JP2001268452A - Solid-state image pickup device and camera system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that an exposure period is repeatedly increased or decreased for each field due to the difference of read timing for each field in a frame read mode and flickers are generated by the difference of the exposure period for each field. SOLUTION: When the frame read mode is set by control signals SSI supplied from a control circuit 30 and also the number of shutter pulses ϕSUB is specified in this solid-state image pickup device provided with a CCD image pickup element 10 provided with an electronic shutter function capable of frame read, a timing generator 20 controls the pulse number so as to satisfy the relation (pulse number of A field)=(pulse number of B field)-2 and sets the number of the shutter pulses ϕSUB so as to make the exposure periods in the respective fields to be the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device and a camera system using the same, and more particularly to a solid-state image pickup device having an electronic shutter function capable of reading out signal charges of each pixel by frame reading. The present invention relates to an imaging apparatus and a camera system using the solid-state imaging device as an imaging device.

[0002]

2. Description of the Related Art Solid-state imaging devices such as CCD (Charge Co.)
In an image pickup apparatus using an upled device (hereinafter simply referred to as a CCD image pickup device), as a readout method for reading out signal charges from each pixel, an interlaced scan is usually performed for each odd / even field. A field readout method and a frame readout method corresponding to the television system are adopted.

[0003] A field readout method is one pixel for each pixel.
/ 60 seconds (one field equivalent period), accumulates signal charges, mixes signal charges read from each pixel between two vertical pixels in the vertical transfer unit, and combines the two vertical pixels to be mixed into an odd field and an even number This is a method that changes in the field. On the other hand, the frame read method is 1/30
In this method, odd-numbered line signal charges and even-numbered line signal charges are alternately read for each field in an accumulation time of seconds (corresponding to one frame).

[0004] Among these readout methods, in the frame readout method, as described above, the signal charges of the odd-numbered lines and the signal charges of the even-numbered lines are alternately read for each field. The read pulse applied to the section is alternately output before and after one line (one horizontal scanning period) for each odd / even field.

[0005] In addition, in a CCD image pickup device, generally, a shutter pulse is applied to a substrate to discard unnecessary charges in each pixel in the direction of the substrate to thereby reduce an exposure period (accumulation period).
That is, an electronic shutter for controlling the shutter time is provided as a standard function. This electronic shutter is controlled in units of one field. Unless a control signal for changing the state of the electronic shutter is newly given, the state is maintained, and the number of shutter pulses for each field does not change.

[0006]

As described above, in the CCD image pickup device having the electronic shutter function, when the frame read mode is executed with the state of the electronic shutter fixed, the exposure period becomes longer due to a difference in read timing for each field. The increase / decrease is repeated for each field.

As an example, when one field is 40H (H is one horizontal scanning period), as shown in the timing chart of FIG. 5, the A field (first field) is 30H and the B field (second field) ), A read pulse is generated at 29H. In this case, the exposure period is 40H in the A field and 38H in the B field.
H. In the timing chart of FIG. 5, the read pulse is omitted, and the time axis position marked with * on the horizontal synchronization signal HD is the read pulse generation timing.

As described above, by repeatedly increasing and decreasing the exposure period by 2H (two lines) for each field, the imaging signal of the CCD image sensor is output to the display device, and the captured image is displayed on the display device. In this case, flicker occurs due to the difference in the exposure period for each field. Here, flicker refers to a phenomenon in which an image looks bright or dark and looks blinking.

To change the state of the electronic shutter for each field in order to prevent flicker, it is necessary to determine whether the field is an A field or a B field. And it is necessary to add a circuit for outputting the field discrimination signal, and the circuit configuration of the entire system becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to eliminate the difference in exposure period for each field without receiving control from the outside and to provide a clear image without flicker. And a camera system using the same.

[0011]

A solid-state imaging device according to the present invention includes a solid-state imaging device having an electronic shutter function capable of reading out a frame, an operation mode of the solid-state imaging device, and the number of shutter pulses during an electronic shutter operation. Control means for generating a control signal for setting, and when a frame reading mode is set by a control signal given from the control means, the first and the second shutter pulses are set based on the number of shutter pulses set by the control signal. A timing generating means for generating, for each field, the number of shutter pulses for making the exposure period in the second field the same is provided. The camera system according to the present invention has a configuration in which the solid-state imaging device is used as an imaging device, and the control unit and the timing generation unit are used as driving units.

In the solid-state imaging device having the above configuration and the camera system using the same, the control means supplies a control signal for setting the operation mode and the number of shutter pulses to the timing generation means. When the operation mode set by the control means is the frame readout mode, the timing generation means first sets the number of shutter pulses given by the control signal, and controls the number by the timing control based on this. , The first
The number of shutter pulses for making the exposure period in the second field the same is generated for each field.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a solid-state imaging device according to an embodiment of the present invention.

Referring to FIG. 1, a solid-state imaging device according to this embodiment includes a CCD imaging device 10 and a timing generator (T) for generating various timing signals for driving the CCD imaging device.
G) 20 and a control circuit 30 for controlling the timing generator 20.

In the CCD image pickup device 10, an image pickup section (image pickup area) 11 includes a plurality of sensor sections (pixels) 12 arranged in a matrix on a semiconductor substrate (not shown).
And a plurality of vertical CCDs 13 provided along the pixel arrangement direction for each of the vertical columns of the sensor units 12, and provided between each of the sensor units 12 and the vertical CCDs 13. And a readout gate section 14 for reading out signal charges.

In the image pickup section 11, the sensor section 12 is composed of, for example, a photodiode having a PN junction, and converts incident light into a signal charge having a charge amount corresponding to the light amount and stores the signal charge. The vertical CCD 13 outputs, for example, a four-phase vertical transfer pulse φ.
The signal charges read and driven from the respective sensor units 12 through the read gate unit 14 are sequentially transferred in the vertical direction in units of lines (rows).

The vertical CCD 13 is applied with four-phase vertical transfer pulses φV1 to φV4 on its transfer channel.
One transfer electrode is repeatedly arranged in the transfer direction.
Then, of these four transfer electrodes, for example, the first phase,
Each transfer electrode to which the third-phase vertical transfer pulses φV1 and φV3 are applied also serves as a gate electrode of the readout gate unit 14.

From this, the four-phase vertical transfer pulse φV
Vertical transfer pulse φ of the first and third phases among 1 to φV4
V1 and φV3 are set to take three values of a low level, an intermediate level, and a high level, and the third high-level pulse is a read pulse applied to the gate electrode of the read gate unit 14. .

On the lower side of the image pickup section 11, that is, on the side to which signal charges are transferred by the vertical CCD 13, a horizontal CC for transferring signal charges vertically transferred in order from the vertical CCD 13 in the horizontal direction.
D15 is arranged. The horizontal CCD 15 is, for example, 2
The transfer is driven by the phase horizontal transfer pulses φH1 and φH2. At the end of the horizontal CCD 15 on the transfer destination side, a charge-voltage conversion unit 16 composed of, for example, a floating diffusion amplifier is arranged.

The timing generator 20 has a vertical CC
Four-phase vertical transfer pulse φV1 to φ for driving D13
V4, various timing pulses for driving the CCD 10 including the two-phase horizontal transfer pulses φH1 and φH2 for driving the horizontal CCD 15 and the shutter pulse φSUB for the electronic shutter.

The shutter pulse φSUB is applied to a substrate (not shown) of the CCD image pickup device 10 so as to be superimposed on the substrate bias voltage Vsub. When the shutter pulse φSUB is applied to the substrate, the potential barrier on the substrate collapses, and the charges accumulated in the sensor unit 12 are swept out in the depth direction of the substrate. This is the principle of the electronic shutter.

The control circuit 30 supplies the system clock SCK, control signal SSI and sense signal SEN shown in FIG.
Timing control of various timing pulses output from the timing generator 20 by SI, that is, CC
The control such as the operation mode of the D imaging device 10 is performed.

As an example, as is apparent from the waveform diagram of FIG. 2, the control signal SSI is composed of 8-bit serial data D.
0 to D7. D0 is a bit for switching the read mode. When D0 is logic "1" (high level), the frame read mode is set. When D0 is logic "0" (low level), the thinning read mode is set as the read mode. I do.

Here, the thinning-out reading mode is one technique for increasing the frame rate. For some lines (rows), signal charges are not read out from each pixel to the vertical CCD 13 and only the remaining lines are read out. In this mode, pixel information is thinned out by reading signal charges from each pixel to the vertical CCD 13.

D1 is ON / OFF of the electronic shutter operation.
The electronic shutter is ON when D1 is logic “1”, and the electronic shutter OF when D1 is logic “0”.
Set F respectively. The remaining 6 bits D7 to D2 are
This bit specifies the number of shutter pulses φSUB generated in one field period, and D7 to D2 are (0000)
00), 0 when (000001), 1
Two at the time of (000010), ..., (11111)
In the case of 1), the number of 63 pulses is set.

When the frame read mode (D0 = 1) is set as the operation mode of the CCD image pickup device 10 by the control signal SSI, in the field read, the signal charges of the odd lines and the signal charges of the even lines are alternated for each field. As shown in the timing chart of FIG. 3, the timing generator 20 generates a read pulse whose generation position (occurrence timing) is about one line for each field.

The read pulse is output as a third-valued pulse superimposed on the first and third phase vertical pulses φV1 and φV3 as described above.
This is omitted in the timing chart of FIG.
However, in the timing chart of FIG. 3, the time axis position marked with * on the horizontal synchronizing signal HD is the generation timing of the read pulse. VD is a vertical synchronization signal.

When the mode is changed from another operation mode to the frame read mode, the timing generator 20
... Timing pulses corresponding to each field in the order of A field → B field → A field →..., That is, vertical transfer pulses φV1 to φV4 including read pulses.
And a shutter pulse φSUB and the like. Note that the read pulse is alternately superimposed on the first and third phase vertical pulses φV1 and φV3 for each field and output.

When the number of shutter pulses φSUB is set by the control signal SSI supplied from the control circuit 30 in the frame read mode, the timing generator 20 changes the read timing for each field as described in the prior art. In view of the fact that the exposure period repeatedly increases and decreases by two lines for each field, the number of pulses is controlled so that (number of pulses in field A) = (number of pulses in field B) -2. The shutter speed (exposure period) is determined by the number of the shutter pulses φSUB.
Is determined.

As described above, in the solid-state imaging device having the CCD imaging device 10 having the electronic shutter function, the frame read mode is set by the control signal SSI provided from the control circuit 30, and the number of shutter pulses φSUB is specified. At this time, the timing generator 20 outputs the number of shutter pulses φSUB set for each field so as to satisfy the relationship of (number of pulses in field A) = (number of pulses in field B) −2. Accordingly, the difference between the exposure periods for two lines generated in the frame read mode can be absorbed by the timing control of the timing generator 20.

The timing chart of FIG. 3 shows, as an example, the timing relationship when one field is set to 40H, and three shutter pulses φSUB in the A field.
Shows a case where five shutter pulses φSUB are respectively generated in the B field. The periods t1 and t2 during which the shutter pulse φSUB is generated are periods in which electric charges are swept away in the electronic shutter operation. And A, B
Each exposure period of the field is 35H.

Thus, in the frame read mode, the control circuit 30 suppresses flicker caused by the difference in the exposure period for each field without controlling the number of shutter pulses φSUB for each field. be able to. That is, the exposure period in each field can be set to the same value only by the timing control of the timing generator 20 without the field discrimination between the A field and the B field in the control circuit 30, so that there is no flicker. A clear image can be obtained.

Further, since it is not necessary to input a field discrimination signal from the control circuit 30 to the timing generator 20, it is not necessary to add a circuit for field discrimination to the control circuit 30 together with the timing generator 20, and the conventional Therefore, flicker can be suppressed while maintaining the probability of occurrence of a failure or malfunction in operation.

FIG. 4 is a block diagram schematically showing an example of the configuration of a camera system according to the present invention, for example, a moving image photographing system.

This camera system comprises a CCD image pickup device 41 as an image pickup device and a lens 4 constituting a part of an optical system.
2. CCD drive circuit 4 for driving CCD image sensor 41
3, an operation unit 44 for setting an operation mode of the CCD image pickup device 41 and a signal processing circuit 45 for performing various signal processing on the image pickup signal of the CCD image pickup device 41;
The configuration uses the CCD image sensor 10 according to the above embodiment as the image sensor 41.

In the camera system having such a configuration, incident light (image light) from a subject (not shown) is formed on the image pickup surface of the CCD image pickup device 41 by the lens 42 of the optical system. As described above, the CCD imaging device 41 (10) has a configuration in which the frame reading mode and the thinning-out reading mode can be selectively adopted. An operation mode, a shutter speed, and the like of the CCD image pickup device 41 are designated and input from the operation unit 44.

The CCD driving circuit 43 includes the timing generator 20 and the control circuit 30 shown in FIG. In the CCD drive circuit 43, the operation unit 4
When the operation mode, shutter speed, and the like of the CCD image sensor 41 are designated and input from the controller 4, the control signal SSI
(See FIG. 2) is output from the control circuit 30, and various timing pulses of a vertical transfer pulse φV1 to φV4 including a read pulse, a shutter pulse φSUB, and horizontal transfer pulses φH1 and φH2 are output from the timing generator 20 at timing based on the output. Is done.

As described above, in the moving image photographing system,
By using the CCD image pickup device 10 according to the above embodiment as an image pickup device and using the timing generator 20 and the control circuit 30 of FIG. 1 as its drive circuit 43, the exposure period of two lines generated in the frame readout mode is reduced. Since the difference can be eliminated, the obtained video has no difference in brightness for each field, and is a smooth moving image in which blinking is suppressed.

[0039]

As described above, according to the present invention,
In a solid-state imaging device having an electronic shutter function capable of frame reading and a camera system using the same,
With a control means for setting the number of shutter pulses, the exposure period in each field can be set to the same value only by timing control by the timing generation means without having to control the number of shutter pulses for each field. And a clear image without flicker can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a waveform chart showing an example of a control signal.

FIG. 3 is a timing chart according to the embodiment.

FIG. 4 is a block diagram showing an example of a configuration of a camera system according to the present invention.

FIG. 5 is a timing chart according to a conventional example.

[Explanation of symbols]

10, 41 CCD image sensor, 12 sensor part (pixel), 13 vertical CCD, 15 horizontal CCD, 16 charge-voltage converter, 20 timing generator (T
G), 30: control circuit, 43: CCD drive circuit, 44:
Signal processing circuit

Claims (2)

[Claims] 1. A solid-state imaging device having an electronic shutter function capable of reading frames, and control means for generating a control signal for setting an operation mode of the solid-state imaging device and the number of shutter pulses at the time of electronic shutter operation. When a frame readout mode is set by the control signal given from the control means, based on the number of shutter pulses set by the control signal,
A solid-state imaging device comprising: timing generation means for generating, for each field, a number of shutter pulses for making the exposure periods in the first and second fields the same. 2. A solid-state imaging device having an electronic shutter function capable of reading out a frame, an optical system for imaging incident light on an imaging surface of the solid-state imaging device, an operation mode of the solid-state imaging device, and an electronic shutter operation. Control means for generating a control signal for setting the number of shutter pulses at the time, and the number of shutter pulses set by the control signal when the frame readout mode is set by the control signal provided from the control means. And a driving means having timing generation means for generating, for each field, a number of shutter pulses for making the exposure periods in the first and second fields the same on the basis of the above.