JPH04343586A - Method for driving solid-state image pickup element - Google Patents

Abstract

PURPOSE:To attain a zooming function or a camera-shake correcting function by changing a reading position in a scanning area based upon the control of a solid-state image pickup element driving circuit. CONSTITUTION:Respective timing pulses Ssw, Sre are outputted from a rapid scanning timing generating circuit 85 and a reading scanning timing generating circuit 86 in a control circuit 24 (34). At the time of receiving the pulse Ssw, a rapid scanning pulse generating circuit 83 in a driving circuit 23 (33) generates a rapid scanning pulse for sweeping a signal in an area other than a scanning area. Receiving the pulse Sre, a reading scanning pulse generating circuit 84 generates a scanning pulse for reading out a signal in the scanning area. Finally an adder 82 adds respective scanning pulses and outputs a vertical CCD scanning pulse 81 from the circuit 23 (33). Thereby the phase of the pulse Sre to the circuit 84 is controlled and the pulse Sre is generated after the lapse of two horizontal scanning periods or more and then the signal in the scanning area is read out. Consequently the leakage of charge left without being transferred to a horizontal CCD into a video signal can be prevented.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an imaging device using a solid-state imaging device, and a method for driving the solid-state imaging device.
In particular, the present invention relates to a driving method that is suitable for imaging devices having electronic zoom functions and image stabilization functions.

0002

2. Description of the Related Art In recent years, with the spread of integrated video cameras, the functions demanded by users have become increasingly diverse. Furthermore, advances in semiconductor technology have led to higher-density packaging on boards, and there is a need to further develop smaller and lighter products.

By the way, one of the functions of an integrated video camera is a zoom function. Conventionally, this function was achieved by combining multiple lenses and providing a complex cam structure as a lens zoom. With this method, if the user desires a lens zoom with even higher magnification, the number of lenses is increased. However, this method only increases the proportion of the lens in the video camera, which is a factor that contradicts the goal of making the camera smaller and lighter.

Therefore, in order to solve this problem, we focused on a method of driving a solid-state image sensor without increasing the number of lenses, as shown in Japanese Patent Laid-Open No. 1-228280, etc., and developed a solid-state image sensor. By adding control to the scanning pulses that drive the element and increasing the number of scanning pulses output in one horizontal scanning period, the vertical transfer section of the solid-state image sensor is scanned at high speed, and zooming is achieved using a driving method of the solid-state image sensor that does not rely on lens zoom. Features are proposed.

[0005] Furthermore, as miniaturization progresses, camera shake becomes more likely to occur during shooting, and when playing back captured images,
Shaking due to camera shake has become noticeable.

[0006] For this reason, Kinugasa et. al
．． ” Electronic Image satb
ilizer for Video Camera U
se” IEEE Trans.on.C.E.,v
ol. 36, No. 3, August 1990, a video integrated camera is provided with a detection circuit for detecting camera shake, and a signal from the detection circuit controls the scanning pulse output from a drive circuit that drives a solid-state image sensor. A method has been proposed for correcting camera shake by changing the readout position of the scanning area by an amount that can cancel camera shake.

[0007]

SUMMARY OF THE INVENTION The above means increases the number of scanning pulses outputted from a driving circuit for driving a solid-state image sensor than the number outputted within one normal horizontal scanning period, Charges outside the scan area are swept out. At this time, normally, a scanning pulse is output from the drive circuit once within one horizontal scanning period, and the horizontal CCD is outputted from the vertical CCD.
In contrast to transferring charge to a CD, in order to transfer charge from the vertical CCD to the horizontal CCD multiple times within one horizontal scanning period, the amount of charge that can be handled by the horizontal CCD exceeds the maximum amount that can be handled by the vertical CCD. Charge transfer will be performed from there.

Therefore, as shown in FIG. 1, by sweeping out signals outside the scanning area by high-speed scanning of scanning pulses, charges exceeding the amount of charge that can be handled by the horizontal CCD remain in the horizontal CCD without being transferred. A problem arises in that the charge remaining without being transferred leaks into the video signal when signal reading of the scanning area is started, and the charge appears as a white band in the upper part of the monitor screen.

[0009]

[Means for Solving the Problem] As a means to solve the above problem, when an area other than the scanning area is scanned at high speed during the vertical retrace period to sweep out the charges, it is necessary to scan the area as early as possible within the vertical retrace period. High-speed scanning is performed from (for example, the beginning of the vertical retrace period).

Furthermore, after two or more horizontal scanning periods have elapsed after the output of the scan pulse for sweeping out the charges in areas other than the scan area, output of the scan pulse for reading out the charges in the scan area is started.

[0011]

[Operation] According to the present invention, when controlling the drive circuit of the solid-state image sensor and varying the readout position of the scanning area, the area other than the scanning area is scanned at high speed in an early period within the vertical retrace period to sweep out the charges. , after two or more horizontal scanning periods have elapsed, the scanning pulse for reading out the charges in the scanning area is started to be output, so it is possible to prevent charges outside the scanning area from leaking into the video signal due to high-speed scanning.

0012

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram of an image pickup device that uses the present invention to realize a zoom function, and FIG. 4 shows a scanning pulse for driving the light receiving surface of the solid-state image pickup device and the vertical CCD of the solid-state image pickup device.

In FIG. 2, 21 is a lens, 22 is a solid-state image sensor, 23 is a drive circuit for driving the solid-state image sensor, and 2
4 is a control circuit that controls the drive circuit, 25 is a signal processing circuit that processes the signal output from the solid-state image sensor and outputs it as a video signal, 26 is an interface from the signal processing circuit 25, and 27 is the signal 28 is a scanning pulse for driving the solid-state image sensor 22; 29 is a video signal; and 30 is a control signal.

The object image formed on the light-receiving surface of the solid-state image sensor 22 is captured by the scanning pulse 2 output from the drive circuit 23.
8 drives the solid-state image sensor 22 to perform photoelectric conversion and output from the solid-state image sensor 22 as an electrical signal.

During the period t1 in FIG. 4, the drive circuit 23:
The horizontal CC output from the drive circuit 23 is controlled by the control signal 30 output from the control circuit 24 according to the zoom magnification.
The scanning pulse 28 of D is set to a higher frequency than the normal frequency, and the vertical CCD of the solid-state image sensor 22 is scanned at high speed during the vertical retrace period to sweep out the charges in the area (a).

Next, during period t2, the vertical C output from the drive circuit 23 is
The scanning pulse 28 of the CD is controlled (for example, once every two horizontal scanning periods when the zoom magnification is 2x), the vertical CCD is thinned out and transferred, and the charges in the area (b) are read out.

Finally, in period t3, the area (
c) Sweep out the charge.

When the signal output from the solid-state image sensor 22 is processed by such a driving method, the scanning pulse for driving the solid-state image sensor is controlled in the period t2, and the charge in the region (b) is , because the vertical CCDs are thinned out and read out, the image is expanded in the vertical direction.

This signal is taken out from the signal processing circuit 25 via the interface 26, and the image processing section 27 performs horizontal zoom processing, and by thinning out and reading the vertical CCD, the missing signals are interpolated. By supplementing the signal, inputting it again to the signal processing circuit 25 via the interface 26, and outputting it as a video signal from the signal processing circuit 25, it is possible to obtain a video zoomed both horizontally and vertically.

FIG. 3 shows a block diagram of an image pickup apparatus that uses the present invention to realize an image stabilization function.

In FIG. 3, 31 is a lens, 32 is a solid-state image sensor, 33 is a drive circuit for driving the solid-state image sensor, 3
4 is a control circuit that controls the drive circuit, 35 is a signal processing circuit that processes the signal output from the solid-state image sensor and outputs it as a video signal, 36 is a scanning pulse that drives the solid-state image sensor 32, and 37 is a video signal. signal, 38 is a camera shake detection circuit,
39 and 40 are control signals.

The object image formed on the light-receiving surface of the solid-state image sensor 32 is captured by the scanning pulse 3 output from the drive circuit 33.
6, the solid-state image sensor 32 is photoelectrically converted and outputted from the solid-state image sensor 32 as an electrical signal.

If camera shake occurs during photographing, the camera shake detection circuit 38 detects the condition and outputs a control signal 39. The control circuit 34 outputs a control signal 40 that controls the drive circuit 33 using the control signal 39 . The drive circuit 33 generates a scanning pulse 3 that drives the solid-state image sensor using a control signal 40.
6 to change the readout position of the scanning area so as to correct camera shake.

FIG. 5 shows a configuration diagram of a solid-state image sensor. 5
11-51N are vertical CCDs, 52 are horizontal CCDs, 53 are photodiodes, 54 are charge readout gates, 551-55
(M+M0)N is a pixel, and 56 is an input terminal.

In the figure, pixels each consisting of a photodiode 53 and a charge readout gate 54 are arranged in an M×N array, with N pixels in the horizontal direction and M pixels in the vertical direction. The pixels in the horizontal direction are arranged in order from the top of the array in the first row, the second row, ..., the pixels in the vertical direction are arranged in order from the left in the first column, the second column, ...,
Then, the pixel in the i-th row and j-th column can be expressed as pixel 55ij.

The first column, the second column, . . . , the Nth column have vertical CCDs 511, CCD 512, .
is connected. These vertical CCDs 511-51N
consists of {4(M+M0)+1} cells, and every fourth cell, that is, cell 1, cell 1,
2, 3, ..., the even numbered cells 2, 6, 10, ..., {4(M+M0)+1} are the 1st row, 2nd row, 3rd row, ..., (M+M0) row, respectively. pixels are connected. Therefore, cell 4 (i-2) of the vertical CCD 51 is connected to the pixel 55ij.

The horizontal CCD 52 consists of 4 (N-1) cells, and every fourth cell is a vertical CCD.
521, CCD 522, . . . , are connected to the first cell of CCD 52N. Assuming that the cells of the horizontal CCD 52 are cell 1, cell 2, ... in order from the left, cell 3 is the vertical CC.
In D511, cell 7 is in vertical CCD 512, ..., cell (
4N-1) are respectively connected to the vertical CCD 51N. Further, cell 1 of the horizontal CCD 52 is connected to an output terminal 47.

FIG. 6 shows scanning pulses for driving the vertical CCD and horizontal CCD of the solid-state image sensor.

As shown in FIG. 6, when the pulse Vs is input from the input terminal 46 during the vertical retrace period, the charge readout gate 54 of the pixel 55 is turned on, and the charge accumulated in the photodiode 53 is read out. The charge read out to the pixel 55ij is transferred to the vertical CCD connected to the pixel 55ij.
It is transferred to cell No. 51.

Furthermore, cells 1, 5, . . . of each vertical CCD 51
4 (M+M0), vertical scanning pulse V1, cells 2, 6,
..., vertical scanning pulse V2 for {4(M+M0)+1},
Vertical scanning pulse V3 is applied to cells 3, 7, ..., {4(M+M0)-2}, and cell 4, 8, ..., {4(M+M0)-1}
is supplied with vertical scanning pulse V4, and when pulse Vs is input, cells 2, 6, 10,..., {4(M+M0
)+1} are all empty.

At this time, the vertical scanning pulses V1 and V3 are "L".
” (low level), vertical scanning pulses V2 and V4 are “H”
(high level), and cell 2 of the vertical CCD 51
, 6, 10, . . . , {4(M+M0)+1}.

Next, at the time when the vertical scanning pulse V3 becomes "H", the vertical scanning pulse V4 becomes "L", and the vertical scanning pulse V3 becomes "L", there is no charge transfer in the vertical CCD 51; When the scanning pulse V1 becomes "H" and the vertical scanning pulse V2 becomes "L", the charge changes to the vertical C
Cells 1, 5, 9, ..., ..., 4 (M
+M0).

Next, when the vertical scanning pulse V4 becomes "H" and the vertical scanning pulse V1 becomes "L", cells 1, 5,
9, the charges of cells 3, 7, 11, . . . of the horizontal CCD 52 are
, (4N-1). In this way, horizontal C
Charges from the vertical CCD 51 are held in cells 3, 7, 11, . . . (4N-1) of the CD 52.

Furthermore, the horizontal scanning pulse H1 is applied to the horizontal CCD.
52, horizontal scanning pulse H2 is applied to cells 3, 7, ..., 4 (N-1) of horizontal CCD 52, cells 4, 8, ..., (4N-4).
), the horizontal scanning pulse H3 is applied to cell 1 of the horizontal CCD 52,
5, 9, ..., (4N-3), by supplying the horizontal scanning pulse H4 to cells 2, 6, 10, ..., (4N-2) of the horizontal CCD 52, the horizontal scanning pulses H4, H3, H
2, H1, H4, . . . , the charges accumulated in the cells are transferred to the left one cell at a time in the horizontal CCD 52 by becoming "H" (high level).

In this way, the charges transferred from the vertical CCD 51 are sequentially transferred to the left within the horizontal CCD 52 at a period equal to the period of the scanning pulse of the horizontal CCD 52.
It is output to the output terminal 57.

FIG. 7 shows scanning pulses for driving the vertical CCD of the solid-state image sensor in an image pickup apparatus that implements a zoom function using the present invention. In order to keep the explanation simple,
The scan pulse shows only V1.

From the start of the vertical retrace period, the vertical CCD 51 is controlled by a control signal from the control circuit according to the zoom magnification.
The scanning pulse V1 for driving is set to a pulse with a higher frequency than the normal frequency, and the vertical CCD 51 is scanned at high speed during the Th period to sweep out charges outside the scanning area. However, as shown in FIG. 5, the transfer of charge from the horizontal CCD 52 to the output terminal 57 is equal to the period of the scanning pulse that drives the horizontal CCD 52, so if the frequency of the pulse that scans the vertical CCD 51 is increased, the normal charge Since charge is transferred from the vertical CCD 51 to the horizontal CCD 52 at a faster period than the period in which the charge is transferred from the vertical CCD 51 to the horizontal CCD 52
It is not possible to output all the charges transferred from the horizontal CCD 52 to the output terminal, and some charges remain without being transferred.

Therefore, after the vertical CCD 51 is scanned at high speed, the pulse V1 for scanning the vertical CCD 51 is not output for the period Ts in order to read out the signals in the scanning area.

After the Ts period (more than 2 horizontal scanning periods) has elapsed, if the scanning pulse for reading out the scanning area is started to be output and treated as a video signal, the video signal of the charge remaining without being transferred to the horizontal CCD 52 leakage can be prevented.

FIG. 8 shows an example of a control circuit for controlling a drive circuit for realizing the present invention.

In FIG. 8, 81 is a vertical CCD scanning pulse, 82 is an adder, 83 is a high-speed scanning pulse generation circuit, and 8
4 is a read scan pulse generation circuit, 85 is a high speed scan timing generation circuit, 86 is a read scan timing generation circuit, 87
88 is a timing generation circuit, and 88 is a synchronization pulse.

As shown in FIG. 8, when a synchronizing pulse 88 indicating a vertical retrace period is input to the control circuit, the timing generating circuit 87 generates a phase and a scanning area signal for sweeping out signals in areas other than the scanning area. The timing pulses Ssw and Sre are generated from the high-speed scan timing generation circuit 85 and the readout scan timing generation circuit 84, respectively.

When the timing pulse Ssw is input, the high-speed scanning pulse generation circuit generates a high-speed scanning pulse for sweeping out signals in areas other than the scanning area, and the readout scanning pulse generation circuit receives the timing pulse Sre. Then, a scanning pulse is generated to read out signals in the scanning area. Finally, the scan pulses are added by an adder 82 and outputted from the drive circuit as a vertical CCD scan pulse.

Therefore, by controlling the phase of the timing pulse Sre input to the readout scanning pulse generation circuit and generating the timing pulse Sre after two or more horizontal scanning periods have elapsed to read out the signals in the scanning area, the horizontal C
It becomes possible to prevent charges remaining without being transferred to the CD from leaking into the video signal.

[0046]

According to the present invention, by controlling the drive circuit of the solid-state image sensor to vary the readout position of the scanning area, it is possible to realize a zoom function or an image stabilization function.

Also, at this time, by scanning the vertical CCD at high speed with pulses to sweep out signals in areas other than the scanning area, charges that remain without being transferred to the horizontal CCD leak into the video signal. This can be prevented by outputting the scanning pulse for reading out the signals in the scanning area after two or more horizontal scanning periods have elapsed after the high-speed scanning.

[Brief explanation of drawings]

[Fig. 1] An explanatory diagram illustrating the leakage of charge into a video signal,

FIG. 2 is a block diagram of an imaging device having a zoom function using the present invention;

FIG. 3 is a block diagram of an imaging device having an image stabilization function using the present invention;

[Fig. 4] A diagram showing the light-receiving surface of the solid-state image sensor and the monitor screen,

[Fig. 5] Configuration diagram of a solid-state image sensor,

[Fig. 6] Waveform diagram of scanning pulses of vertical CCD and horizontal CCD,

FIG. 7 is a waveform diagram of a scanning pulse of a vertical CCD in an imaging device that changes the readout position of a scanning area;

FIG. 8 is a circuit diagram showing a drive circuit and its control circuit.

[Explanation of symbols]

21...Lens, 22...solid-state image sensor, 23...drive circuit, 24...control circuit, 25...signal processing circuit, 26...Interface, 27...Image processing section, 28...scanning pulse, 29...Video signal, 30...control signal, 31...Lens, 32...solid-state image sensor, 33...drive circuit, 34...control circuit, 35...signal processing circuit, 36...scanning pulse, 37...Video signal, 38... Shake detection circuit, 39, 40...control signal, 511~51N...Vertical CCD, 52...Horizontal CCD, 53...Photodiode, 54...charge readout gate, 551 to 55 (M+M0)N...pixels, 56...input terminal, 57...output terminal, 81...Vertical CCD scanning pulse, 82...adder, 83...High-speed scanning pulse generation circuit, 84...Read scanning pulse generation circuit, 85...High-speed scanning timing generation circuit, 86...Read scan timing generation circuit, 87...timing generation circuit, 88...Synchronization pulse.

Claims (3)

[Claims] Claim 1: An effective pixel area consisting of M×N pixels, and m×n pixels within the effective scanning area (wherein M>m, N>n
a solid-state image sensor having a scanning area consisting of
a drive circuit that scans the solid-state image sensor and generates a scan pulse for reading charges in the scan area and a scan pulse for sweeping out charges in an effective pixel area other than the scan area; It includes a signal processing circuit that processes the output signal and generates a video signal, and a control circuit that controls the drive circuit, and controls the scanning pulses output from the drive circuit based on the control signal from the control circuit. A method for driving a solid-state image pickup device, comprising: scanning an effective pixel area other than the scanning area at high speed during a vertical retrace period, and preventing charges swept out during the high-speed scanning from leaking into the video signal. 2. The method of driving a solid-state image sensing device according to claim 1, wherein the control circuit controls a phase of a scanning pulse for reading out charges in the scanning area. 3. The phase at which the scanning pulse for reading out the charges in the scanning area is started is set to 2 after the outputting of the scanning pulse for sweeping out the charges in the area other than the scanning area.
3. The method of driving a solid-state image sensor according to claim 1, wherein the method is performed after a horizontal scanning period or more has elapsed.