Image signals such as an arithmetic mean image signal and a differential image signal can be obtained, and the configuration is extremely simple and inexpensive.

〔Example〕

FIG. 1 is a plan view diagrammatically showing an arrangement configuration example of SIT light receiving elements of a SIT image pickup apparatus used in the present invention. In the example of FIG. 1A, two vertically adjacent SIT light receiving elements are paired to form one pixel, and a matrix of K (column) × L (row) pixels constitutes a two-dimensional imaging device. Therefore, the number of SIT light receiving elements is K (column) × 2L (row). In the example of FIG. 1 (b), two SIT light receiving elements that are diagonally adjacent to each other are paired to form one pixel. In principle, the above (a) and (b)
Not limited to the above example, two adjacent elements may be paired.

In this image pickup device, one of the two light receiving elements forming each pixel is used for an odd field and the other is used for an even field so that they can be selectively connected to the odd field output terminal and the even field output terminal, respectively.

FIG. 2 is a block diagram showing the principle of the image input device of the present invention using such a SIT image pickup device. In FIG. 2, 9 is described above
The SIT image pickup device is driven by the control circuit 12 and simultaneously generates an odd field output signal and an even field output signal at its odd field output terminal and even field output terminal. These two output signals are the signal processing circuit
10, the signal processing circuit outputs from these two output signals a field accumulation interlaced image signal, an inter-field arithmetic average image signal, an inter-field difference image signal,
Pseudo frame image signals (each described later in detail) are output in parallel. These image signals are supplied to the signal selection circuit 11 controlled by the control circuit 12, and this signal selection circuit selects a desired image signal and supplies it to the monitor 13 for display.

FIG. 3 shows an embodiment of the SIT image pickup device used in the present invention. For simplicity, in this example, 3 ^H × 6 ^V SIT photo detectors 30-1
It is assumed that 1 to 30-63 are arranged as shown in FIG. That is, the light receiving elements 30-11 to 30-13, 30-31 to 30-
33, 30-51 to 30-53 are photo detectors for odd fields.
Reference numerals 21 to 30-23, 30-41 to 30-43, and 30-61 to 30-63 are light receiving elements for even fields, which are two light receiving elements 30-11 and 30-21, 30-12 that are vertically adjacent to each other. And 30-22, ..., 30-53 and 3
0-63 constitutes one pixel.

In this example, sequential pixels arranged in a matrix like this are selected by the source / gate selection method, and the output signals of the two SIT light receiving elements of the selected pixels are simultaneously read by the source follower method. 31 is a vertical scanning shift register, which is an odd field SIT light receiving element 30-11 to 30-1 for each pixel in each row arranged in the horizontal direction.
3, 30-31 to 30-33, 30-51 to 30-53 gate and even field SIT light receiving element 30-21 to 30-23, 30-41 to 30-4
Vertical selection pulses φ _GiO and φ _GiE (i = 1 to 3) are supplied to the gates of 3 and 30-61 to 30-63, respectively. 32 is a horizontal scanning shift register, which is a horizontal selection switch 33-1 to 33-3.
The horizontal selection pulse φ _Di (i = 1 to 3) is supplied to. Each of these switches 33-1 to 33-3 is a switch SW for an odd field light receiving element, which comprises two transistors, a first transistor controlled by a horizontal selection pulse φ _Di and a second transistor controlled by its inversion pulse. _O1 ~ SW _O3
And even field light receiving element switches SW _{E1 to} SW _{E3. When} receiving horizontal selection pulse φ _Di , switch SW _Oi and
The source of the odd field light receiving element and the even field light receiving element of each pixel in each column arranged in the vertical direction when the first transistor of SW _Ei is turned on is set to the odd field output terminal 36.
And the even field output terminal 37 and the horizontal selection pulse φ _Di is not received, the second transistors of the switches SW _Oi and SW _Ei are turned on to supply the voltage source 39 to the sources of both SIT light receiving elements of each pixel in each column. The voltage V (0V) is supplied to maintain the non-selected state. The drain of the SIT light receiving element of each pixel is commonly connected to the video voltage source 38 (V _DD ).
4 and 35 are load resistances.

FIG. 4 is a waveform diagram for explaining the operation of the SIT image pickup apparatus shown in FIG. As shown in the figure, the vertical selection pulses φ _GiO and φ _GiE have the read voltage Vφ _G during the horizontal scanning period t _H , and the vertical selection pulse φ _GiO has the reset voltage Vφ _R for each even field. φ _GiE has a reset voltage Vφ _R for each odd field. By doing so, in the odd field, the odd field and even field light receiving elements 30-11 to 30-13 and 30-21 to 30- of the pixels in the first row are _generated by the vertical selection pulses φ _G1O and φ G1E.
23 are selected at the same time, and the signals of the odd field and even field light receiving elements are output as odd field and even field output terminals 36 by horizontal selection pulses φ _D1 , φ _D2 , and φ _D3 , respectively.
And 37 sequentially read, and after that, the even field light receiving element
Only 30-21 to 30-23 are reset by the reset voltage Vφ _R , and then the pulses φ _G2O and φ _G2E and the pulses φ _{D1 to} φ
Odd and even fields of the second row of pixels due to _D3
The SIT light receiving elements 30-31 to 30-33 and 30-41 to 30-43 are sequentially read out to the respective output terminals 36 and 37, the even field light receiving elements 30-41 to 30-43 are reset, and so on. Then, the pixels in the third row are sequentially read out, and the odd field and even field output signals are obtained at the output terminals 36 and 37. Similarly, in the next even field, the pixels in each row are sequentially read, but in this field, only the odd field light receiving element is reset after reading each row. In this case, the output signal of the odd field light receiving element of each pixel which is sequentially read during the odd field becomes an odd field signal component integrated over the preceding one field period, and the output signal of the even field light receiving element is before that. Signal component integrated over two field periods, that is, the sum of the previous even field signal component and the odd field signal component, and the output signal of the even field light receiving element of each pixel outputs the even field during the even field. It becomes a signal component, and the output signal of the odd field light receiving element becomes the sum of the previous odd field output signal component and the even field signal component. This is shown in the lower part of FIG.
The T light receiving elements 30-32 and 30-42 are shown.

That is, when the vertical selection pulses φ _G2O and φ _G2E are applied and the horizontal selection pulse φ _D2 is applied, the odd field and even field outputs V _O and V _E read to the odd field and even field output terminals 36 and 37, respectively. Is a signal (field accumulation signal) proportional to the surface potential change ΔV _{0 (n)} immediately below the gate of the odd-field light receiving element 30-32 in which light integration was performed for the previous one field period, and the two fields before it. Change in surface potential directly under the gate of the even field light receiving element 30-42 that has been integrated over a period ΔV _{E (n-1)} + V _{O (n)}
Is a signal proportional to (frame accumulation signal). That is, V _O (t = t _n-1 ) = k · ΔV _{O (n)} V _E (t = t _n-1 ) = k (ΔV _{E (n-1)} + ΔV _{O (n)} ) (k Is a coefficient). At this time, the optical information of these SIT light receiving elements is not destroyed due to the nondestructive read characteristic. After this reading, the even field light receiving element 30-42 _{outputs a} pulse φ _G2E.
This light receiving element 30 is reset by the reset voltage Vφ _R of
The −42 newly starts the integration of the photocharges, but the odd field light receiving element is not reset and the integration of the photocharges is continued.

Therefore, at the time of reading out this pixel at the next even field, at the time t = t _n , an odd field and an even field are output.
V _O and V _E become respectively _{V O (t = t n)} = k (ΔV O (n) + ΔV E (n)) V E (t = t n) = kΔV E (n), odd after this read The field light-receiving elements 30-32 are reset to newly start the integration of photocharges, and the even field light-receiving elements 30-42 are not reset but continuously perform light integration.

From the odd field and even field outputs V _O and V _E described above, the following four types of images can be obtained.

1) Field accumulation interlace If the output at t = t _n-1 , t _{n + 1} is output as an odd field output and the output at t = t _n , t _{n + 2} is output as an even field output, the odd field is output. The output is V _O = kΔV _{O (n)} , kΔV _{O (n + 1)} , ... Even field output is V _E = kΔV _{E (n)} , k ΔV _{E (n + 1)} , ... Is obtained.

2) Additive average image between fields Outputs when t = t _n , t _{n + 2} ... Are output as odd field outputs and outputs when t = t _n-1 , t _{n + 1} , ... are output as even field outputs. Taking out and multiplying each by 1/2, the odd field output is V _O = k ((ΔV _{O (n)} + ΔV _{E (n)} ) / 2), k ((ΔV _{O (n + 1)} + ΔV _{E (n + 1)} ) / 2),… Even field output is V _E = k ((ΔV _{E (n-1)} + ΔV _{O (n)} ) / 2), k ((ΔV _{E (n)} + ΔV _{O (n + 1)} ) / 2), ..., and an averaged image between fields is obtained.

3) Difference image between fields When t = t _n-1 , from odd field output V _O = kΔV _{O (n)} and even field output V _E = ΔV _{E (n-1)} + ΔV _{O (n)} | 2V _O −
V _E | = k | ΔV _{O (n)} −ΔV _{E (n-1)} | is created, and this is used as an odd field output.

When t = t _n , odd field output V _O = k (ΔV _{O (n)} +
[Delta] V _E and _(n)), from an even field output _{V E = kΔV E (n)} | 2
V _E −V _O | = k | ΔV _{E (n)} −ΔV _{O (n)} | is created and used as the even field output. In this way, a difference image between fields can be obtained as is clear from the above equation.

4) Pseudo frame image (frame image in which odd field and even field are completely the same data) As odd field output, odd field output when t = t _n-1 , t _{n + 1} , ... V _O = kΔV _{O (n )} , kV _{O (n + 1)} , ... Is taken out and V _O when t = t _n , t _{n + 2} , ... is output as an even field output.
By extracting the difference V _O −V _E = kΔV _(n) , kΔV _{(n + 1)} , ... Between V _E and V _E , it is possible to obtain a pseudo frame image composed of data in which the odd field and the even field are exactly the same.

The fifth embodiment of the signal processing circuit 10 for obtaining the image described above
Shown in the figure.

In FIG. 5, 40-1 and 40-2 are amplifiers with a gain of 1/2, 4
Reference numerals 1-1 and 41-2 are amplifiers having a gain of 2, 42-1, 42-2 and 42-3 are subtractors, and 43-1 and 43-2 are absolute value circuits. Output terminals 44-1 to 44-3 of the signal processing circuit are for odd fields, 44-4
~ 44-7 are for even fields, 44-1 and
44-5 is for field-stored interlaced images, 44-2 and 44-6 are for averaged images, 44-3 and 44-7 are for differential images, and 44-1 and 44-4 are for pseudo frame images. is there.

The signal selection circuit 11 is controlled by the control signal 15 from the control circuit 12, selects a signal for obtaining a desired image from the signals from the signal processing circuit 10, and outputs it to the output terminal 45.

In the example of FIG. 5, the output of the signal processing circuit is selected by the signal selection circuit 11 to output one desired image, but it is not necessary to have one output of the signal selection circuit. As shown in FIG. 6, four images are output to four output terminals 45.
You may make it output to -1 to 45-4 in parallel.

[Advantages of the Invention] As described above, according to the present invention, by using the non-destructive readable SIT image pickup device, the A / D converter, the frame memory, and the D / A converter required in the conventional image input device are used. Is unnecessary, and a very compact and inexpensive image input device can be realized, and such a device is extremely useful as an input device for generating a difference image and recognizing the shape of a moving object particularly in the field of FA.

[Brief description of drawings]

1 (a) and 1 (b) are plan views showing two examples of the arrangement of SIT light receiving elements of the SIT image pickup device used in the image input device of the present invention, and FIG. 2 is a block configuration diagram of the image input device of the present invention, FIG. 3 is a block diagram of an embodiment of the SIT image pickup device used in the image input device of the present invention, FIG. 4 is a waveform diagram for explaining the operation of the SIT image pickup device of FIG. 3, and FIG. 5 is the image input of FIG. FIG. 6 is a configuration diagram of an embodiment of a signal processing circuit of the device, FIG. 6 is a configuration diagram of a modification of the image input device of the present invention, and FIG. 7 is a block configuration diagram of a conventional image input device. 9 ... SIT image pickup device, 10 ... Signal processing circuit 11 ... Signal selection circuit, 12 ... Control circuit 13 ... TV monitor 30-11 to 30-13, 30-31 to 30-33, 30-51 ... 30−53 …… SIT light receiving element for odd field 30−21 to 30−23,30−41 to 30−43,30−61 to 30−63 …… Light receiving element for even field 31 …… Vertical scan shift register 32… … Horizontal scan shift register 33-1 to 33-3 …… Horizontal selection switch SW _{O1 to} SW _O3 …… Switch for odd field light receiving element SW _{E1 to} SW _E3 …… Switch for even field light receiving element 34, 35 …… Load resistance 36 …… Odd field output terminal 37 …… Even field output terminal 38 …… Video voltage source φ _GiO , φ _GiE …… Vertical selection pulse φ _Di …… Horizontal selection pulse 40-1, 40-2 …… Gain 1/2 Amplifier 41-1, 41-2 ... Gain 2 amplifier 42-1 to 42-3 ... Subtractor 43-1, 43-2 ... Absolute value circuit

Front page continuation (72) Inventor Hirozen Fujimori 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Masatoshi Ida 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus In optical industry Co., Ltd. (72) Inventor Kazuya Matsumoto 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd. JP-A-60-12765 (JP, A) JP-A-58-137371 (JP, A)

Claims (1)

(57) [Claims] 1. A non-destructive readable light-receiving element is arranged in a matrix, two adjacent light-receiving elements are paired to form one pixel, and two light-receiving elements forming each pixel are two.
One field output signal is selectively connected to one output terminal, and the field output signal is output from one output terminal, and the frame output signal obtained by adding the previous field output signal to the field output signal is output from each of the other output terminals for each field. , An image pickup device configured to read two output terminals alternately and simultaneously, a field-stored interlaced image signal and an arithmetic mean image signal between fields by calculating output signals of the field-stored and frame-stored read simultaneously , A differential image signal between fields, a signal processing circuit for generating a pseudo frame image signal in which an odd field and an even field are the same data, and a selection circuit for selecting a desired signal of these image signals. Image input device.