JP2713295B2 - Driving method of solid-state imaging device and imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for driving a solid-state imaging device and an imaging apparatus using the driving method. More specifically, the present invention relates to an imaging apparatus capable of obtaining a sequentially-scanned video signal using an existing solid-state imaging device and a driving method of the solid-state imaging device therefor. 2. Description of the Related Art As shown in FIGS. 4A and 4B, the scanning order of a general solid-state imaging device used for an electronic still camera or a video camera with respect to each horizontal pixel row is roughly two.
There are two ways. In a first method, as shown in FIG. 4A, a signal charge stored in each pixel is transferred to a first field (Odd).
Field), a horizontal pixel row in which the pixels 20 are arranged is scanned every other row in the vertical direction (scanning indicated by a solid line in FIG.
In the second field (even field), scanning is not performed first or the remaining horizontal pixel rows are scanned (scanning indicated by a broken line in FIG. 4A), and two fields (= 1 frame)
Is a method of reading out all signal charges. [0004] The second method is as shown in FIG.
Two adjacent horizontal pixel rows are scanned in one horizontal scan,
This is a method of reading out all signal charges in one field. In order to prevent resolution degradation in the vertical direction when used in a video camera, a first field (odd field) as shown by a scan shown by a solid line and a scan shown by a broken line in FIG. In the second field (even field), two horizontal pixel columns, which are simultaneously read out in the horizontal scanning of FIG. 1, are scanned while being shifted by one column in the vertical direction. The first method has an advantage that a frame image can be obtained, and is suitable for photographing and recording an image having a good vertical resolution. The second method has a drawback that a vertical resolution is deteriorated because only a field image is obtained. However, generally, an image has a strong vertical correlation, and even if the vertical resolution is halved, the overall image quality is a frame image. There is an advantage that there is no significant difference between the two and the number of images that can be recorded on one recording medium is twice as large as the frame image. Therefore, in the electronic still camera, switching between the first and second scanning methods according to the situation has been conventionally considered. However, in the case of a color solid-state imaging device in which a mosaic color filter is arranged in each pixel as shown in FIGS. 5 and 6, in the first scanning method, the horizontal scanning corresponding to both the odd field and the even field is performed. Although the same output is obtained in the scanning row, the signal output obtained in the odd field and the signal output obtained in the even field are different in the second scanning method. That is, the signal output of the odd field is the first
And the necessary signals (for example, a luminance signal Y and two color difference signals of approximately RY and BY) are obtained by performing color separation by the same signal processing method. However, the signal output of the even field cannot be color-separated by the same signal processing method, and a necessary signal cannot be obtained. This will be described in more detail. In the color filter shown in FIG. 5, in the first scanning method, both the odd field and the even field have the Nth and n'H horizontal scannings, respectively, during the horizontal scanning.
By scanning the row and the (N + 1) row, R and G components are obtained for each pixel, and (n + 1) H and even of the odd field are obtained.
At the (n + 1) 'H-th field of the n-th field, (N +
2) Since the G and B components are obtained for each pixel by scanning the row and the (N + 3) row, by utilizing the correlation in the 1H period,
A luminance signal composed of (R + 2G + B) components and two kinds of color difference signals of RG and BG are obtained, and a signal conforming to the standard television system can be formed. On the other hand, in the second scanning method, the signals of the Nth row and the (N + 1) th row are simultaneously read out at the nHth time in the odd field to obtain 2R and 2G components, and the (N + 1) H
The eyes simultaneously read the signals of the (N + 2) th row and the (N + 3) th row to obtain 2G and 2B components. Therefore, it is possible to obtain the same kind of signal by the same signal processing method as that in the first scanning method. it can. However, in the even field, n'H
The (N + 1) -th and (N + 2) -th rows are read out at the same time to obtain (R + G) and (B + G) components, and (n)
The (N + 3) -th row and the (N + 4) -th row are read out simultaneously at the (+1) 'H-th time, and the (R + G) component and the (G + B) component are obtained. Therefore, in the same signal processing method as in the first scanning method, Color separation cannot be performed, and the same type of signal cannot be obtained. Next, in the color filter shown in FIG. 6, in the first scanning method, both the odd field and the even field have the Nth and n'H horizontal scannings, respectively.
Row and (N + 1) row are scanned to obtain 1/2 as a low frequency component.
(Cy + G + Ye + Mg) = R + B + 3 / 2G signal
1/2 ｛(Cy + G) − (Ye + M)
g) The signal｝ =-(RG / 2) is obtained. Also, (n + 1) H and e in the odd field
The (N + 1) 'Hth of the ven field is (N
+2) row and (N + 3) row are scanned to obtain 1
/ 2 (Cy + Mg + Ye + G) = R + B + 3 / 2G signal becomes 1/2 ｛(Cy + Mg) − (Ye +
G)｝ = BG / 2 signal is obtained. Therefore, by utilizing the correlation in the 1H period, a luminance signal of R + B + 3 / 2G and two kinds of color difference signals of RG / 2 and BG / 2 are obtained, and a signal matching the standard television signal is obtained. Can be formed. On the other hand, in the second scanning method, the signals of the Nth row and the (N + 1) th row are simultaneously read out at the nHth time in the odd field, and 2 × 1/2 (Cy + G
+ Ye + Mg) = 2R + 2B + 3G signal is 2 × 1/2 {(Cy + G) − (Ye + Mg)} = −
(2R-G) signal is obtained, and the (N + 1) th H-th (N
+2) row and (N + 3) row signals are read out simultaneously, and 2 × 1/2 (Cy + Mg + Ye + G) =
2R + 2B + 3G signal is 2 × 1/2 as a modulation component
Since ｛(Cy + Mg) − (Ye + G) = 2B−G signal is obtained, the same kind of signal can be obtained by the same signal processing method as in the first scanning method. However, in the even field, n'H
The (N + 1) -th row and (N + 2) -th row are read simultaneously at the eye, and the (N + 3) -th row and (N + 4) at the (n + 1) 'H-th eye
The rows are read out at the same time, and both the n'H-th and (n + 1) 'H-th are 1/2 (Cy + G) + (C
y + Mg) + (Ye + G)｝ = 2R + 2B + 3G is {(Cy + G) + (Cy + Mg) − (Ye) as a modulation component.
+ Mg) − (Ye + G)｝ = BR signal is obtained, so that the same signal processing method as in the first scanning method cannot perform color separation and cannot obtain the same kind of signal. Therefore, a color solid-state imaging device provided with a color filter which can obtain a necessary signal for each field by the first scanning method as shown in FIGS. 5 and 6 is applied to an electronic still camera. In the case of using the second scanning method, it is necessary to read out a signal corresponding to a subject image stored in the solid-state imaging device using an optical shutter in synchronization with a field where a necessary signal is obtained (that is, in frame synchronization). . FIG. 7 shows an example of the electronic still camera configured as described above. In the figure, 1 is a lens, 2 is an aperture,
3 is a shutter, 4 is a solid-state image sensor, 5 is a signal processing circuit, 6 is a photometric device, 8 is an exposure control circuit, 9 is a solid-state image sensor scanning method switch, 13 is an element driving circuit, 11 is a recording method switch, 12, a recording head changeover switch; 14, a recording device; 15, a first recording head; 16, a second recording head; 17, a first recording area;
, A recording mode changeover switch 19, a synchronization signal generator 20, and a gate circuit 21. Next, the operation of FIG. 7 will be described. Light from a subject (not shown) is guided to the photometric element 6 through the lens 1 to measure the brightness of the subject, and the information from the photometric element 6 determines an appropriate exposure amount in the exposure control circuit 8. The aperture of the aperture 2 and the shutter time of the shutter 3 at the time of imaging the subject are controlled to values that give the fixed image sensor 4 an appropriate exposure amount based on The solid-state image pickup device 4 is driven by a drive signal (a synchronous signal signal generator 20) generated by the device drive circuit 13.
It is assumed that it is synchronized with the generated synchronization signal. )
Is scanned by the driving signal switched by the scanning method changeover switch 9, and the signal charges are read out and guided to the signal processing circuit 5. The signal processed by the signal processing circuit 5 into a signal form suitable for recording on the recording device 14 is guided to the recording method switch 11. On the other hand, when either the frame recording mode or the field recording mode is selected by the recording mode changeover switch 19 and the frame recording mode is selected based on this information, the scanning method changeover switch 9 is set to the terminal A of the terminal A. On the other hand, the recording method switch 11 is switched to the terminal A. When the recording mode changeover switch 19 selects the field recording mode, the scanning method changeover switch 9 is connected to the terminal B and the recording method changeover switch 11 is turned on.
Is switched to the terminal B. Note that a first drive signal for performing the above-described first scanning method and a signal from the element driving circuit 13 are directly guided to a terminal A of the scanning method changeover switch 9. The driving signal for performing the above-described second scanning method is guided after being gated by the gate circuit 21 in accordance with the field determination signal. As described above, in the second scanning method, a necessary signal can be obtained only by scanning one of the odd field and the even field.
This is for reading out signal charges from the solid-state imaging device in synchronization with an appropriate field. For example, in FIG.
In the case of the solid-state imaging device provided with the color filter shown in (1), reading of the charge corresponding to the subject image which is guided to and stored in the solid-state imaging device 4 by opening the shutter is performed in the odd field period. As described above, when the frame recording mode is selected, the solid-state imaging device 4 is scanned by the first scanning method, and the signal from the signal processing circuit 5 is transmitted to the terminal A of the recording method switch 11. The signal is supplied to the first recording head 15 in the first field by the head changeover switch 12 and to the second recording head 16 in the second field.
, The signal of the first field is recorded in the first recording area 17, and the signal of the second field is recorded in the second recording area 18. When the field recording mode is selected, the solid-state imaging device 4 is scanned during a field period in which a required signal can be obtained by the second scanning method, and a signal from the signal processing circuit 5 is supplied to a terminal B of the recording method switch 11.
And is recorded in the first recording area 17 by the first recording head 15. In the above-described conventional method of driving a solid-state image pickup device and an image pickup apparatus using this driving method, although an interlaced scan image signal is obtained, a progressive scan image signal is obtained. A signal cannot be obtained, and an imaging device having good compatibility with a personal computer and a communication field cannot be obtained. It is an object of the present invention to solve the above-mentioned problems and to provide an imaging apparatus capable of obtaining a progressively scanned video signal using an existing solid-state imaging device and a method of driving the solid-state imaging device therefor. According to the present invention, there is provided a horizontal pixel column of a fixed image pickup device having 2N (N is an integer of 2 or more) horizontal pixel columns in a vertical direction. Is read out by mixing signal charges of two pixels adjacent in the vertical direction and reading out the signals of two adjacent horizontal pixel columns simultaneously in one horizontal scan, and scanning the entire screen in one vertical scan period A method of driving a solid-state imaging device, wherein a combination of two horizontal pixel columns read simultaneously in one horizontal scan is always the same horizontal pixel column in each vertical scanning period, and 2N (N Is an integer of 2 or more). A solid-state imaging device having a horizontal pixel column of two or more rows and a scanning state of the horizontal pixel column of the solid-state imaging device are read out after mixing signal charges of two vertically adjacent pixels. Yo The signals of two adjacent horizontal pixel columns are simultaneously read out in one horizontal scan, and when scanning the entire screen in one vertical scan period, the combination of two horizontal pixel columns read out simultaneously in one horizontal scan is used for each vertical scan. A solid-state imaging device driving circuit that always has the same horizontal pixel row in the period; and a signal processing circuit that processes the solid-state imaging device output signal and outputs a video signal of N vertical scanning lines in sequential scanning. Is an imaging device. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a lens, 2 is an aperture, 3 is a shutter, 4 is a color solid-state imaging device provided with a color filter capable of switching a scanning method as shown in FIGS. 2 and 3, 5 is a signal processing circuit, 6 is a photometric element, 8 is an exposure control circuit, 9 is a solid-state image sensor scanning method switch, 1
0 is an element driving circuit, 11 is a recording method switch, 12
Is a recording head changeover switch, 14 is a recording device, 15 is a first recording head, 16 is a second recording head, and 17 is a first recording head.
Is a second recording area, 19 is a recording mode changeover switch, and 20 is a synchronization signal generator. The light from the subject (not shown) is guided to the photometric element 6 through the lens 1 to measure the brightness of the subject, and the information from the photometric element 6 determines an appropriate exposure light amount in the exposure control circuit 8. The aperture value of the aperture 2 and the shutter time of the shutter 3 are controlled to values that give the solid-state imaging device 4 an appropriate exposure amount at the time of subject photographing. The solid-state imaging device 4 scans the driving signal generated by the device driving frequency 10 with the driving signal switched by the scanning method changeover switch 9, reads out the signal charge, and sends it to the signal processing circuit 5. Be guided. The drive signal is synchronized with the synchronization signal generated by the synchronization signal generator 20. Signal processing circuit 5
The signal processed into a signal form suitable for recording on the recording device 14 is guided to the recording method switch 11. on the other hand,
When either the frame recording mode or the field recording mode is selected by the recording mode switch 19, and the frame recording mode is selected based on this information,
The scanning method switch 9 is switched to the terminal A, and the recording method switch 11 is switched to the terminal A. Since the first drive signal for performing the first scanning method described in the description of the conventional example is led to the terminal A, for example, the first scanning method shown in FIGS. , One horizontal row is sequentially read out in one horizontal scanning period, and the signal of the entire screen is read out in two field periods, so that signals for two fields, that is, one field are obtained. After this signal is processed by the signal processing circuit 5, it is led to the terminal A of the recording method changeover switch 11, and the signal is sent to the first recording head 15 in the first field by the head changeover switch 12. In the second field, the signal is guided to the second recording head 16, and the signal of the first field is recorded in the first recording area 17 and the signal of the second field is recorded in the second recording area 18. In this frame recording mode, since the method of scanning the solid-state image pickup device provided with the color filters shown in FIGS. 2 and 3 is the same as that of the conventional example, the signals obtained are all the same. On the other hand, when the field recording mode is selected by the recording mode switch 19, the scanning method switch 11 is switched to the terminal B. To this terminal B, a second drive signal for simultaneously reading out two adjacent horizontal rows of signals in one horizontal scan and reading out signals of the entire screen in one field period is led. The scanning by the second drive signal is different from the conventional example, and as shown in the scanning order described in the second scanning method of FIGS.
The set of two horizontal rows that are simultaneously read out in one horizontal scan is two horizontal rows in which the arranged color filters are the same, and the same signal processing method as in the frame recording mode is used regardless of the readout during any field period. Is a scanning method in which a necessary signal is obtained at the output of the signal processing circuit 5. Therefore, even in the field recording mode, the subject image photographed by opening the shutter can be read out not in frame synchronization but in synchronization with the vertical synchronization signal immediately after the end of photography, that is, in field synchronization. The signal read out in this way is processed by the same signal processing circuit 5 as used in the frame recording to have the same signal form as that used in the frame recording. Then, the data is recorded in the first recording area 17 by the first recording head 15. According to the present invention, as described above, two vertical
The scanning state of a horizontal pixel column of a solid-state imaging device having N (N is an integer of 2 or more) horizontal pixel columns or more is read by mixing signal charges of two pixels that are vertically adjacent to each other and then reading out. The signals of two horizontal pixel columns are read out simultaneously in one horizontal scan, and when scanning the entire screen in one vertical scan period, the combination of two horizontal pixel columns read out simultaneously in one horizontal scan is always the same in every vertical scan period By using a horizontal pixel array, it is possible to obtain a progressively scanned video signal using an existing solid-state imaging device, and to obtain a photographing apparatus having good compatibility with a personal computer and a communication field, thereby achieving an industrial effect. Is big.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a first embodiment of a color filter array of a solid-state imaging device used in the present invention and a scanning method thereof. FIG. 3 is an explanatory diagram showing a second embodiment of a color filter array of a solid-state imaging device used in the present invention and a scanning method thereof. FIG. 4 is an explanatory diagram showing a scanning method of a solid-state imaging device. FIG. 5 is a block diagram of a conventional electronic still camera. FIG. 6 is an explanatory view showing an example of a solid-state image pickup device with a color filter used in a conventional electronic still camera and a scanning method thereof. Reference numeral 7 denotes a block diagram of a conventional electronic still camera. [Description of References] 1 Lens 2 Aperture 3 Shutter 4 Solid-state imaging device 5 Signal processing circuit 6 Photometry device 8 Exposure control circuit 9 Scanning method switch 10 Element drive circuit 11 Recording method switch 12 f Switch 14 recording device 19 recording mode switch 20 synchronization signal generator

Claims (1)

(57) [Claims] The scanning state of a horizontal pixel column of a solid-state imaging device having 2N (N is an integer of 2 or more) horizontal pixel columns in the vertical direction is read by mixing signal charges of two vertically adjacent pixels. The signals of two adjacent horizontal pixel columns are simultaneously read out by one horizontal scan, and simultaneously read out by one horizontal scan when scanning the entire screen in one vertical scan period.
A method for driving a solid-state imaging device, wherein a combination of two horizontal pixel columns is always the same horizontal pixel column in each vertical scanning period. 2. A color solid-state imaging device in which horizontal rows of color filters are arranged in a first arrangement and horizontal rows which are a second arrangement different from the first arrangement are alternately arranged in two rows in a vertical direction. Is read out after mixing the signal charges of two pixels adjacent in the vertical direction after mixing the signal charges of two adjacent pixels in the vertical direction, thereby simultaneously reading out the signals of two adjacent horizontal pixel columns in one horizontal scan and in one vertical scan period. 2. The driving of the solid-state imaging device according to claim 1, wherein a combination of two horizontal pixel rows read simultaneously in one horizontal scan when scanning the entire screen is always the same horizontal pixel row in each vertical scanning period. Method. 3. A solid-state imaging device having 2N (N is an integer of 2 or more) horizontal pixel columns in the vertical direction and a signal state of two adjacent pixels in the vertical direction are mixed by scanning the horizontal pixel column of the solid-state imaging device. And then read out to get
The signals of two horizontal pixel columns are read out simultaneously in one horizontal scan, and the combination of two horizontal pixel columns read out simultaneously in one horizontal scan when scanning the entire screen in one vertical scan period is always the same in every vertical scan period An image pickup apparatus comprising: a solid-state image sensor driving circuit for forming a horizontal pixel row; and a signal processing circuit for processing the solid-state image sensor output signal and outputting a video signal of N vertical scanning lines sequentially scanned. . 4. A color solid-state imaging device in which horizontal rows of color filters are arranged in a first arrangement and horizontal rows which are a second arrangement different from the first arrangement are alternately arranged in two rows in a vertical direction. And reading out the scanning state of the horizontal pixel row of the color solid-state imaging device by mixing signal charges of two vertically adjacent pixels and reading out the signals of two adjacent horizontal pixel rows in one horizontal scan. A solid-state imaging device driving circuit in which a combination of two horizontal pixel columns simultaneously read in one horizontal scan when scanning the entire screen in one vertical scanning period at the same time is always the same horizontal pixel column in each vertical scanning period; 4. The image pickup apparatus according to claim 3, further comprising a signal processing circuit that processes the output signal of the solid-state image pickup device and outputs a video signal of a sequential scan of N vertical scanning lines.