JP2009225023A - Solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve the following problem: when receiving a trigger pulse signal continuously, an auto iris mechanism is operated by an image signal due to the trigger pulse signal, consequently an image signal obtained in a random shutter mode is varied caused by the auto iris mechanism. <P>SOLUTION: A solid-state imaging device images an image with an exposure time of a continuous shot exposure pulse circuit 7 in a random shutter mode of imaging a moving image and images an image with an exposure time of a random shutter exposure pulse circuit 8 by input of the trigger pulse signal from the outside in a random shutter mode of imaging a still image. The solid-state imaging device includes means 12 and 14 which hold set value of an optical system at an approximately fixed value at least from the time of input of the first trigger pulse signal from the outside to the time of completion of output of an image signal due to the last trigger pulse signal from the outside in the consecutive input of the trigger pulse signals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device including a photoelectric conversion element driving circuit that uses an electronic shutter and performs imaging using an external trigger signal.

  In a solid-state imaging device using a photoelectric conversion element such as a CCD (Charge Coupled Device) or CMOS as a solid-state imaging element, in addition to optical components such as a lens, the aperture (iris) is changed by changing the charge accumulation time of the photoelectric conversion element. There is known an electronic shutter that can obtain a video signal equivalent to that obtained by changing (). Some solid-state imaging devices are called a random shutter mode (trigger function), and usually do not perform a shooting operation, but it is known that an image can be taken out at an arbitrary timing by an external trigger signal. It has been. At the time of shooting in the random shutter mode, an auto iris mechanism that is controlled by the average value of the luminance level of the video signal cannot be used in order to instantaneously take one field or one frame still image.

The prior art will be described in detail with reference to FIG. FIG. 4 is a block diagram of the CCD camera device disclosed in Patent Document 1. In FIG. The photoelectric conversion element 401 receives light incident through the optical system, performs photoelectric conversion while being driven and controlled by the drive circuit 403, and converts the light into an electric signal. The video signal processing circuit 402 is a circuit that performs processing for converting the output of the photoelectric conversion element 401 into a video signal. Output based on the synchronization signal from the synchronization signal generation circuit 411. The drive circuit 403 generates a drive signal for the photoelectric conversion element 401 based on synchronization signals from the electronic shutter circuit 404, the PD (photodiode) charge transfer signal generation circuit 405, the charge transfer circuit 406, and the synchronization signal generation circuit 411. Control. The electronic shutter circuit 404 outputs a signal for resetting the PD of the photoelectric conversion element to the drive circuit 403 based on output signals from the continuous shooting exposure pulse circuit 407 and the random shutter exposure pulse circuit 408. The PD charge transfer signal generation circuit 405 is a circuit for generating a signal for transferring the charge of the CCD PD based on the output from the random shutter exposure pulse circuit 408. The charge transfer circuit 406 generates and outputs a control signal to the drive circuit 403 based on the output signal of the charge sweeping high-speed transfer circuit 409. The continuous shooting exposure pulse circuit 407 is an exposure pulse generating circuit for setting a shutter time for continuous shooting, that is, normal moving image shooting. The random shutter exposure pulse circuit 408 is an exposure pulse generation circuit for setting a shutter time when the random shutter is used when a random shutter trigger signal for capturing a still image is input. The charge sweeping high-speed transfer circuit 409 generates a control signal for causing the charge transfer circuit 406 to sweep away charges at high speed when a random shutter trigger signal is input. The shutter mode switching control circuit 410 is a control circuit that switches from the continuous shooting shutter to the random shutter mode when a random shutter trigger signal is input. The shutter mode switching control circuit 410 outputs a signal to the charge sweeping high-speed transfer circuit 409 and the synchronization signal generation circuit 411. The synchronization signal generation circuit 411 generates a synchronization signal based on the output of the shutter mode switching control circuit, and outputs the synchronization signal to the video signal processing circuit 402 and the drive circuit 403.
JP 2002-185865 A

  Since the conventional technique disclosed in Patent Document 1 is configured so that the continuous shooting exposure time and the random shutter exposure time can be set separately, the auto iris mechanism is provided in the random shutter mode (the mode in which shooting is performed using an external trigger pulse signal). It has become possible to use the image, and a clear video signal with an optimum exposure can be obtained at the time of one random shutter photographing. However, since the auto iris mechanism is operated by the video signal based on the trigger pulse signal, if the above two exposure times are set differently, the auto iris will fluctuate due to the use of a random shutter. The subject that the influence became remarkable occurred.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device in which fluctuations caused by an optical system mechanism such as auto iris are not generated even when a random shutter is continuously operated.

  In order to solve the above-described problem, a solid-state imaging device of the present invention includes continuous shooting exposure time setting means and random shutter exposure time setting means, and in the continuous shooting shutter mode for shooting a moving image, the continuous shooting exposure setting means. In the random shutter mode in which the image is taken with the exposure time of the image, and in the random shutter mode for taking a still image, the trigger pulse signal from the outside is used in the solid-state imaging device for taking an image with the time of the random shutter exposure time setting means by inputting the trigger pulse signal from the outside. When the signal is continuously input, at least the setting of the optical system is performed from the time when the first external trigger pulse signal is input until the end of the output of the video signal by the external external trigger pulse signal. Means is provided for maintaining the value almost constant.

  According to the present invention, in the solid-state imaging device, even if the random shutter is operated continuously, there is an effect that the fluctuation caused by the mechanism of the optical system such as auto iris can be prevented.

  FIG. 1 shows a block diagram of a first embodiment of the present invention.

  The present embodiment has continuous shooting exposure time setting means and random shutter exposure time setting means. In the continuous shooting shutter mode for shooting a moving image, an image is taken according to the exposure time of the continuous shooting exposure setting means, and a still image is taken. In the random shutter mode for photographing the image, in the solid-state imaging device for imaging by the time of the random shutter exposure time setting means by the input of the trigger pulse signal from the outside, when the trigger pulse signal from the outside is input, at least the trigger pulse The setting value of the auto iris is not updated until the video output at the time of the random shutter is finished from the interrupted video signal at the time of inputting, or the change due to the update is made small enough to be ignored. Further, when not updating, it is possible to output a preset value as a set value of the auto iris. When in the continuous shooting shutter mode, the calculation value is updated each time and the setting value of the auto iris is updated.

Hereinafter, a description will be given with reference to FIG.
The solid-state imaging device 1 receives light incident through the optical system, performs photoelectric conversion while being driven and controlled by the drive circuit 3, and converts the light into an electric signal.

  The video signal processing circuit 2 is a circuit that performs processing for converting the output of the photoelectric conversion element 1 into a video signal. The video signal processing circuit 2 outputs a video signal based on the synchronization signal from the synchronization signal generation circuit 11.

  The drive circuit 3 generates a drive signal for the photoelectric conversion element 1 based on synchronization signals from the electronic shutter circuit 4, the PD (photodiode) charge transfer signal generation circuit 5, the charge transfer circuit 6, and the synchronization signal generation circuit 11. To control.

  The electronic shutter circuit 4 outputs a signal for resetting the PD of the photoelectric conversion element to the drive circuit 3 based on output signals from the continuous shooting exposure pulse circuit 7 and the random shutter exposure pulse circuit 8.

  The PD charge transfer signal generation circuit 5 is a circuit that generates a signal for transferring the charge of the PD of the photoelectric conversion element based on the output from the random shutter exposure pulse circuit 8.

  The charge transfer circuit 6 generates and outputs a control signal to the drive circuit 3 based on the output signal of the charge sweeping high-speed transfer circuit 9.

  The continuous shooting exposure pulse circuit 7 is an exposure pulse generating circuit for setting a shutter time in continuous shooting shutter mode, that is, normal moving image shooting.

  The random shutter exposure pulse circuit 8 is an exposure pulse generation circuit for setting a shutter time in a random shutter mode for taking a still image.

  The charge sweeping high-speed transfer circuit 9 generates a control signal for causing the charge transfer circuit 6 to sweep away charges at a high speed in response to a random shutter trigger signal.

  The shutter mode switching control circuit 10 is a control circuit that switches between a continuous shooting shutter mode and a random shutter mode. The shutter mode switching control circuit 10 outputs a signal to the charge sweeping high-speed transfer circuit 9 and the synchronization signal generating circuit 11.

  The synchronization signal generation circuit 11 generates a synchronization signal based on the output of the shutter mode switching control circuit, and outputs the synchronization signal to the video signal processing circuit 2 and the drive circuit 3.

  The control signal generation circuit 12 outputs a signal for switching the control value output to the optical system (auto iris circuit 15) to the switching circuit 14 based on the output from the synchronization signal generation circuit 11.

  The rectifier circuit 13 rectifies the output video signal of the video signal processing circuit 2 and outputs a DC value for controlling the optical system (iris).

  The switching circuit 14 uses a sample and hold circuit to switch whether to update the DC value of the output of the rectifying circuit 13 or not to update only for a predetermined time by the control signal from the control signal generating circuit 12. In the random shutter mode, the auto iris setting value is updated during the period from the time when the video signal is interrupted when the trigger is input to the time when the video signal output by a series of consecutive random shutters ends (substantially ignore the change) (Including making it as small as possible).

  The switching circuit 14 updates the DC value of the output of the rectifier circuit 13 by a control signal from the control signal generation circuit 12 to such an extent that the output to the auto iris circuit 15 is not substantially affected by fluctuations, or updates for a predetermined time. Since it is only necessary to be able to switch whether or not to prevent, the DC value of the output of the rectifier circuit 13 is updated by the control signal from the control signal generation circuit 12 using the sample hold circuit, or is not updated for a predetermined time. In addition to the method of switching whether or not to use, a low-pass filter that can switch the time constant for a predetermined time is used, and the longer time constant for suppressing the fluctuation is set to, for example, 10 seconds or more to substantially influence the fluctuation. You may make it hold | maintain the DC value of the output of the rectifier circuit 13 to such an extent that there is no.

  As yet another method, whether or not to output the auto iris set value at the time of the random shutter set in advance during this period can be switched.

  Further, the calculation may be performed using the auto iris value of the frame (which may be several frames or several fields) used in the continuous shooting shutter mode before trigger input.

  Switching between updating the DC value of the output of the rectifier circuit 13 according to the control signal from the control signal generation circuit 12 or not updating it for a predetermined time. Alternatively, when the continuous time of the random shutter mode is set in advance, the time corresponding to the number of repetitions or a predetermined time (for example, the first random shutter trigger signal is input and the video signal is interrupted) The switching circuit 14 can be switched according to the time from the time point until the final output of the video signal by the random shutter. For this purpose, it is only necessary to know that the pulse signal of the predetermined time is generated by the control signal generation circuit 12 and input to the switching circuit 14 from the time of the first pulse generation of the random shutter trigger signal.

  The auto iris circuit 15 converts the output of the switching circuit 14 into a control value of the optical system (iris) to be used and outputs the control value.

  In the continuous shooting shutter mode, calculation is performed for one frame, and the auto iris setting value is updated each time.

  FIG. 2 is a flowchart of the operation when the random shutter is used. In step S1, a random shutter trigger signal is input. In step S2, the shooting mode of the solid-state imaging device is switched from the continuous shooting shutter mode to the random shutter mode. In step S3, the photoelectric conversion element is controlled to sweep away the charge signal currently being output. Step S4 generates a random shutter pulse. In step S5, the charge of the PD of the photoelectric conversion element is reset. In step S6, the PD of the photoelectric conversion element is instructed to accumulate charges. In step S7, the charge accumulated in step S6 is controlled to be transferred to the transfer path of the photoelectric conversion element. In step S8, the photoelectric conversion element output is converted into a video signal and output. In step S9, the shooting mode is switched to the continuous shooting shutter mode. Step S10 returns to the continuous shooting shutter mode.

  FIG. 3 is a timing chart of FIG.

(A) is a switching mode signal. The random shutter mode starts in the middle of the continuous shooting shutter mode, and after the random shutter mode ends, the continuous shooting shutter mode is set.

(B) is a random shutter trigger signal. Random shutter mode is entered at the falling edge of the pulse. After one frame shooting, the continuous shooting shutter mode is set. The polarity of the trigger may be reversed or may start from the rising edge.

(C) is an output video signal. When the random shutter trigger signal is input, the video signal at that time (time t1) is interrupted, and after one frame of the video signal at the time of the random shutter is output, it becomes the video signal in the continuous shooting shutter mode. When the random shutter trigger signal is input again, the video signal is interrupted, and after one frame of the video signal for the random shutter is output, the video signal for the continuous shooting shutter mode is obtained.

(D) is an image integration waveform (rectifier circuit output) for auto iris. The auto iris setting value is not updated from the time when the random shutter trigger signal is input (time t1) until the end of the video output during the random shutter (time t2). Alternatively, the filter time constant is increased to such an extent that fluctuations can be substantially ignored. Alternatively, a preset set value is output. Alternatively, the setting value used in the continuous shooting shutter mode is calculated and output. When returning to the continuous shooting shutter mode, calculation is performed with the integrated video waveform, and updating is performed each time.

(E) is a vertical transfer pulse of the photoelectric conversion element. In the continuous shooting shutter mode, a pulse is output for one frame, and in the random shutter mode, the vertical transfer pulse is paused in the middle, and the photoelectric conversion element is swept away. The vertical transfer pulse is sent, and after returning to the continuous shooting shutter mode, the vertical transfer pulse is sent again continuously every frame.

(F) is reset once per frame by a PD reset pulse of the photoelectric conversion element by an electronic shutter pulse.

(G) is a charge transfer pulse of PD, which is sent once in vertical blanking.

(H) represents the exposure time of the photoelectric conversion element. The exposure time in the continuous shooting shutter mode is T1, and the exposure time in the random shutter is T2.

  As described above, according to the embodiment of the present invention, the auto iris mechanism is used, the accumulation time in the continuous shooting shutter mode and the accumulation time in the random shutter mode are set separately, and a plurality of continuous external trigger signals are used. Since the setting value of the auto iris is held at the time of the video signal in the random shutter mode, or the change can be substantially ignored, a clear video signal can be obtained by the optimum exposure in which the video signal by the continuous external trigger signal does not fluctuate. Moreover, when not updating, the preset value of the auto iris can be used. When the trigger cycle is very short, the calculated auto iris value may not be output. However, by using a preset value, the lens can be controlled even with a short cycle trigger. In addition, the video signal in the continuous shooting shutter mode and the video signal in use of the random shutter can be distinguished significantly.

  In the above embodiment, the setting value of the auto iris is not updated until the video output in the random shutter mode is completed after the random shutter trigger signal is input, or the change due to the update is made small enough to be ignored. The present invention is not limited to the auto iris setting value, and can be similarly applied to the setting value of the optical system in which there is a difference in the setting value between the continuous shutter and the random shutter.

  Although the present invention has been specifically described with the embodiment, it is needless to say that the present invention is not limited to the above embodiment.

It is a block diagram of an embodiment of the invention. It is a flowchart at the time of a random shutter mode. It is a time chart of a block diagram. It is a block diagram of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photoelectric conversion element 2 ... Video signal processing circuit 3 ... Drive circuit 4 ... Electronic shutter circuit 5 ... PD charge transfer signal generation circuit 6 ... Charge transfer circuit 7 ... Continuous Imaging exposure pulse circuit 8... Random shutter exposure pulse circuit 9... High-speed transfer circuit 10 for sweeping out charges 10... Shutter mode switching control circuit 11. ... Rectifier circuit 14 ... Switch circuit 15 ... Auto iris circuit 401 ... Photoelectric conversion element 402 ... Video signal processing circuit 403 ... Drive circuit 404 ... Electronic shutter circuit 405 ... PD Charge transfer signal generation circuit 406... Charge transfer circuit 407... Continuous shooting exposure pulse circuit 408... Random shutter exposure pulse circuit 409. Shutter mode switching control circuit 411 ... synchronizing signal generating circuit

Claims (1)

Random shutter mode that has continuous shooting exposure time setting means and random shutter exposure time setting means, and in continuous shooting shutter mode for shooting moving images, images are taken according to the exposure time of the continuous shooting exposure setting means, and still images are shot. In a solid-state imaging device that images by the time of the random shutter exposure time setting means by the input of a trigger pulse signal from outside,
When the external trigger pulse signal is continuously input, the video signal output by the last external trigger pulse signal is completed from the time when the first external trigger pulse signal is input. A solid-state imaging device comprising means for holding the set value of the optical system substantially constant during the interval.

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