JPH05292409A - Ccd image pickup device - Google Patents

Abstract

PURPOSE:To provide a digital output CCD image pickup device with simple configuration. CONSTITUTION:Wells 2 respectively provided with prescribed potentials are connected to a photo-electric conversion part 1. Stock parts 3 to respectively stock the prescribed amounts of charges are connected to these wells 2. Further, the wells 2 are provided with detecting means 4 to detect the overflow of charges. On the other hand, an oscillator 5 is connected through a multiplexer 6 to the stock part 3 for each horizontal scan line and connected to a counter 7, and this counter 7 is connected to a latch circuit 8 for the number of valid horizontal picture element. The detecting means 4 are respectively connected to these latch circuits 8. These latch circuits 8 are cascade connected. Further, the respective photo-electric conversion parts 1 at the right edge are provided with black stripes 10. Then, the cascade connected latch circuits 8 are connected through a switch 11 to a reference value latch circuit 12, and an operation processing circuit 13 and further, the reference value latch circuit 12 is connected to the arithmetic circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCD image pickup device used in a VTR integrated video camera or the like.

[0002]

2. Description of the Related Art For example, in a VTR-integrated video camera, extraction of a signal from a CCD image pickup device is conventionally performed as follows. That is, for example, in FIG. 3, a signal from the photoelectric conversion unit (sensor) 31 is temporarily transferred to the vertical (V) register 32 for each vertical period. The signal of the vertical register 32 is sequentially transferred downward in each horizontal period and then transferred to the horizontal (H) register 33. The signal of the horizontal register 33 is sequentially transferred to the right in each pixel period, and the signal charge of each pixel is transferred to the terminal 34.
Taken out. The drawing shows an example of a so-called complementary color checker filter type color CCD image pickup device, in which two signals of the photoelectric conversion unit 31 are supplied to one stage of the vertical register 32.

Further, the signal from the terminal 34 is supplied to the CCD signal detecting section as shown in FIG. That is, the signal (charge) from the terminal 44 is supplied to the capacitor 45, and the terminal voltage of the capacitor 45 is changed to the FET4.
6 gates. The reset drain bias (terminal 47) of the FET 46 is the reset switch 48.
Through the gate of the FET 46. The source of the FET 46 is grounded through the resistor 49,
The voltage output is taken out to the terminal 40 from the source of the FET 46.

By the way, in such a VTR-integrated video camera, for example, digitalization of signal processing is in progress. In that case, conventionally, for example, as shown in FIG. 5, the signal from the above-mentioned CCD image pickup device 50 is taken out through the CCD signal detection section 51. The signal from the CCD signal detector 51 is supplied to the AGC amplifier 53 through the sample hold circuit 52. Then, the signal from the AGC amplifier 53 is supplied to the A / D conversion circuit 54, and the digitized signal is supplied to the processing circuit 55 in the subsequent stage.

That is, in the conventional device, digitization was performed only by the circuits after the AGC amplifier 53.
Therefore, in the conventional device, analog processing is performed in the circuit from the CCD image pickup device 50 to the AGC amplifier 53.
There is a possibility that problems may occur in the deterioration of the S / N during this period, phase management of the clock of the sample hold circuit 52, and the like.
Also in the CCD signal detector 51, when the floating diffusion amplifier by the capacitor 45 or the source follower of the FET 46 is used, it is difficult to manage the output waveform.

On the other hand, there has been proposed a method in which a capacitor is connected to each pixel of a CCD image pickup device to measure a charged voltage and directly digitize it. However, according to this method, different types of elements are provided in the CCD image pickup device, which is not easy to form, and there is a problem that the device becomes large-scaled. This application is made in view of such a point.

[0007]

The problem to be solved is that in the conventional device, analog processing is performed in the circuit from the CCD image pickup device to the AGC amplifier, and S / N and clock phase management during this period are performed. There was a risk of problems.

[0008]

According to the present invention, photoelectrically converted charges (part 1) are accumulated in a well 2 having a predetermined potential, and a fixed small amount of charges (reservoir 3) is stored in this well. Is added and the well is overflowed (detection means 4), based on the number of times the charge is added (counter 7), calculation with a reference value (black stripe 10, latch circuit 12) (circuit 13) This is a CCD image pickup device in which an output is taken out (output terminal 14) by.

[0009]

According to this, the CCD image pickup device of digital output can be formed with a simple structure by taking out the output by the calculation based on the number of times the charge is added until the well overflows.

[0010]

1 shows an example of a CCD image pickup device according to the present invention. In the figure, 1 is a photoelectric conversion unit (sensor), and wells 2 each having a predetermined potential are connected to the photoelectric conversion unit 1. Reservoir 3 in which a predetermined amount of electric charge is stored in each well 2
Are connected. Further, the well 2 is provided with a detecting means 4 for detecting the overflow of charges. The figure shows an example of a so-called complementary color checker filter type color CCD image pickup device.

Reference numeral 5 indicates, for example, that the horizontal effective screen period is 256.
It is a clock oscillator with equally divided timing. The oscillator 5 is connected to the storage unit 3 for each horizontal scanning line via the multiplexer 6.

Further, the oscillator 5 is connected to a counter 7, and the counter 7 is connected to a latch circuit 8 for the number of horizontal effective pixels. The detection means 4 is connected to each of the latch circuits 8. These latch circuits 8 are connected in cascade, and, for example, a transfer clock oscillator 9 having a timing obtained by dividing the horizontal blanking period into the number of horizontal effective pixels is connected to the transfer unit of the latch circuit 8.

Further, a black stripe 10 is provided on each of the rightmost photoelectric conversion sections 1. The latch circuit 7 connected in cascade is connected to the reference value latch circuit 1 via the switch 11.
2 and the arithmetic circuit 13. Further, the reference value latch circuit 12 is connected to the arithmetic circuit 13. Reference numeral 14 is an output terminal.

In this device, a photoelectric conversion unit 1 (not shown) is provided in a well 2 having a predetermined potential as shown in FIG.
The signal charge from is accumulated. On the other hand, the boundary between the predetermined charge and the reservoir 3 is raised and lowered according to the clock from the oscillator 5, and the charge from the reservoir 3 is added every clock. When the electric charge overflows from the well 2, the overflowing electric charge is detected by the detecting means 4.

The signal detected by the detecting means 4 is supplied to the latch circuit 8. Here, the count value of the clock from the counter 7 is supplied to the latch circuit 8, and the number of times the charge from the reservoir 3 is added until the charge overflows from the well 2 is latched. Then, the latched count value is sequentially transferred, for example, in the horizontal blanking period, processed by the arithmetic circuit 13 and taken out to the output terminal 14.

That is, in this device, the potential of the well 2 is defined in advance, and the signal charges are accumulated in the well 2. A predetermined charge is added to this every clock to supplement the shortage of the signal charge with respect to the potential of the well 2, and when the charge corresponding to this shortage is added, the charge overflows from the well 2. . Therefore, the shortage of the signal charge with respect to the potential of the well 2 is measured by counting the number of times the charges are added until the charges overflow.

Further, a reference black level value is measured from the rightmost well 2 and the measured value is latched in the reference value latch circuit 12. Then, by subtracting the measured value of each latch circuit 8 from this reference value in the arithmetic circuit 13, for example, the value corresponding to each signal charge can be taken out to the output terminal 14.

Thus, according to the above-mentioned device, the output is taken out (the output terminal 14) by the calculation (the circuit 13) based on the number of times the electric charge is added until the well 2 overflows (the counter 7), which is simple. With the configuration, a CCD image pickup device having a digital output can be formed.

Further, according to the above-mentioned device, the CC of the conventional device is used.
The analog processing performed from the D image pickup device 50 to the AGC amplifier 53 is deleted, and S / N deterioration during this period,
Problems such as phase management of the clock of the sample hold circuit 52 are solved. Further, since the floating diffusion amplifier by the condenser 45 and the source follower of the FET 46 are not used, it is not necessary to manage the output waveforms of these.

Further, unlike the method in which a capacitor is connected to each pixel of the CCD image pickup device and the charged voltage is measured to directly digitize the CCD image pickup device, the CCD image pickup device can be formed by only the same kind of elements, and the formation can be facilitated. There is no fear that the device will become large-scale.

In the above-mentioned apparatus, each detecting means 4 can be composed of one electrode. Further, the above-described configuration is a so-called complementary color checkered filter type color CCD.
It can be applied to other than the imaging device.

[0022]

According to the present invention, the digital output CC can be obtained with a simple structure by taking out the output by calculation based on the number of times the charge is added until the well overflows.
It is now possible to form a D imaging device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of a CCD image pickup device according to the present invention.

FIG. 2 is a diagram for explaining the explanation.

FIG. 3 is a configuration diagram of a conventional CCD image pickup device.

FIG. 4 is a diagram for explaining the explanation.

FIG. 5 is a diagram for explaining the explanation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoelectric conversion part 2 Well with a predetermined potential 3 Storage part for storing a predetermined amount of charge 4 Detection means for detecting overflow of charge 5 Clock oscillator 6 Multiplexer 7 Counter 8 Latch circuit 9 Transfer clock oscillator 10 Black stripe 11 Switch 12 reference value latch circuit 13 arithmetic circuit 14 output terminal

Claims (1)

[Claims] 1. A photoelectrically converted charge is accumulated in a well having a predetermined potential, and a fixed small amount of charge is added to the well until the well overflows. A CCD image pickup device in which an output is taken out by calculation with a reference value based on the number of times.