JP5086731B2 - camera - Google Patents

Description

  The present invention relates to a camera capable of recording a still image, and more particularly, to a release time lag from when a release button is operated until an exposure operation for recording a still image is performed.

  In a digital camera, when a shooting mode is set, a moving image is displayed on a display such as an LCD provided on the back of the camera. When the release button is operated, an exposure operation is performed to record a still image.

The period from when the release button is operated until the actual exposure operation is performed, that is, the period until the light receiving surface of the image sensor is exposed for a predetermined period by the opening / closing of the shutter or the electronic shutter function (release time lag) In general, it is long. In order to shorten the release time lag, for example, before a release operation is performed, a shooting mode suitable for a still image is set in advance (see Patent Document 1).
JP 2003-348433 A

  Various operation control processes must be performed between the release operation and the actual start of the exposure operation, and it is difficult to shorten the release time lag. On the other hand, it is required to shorten the release time lag as much as possible in order to shorten the still image recording operation time in continuous shooting and to prevent the time lag from affecting the image quality such as image blurring.

  The camera of the present invention is a camera in which the release time lag from when the release operation is performed to when the exposure operation is actually started is shortened.

  The camera according to the present invention executes an exposure operation for recording a still image in accordance with a recording operation for an image sensor driving means for outputting a driving signal including a clock pulse signal for reading a pixel signal from the image sensor and a release button. And a still image photographing means. And the drive signal control means which outputs the control signal for controlling the drive signal output from the image sensor driving means to the image sensor drive means, and the update timing at which the image sensor drive means receives the control signal and reflects it in the drive signal And an operation timing adjusting means for adjusting.

  As the drive signal, for example, a drive signal for still image recording and a drive signal for moving image display are selectively output, and the clock pulse period and the like are changed. When displaying a moving image in the shooting mode, the operation timing adjusting means outputs the control signal while synchronizing with the clock pulse signal, and synchronizes the update timing with the clock pulse signal in order to prevent noise from being generated in the moving image. . For example, when the control signal is output in synchronization with the control processing of the still image capturing unit, the operation timing adjustment unit sets the update timing before the output timing of the control signal until a recording operation is performed on the release button. .

  In the present invention, the operation timing adjusting means shifts at least one of the output timing and update timing of the control signal from the synchronization timing of the clock pulse signal in accordance with the recording operation on the release button. For example, in a predetermined field period after the release button operation, the update timing may be set after the output timing of the control signal for switching the drive signal. When synchronizing the output timing and update timing of the control signal with the clock pulse signal, the CCD 16 cannot be driven in accordance with the synchronized update timing even if the image sensor driving means receives the control signal. In this case, the drive signal is adjusted with a delay of one cycle (one field period) of the clock pulse signal. However, by shifting from the synchronization timing of the clock pulse signal, an exposure operation for recording a still image can be executed in the next field period, and a drive signal such as a clock pulse signal or a stored charge sweep signal is recorded in the still image recording. Switch for use.

  When it takes a processing time to shift the output timing of the control signal, it is preferable that the operation timing adjusting means shifts the update timing from the synchronization timing of the clock pulse signal.

  The photographing operation apparatus of the present invention includes a still image photographing means for performing an exposure operation for recording a still image in accordance with a recording operation on a recording member, and a drive signal including a clock pulse signal for reading a pixel signal from the image sensor. Drive signal control means for outputting a control signal for controlling a drive signal output from the image sensor driving means for outputting to the image sensor drive means in synchronization with the clock pulse signal, and a control signal in the image sensor drive means. And an operation timing adjusting means for synchronizing the update timing reflected to the drive signal with the clock pulse signal, and the operation timing adjusting means at least outputs the control signal output timing and the update timing according to the recording operation on the recording member. One of the features is shifted from the synchronization timing of the clock pulse signal. To.

  The program of the present invention outputs a drive signal including a still image photographing means for performing an exposure operation for recording a still image and a clock pulse signal for reading out a pixel signal from the image pickup device in accordance with a recording operation on the recording member. A drive signal control means for outputting a control signal for controlling a drive signal output from the image pickup element drive means to the image pickup element drive means in synchronization with the clock pulse signal, and receiving the control signal in the image pickup element drive means An operation timing adjustment unit that synchronizes the update timing reflected in the drive signal with the clock pulse signal functions, and at least one of the output timing of the control signal and the update timing according to the recording operation on the recording member is the clock pulse signal The operation timing adjustment means Characterized in that to ability.

  The imaging operation method according to the present invention performs an exposure operation for recording a still image in accordance with a recording operation on a recording member, and outputs a drive signal including a clock pulse signal for reading out a pixel signal from the imaging device. A drive signal control means for outputting a control signal for controlling a drive signal output from the drive means to the image sensor driving means in synchronization with the clock pulse signal, and a control signal received by the image sensor drive means as a drive signal. The update timing to be reflected is synchronized with the clock pulse signal, and at least one of the output timing and update timing of the control signal is shifted from the synchronization timing of the clock pulse signal in accordance with the recording operation on the recording member.

  According to the present invention, the release time lag can be shortened without affecting the image quality of a still image.

  Below, with reference to drawings, the digital still camera which is embodiment of this invention is demonstrated.

  FIG. 1 is a block diagram of a digital camera according to the present embodiment.

  The digital camera 10 includes a signal processing circuit 20 and a system control circuit 30, and a memory card 36 is detachably attached to the camera 10. The signal processing circuit 20 is configured by a DSP (Digital Signal Processor) and stores a program for controlling operations related to image signal processing. The system control circuit 30 is connected to an operation unit such as a release button (not shown), the lens driving unit 28, and the like, and performs operation control other than image processing of the camera 10.

  When the shooting mode is set, a processing operation for displaying a moving image is executed. The light passing through the photographing optical system 12 reaches the CCD 16 via the lens shutter 14, and as a result, a subject image is formed in the CCD 16, and an analog pixel signal corresponding to the subject image is generated in the CCD 16 by photoelectric conversion. The generated pixel signals are sequentially read from the CCD 16 at predetermined time intervals and sent to an AFE (Analog Front End) circuit 18.

  The AFE circuit 18 includes an amplifier 42, an A / D converter 44, and a CCD driving circuit 46. The CCD driving circuit 46 outputs a driving signal DS including a clock pulse signal for reading out a pixel signal from the CCD 16. The pixel signal read from the CCD 16 is amplified by the amplifier circuit 42 and converted into a digital image signal by an A / D converter (not shown). The digital image signal is sent to the signal processing circuit 20.

  In the signal processing circuit 20, various processes such as a white balance adjustment process and a gamma correction process are performed on the digital image signal. The processed image signal is temporarily stored in a field memory (not shown) and sent to the LCD driver 22. The LCD driver 22 is controlled by the signal processing circuit 20 and outputs a drive signal based on the sent image signal to drive the LCD monitor 24. As a result, the subject image is displayed on the LCD monitor 24 as a moving image.

  When the release button is half-pressed, the release half-push switch 40 is turned on, and the brightness of the subject and the distance to the subject are detected by an exposure detector (not shown), etc. A focusing lens (not shown) in the photographic optical system 12 is driven by the lens driving unit 28.

  When the release button is fully pressed, the release full press switch 38 is turned on, and the photographing operation is executed. That is, the shutter 14 is opened at a predetermined opening for a predetermined period by a drive signal from the exposure control circuit 26. As a result, a subject image for a still image is formed on the CCD 16, and a pixel signal corresponding to the still image for one frame is read from the CCD 16.

  The signal processing circuit 20 outputs the control signal CS to the CCD drive circuit 46, and outputs the control signal CS to the CCD drive circuit 46 so as to output the drive signal DS in accordance with moving image display and still image recording. The CCD drive circuit 46 is provided with a plurality of registers for storing data related to the drive signal DS, and updates data based on a control signal CS from the signal processing circuit 20 as will be described later. At the time of still image recording, the driving signal DS for the CCD 16 such as a clock pulse signal and a charge discharging signal is switched from the moving image display driving signal to the still image recording driving signal according to the data. The timing generator 32 outputs a reference clock pulse signal TN that determines the output timing of a clock pulse signal, a drive signal, a control signal, and the like to each circuit.

  The pixel signal for one frame read from the CCD 16 is processed by the signal processing circuit 20 via the amplifier circuit 42 and the A / D converter 44. The generated image data is compressed by the recording control circuit 34 and recorded on the memory card 36.

  FIG. 2 is a timing chart of the photographing operation process. FIG. 3 is a flowchart of the photographing operation process executed by the signal processing circuit 20.

  In FIG. 2, a clock pulse signal (vertical synchronizing signal) output from the CCD drive circuit 46 to the CCD 16 is “VD”, a charge sweep signal is “Vsub”, and a sensor for sweeping charges accumulated in the CCD 16 at a predetermined timing. The gate signal is represented by “SG”. While a moving image is displayed in the photographing mode, a clock pulse signal VD having a predetermined period P0 (for example, 30 to 40 ms) is sent to the CCD 16 for moving image display. The cycle of this clock pulse signal VD corresponds to one field period. The electronic shutter functions based on the drive signal DS from the CCD drive circuit 46, charges accumulated in the exposure period T0 are transferred, and pixel signals corresponding to moving images are sequentially read out. The output timing of the charge sweep signal “Vsub” or the like is based on the reference clock pulse signal TN from the timing generator 32. The output content of the drive signal is based on the control signal CS from the signal processing circuit 20.

  The control signal CS from the signal processing circuit 20 to the CCD drive circuit 46 is output in synchronization with the clock pal signal VD in order to prevent the influence of noise on the moving image display, and the output period K (rise of the clock pal signal VD) Output during the period from the start to the end). In FIG. 2, the output timing of the control signal CS is represented by a one-dot chain line ST. The signal processing circuit 20 operates in synchronization with the synchronization timing corresponding to the pixel detection of the CCD 16 represented by the broken line MT.

  On the other hand, the CCD drive circuit 46 receives a control signal CS from the signal processing circuit 20 and outputs a drive signal reflecting the contents of the control signal CS to the CCD 16 (renewing the drive signal) (hereinafter, a signal representing the timing). The update signal VHD is synchronized with the clock pulse signal VD, that is, rises within the output period K and is positioned before the output timing (ST) of the control signal. Accordingly, during the moving image display, after the CCD drive circuit 46 receives the control signal CS, the timing of outputting the drive signal DS reflecting the content is delayed by one field period.

  When the release button is fully pressed, a still image recording operation is started (step S101), and initial operations such as memory setting are executed. In FIG. 2, the recording operation is started in the field period (1). Further, when the release button is fully pressed, the LCD driver 22 is controlled so that the LCD 24 displays black.

In the next field period (2), the drive signal DS is switched to a still image drive signal, and the timing of the update signal VHD in the CCD drive circuit 46 is switched to still image use. Is output. When the CCD drive circuit 46 receives the control signal CS based on the reference clock pulse signal TN from the timing generator 32 having a sufficiently larger frequency than the clock pulse signal VD, the CCD drive circuit 46 updates the data of the drive signal DS stored in the register. Then, the rising timing of the update signal VHD is changed. In the field period (2), a control signal for executing exposure control processing such as opening / closing of the shutter 14 and exposure value setting is output, and the output timing of the control signal output from the signal processing circuit 20 is changed. (Step S102).

  When the CCD drive circuit 46 receives the control signal, the update signal “VHD” in the CCD drive circuit 46 is removed from the output period K of the clock pulse signal VD, as shown in FIG. Here, it is represented by “VHD ′”. Thereby, in the field period (2), the update timing (VHD ′) comes after the output timing (ST) of the control signal and within the field period (2), so that the exposure operation is performed in the next field period (3). Can be executed. That is, in the field period (exposure field period) (3), the cycle of the clock pulse signal VD is changed to the cycle P1 for recording a still image, and the charge sweep signal Vsub is accumulated so that charges are accumulated only during the exposure period T. The drive signal DS is switched to a drive signal for still image recording.

  In the field period (3), the control signal CS for returning the update timing of the drive signal DS, that is, for returning to the output period K is output (step S103). In the field period (dummy field period) (4), a control signal is output from the signal processing circuit 20 to the LCD driver 22 so as to stop (OFF) driving of the LCD driver 22 (step S104). As a result, after the black display on the LCD 24 during the field periods (1) to (3), the LCD 24 stops displaying. The dummy field period (4) is a field period set after the exposure period T and before the pixel signal readout period, and is provided to stabilize charge transfer. Here, for example, a time of 30 to 50 ms may be considered to stop the operation of the LCD driver 22.

  The charges accumulated in the CCD 16 are sequentially supplied over the field period (5) (first field period), the field period (6) (second field period), and the field period (7) (third field period). Read out. In the field period (7), switching processing for displaying a moving image is performed again. That is, the clock pulse signal VD is changed to a moving image display cycle, and setting and updating processes are performed to synchronize the output timing of the control signal with the clock pulse signal VD. In the field period (9), a control signal is output to the LCD driver 22 so that the LCD driver 22 is activated again, and the LCD driver 22 drives the LCD monitor 24 (step S106). Thereby, the moving image is displayed on the LCD monitor 24.

  As described above, according to the present embodiment, when the release button is fully pressed and the still image photographing operation process is started, the exposure operation is first executed, and black is displayed in the field periods (1) to (3). The Then, in the dummy field period (4) for stabilizing the output, a control signal is output from the signal processing circuit 20 so as to stop the driving of the LCD driver 22. Since the LCD driver 22 is stopped during the field periods (5) to (7) in which the pixel signals are read from the CCD 16, no noise is generated in the still image. Further, the control process for stopping the driving of the LCD driver 22 restricts the simultaneous execution of other routines of the signal processing circuit 20, but does not stop the driving of the LCD driver 22 before the exposure operation starts (in order to display black). ), The exposure operation is executed immediately after the release operation, and the release time lag is shortened.

  According to the present embodiment, when the release button is fully pressed, the drive signal DS in the CCD drive circuit 46 is updated, and further, the control signal CS for changing the update timing is driven from the signal processing circuit 20 to the CCD. It is output to the circuit 46. In the CCD drive circuit 46, the rising timing of the update signal VHD deviates from the synchronization timing of the clock pulse signal to the CCD 16 (output period K of the clock pulse signal VD), and the update signal VHD 'rises in the field period (2). This makes it possible to perform an exposure operation for recording a still image in the next field period (3). While the through image is displayed, the update signal VHD is output within the output period K in order to prevent noise from being generated in the moving image. However, the through image is not displayed in the field period (2). There is no.

  Note that the driving of the LCD driver 22 may be stopped in the exposure field period (3) instead of the dummy field period (4). In the field periods (1) to (3), the display is not limited to the black display, and display other than the through image may be performed.

  Instead of changing the switching timing (VHD) of the drive signal DS in the CCD drive circuit 46, the output timing of the control signal CS output from the signal processing circuit 20 is excluded from the synchronization timing of the clock pulse signal VD. Also good.

  The release time lag may be shortened by a camera only configured to stop driving the LCD driver 22, or the release time lag may be shortened by a camera only configured to change the drive signal switching timing. Further, the present invention may be applied to a movie camera other than a digital still camera or an electronic device such as a mobile phone having a photographing function. In this case, it is executed in accordance with a recording operation on a still image recording member (button or the like) instead of the release button.

  On the other hand, the camera executes an exposure operation for recording a still image in accordance with a display unit capable of displaying a moving image on a display unit based on a pixel signal read from the image sensor and a recording operation for a release button. And a still image photographing means. Here, the exposure operation indicates an operation of exposing a light receiving surface of an image sensor or the like by opening / closing a mechanical shutter or an electronic shutter function. For example, the display means includes a liquid crystal panel capable of displaying a moving image as a display unit, and a liquid crystal driver.

  The camera includes a display control unit that stops the operation of the display unit between the start of the exposure operation and the time when the pixel signal corresponding to the still image is read from the image sensor. For example, when the display means is a liquid crystal display mechanism, the display control means may stop the operation of the LCD driver.

  When a drive signal such as a clock pulse signal is output from the display means during the transfer of the charge accumulated in the image sensor, noise is generated in the still image. On the other hand, when the still image capturing means or the like is configured by a control mechanism such as a DSP (Digital Signal Processor), the control signal is transmitted while being synchronized with a clock pulse signal output from the image sensor driving means to drive the image sensor. However, if a routine for stopping the operation of the display means such as the LCD driver is executed, it becomes difficult to perform other controls, and the exposure operation cannot be started until the display means stops driving. In the present invention, since the operation of the display unit is stopped before the pixel signal is read, no noise is generated in the still image. On the other hand, since the operation of the display unit is not stopped before the exposure operation starts, the release operation can be quickly performed. The exposure operation can be executed promptly.

  When a period (dummy period) for stabilizing charge output is provided between an exposure period for recording a still image and a pixel signal readout period corresponding to the still image, In order to shift the timing, the display control means may stop the operation of the display means during the output stabilization period.

  The photographing operation device includes a still image photographing unit that performs an exposure operation for recording a still image in accordance with a recording operation on a recording member, and a pixel signal corresponding to the still image is read from the image sensor after the exposure operation is started. Display control means for stopping the operation of the display means until it is displayed.

  The program includes a still image photographing unit that performs an exposure operation for recording a still image according to a recording operation on the recording member, and a pixel signal corresponding to the still image is read from the imaging element after the exposure operation is started. In the meantime, the display control means for stopping the operation of the display means is made to function.

  In the shooting operation method, an exposure operation for recording a still image is performed according to a recording operation on the recording member, and the pixel signal corresponding to the still image is read from the image sensor after the exposure operation is started. The operation of the display means is stopped.

It is a block diagram of the digital camera which is this embodiment. It is a timing chart of imaging operation processing. It is a flowchart of the imaging | photography operation | movement process performed by a signal processing circuit.

Explanation of symbols

10 Digital Camera 12 Imaging Optical System 16 CCD (Imaging Device)
18 AFE
20 Signal Processing Circuit 22 LCD Driver 24 LCD Monitor
46 CCD drive circuit VD clock pulse signal VHD, VHD 'update signal DS drive signal CS control signal

Claims (3)

An image sensor driving means for outputting a drive signal for reading a pixel signal from the image sensor and outputting a clock pulse signal which is a vertical synchronizing signal with a period of one field period;
A still image photographing means for performing an exposure operation for recording a still image in accordance with a recording operation for the release button;
By outputting a control signal for controlling the drive signal output from the image sensor driving means to the image sensor drive means within an output period from a rising edge to a falling edge of the clock pulse signal, Drive signal control means for outputting while synchronizing with the clock pulse signal;
In the imaging device driving means, by outputting before the control signal even before Symbol in the output period update signal representing an update timing to be reflected on the driving signal by receiving the control signal, the update timing clock pulses An operation timing adjusting means for synchronizing with a signal,
When the drive signal control means performs a recording operation on the release button, the drive signal output while displaying a moving image is switched to a still image drive signal, and the output timing of the update signal is set. A control signal for switching to a still image is output to the image sensor driving means,
The operation timing adjusting means, when the control signal is output, the rise timing of the update signal removed from the output period, the image sensor driving unit an update signal to the field period immediately after the control signal output in the output period by outputting at the update timing is shifted from the synchronization timing of the clock pulse signal,
The camera, wherein the image sensor driving means receives the control signal and switches from a field period next to a field period in which an update signal is output to a still image driving signal .   The camera according to claim 1, wherein the image sensor driving unit receives a control signal based on a reference clock pulse signal having a frequency higher than that of the clock pulse signal. Still image photographing means for performing an exposure operation for recording a still image according to a recording operation on the recording member;
Control for controlling the drive signal output from the image sensor driving means for outputting a clock pulse signal which is a vertical synchronizing signal with a period of one field period as well as outputting a drive signal for reading a pixel signal from the image sensor Drive signal control for outputting a signal to the image sensor driving means in synchronization with the clock pulse signal by outputting a signal to the image sensor driving means within an output period from the rising edge to the falling edge of the clock pulse signal Means,
In the imaging device driving means, by outputting before the control signal even before Symbol in the output period update signal representing an update timing to be reflected on the driving signal by receiving the control signal, the update timing clock An operation timing adjusting means for synchronizing with a pulse signal,
When the drive signal control means performs a recording operation on the release button, the drive signal output while displaying a moving image is switched to a still image drive signal, and the output timing of the update signal is set. A control signal for switching to a still image is output to the image sensor driving means,
The operation timing adjusting means, when the control signal is output, the rise timing of the update signal removed from the output period, the image sensor driving unit an update signal to the field period immediately after the control signal output in the output period by outputting at the update timing is shifted from the synchronization timing of the clock pulse signal,
An imaging operation apparatus, wherein the image sensor driving means receives the control signal and switches from a field period next to a field period in which an update signal is output to a still image driving signal .

Images