JP2005345724A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumed by the driving of a mechanical shutter. <P>SOLUTION: A digital camera 2 includes: a shutter vane 24 designed to be freely movable between a closing position where an exposure aperture 21 for admitting subject light into a CCD 46 is closed and an opening position where the exposure aperture 21 is opened, and to be moved from the opening position to the closing position, in response to a release operation; and a governor mechanism 29 for delaying the movement of the shutter vane 24 so that a length of time that the shutter vane 24 moves from the opening position to the closing position, after the release operation, is greater than the maximum value of exposure time. According to the exposure time determined based on the result of detection by a photometer/range-finder circuit 59, a CPU 44 changes the timing of the start of exposure with the CCD 46 so that time when the exposure aperture 21 closes, after the shutter vane 24 moves to the closing position and time when the exposure with the CCD 46 finishes, almost coincide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an image sensor that captures subject light and outputs an image signal, an exposure condition detection unit that detects an exposure condition of the subject before a release operation, and an object based on the detection result of the exposure condition. The present invention relates to a digital camera having an exposure time for taking in light and a control means for controlling driving of an image sensor so that exposure is performed with the determined exposure time.

  2. Description of the Related Art Digital cameras that convert subject light imaged by a solid-state imaging device such as a CCD into digital image data and record it in a built-in memory or a memory card have become widespread. In such a digital camera, the exposure time of the subject light is controlled by controlling the charge sweep timing of the CCD. In addition, a so-called mechanical shutter is mounted for the purpose of preventing smear (see Patent Document 1).

JP 2002-290823 A

  A mechanical shutter mounted on a conventional digital camera is driven to open and close by an electromagnet or a coil. For this reason, a large amount of electric power is applied to drive the mechanical shutter, and it is necessary to replace the battery frequently.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a digital camera that can reduce power consumption by driving a mechanical shutter.

  In order to achieve the above object, the present invention provides an image sensor that captures subject light and outputs an imaging signal, an exposure condition detection unit that detects an exposure condition of the subject before a release operation, and detection of the exposure condition In the digital camera having a control means for controlling the driving of the image sensor so as to determine an exposure time for capturing the subject light by the image sensor based on the result and performing exposure with the determined exposure time. It is movable between a closed position for closing an exposure opening for taking light into the image sensor and an open position for opening the exposure opening, and in response to the release operation, from the open position to the closed position. The shutter blade that moves to the closed position and the time from when the release operation is performed until the shutter blade moves from the open position to the closed position is the exposure time. A delay mechanism that delays the movement of the shutter blades so as to be larger than the maximum value, and the control means moves the shutter blades to the closed position according to the determined exposure time, thereby exposing the exposure. The timing for starting exposure with the image sensor is changed so that the time for which the opening is closed substantially coincides with the time for completing the exposure with the image sensor.

  According to the digital camera of the present invention, it is movable between the closed position for closing the exposure opening for taking the subject light into the image sensor and the open position for opening the exposure opening, and in response to the release operation. The shutter blades that move from the open position to the closed position, and the shutter blades so that the time from when the release operation is performed until the shutter blades move from the open position to the closed position is greater than the maximum exposure time. A delay mechanism for delaying the movement, and the control means approximately determines a time for the shutter blade to move to the closed position and the exposure opening to be closed according to the determined exposure time, and a time for the exposure to be completed by the image sensor. Since the timing of starting exposure with the image sensor is changed so as to match, it is possible to reduce power consumption due to driving of the mechanical shutter.

  1 and 2, a lens barrel 11 for holding an imaging lens 10 and a viewfinder objective window 12 are incorporated in the front surface of a digital camera 2 to which the present invention is applied. A release button 13 is provided on the top surface of the digital camera 2, and a lid 14 is provided on the side surface to cover a memory card slot into which a memory card 56 (see FIG. 5) is detachably loaded.

  On the back surface of the digital camera 2, a finder eyepiece window 15, a liquid crystal display (LCD) 16, an operation unit 17, a shutter charge member 18, and the like are provided. The LCD 16 displays captured images, so-called through images, and various menu screens. The operation unit 17 includes a power button that is operated when the power of the digital camera 2 is turned on and off, a zoom operation button that is operated when the zoom magnification of the imaging lens 10 is changed from the wide side to the tele side, and the LCD 16. The menu button is operated when a menu screen is displayed, selection contents are determined / cancelled, a cross key operated when the cursor is moved in the menu screen displayed on the LCD 16, and the like.

  The release button 13 is a two-stage push switch. When the release button 13 is lightly pressed (half-pressed) after the framing of the subject, various shooting preparation processes such as automatic exposure adjustment (AE) and automatic focus adjustment (AF) are performed. In this state, when the release button 13 is pressed once more (fully pressed), the imaging signal for one screen subjected to the imaging preparation process is converted into image data, and then image processing and compression processing described later are performed. Recorded in the memory card 56.

  In the digital camera 2, a still image shooting mode for taking a still image, a playback mode for displaying the shot image on the LCD 16, and a setting mode for making various settings can be selected. Switching between these modes is performed by operating the operation unit 17.

  As shown in FIGS. 3 and 4, the digital camera 2 has a built-in shutter device 20. The shutter device 20 is rotatably attached to a dark box 22 in which an exposure opening 21 is formed on the front surface and a CCD 46 (see FIG. 5), which will be described later, is disposed behind the pin, and a pin 23 protruding from the front surface of the dark box 22. The shutter blade 24, the shutter drive lever 26 pivotally attached to the shaft 25 protruding from the upper surface of the dark box 22, and the locking lever 28 pivotally attached to the shaft 27 protruding from the upper surface of the dark box 22. A governor mechanism 29 as a delay mechanism and a cam 30 are included.

  The shutter blade 24 is composed of one sector blade, and includes a blade portion 24a and a mounting portion 24b. In addition to the pin 23 described above, the other end of the spring 31 whose one end is attached to the dark box 22 is attached to the attachment portion 24b. The shutter blade 24 is held at an open position for opening the exposure opening 21 with the blade portion 24a abutting against a stopper 32 projecting from the front surface of the dark box 22 by the bias of a spring 31. .

  The shutter drive lever 26 includes a kicking arm 26a for kicking the tip of the mounting portion 24b of the shutter blade 24, a hook 26b that contacts the semicircular plate 30a of the cam 30, a gear 26c that meshes with the switch gear 29a of the governor mechanism 29, A protrusion 26d that is in contact with the protrusion 28b provided on the back surface of the stop lever 28, and a locking portion 26e that locks one end of the torsion spring 33 that is hung around the shaft 25 are formed. The shutter drive lever 26 is urged counterclockwise by a torsion spring 33 in the drawing.

  The tip portion of the kicking arm 26 a is a widened portion 26 f that is wide in the direction of the front surface of the dark box 22. Below the widened portion 26f, the shutter driving lever 26 is driven and the kicking arm 26a kicks the tip of the mounting portion 24b of the shutter blade 24, and then the tip of the mounting portion 24b of the shutter blade 24 abuts. Thus, the exposure opening 21 is closed in a state where the blade portion 24a of the shutter blade 24 is in contact with the stopper 34 protruding from the front surface of the dark box 22 until the shutter charge member 18 is operated and the shutter charge is performed. Stay in position.

  The locking lever 28 includes a hook 28a that enters a notch 35 formed in the disc 30b of the cam 30, a projection 28b that contacts the projection 26d of the shutter drive lever 26, a release portion 28c, a winding stop 28d, and a torsion spring. A locking portion 28e is formed to which the other end of 33 is locked. The locking lever 28 is urged clockwise by a torsion spring 33 in the drawing. Further, the projection 28b contacts the projection 26d of the shutter drive lever 26, thereby holding the shutter drive lever 26 in the illustrated charging position.

  The release portion 28 c is pressed by a pressing piece (not shown) formed in the lower part of the release button 13 by a full pressing operation of the release button 13. As a result, the contact state between the protrusion 26d and the protrusion 28b is released, and the shutter drive lever 26 rotates counterclockwise in the figure by the urging force of the torsion spring 33, and the locking lever 28 is rotated by the torsion spring 33. It rotates counterclockwise in the figure against the bias of. The winding stop 28d has a groove 18a formed on the outer peripheral portion of the shutter charge member 18 when the shutter charge member 18 is operated and the shutter drive lever 26 is rotated clockwise in the drawing and returned to the charge position. Engage and lock the rotation of the shutter charge member 18.

  The governor mechanism 29 includes a switch gear 29a and an ankle 29b, and these are attached to the mounting plate 36 as a unit. The rotational speed of the switch gear 29a is adjusted by the ankle 29b. As described above, the switch gear 29a meshes with the gear 26c of the shutter drive lever 26, and follows the rotation of the shutter drive lever 26.

  The mounting plate 36 is movable in the direction of the arrow in the figure by a moving mechanism such as a slide mechanism (not shown). The mounting plate 36 remains in a position where the switch gear 29a meshes with the gear 26c until the predetermined time elapses after the release button 13 is fully pressed, and until the meshing between the switch gear 29a and the gear 26c is released after the predetermined time elapses. evacuate.

  The cam 30 rotates in conjunction with the operation of the shutter charge member 18 and pushes the hook 26a of the shutter drive lever 26 with the semi-disc 30a, thereby returning the shutter drive lever 26 to the charge position.

  When the release button 13 is fully pressed, the pressing piece formed at the lower part of the release button 13 presses the release portion 28c of the locking lever 28, and the locking lever 28 resists the bias of the torsion spring 33. Rotate counterclockwise in the figure. In conjunction with this, the shutter drive lever 26 also rotates counterclockwise in the figure by the urging force of the torsion spring 33. At this time, the hook 28a and the notch 34 of the locking lever 28 are fitted, the engagement of the winding preventing portion 28 and the groove 18a of the shutter charge member 18, and the protrusion 26d of the shutter drive lever 26 and the locking lever 28. The contact state with the projection 28b is released.

  When the shutter drive lever 26 rotates counterclockwise, the kicking arm 26a kicks the tip of the mounting portion 24b of the shutter blade 24. Thereby, the shutter blade 24 rotates in the clockwise direction in the drawing against the bias of the spring 31 and moves to the closed position where the exposure opening 21 is closed by the blade portion 24a of the shutter blade 24. Thereafter, the shutter blade 24 stays in the closed position until the shutter charge member 18 is operated and shutter charge is performed by the tip of the attachment portion 24b of the shutter blade 24 coming into contact with the widened portion 26f of the kicking arm 26a.

  The shutter drive lever 26 continues to rotate counterclockwise even after the tip of the mounting portion 24 b of the shutter blade 24 is kicked, and the kick arm 26 a is moved to the release portion 28 c of the locking lever 28 and the semicircular plate 30 a of the cam 30. The rotation is stopped when the hook 26b comes into contact. The shutter drive lever 26 returns to the original charge position by rotating the shutter charge member 18. At this time, the shutter blade 24 is released from the contact state between the widened portion 26 f of the kicking arm 26 a and the tip of the mounting portion 24 b of the shutter blade 24, so that the shutter blade 24 returns to the open position by the bias of the spring 31.

  The governor mechanism 29 is configured such that the time from when the release button 13 is fully pressed until the shutter blade 24 moves from the open position to the closed position is longer than the maximum exposure time for capturing the subject light by the CCD 46. In addition, the movement of the shutter blade 24 is delayed. Specifically, until the kicking arm 26a of the shutter drive lever 26 kicks off the tip of the mounting portion 24b of the shutter blade 24, the switch gear 29a and the gear 26c are engaged with each other for a predetermined time T1 (the movement time of the shutter blade 24). The rotation of the shutter drive lever 26 is delayed for a preset time (see FIG. 6) such that T2 is greater than the maximum value of the exposure time T. Then, after the predetermined time T1 has elapsed, the mounting plate 36 is retracted, and the meshing between the switch gear 29a and the gear 26c is released.

  In FIG. 5 showing the electrical configuration of the digital camera 2, a lens motor 41 and an iris motor 42 are connected to the imaging lens 10 and the aperture 40. These motors 41 and 42 are stepping motors, which are driven and controlled by a motor driver 45 connected to the CPU 44 via a bus 43 and a photometry / ranging circuit 59 described later, and a shooting preparation process in response to half-pressing of the release button 13. I do.

  The lens motor 41 moves the zoom lens of the imaging lens 10 to the wide side or the tele side in conjunction with the operation of the zoom operation button of the operation unit 17. Further, the focus lens of the imaging lens 10 is moved in accordance with the subject distance and zoom lens zooming, and the focus adjustment is performed so that the shooting conditions are optimized. The iris motor 42 operates the aperture 40 to adjust exposure.

  The shutter blade 24 described above is disposed behind the aperture 40. The shutter blade 24 is connected to the shutter drive lever 26 and the governor mechanism 29 described above. As described above, the shutter drive lever 26 and the governor mechanism 29 drive the shutter blade 24 as a mechanical shutter in response to a full pressing operation of the release button 13.

  Behind the shutter blade 24 (in the dark box 22), a CCD 46 for converting subject light incident from the imaging lens 10 into an imaging signal is disposed. The imaging signal converted by the CCD 46 is input to a correlated double sampling circuit (CDS) 47. The CDS 47 outputs the image pickup signal input from the CCD 46 as R, G, and B image data that accurately corresponds to the accumulated charge amount of each cell of the CCD 46.

  Image data output from the CDS 47 is amplified by an amplifier (AMP) 48. An A / D converter (A / D) 49 converts the image data amplified by the AMP 48 into digital image data. The digital image data output from the A / D 49 is transmitted to the image signal processing circuit 50.

  The image signal processing circuit 50 performs various kinds of image processing such as gradation conversion, white balance correction, and γ correction processing on the image data. The image data that has been subjected to various processes by the image signal processing circuit 50 is temporarily stored in the SDRAM 51. The image data stored in the SDRAM 51 is converted into a composite signal by the LCD driver 52 and displayed on the LCD 16.

  The YC processing circuit 53 reads the image data that has been subjected to various processes by the image signal processing circuit 50 from the SDRAM 51, and converts it into a luminance signal Y and color difference signals Cr and Cb. The compression / decompression processing circuit 54 performs image compression on the converted image data in a predetermined compression format (for example, JPEG format). The image data compressed by the compression / decompression processing circuit 54 is recorded on the memory card 56 via the card I / F 55.

  The timing generator (TG) 57 is connected to the CCD driver 58 that controls the driving of the CCD 46 together with the A / D 49 and the YC processing circuit 53 described above. The TG 57 transmits timing signals (clock pulses) to these units. The CCD driver 58 adjusts the shutter speed of the electronic shutter by the CCD 46 based on the timing signal transmitted from the TG 57.

  The photometry / ranging circuit 59 detects the luminance of the subject and the distance between the subject and the imaging lens 10 and transmits the detection result to the CPU 44. Based on this detection result, the CPU 44 adjusts various parameters of the imaging lens 10 so as to obtain an appropriate focal length and exposure amount. The photometry / ranging circuit 59 drives and controls the motor driver 45 based on the adjustment signal fed back from the CPU 44 to drive the imaging lens 10.

  The CPU 44 is connected to each unit via the bus 43 and controls the overall operation of the digital camera 2. In addition to the release button 13 and the operation unit 17 described above, an EEPROM 60 is connected to the CPU 44. The EEPROM 60 stores various control programs and setting information. The CPU 44 reads these pieces of information from the EEPROM 60 to the SDRAM 51 which is a working memory, and executes various processes.

  In accordance with the exposure time determined based on the detection result of the photometry / ranging circuit 59, the CPU 44 moves the shutter blade 24 to the closed position and closes the exposure aperture 21, and sets the exposure time of the CCD 46 to end. Are changed so that the CCD 46 starts exposure.

  Next, the effect | action by the said embodiment is demonstrated with reference to the timing chart of FIG. First, when the operation unit 17 is operated and the still image shooting mode is selected, the subject light incident through the imaging lens 10 is photoelectrically converted by the CCD 46 and sampled by the CDS 47.

  The image data output from the CDS 47 is amplified by the AMP 48 and converted to digital image data by the A / D 49. The digitally converted image data is subjected to various image processing by the image signal processing circuit 50 and sequentially stored in the SDRAM 51. The image data stored in the SDRAM 51 is displayed as a through image on the LCD 16 via the LCD driver 52. When the release button 13 is pressed halfway in this state, various shooting preparation processes such as automatic exposure adjustment (AE) and automatic focus adjustment (AF) are performed.

  After shooting preparation processing, when shooting is performed by fully pressing the release button 13, the release piece 28c of the locking lever 28 is pressed by the pressing piece formed at the lower part of the release button 13, and the locking lever 28 is torsioned. It is rotated counterclockwise in the figure against the bias of the spring 33. In conjunction with this, the shutter drive lever 26 is also rotated counterclockwise in the figure by the urging force of the torsion spring 33, and the hook 28a of the locking lever 28 and the notch 35 are fitted, and the anti-winding portion 28 and the shutter charge. The engagement of the member 18 with the groove 18a and the contact state between the protrusion 26d of the shutter drive lever 26 and the protrusion 28b of the locking lever 28 are released.

  When the shutter drive lever 26 is rotated counterclockwise, the tip of the attachment portion 24b of the shutter blade 24 is kicked by the kicking arm 26a. As a result, the shutter blade 24 is rotated clockwise in the drawing against the bias of the spring 31, and is moved to the closed position where the blade portion 24a of the shutter blade 24 closes the exposure opening 21. Thereafter, the shutter blade 24 is held in the closed position until the shutter charge member 18 is operated and shutter charge is performed by the tip of the mounting portion 24b of the shutter blade 24 coming into contact with the widened portion 26f of the kicking arm 26a. .

  When the kicking arm 26a is brought into contact with the release portion 28c of the locking lever 28 and the hook 26b is brought into contact with the semicircular plate 30a of the cam 30, the rotation of the shutter driving lever 26 is stopped. Thereafter, the shutter drive lever 26 is returned to the original charge position by rotating the shutter charge member 18. At this time, the shutter blade 24 is returned to the open position by the bias of the spring 31 by releasing the contact state between the widened portion 26f of the kicking arm 26a and the tip of the mounting portion 24b of the shutter blade 24.

  The switch gear 29a of the governor mechanism 29 and the gear 26c of the shutter drive lever 26 until the kick arm 26a of the shutter drive lever 26 kicks the tip of the mounting portion 24b of the shutter blade 24 after the release button 13 is fully pressed. And the rotation of the shutter drive lever 26 is delayed for a predetermined time T1. Then, after the predetermined time T1 has elapsed, the mounting plate 36 is retracted, and the meshing between the switch gear 29a and the gear 26c is released. Thus, the time (T1 + T2) from when the release button 13 is fully pressed until the shutter blade 24 moves from the open position to the closed position is larger than the maximum value of the exposure time T for capturing the subject light by the CCD 46. Thus, the movement of the shutter blade 24 is delayed.

  The CPU 44 changes the time T3 in FIG. 6 according to the exposure time determined based on the detection result of the photometry / ranging circuit 59, and sets the timing at which the CCD 46 starts exposure. In the CCD 46, based on the timing signal from the TG 57, the electronic shutter is opened and exposure is started at the set timing. Then, the electronic shutter is closed at a time substantially coincident with the time when the shutter blade 24 moves to the closed position, and the exposure is completed. After the exposure is completed, the charges accumulated in each cell of the CCD 46 are swept out to the transfer path. After the above process, one shooting operation is completed.

  The subject light thus captured by the CCD 46 is stored in the SDRAM 51 through the CDS 47, the AMP 48, the A / D 49, and the image signal processing circuit 50. The image data stored in the SDRAM 51 is read out to the YC processing circuit 53, converted into the luminance signal Y and the color difference signals Cr and Cb, and then subjected to compression processing in the compression / decompression processing circuit 54, and the card I / F 55. To the memory card 56.

  As described above, an electromagnet or a coil is not necessary, and the shutter blade 24 that operates by mechanical braking is used as a mechanical shutter. Therefore, a great amount of power is not consumed to drive the mechanical shutter. Therefore, it can be said that the digital camera 2 to which the present invention is applied is advantageous in terms of running cost as compared with a conventional camera using an electromagnet or a coil for a mechanical shutter.

  In the above embodiment, the release button 13 is a two-step switch, and the shooting preparation process is performed by half-pressing. However, an operation member that performs the shooting preparation process may be provided separately from the release button 13.

  In the above embodiment, the governor mechanism 29 has been described as an example of the delay mechanism. However, the present invention is not limited to this, and for example, the tip of the leaf spring is brought into contact with the shaft 25 of the shutter drive lever 26. The rotation of the shutter drive lever 26 may be delayed by friction with the leaf spring. Further, although the mode in which the shutter blade 24 is urged to the open position by the spring 31 is illustrated, the shutter blade 24 is urged to the closed position and held in the open position by a stopper or the like before the release operation is performed. In addition, when the release operation is performed, the holding state by the stopper may be released, and the shutter blade 24 may be moved from the open position to the closed position.

It is a front external perspective view of a digital camera to which the present invention is applied. It is a back external appearance perspective view of a digital camera. It is an external appearance perspective view which shows the structure of a shutter apparatus. It is a top view which shows the structure of a shutter apparatus. It is a block diagram which shows the electric constitution of a digital camera. It is a graph which shows the timing chart at the time of imaging | photography with a digital camera.

Explanation of symbols

2 Digital Camera 10 Imaging Lens 13 Release Button 16 Liquid Crystal Display (LCD)
18 Shutter Charge Member 20 Shutter Device 21 Exposure Opening 24 Shutter Blade 26 Shutter Drive Lever 28 Locking Lever 29 Governor Mechanism 30 Cam 44 CPU
46 CCD
57 Timing Generator (TG)
59 Metering / ranging circuit

Claims (1)

An image sensor that images subject light and outputs an imaging signal, an exposure condition detection unit that detects an exposure condition of the subject before a release operation, and the subject light by the image sensor based on a detection result of the exposure condition In a digital camera having a control means for controlling the drive of the image sensor so as to determine an exposure time for capturing the image and to perform exposure with the determined exposure time,
It is movable between a closing position for closing an exposure opening for taking the subject light into the image sensor and an opening position for opening the exposure opening, and the opening position is opened from the opening position in response to the release operation. A shutter blade that moves to a closed position;
A delay mechanism that delays the movement of the shutter blades so that the time from when the release operation is performed until the shutter blades move from the open position to the closed position is greater than the maximum value of the exposure time. And
In accordance with the determined exposure time, the control means is configured so that the time when the shutter blade moves to the closed position and the exposure opening is closed substantially matches the time when the image sensor completes exposure. A digital camera characterized in that the timing at which exposure starts at the image sensor is changed.

Images