JP2007067915A - Photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device that can eliminate deficiency in a quantity of light during still picture photography, and adjust the quantity of light during moving picture photography without generating any sound according to a variation in field luminance. <P>SOLUTION: A liquid crystal stop 1011 is used for moving picture photography. To put the liquid crystal stop 1011 in an optical path of photography, a control unit 100 informs a white balance of spectral transmissivity corresponding to a voltage applied to the liquid crystal stop in the form of a parameter set etc., to perform suitable white balance adjustment. During still picture photography, the liquid crystal stop is retracted and a stop plate is used to adjust the quantity of light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photographing apparatus that forms an image of a subject on an image sensor with a photographing optical system and generates an image signal representing the subject with the image sensor.

  Modern digital cameras can also shoot moving images in addition to still images. When taking a still image, it is necessary to detect the subject brightness immediately before shooting to adjust the aperture diameter in order to capture a subject for a moment, but when shooting a movie, In the case of a two-stage aperture, a small aperture and an open aperture are set in accordance with the luminance so that the change in luminance on the subject side can be dealt with since continuous shooting is performed for a predetermined time. It is necessary to shoot while adjusting the amount of light by switching. For this reason, in many digital cameras, moving pictures are taken by rotating a diaphragm plate having a small diaphragm and an open diaphragm so that the small diaphragm is advanced and retracted in the photographing optical path. When driving the aperture plate, the aperture plate is brought into contact with a stopper or the like so that the small aperture and the open aperture can be switched frequently according to the luminance change of the object field, and then the aperture plate is directly attached to the stopper. In many digital cameras, the small aperture or the wide aperture is positioned in the photographing optical path or held in the retracted position by holding it.

  However, when shooting movies, audio is often recorded, and as described above, if the diaphragm plate is moved into or out of the shooting optical path during recording, the diaphragm plate is moved into the shooting optical path. The contact sound between the stopper and the diaphragm plate when being retracted to the retracted position is recorded.

  Therefore, a technique using diaphragm blades has been proposed as a technique for suppressing such contact noise of the diaphragm plate (see, for example, Patent Document 1). However, if this diaphragm blade is to be used, an actuator for driving the diaphragm blade is required, which causes a problem that the lens portion becomes large.

  By the way, it is not intended to suppress the contact noise that occurs when the aperture plate is switched as described above, but in order to prevent lens performance from being deteriorated due to diffraction phenomenon occurring at the edge of the aperture when the aperture is small. There has been proposed a technique for allowing a liquid crystal shutter to advance on a photographing optical path instead of using an aperture plate (see, for example, Patent Document 2). When this technology is applied, the amount of light can be adjusted by using liquid crystal as a liquid crystal diaphragm instead of a liquid crystal shutter.

However, when the light amount adjusting means such as the liquid crystal diaphragm is inserted on the photographing optical path, there is a problem that the transmitted light amount is reduced due to the insertion loss of the light amount adjusting means. Since the reduction of the transmitted light amount narrows the photographing area, it is not desirable that the light amount adjusting means is on the optical path when photographing a still image that does not require silence.
JP 2004-128539 A JP 2005-323264 A

  In view of the above circumstances, the present invention prevents the occurrence of light shortage in still image shooting, and can adjust the light amount silently in accordance with changes in the field luminance in movie shooting. An object is to provide an apparatus.

The imaging device of the present invention that achieves the above object is an imaging device that forms an image of a subject on an imaging element with a shooting optical system and generates an image signal representing the subject with the imaging element.
This photographing apparatus has a moving image photographing mode for photographing a moving image and a still image photographing mode for photographing a still image,
A light amount adjusting means for adjusting the amount of light traveling in the photographing optical path when it is in a position retracted from the photographing optical path of the photographing optical system and can freely advance into the photographing optical path,
When the moving image shooting mode is selected by operation, the light amount adjusting means is advanced to the shooting optical path, and when the still image shooting mode is selected by operation, the light amount adjusting means is moved from the shooting optical path. And advancing / retreating control means for retreating.

According to the photographing apparatus of the present invention, when the moving image photographing mode is selected, the light amount adjusting means advances into the photographing optical path and the light amount is adjusted by the light amount adjusting means according to a change in the field luminance. Adjusted.

  In this case, it is not necessary to move the diaphragm plate into and out of the photographing optical path during moving image shooting, and a contact sound between the diaphragm plate and the stopper is not recorded during moving image shooting.

  In addition, when the still image shooting mode is selected, the light amount adjusting unit can be retracted from the shooting optical path by the advance / retreat control unit, so that a shortage of light amount does not occur during still image shooting.

  As described above, an imaging device that prevents the occurrence of insufficient light intensity for still image shooting and can adjust the light intensity silently according to changes in the field luminance for moving image shooting is realized. To do.

  Here, the light amount adjusting means is preferably a liquid crystal diaphragm that adjusts the amount of light using liquid crystal.

  When the light amount adjusting means is a liquid crystal diaphragm, the transmitted light amount is adjusted by applying a predetermined voltage between the electrodes. Note that the entire transmitted light amount may be adjusted by using a single liquid crystal like an ND filter, and a small aperture may be used by switching between the central liquid crystal and the entire liquid crystal using a liquid crystal array. And the open aperture may be switched electrically.

  Furthermore, a white balance adjusting unit that adjusts the white balance of the image signal generated by the image sensor is provided, and the white balance adjusting unit is configured to adjust the light amount adjusting unit when the light amount adjusting unit has advanced into the photographing optical path. It is preferable to perform white balance adjustment in consideration of spectral transmittance.

  Then, even if the amplitude of each of the red light, green light, and blue light of the photographing light after passing through the liquid crystal diaphragm is changed due to the advancement of the liquid crystal diaphragm, the change is taken into consideration by the white balance adjusting unit. As a result, white balance adjustment equivalent to that when the liquid crystal diaphragm has not advanced into the photographing optical path is performed.

   As described above, there is an imaging device capable of preventing the occurrence of a shortage of light in still image shooting, and silently adjusting the light amount according to a change in field luminance in moving image shooting. Realize.

  Embodiments of the present invention will be described below.

  FIG. 1 is a view showing an appearance of a digital camera 1 according to an embodiment of the present invention.

  A lens barrel 10 is provided at the center of the camera body 1a of the digital camera 1 shown in FIG. A finder 11 is provided above the lens barrel 10, and a flash emission window 12 is provided next to the finder 11.

  A shutter button 13 and a mode dial 14 are provided on the upper surface of the camera body 1a. The digital camera 1 has a moving image shooting mode for shooting a moving image, a still image shooting mode for shooting a still image, and a playback mode. The mode dial 14 switches between these modes. When the shutter button 13 is operated while the mode dial 14 is switched to the moving image shooting mode or the still image shooting mode, the subject is shot in any shooting mode. When one of the moving image shooting modes is selected, the voice of the person on the subject side can be recorded through the microphone 15 in addition to shooting a moving image. Further, on the back side, a speaker 16 for reproducing and outputting sound recorded during reproduction is also provided.

  FIG. 2 is a block diagram showing an internal configuration of the digital camera shown in FIG.

  As shown in FIG. 2, in the lens barrel 10, in addition to the photographing lens, a photographing optical system including a diaphragm plate 1010 having a small diaphragm and an open diaphragm and a liquid crystal diaphragm 1011 is provided. In this example, when the mode dial 14 is switched to the moving image shooting mode, the liquid crystal aperture 1011 is moved instead of moving the small aperture provided on the aperture plate 1010 into or out of the imaging optical path as in the prior art. The liquid crystal aperture 1011 is adjusted by advancing to the photographing optical path and changing the voltage applied between the electrodes of the liquid crystal aperture 1011 using the driver 100d. By doing so, it is not necessary to switch the aperture plate 1010 during moving image shooting, so that the switching sound is not picked up by the microphone 15. This liquid crystal diaphragm corresponds to the light amount adjusting means in the present invention. In this example, the liquid crystal diaphragm 1011 is made to act as an ND filter when adjusting the amount of light.

  Here, the configuration of the advancing / retreating control means for moving the liquid crystal diaphragm 1011 into the photographing optical path or retracting it from the photographing optical path will be described.

  As shown in FIG. 2, the liquid crystal diaphragm 1011 is held by a frame having a gear at the peripheral edge. The gear provided on the frame and the gear head 100G of the motor 100M mesh with each other. When the motor 100M on the gear head side rotates in the forward direction, the liquid crystal diaphragm 1011 advances into the photographing optical path, and when it rotates in the reverse direction, it retracts from the photographing optical path. ing. Here, when the mode dial is switched to the moving image shooting mode, the control unit 100 instructs the drive unit 100b to rotate the motor 100M in the forward direction so that the liquid crystal diaphragm 1011 advances into the shooting optical path, and switches to the still image shooting mode. When in this state, the control unit 100 instructs the drive unit 100b to rotate the motor 100M in the reverse direction to retract the liquid crystal diaphragm 1011 from the photographing optical path. The control unit 100, the drive unit 100b, the motor 100M, the gear 100G, and the geared frame that holds the liquid crystal diaphragm correspond to the advance / retreat control means.

  In the present embodiment, the conventional diaphragm plate 1010 is used because the liquid crystal diaphragm need not be used when the still image shooting mode is selected. The diaphragm plate 1010 provided with both the small diaphragm and the wide diaphragm is driven by a drive unit 100c having a moving coil, as in the prior art, and one of the small diaphragm and the wide diaphragm is photographed. It is configured to advance and retreat into the optical path. With such a configuration, at the time of still image shooting, the liquid crystal diaphragm can be retracted from the photographing optical path, so that the occurrence of insufficient light quantity due to the insertion of the liquid crystal diaphragm is prevented.

  Here, the internal configuration and operation of the digital camera of FIG. 1 will be briefly described with reference to FIG.

  The operation of the digital camera 1 shown in FIG. 1 is controlled by the control unit 100 in an integrated manner.

  When the mode dial 14 and the shutter button 13 are connected to the input unit of the control unit 100 and the shutter button 13 is pressed when the mode dial 14 is switched to the moving image shooting mode or the still image shooting mode. Then, the imaging process is started by the control unit 100.

  When the mode dial 14 is switched to the still image shooting mode, the control unit 100 receives the operation signal and instructs the drive unit 100b to retract the liquid crystal aperture 1011 from the imaging optical path and provide it on the aperture plate 1010. The photographing process is performed after the small aperture or the wide aperture is advanced into the photographing optical path. When the mode dial is switched to the moving image shooting mode, the open aperture of the small aperture and the open aperture provided on the aperture plate 1010 is advanced into the imaging optical path, and the liquid crystal aperture 1011 is further moved. The shooting process is performed after entering the shooting optical path. When performing the shooting process in moving image shooting in this way, the control unit 100 instructs the driver 100d to adjust the voltage applied to the liquid crystal diaphragm 1011 according to the AE measurement result by the signal processing unit at the subsequent stage, thereby adjusting the liquid crystal. The amount of light can be adjusted to the aperture 1011.

  First, the shooting process when the mode dial 14 is switched to the still image shooting mode will be briefly described.

  When the mode dial 14 is switched to the still image shooting mode, the control unit 100 receives the operation signal and retracts the liquid crystal aperture 1011 from the imaging optical path, or a small aperture provided on the aperture plate 1010, or The photographing process is performed by advancing the wide aperture to the photographing optical path. In this example, the control unit 100 determines which of the small aperture and the wide aperture is advanced into the photographing optical path based on the AE detection of the signal processing unit 106 on the rear stage side. The focus position is also detected by the control unit 100 based on the AF detection result of the signal processing unit 106.

  Here, in order to make the photographing process easy to understand, the flow of the image signal related to the photographing process when the mode dial 14 is switched to the still image photographing mode will be described.

  When the mode dial 14 is switched to the still image photographing mode, image signals representing the subject imaged on the CCD 102 by the photographing optical system 101 shown in FIG. 2 are successively generated by the CCD. At this time, the control unit 100 controls the clock generator 100a to supply a timing signal from the CG 100a to the CCD 102 at every predetermined time (for example, 33 ms), and outputs an image signal to the CCD 102 to the CDS unit 103 at every predetermined time. By doing so, the CCD 102 is made to generate image signals one after another. The CDS unit 103 receives an image signal at every predetermined time and reduces noise each time. Further, the noise-reduced image signal is supplied to the white balance unit 104 at the next stage. When the white balance is adjusted by the white balance unit 104, the R / G / B signals with the adjusted white balance are supplied to the A / D unit 105 at the next stage. Then, the A / D unit 105 converts the analog signal into the digital signal, and the image signal converted into the digital signal is supplied to the signal processing unit 106. Further, the signal processing unit 106 converts the signal into a YC signal, and the YC signal is supplied to the display unit 107. The display unit 107 displays an image based on the image signal represented by the YC signal. Since this image is switched and displayed every predetermined time, the image captured by the photographing optical system is displayed as it is on the display screen of the display unit as a through image.

  When the shutter button 13 is pressed by the user viewing the through image while the through image is displayed on the display screen in this way, the control unit 100 controls the CG 100a in response to the pressing of the shutter button 13. A timing signal notifying the start of exposure is supplied to the CCD 102. Thereafter, when a predetermined shutter time elapses, a timing signal for notifying the end of exposure is supplied to the CG 100 a and an image signal is output from the CCD 102. The CDS unit 103 performs noise reduction, and after the white balance unit 104 performs white balance adjustment, the A / D unit 105 performs conversion to a digital signal. Further, the image signal converted into the digital signal is supplied to the signal processing unit 106, and the signal processing unit 106 performs conversion into a YC signal and JPEG compression, and the JPEG compressed image signal is applied to the medium by the recording unit 108. To be recorded.

  Next, shooting processing when the mode dial 14 is switched to the moving image shooting mode will be described.

  When the mode dial 14 is switched to the moving image shooting mode, the aperture stop of the aperture plate 101 is left advanced in the imaging optical path, and the liquid crystal aperture 1011 is advanced in the imaging optical path. In this way, the control unit 100 applies a voltage to the electrode of the liquid crystal diaphragm 1011 according to the AE result from the signal processing unit 106 to change the transmittance of the liquid crystal diaphragm 1011. The liquid crystal diaphragm 1011 is adjusted to adjust the amount of photographing light. Except for making the liquid crystal diaphragm adjust the light amount in this way, the same processing as that in the still image shooting mode is performed, and a through image is displayed on the display unit.

  When the shutter button 13 is pressed, the control unit 100 causes the CG 100 a to supply a timing signal to the CCD 102 in response to the pressing of the shutter button 13. With this timing signal as the head, the timing signal is supplied one after another at predetermined timings and the image signal is output one after another. In the CDS unit 103 and thereafter, the same processing is performed, and an image signal representing a moving image compressed by the recording unit 108 is recorded on the medium.

  FIG. 3 is a diagram for explaining how the liquid crystal diaphragm 1011 operates in the moving image shooting mode. FIG. 3A shows that the liquid crystal diaphragm is in the retracted position during still image shooting, and FIG. 3B shows a state in which the liquid crystal diaphragm has advanced into the shooting optical path in the moving image shooting mode. ing.

  As shown in FIG. 3A, at the time of still image shooting, the control unit 100 drives the aperture plate 1010 to the driver 100d in accordance with the AE detection result of the signal processing unit 106 to capture either a small aperture or an open aperture. The camera is advanced to the optical path to perform shooting processing.

  In the case of still image shooting, recording is not performed, and shooting is not performed in a shooting environment in which a change in field luminance occurs. Therefore, the liquid crystal diaphragm 1011 is retracted from the shooting optical path and the diaphragm plate is moved. The light quantity is adjusted to 1010.

  On the other hand, in the case of moving image shooting, since recording is performed and the field luminance frequently changes, a liquid crystal diaphragm 1011 is advanced into the shooting optical path and the AE by the signal processing unit 106 is performed. The driver adjusts the amount of light by changing the voltage applied to the liquid crystal diaphragm 1011 by the driver in accordance with the detection result.

  Further, in the example of the present embodiment, when the liquid crystal diaphragm 1011 is advanced into the photographing optical path, it is expected that the influence of the spectral transmittance of the liquid crystal 1011 appears in white balance. Therefore, the control unit 100 applies the liquid crystal diaphragm 1011 to the driver. The white balance unit 104 is configured to perform white balance adjustment in consideration of the spectral transmittance by notifying the white balance unit 104 of the spectral transmittance corresponding to the voltage being applied.

  In this way, at the time of moving image shooting, the brightness is adjusted without rotating the aperture plate to prevent recording of sound other than the sound of the subject. Further, at the time of still image shooting, shooting is performed using a diaphragm plate without using a liquid crystal diaphragm that causes a shortage of light, thereby preventing the shortage of light from occurring.

  As described above, an imaging device capable of preventing the occurrence of a shortage of light in still image shooting and capable of silently adjusting the light amount in accordance with a change in field luminance in moving image shooting is realized. .

  Finally, the procedure of the photographing process performed by the control unit 100 described so far will be described in the form of a flowchart.

  FIG. 4 is a flowchart showing the procedure of the photographing process.

  In step S401, it is determined whether the still image shooting mode is selected by the mode dial or the moving image shooting mode is selected.

  If it is determined in step S401 that the moving image shooting mode is selected, the process proceeds to step S402, and the liquid crystal diaphragm 1011 is advanced to the shooting optical path.

  In step S403, it is determined whether or not the shutter button 13 is half-pressed. If it is determined in step S403 that the shutter button 13 is half-pressed, in step S404, the image is captured on the liquid crystal aperture 1011 based on the AE detection result of the signal processing unit. The amount of transmitted light is adjusted by applying a voltage according to the field luminance. Further, the process proceeds to the next step S405, and this time, the focus lens is arranged at the in-focus position by driving a driving unit (not shown) according to the AF processing result of the signal processing unit 106.

  If it is determined in step S406 that the shutter button 13 has been fully pressed, a timing signal synchronized with the timing of pressing the shutter button 13 is supplied to the CG 100a in step S407 to cause the CCD 102 to start exposure. When the predetermined shutter time has elapsed, the process proceeds to step S408, where an exposure end signal is supplied from the CG 100a to the CCD 102, and the CCD 102 outputs an image signal. Here, since the moving image shooting mode is selected, the CG is supplied with an exposure start signal and an exposure end signal one after another toward the CCD at every predetermined time. Proceeding to the next step S409, it is determined again in step S409 whether it is moving image shooting or still image shooting. If it is determined in this step S409 that the moving image is being shot, the process advances to step S410 to cause the white balance unit 104 to perform white balance processing in consideration of the spectral transmittance of the liquid crystal diaphragm 1011.

  Proceeding to the next step S411, the A / D unit converts the signal into a digital signal, the signal processing unit supplies the image signal converted into the digital signal, and the signal processing unit 106 performs JPEG compression processing in step S412. Then, the image signal subjected to JPEG compression processing is supplied to the recording unit 108. When the recording unit 108 performs recording on the medium in the next step S413, and in the next step S414, it is determined whether it is moving image shooting or still image shooting by detecting a flag or the like, and it is determined that it is moving image shooting. Returning to step S406, the process from step S407 to step S414 is repeated until the full-press operation is performed again, and the recording unit repeatedly records the MPEG compressed signal on the medium at every predetermined time.

  If it returns to step S406 and it determines with the shutter button being fully pressed again, it will determine with it being the video recording end, and will complete | finish the process of this flow.

  If it is determined in step S401 that the still image shooting mode is set, the process proceeds to step S415, and the liquid crystal diaphragm 1011 is retracted from the shooting optical path in step S415. If it is determined in step S403 that the shutter button 13 has been half-pressed, in step S404, the aperture plate 1010 is driven by the drive unit 100c based on the AE measurement result of the signal processing unit to photograph a small aperture or an open aperture. Advance into the optical path. Proceeding to next step S405, the focus lens is arranged at the in-focus position according to the AF result of the signal processing unit 106.

  If it proceeds to the next step S406 and determines that it has been fully pressed, the exposure of the CCD 102 is started by supplying an exposure start signal to the CG in the next step S407. When the predetermined shutter time has elapsed, the process proceeds to the next step S408, where the CG 100a is supplied with an exposure end signal to output an image signal. If it is determined in step S409 that a still image is captured by detecting a flag or the like, normal white balance processing is performed in the white balance unit in step S416, and A / D conversion is performed in the A / D unit 105 in next step S411. To cause the signal processing unit 106 to supply an image signal converted into a digital signal. The signal processing unit 106 that has received the supplied image signal performs image compression processing, and in the next step S413, the recording unit 108 records the image signal on the medium. In step S414, a flag or the like is detected. If it is determined that the image is still image shooting, the processing of this flow is terminated.

  FIG. 5 is a diagram showing a second embodiment.

  In FIG. 5, only the arrangement of the liquid crystal diaphragm is shown for the sake of simplicity, but a diaphragm plate is used when taking a still image.

  In the first embodiment, since the liquid crystal diaphragm is disposed on the front surface of the CCD 102, it must act as an ND filter. However, the liquid crystal diaphragm 1011M is further disposed at the position where the diaphragm plate is disposed. If a liquid crystal array is used for the liquid crystal diaphragm, the liquid crystal diaphragm can be operated in the same manner as when the diaphragm plate is used.

  At this time, by using a liquid crystal array for the liquid crystal diaphragm 1011M, a voltage is applied to only the electrode at the central portion of the liquid crystal to operate the liquid crystal array as a small diaphragm, or the voltage is applied not only to the central portion of the liquid crystal but also to a wide range of electrodes. The liquid crystal diaphragm may be operated as an open diaphragm by applying. Even if it does in this way, the same effect is acquired.

It is a figure which shows the external appearance of the digital camera 1 which is one Embodiment of this invention. It is a block diagram which shows the internal structure of the digital camera shown in FIG. It is a figure explaining how the liquid crystal diaphragm 1011 is made to act in the moving image shooting mode. It is a flowchart which shows the procedure of an imaging | photography process. It is a figure which shows 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 10 Lens barrel 11 Finder 12 Flash emission window 13 Shutter button 14 Mode dial 15 Microphone 16 Speaker 100 Control part 101 Shooting optical system 1010 Aperture plate (small aperture or wide aperture)
1011 1011M Liquid crystal diaphragm 102 CCD
103 CDS section 104 White balance section 105 A / D section 106 Signal processing section 107 Display section 108 Recording section

Claims (3)

In a photographing apparatus that forms an image of a subject on a photographing element with a photographing optical system and generates an image signal representing the subject with the photographing element.
This photographing apparatus has a moving image photographing mode for photographing a moving image and a still image photographing mode for photographing a still image,
A light amount adjusting means for adjusting the amount of light traveling in the photographing optical path when it is in a position retracted from the photographing optical path of the photographing optical system and can freely enter the photographing optical path, and is in a state of having advanced into the photographing optical path;
When the moving image shooting mode is selected by operation, the light amount adjusting means is advanced to the shooting optical path, and when the still image shooting mode is selected by operation, the light amount adjusting means is moved from the shooting optical path. An imaging apparatus comprising: advancing / retreating control means for retracting the camera.   2. The photographing apparatus according to claim 1, wherein the light amount adjusting means is a liquid crystal diaphragm that adjusts the light amount using liquid crystal.   A white balance adjusting unit configured to adjust a white balance of an image signal generated by the image sensor, wherein the white balance adjusting unit is configured to perform spectral analysis of the light amount adjusting unit when the light amount adjusting unit has advanced into the photographing optical path; 3. The photographing apparatus according to claim 1, wherein white balance adjustment is performed in consideration of transmittance.

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