JPS63173473A - Image pickup device - Google Patents

Abstract

PURPOSE:To obtain an excellent image without any hand shake by providing an image pickup element having a storage part which stores an image pickup element after photoelectric conversion for longer than one frame period, a driving control circuit which controls the operation of the image pickup element, and a signal processing circuit which converts a picked-up and processed image into a necessary signal. CONSTITUTION:In a period A in a figure (b), signal charges in an odd field are read out of a photodiode 1a to V-CCD 2. In a period B, on the other hand, the signal charges in the odd field which are read out to the V-CCD 2 are transferred to the storage part 1 at a high speed. When transfer pulses applied to phiV1-phiV4 are 1 MHz, they are transferred in 0.24 mS, or about four horizontal scanning periods at the time of a 250-stage V-CCD. In a period D, signal charges in an even field are transferred from the V-CCD 2 to the storage part 1 while the signal charges in the odd field are read out of the storage part 11 as a signal output through H-(CCD 3 and an) output amplifier(FDA) 4. Consequently, signals are obtained which have reduced time deviation in the period where the signals of the even and odd fields are converted photoelectrically by the photodiode, i.e. storage period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an imaging device such as a video camera or an electronic still camera that converts an optical image into an electrical signal.

2. Description of the Related Art Imaging elements used in conventional imaging devices are described in, for example, the Technical Report of the Television Society Vol. s No. 44 P33-4.
2. Figures 7(&) and (b) show the image sensor and its driving waveform, where 1 is a photodiode that performs photoelectric conversion, and 2 is a v-ca that performs vertical scanning.
3 is an H-COD that performs horizontal scanning, 4 is an output amplifier that converts signal charges into voltage, and 6 is a drive waveform applied to v-can.

The v-ccnoxv, yIv3oi poles of the image sensor have a structure in which charges photoelectrically converted by the photodiode 1 can be read out to the V-COD 2 by applying a high voltage. For example, by applying the high voltage shown in 62L to Ovl, the signal charge of the odd field is reduced to V-C.
By applying the high voltage shown by 6b to glV3, the even field signal charge is read out to OD2 and becomes V-CC.
It is read out in D2. The signal charges read from the V-CCD 2 are sequentially transferred to the H-CCD 3 and output from the output amplifier 4 as a signal voltage.

Problems to be Solved by the Invention As described above, when a conventional image sensor (COD) and a conventional driving method are used, the time required to obtain an odd field signal and an even field signal (the time difference in which the signals are obtained is simply For example, in scanning to obtain an NTSC signal, there is a time difference of 1/60 second. Therefore, when a standard television signal consisting of two frames per field is played back as a still image and the subject is moving, the played still image will have flickering in the played part. This poses a problem in that the image quality of still images deteriorates.

In view of the above, when a moving image of a standard television signal, in which an image is composed of two frames per field, is played back as a still image, the portion that is being played for the moving image is played back with flicker. It is an object of the present invention to provide an imaging device capable of outputting a standard 1m TV signal that is not transmitted.

Means for Solving the Problems The present invention provides an image sensor having a storage section that photoelectrically converts an optical image and stores the photoelectrically converted imaging signal for one frame period or more;
This imaging device includes a drive control circuit that controls the operation of an imaging device, and a signal processing circuit that converts captured and processed images into necessary signals.

Operation The present invention uses the above-described configuration to read out signals for two fields by reducing the time difference between the storage periods of two fields of an image consisting of two fields per frame. The read signal is temporarily stored in a storage section provided on the image sensor or in a V-CCD that performs vertical transfer, and then output as a subsequent image signal. By reducing the time difference between the accumulation periods as described above, it is possible to realize an imaging apparatus that can obtain high-quality images without blurring even when a moving image consisting of two frames per field is reproduced as a still image.

Embodiment FIG. 1 (IL) schematically shows the configuration of an image pickup element of an image pickup device and its driving waveform in a first embodiment of the present invention. In FIG. 1(a), 1 is a photodiode that converts light into charge, and 2 is a v-c CD that transfers the charge from the photodiode to perform vertical scanning.

3 is an H-CO that transfers charges in the horizontal direction and performs horizontal scanning.
Reference numeral D and 4 denote an output amplifier that converts charge into voltage and outputs it, which is similar to a conventional image sensor.

Reference numeral 11 denotes an accumulation section that temporarily accumulates charges transferred from VC; OD2 and transfers the charges to H-CCD3. A voltage shown in ) in FIG. 1 is applied to the image pickup device configured as described above, and the operation shown below is performed. In the period of the person shown in (b) of the same figure, the odd field signal charge is transferred to photodiode 1.
Read from a to V-CCD2. In period B, V-COD
The odd field signal charges read out in step 2 are transferred to the storage section 11 at high speed. Transfer pulses added to gv1 to gv4 are 1
In terms of MHz, if the v-can is 250 steps, it is 0.25m.
5, which is approximately 4H scanning period. In period C, even field signal charges are read out from photodiode 1b to V-COD2. During the period D, H from the storage unit 11
-can3. At the same time, the odd field signal charge is read out as a signal output through the output amplifier (FD driver) 4, and the even field field charge is read out from the V-CCD 2 through the storage unit 11.
Transfer to. Period E is a vertical blanking period and F
During the period, data from the storage unit 11 to the H-CCD 3. The even field signal charge is read out as a signal output through the output amplifier 4.

As described above, by providing the storage section 11 in the image sensor and reading out the signal using the method described above, a signal is obtained in which the time difference in the period during which the odd and even field signals are photoelectrically converted by the photodiode, that is, the storage period is reduced. is obtained. In this example, the difference in storage period is 0.25 m S =
, o o o seconds, and when a moving image consisting of two fields per screen is reproduced as a still image, an image without blurring between fields can be obtained.

Next, an example of an imaging device configured using this imaging element will be described. FIG. 2 is a block diagram of the imaging device, and FIG. 3 is a color filter used in the imaging device. In FIG. 2, 12 is an image sensor shown in FIG. 1(a), and 13 is a drive circuit that generates the drive pulses shown in FIG. 1(b). A low-pass filter (LPF) 14 attenuates carriers of color signals multiplexed by the image sensor. 16
The color separation circuit separates RGB primary color signals. 16 is a process circuit that performs γ correction, matrix, etc.

As shown in FIG. 1('b), the image sensor 12 is driven to read out signals by reducing the time difference in the accumulation period between fields. The read signal is a repetition of W (white), 1 green) or Gy, corresponding to the dye of the color filter shown in Fig. 3.
(cyan) and Ye (yellow) signals are obtained. The LPF 4 smoothes the changes in the signal level of each color to produce a luminance signal (Y). The color separation circuit 16 is w, G
,cy.

Red (R) and blue (B) signals are separated from the four colors of Yo as shown in the following equation.

R = (W-C) + (Y, -G) B = (w-y, ) + (Gy-G) The process circuit 16 performs processing such as γ correction and matrix on each of the Y, R, G, and B signals. , Y , RY , B-Y3
Convert to one component output or NTSC signal and output.

As described above, according to this embodiment, by configuring the image sensor as described above, reading out signals from the image sensor so as to reduce the time difference between accumulation periods, and performing the signal processing as described above, one screen 2 Even when a moving image consisting of fields is played back still, it is possible to obtain a good color image without blurring between fields.

FIG. 4(&) shows the configuration of an imaging element used in an imaging device according to a second embodiment of the present invention. 1
is a photodiode that converts light into charge, 2 is a V-CCD that transfers charge vertically and performs scanning, 3 is H-COD that transfers charge horizontally and performs scanning, and 4 converts signal charge into voltage. It is an output amplifier, and has the same configuration as the image sensor of the first embodiment, except that 21.
The electrode that drives the storage section of O is made independent of V-CCD2, and
M1 to OM4 and V-CCD2 (D storage section 21
The point is that the drain section 22 is provided on the opposite side.0 The operation of the image sensor used in the second embodiment configured as described above will be explained below. FIG. 4(b) shows the driving waveform of the image sensor. OM that drives the storage unit 21, ~
Regarding OM4, it is the same as that shown in FIG. 1(b)K except for periods M and C. Mari V-COD 2 No.1E
The K dynamic waveforms Ov, to yIv4 have the same period from the person to E, and the operation of the image sensor is also the same. Person's period is odd field signal charge photodiode 1! L to V-
This is the period for transferring to CCD2. The period B is a period in which the odd field charges are transferred from the V-CCD 2 to the storage section 21 at high speed. The steps C to E are exactly the same as the first embodiment, and the explanation will be omitted. During period F,
The operation of the storage unit 21 is to sequentially store signal charges of even fields in H.
-Transfer to CGD3 and perform normal scanning. What is different from the first embodiment is the drive pulse for the V-CCD 2, during which charges are again read out from the odd field photodiodes.

In period J, this read charge is transferred to the drain/unit 22 using the V-CCD 2. The drain part 22 has a positive voltage 1
absorbs the transferred charge. During the period K, the charge from the even field photodiode is V-C;
This charge is transferred to the drain section 22 during the readout L period to D2.

The processing of the signal obtained from the image sensor is the same as in the first embodiment, and its explanation will be omitted.

By configuring as described above, it is possible to arbitrarily set the accumulation period of the signal read out as a signal to a period shorter than one field period. The accumulation period is from the end of K to the beginning of M in odd-numbered fields, and from the end of K to the beginning of C in even-numbered fields. from engineering to L
The discharge period of charge at ``&'' can be any period between E and F, and when the field frequency is 60H2, the accumulation period can be varied from about 6'O seconds to about 33 stone seconds. At this time, the difference in storage period between fields in one image consisting of two fields on one screen can be set to about 1-second as in the first embodiment, and it is possible to Even when a still image is reproduced, it is possible to reproduce a good image without distortion due to differences between fields.

FIG. 6(&) is a diagram showing an image sensor used in the third embodiment of the present invention. 1 to 4 are the same as the first embodiment, and the difference is that 22 storage units 1 and 23 storage units 2 are provided. The motion waveform of the image sensor is shown in FIG. 6(b). The driving waveforms that differ from the first example are C and D.
The difference is that a period B' is added to the period B', and the operation other than B' is the same as that of the first embodiment, so a description thereof will be omitted. During period B', signal charges of even fields read during period C are transferred at high speed. Therefore, all the signal charges of two fields are transferred to the storage section at high speed during the period from time to time B'. The signal charges thus transferred to the storage section 1.degree. 2 are sequentially read out through the H-CCD 3 and the output amplifier 4 to obtain an imaging signal. The processing of the imaging signal is the same as that in the first embodiment, so a description thereof will be omitted.

As described above, according to this embodiment, the time difference in the storage period between fields of an image consisting of two fields on one screen can be determined.

. . . By reducing the size to about a second and transferring both odd and even fields from the imaging unit to the storage unit at high speed, it is possible to produce good images with no blur between fields even when playing still images from moving images on a VTR etc. At the same time, a good image with very little smear component, which is characteristic of solid-state imaging devices, can be obtained.

FIG. 6 (IL) shows an imaging element of an imaging apparatus according to a fourth embodiment of the present invention. The difference from the imaging device of the third embodiment is that the electrodes for driving the storage section 24.25 are provided as OM and ~OM4 independently of the v-COD 2, and the drain electrode 22 is provided to absorb charges. 1 to 4 are the same as the other embodiments, and their explanation will be omitted. FIG. 6(b) shows the driving waveform of the image sensor. Accumulation section 1
The waveforms applied to the second electrodes OM and OM4 are the same as in the third embodiment except for periods A and C. The difference in waveforms between the human and C periods is the readout portion from the photodiode, and the transfer of stains is the same. Add to V-COD n
The periods v1 to yIv4 from M to B' are the same as in the third embodiment, and the signal charge photoelectrically converted by the photodiode is transferred to the storage section at high speed. In the period from D to F, a high-speed transfer section from F to L is installed in a part of the period, and the V-CO
Charge is transferred to the drain section 22 using D2. By reading out the unnecessary charges photoelectrically converted to the photodiode in this way, the accumulation period of the charges used as a signal can be arbitrarily set to the period D to F. The processing method is the same as in the first embodiment, and will therefore be omitted.

By configuring and driving the image sensor as described above, even when an image consisting of two fields per screen is played back statically on a VTR or the like, a good image without inter-field blur can be obtained. Furthermore, the resulting images have less smear and the accumulation period is from about 6 seconds. . . It can be varied up to seconds.

Although only one colorization method is shown in the above embodiments, it is needless to say that the colorization method is not limited to the colorization method using this color filter, and a colorization method in a normal frame accumulation mode can be used.

Furthermore, it is natural that the imaging device of the present invention can be used not only for digital cameras but also for electronic still cameras.Furthermore, the time lag in the storage period between frames for photoelectric conversion to obtain imaging signals may be increased to some extent. It is also clear in principle that the storage section provided in the image sensor can be reduced if the image sensor is suitable.

According to the present invention, as described in detail, there are two screens constituting one screen.
Temporal lag in the storage period of field images. . It is possible to reduce the time to about a second, and it is possible to obtain an imaging device that can obtain a good image without inter-field blur even when a moving image is reproduced as a still image using a VTR or the like.

Furthermore, the storage period during which photoelectric conversion is performed can be arbitrarily and electronically changed to about 7500 seconds, allowing electronic still cameras to eliminate the need for a mechanical shutter.

Furthermore, since signal charges can be transferred at high speed, smear, which is a problem with solid-state imaging devices, can be sufficiently reduced.

As mentioned above, the practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram and drive waveform diagram of an image sensor used in an imaging device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of the embodiment, and Fig. 3 is a color filter used in the embodiment. FIG. 4 is a schematic diagram showing the configuration of an image sensor used in other embodiments of the present invention and a drive waveform diagram, and FIGS. Driving Waveform Diagram FIG. 7 is a configuration diagram and a driving waveform diagram of an image sensor used in a conventional imaging device. 11L, 1b...Photodiode, 2...
...Vertical CCD, 3...Horizontal COD, 4...
...Output amplifier, 11.21.22, 23, 24.2
5...accumulation section, 22...drain section,
12...Image sensor, 13...Drive circuit, 14...Low pass filter, 16...
- Color separation circuit, 16...process circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 4 (Otsu and 2 PrlT -F/21+1114 Figure 4 (b) KushiliLfurufushisenku7hblindi Figure 5 (υ? Figure 6

Claims (3)

[Claims] (1) An image sensor that has a photoelectric conversion section that photoelectrically converts an optical image and a storage section that accumulates the image signal after photoelectric conversion outside the photoelectric conversion section, and a method that reduces the time difference in the period during which photoelectric conversion is performed between fields. An imaging device comprising: a drive circuit that drives the imaging device; and a signal processing circuit that converts a signal obtained from the imaging device into a required signal. (2) The drive circuit is characterized in that the drive circuit transfers at least a portion of the photoelectrically converted signal of the image sensor to the storage section for each field at high speed, thereby reducing the difference in storage time of one image between two fields. An imaging device according to claim 1. (3) The image sensor has a drain section that discharges unnecessary charges in the charge transfer section, and the drive circuit is configured to transfer charges from the photoelectric conversion section to the drain section during a period in which there is no signal charge in the charge transfer section. An imaging device according to claim 1 or 2 characterized by: