JP2010020176A - Quick-return mirror driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quick-return mirror driving device which drives a mirror at high speed and with low power consumption. <P>SOLUTION: The quick-return mirror driving device includes: a main mirror 103 which is a quick-return mirror part moving between an advance position where the quick-return mirror part enters the optical path of a photographing lens and which is for observing a subject image and adjusting a focus and a retreat position where the quick-return mirror part is retreated from the optical path of the photographic lens and which is for imaging; a driving motor 107 for driving the main mirror 103; a battery which supplies electric power to the driving motor 107; and a capacitor C24 which accumulates electric energy generated when the driving motor 107 while driving the main mirror 103 is stopped and which, together with the battery, supplies the driving motor 107 with the accumulated electric energy when the driving motor 107 is driven again after stopping. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a quick return mirror driving device applied to a digital single lens reflex camera or the like.

  In recent digital single-lens reflex cameras, it is desired to further increase the shooting speed and reduce the power, that is, to secure a desired number of shots when the battery is driven. To achieve high-speed shooting, speed up the mechanism required for shooting and the imaging function that controls it, or perform image processing on the output results of the imaging device, and save the results in a predetermined storage device Speeding up the function is necessary.

  Conventional single-lens reflex cameras use a quick return mirror to switch the optical path between shooting preparation and shooting. In the stage of shooting preparation, the light beam that has passed through the shooting lens is focused on the optical finder and the distance measuring sensor, and in the stage of shooting, the beam is focused on the imaging device. Such shortening of the optical path switching time, in other words, the mirror settling time, is an important factor that determines high-speed continuous shooting performance. That is, it is desired to further shorten the operation time of the quick return mirror. In order to solve this problem, it is necessary to devise measures such as increasing the driving voltage (driving energy) of the motor that drives the mirror or the motor that charges the mirror driving spring. On the other hand, by increasing the drive voltage, battery power is consumed quickly, and it is difficult to achieve both high speed performance and a desired number of shots.

  Here, the configuration of a conventional digital single-lens reflex camera will be described with reference to the configuration diagram of FIG. The conventional digital single-lens reflex camera 100 includes an interchangeable lens 101 incorporating a photographing lens and a camera body 102.

  The camera body 102 includes a mirror unit including a main mirror 103 that is a quick return mirror for reflecting a subject luminous flux from the photographing lens to the optical finder side, and a sub mirror 104 for subject distance measurement, and a pentaprism 105. An optical finder unit (hereinafter referred to as a finder unit) for observing a subject image, a shutter unit 108, a CCD 109 which is an imaging element for converting a subject image by a subject light beam into an imaging signal, and an output signal of the CCD 109 ADC (AD converter) 110 for AD conversion, a distance measuring sensor 111 that takes a reflected subject light flux from the sub-mirror 104 to measure the subject, and a drive motor for charging the main mirror biasing spring via a reduction gear 107 and the rotation amount of the drive motor 107 are detected. AF control of the interchangeable lens 101 is performed based on an output of a PI (photo interrupter) 107a, a mirror control unit 112 including a microcomputer for controlling driving of the driving motor 107 and a power transistor mounting circuit, and a distance sensor 11. It includes an AF control unit 113 that performs and an image processing unit 114 that generates captured image data based on the output of the ADC 110.

  When the main mirror 103 is switched to the finder observation state, the main mirror 103 is driven and controlled by the mirror control unit 112, accelerated and driven toward the stopper 116, and stopped at the entry position P1 that has entered the subject light beam optical path. . Further, at the start of photographing, the main mirror 103 is driven and controlled by the mirror control unit 112, is accelerated and rotated toward the stopper 115, is applied, and stops at the retracted position P2 retracted from the subject light beam optical path.

  FIG. 8 is a time chart showing changes in the drive current of the drive motor 107 and the position of the main mirror 103 in the rotation control of the main mirror 103 in the conventional single-lens reflex camera system 100. A widely used DC motor is applied to the drive motor. Prior to driving the main mirror 103 to the retracted position P2, the drive motor 107 is driven at an elapsed time t21 to charge the biasing spring. When the PI 107a detects that the drive motor 107 has reached the predetermined rotational position at the elapsed time t22, the drive motor 107 is switched from the drive state to the braking state and stopped. Then, at the elapsed time t23 after the start of photographing, the urging spring in the charged state is released, and the main mirror 103 is rotationally driven to the retracted position P2. Thereafter, the main mirror 103 is rotationally driven to the entry position P1 at the elapsed time t24 by the urging force of another urging spring according to the end of photographing.

  In the above-described mirror driving method by the mirror control unit 112 of the conventional digital single-lens reflex camera system, power consumption sufficient to withstand the securing of the number of frames necessary for shooting together with the high-speed driving of the mirror to support high-speed shooting and high-speed continuous shooting. It is required to suppress this.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a quick return mirror driving device that enables high-speed driving of a mirror and suppresses power consumption.

  The quick return mirror driving device according to claim 1 of the present invention includes a first position for focus adjustment that enters the optical path of the imaging optical system, and a second position for imaging that retracts from the optical path of the imaging optical system. A quick return mirror that moves between the positions of the motor, a drive motor for driving the quick return mirror, a power supply that supplies power to the drive motor, and a drive that is driving the quick return mirror An electrical energy storage and supply unit that stores electrical energy generated when the motor is stopped and supplies the electrical energy stored together with the power source to the drive motor when the drive motor is driven again after the motor is stopped. It has.

  ADVANTAGE OF THE INVENTION According to this invention, the quick return mirror drive device which enables the high-speed drive of a mirror and can suppress electric power consumption can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a digital single-lens reflex camera (hereinafter referred to as a single-lens reflex camera) to which the first embodiment of the present invention is applied. FIG. 2 is a block configuration diagram of a mirror control unit and a main mirror driving unit constituting the quick return mirror driving device of the single-lens reflex camera. FIG. 3 is a time chart showing changes in the drive current of the drive motor, on / off state of the control changeover switch group, and changes in the main mirror position when the main mirror is driven in the single-lens reflex camera.

  The single-lens reflex camera 100A according to the present embodiment includes an interchangeable lens 101 having a photographing lens and a camera body 102A.

  The interchangeable lens 101 has the same configuration as the interchangeable lens applied to the conventional single-lens reflex camera 100 described with reference to FIG.

  The camera body 102A differs from the camera body 102 of the conventional single-lens reflex camera 100 described in FIG. 7 as shown in FIG. 1 in particular in the configuration of a mirror control unit 112A for controlling the drive motor. Other configurations are the same as the configuration of the camera body 102 of the conventional single-lens reflex camera 100. Accordingly, the same components are denoted by the same reference numerals, and different parts will be described below.

  The single-lens reflex camera 100A of the present embodiment employs a mirror drive system using a mirror control unit 112A that stores the braking energy of the drive motor at the end of charging of the mirror biasing spring in a capacitor and controls the power consumption to be suppressed. To do.

  As shown in FIG. 2, the mirror control unit 112A includes a control CPU 10A, SW11, SW12, SW13, SW14, SW15, SW16, and a diode D22 as a switch group controlled to be turned on and off by the control signals Sa, Sb, Sc of the control CPU 10A. , D23, a charging capacitor C24 as an electric energy storage and supply unit for storing electric charge by a driving motor current during motor braking, and a capacitor residual charge discharging resistor R25. The mirror control unit 112A is supplied with a supply voltage Vbat of a battery which is a power supply unit.

  The battery drive voltage Vbat line of the mirror control unit 112A is applied to the charge drive motor 107 via the SW11, and the biasing spring A103a for driving the main mirror 103 up through the reduction gear 107b, and the drive motor for down driving. The urging spring B103b is charged. Note that the output signal of the PI 107a that detects the rotational position of the output shaft of the reduction gear 107b is input to the control CPU 10A.

  The energizing spring A103a and the energizing spring B103b that are charged by the drive motor 107 are released from the charged state by turning on and off the electromagnetic switches 17 and 18 controlled by the control signal Sd of the control CPU 10A, and are main mirrors that are quick return mirrors. 103 is rotated from the entry position P1 to the retracted position P2 as the second position, or from the retracted position P2 to the entry position P1 as the first position.

  The main mirror up / down control operation by the mirror control unit 112A having the above-described configuration will be described with reference to the time chart of FIG.

  When charging the urging spring A103a, the SW11 is turned on, the SW13 is turned on, and the SW15 is turned on, and the voltage of the electric charge accumulated in the capacitor C24 is superimposed on the supply voltage Vbat of the battery that is the power supply unit. High-speed driving is started (elapsed time t1).

  After a certain time from the start of the spring charge (elapsed time t2), SW13 and SW15 are turned off and SW16 is turned on to discharge the remaining charge of the capacitor C24. When the spring charge end rotation position of the drive motor 107 is detected by the detection signal of the PI 107a (elapsed time t3), SW11 is turned off, SW12 is turned on, SW15 is turned on, and the drive motor 107 is braked. Electric energy generated by the drive motor 107 is stored in the capacitor C24.

  SW14 is turned on and SW15 is turned off at an elapsed time t4 after a certain time from the start of the motor brake operation, the accumulation of electric energy in the capacitor C24 is stopped, and the drive motor 107 is stopped by a normal short brake. After the drive motor is stopped (elapsed time t5), the SW17 is turned on to release the charge of the biasing spring A103a and start the up operation of the main mirror 103 to the retracted position P2.

  When the SW 18 is turned on at the elapsed time t6, the main mirror 103 is lowered from the retracted position P2 to the entry value P1.

  During the elapsed time t5 to t6, the charge and discharge operations for the capacitor C24 are performed on the biasing spring B103b in the same manner as in the charging operation of the biasing spring A103a described above.

  According to the single-lens reflex camera 100A of the present embodiment described above, the braking electric energy of the drive motor 107 at the end of the charging of the biasing springs 103a and 103b for driving the main mirror 103 up and down is accumulated as a charge in the capacitor C24. By superimposing the accumulated power on the battery supply power at the start of the next spring charge to suppress the power consumption of the battery, the main mirror 103 can be driven at a high speed and the power consumption of the battery can be suppressed.

  Next, a single-lens reflex camera to which a mirror control unit according to a second embodiment of the present invention is applied will be described with reference to FIGS.

  FIG. 4 is a block configuration diagram of the mirror control unit and the main mirror driving unit of the present embodiment. FIG. 5 is a block diagram of a charge pump circuit built in the mirror control unit of FIG. FIG. 6 is a time chart showing changes in the drive current of the drive motor and changes in the on / off state of the control changeover switch group during the bias spring charging operation in the single-lens reflex camera.

  The single-lens reflex camera of this embodiment has the same configuration as that of the conventional single-lens reflex camera 100 described with reference to FIG. 7 except for the mirror control unit, similarly to the single-lens reflex camera 100A of the first embodiment. In this embodiment, a mirror driving method using a mirror control unit 112B that controls to store braking energy in a capacitor and suppress power consumption is employed.

  As shown in FIG. 4, the mirror control unit 112B applied to this embodiment includes a control CPU 10B, a charge pump circuit 31, a regulator circuit 32, and diodes D33 and D34.

  In the mirror control unit 112B, the supply voltage Vbat of the battery serving as the power supply unit is superimposed on the output of the regulator circuit 32 and applied to the drive motor 107 during the charging operation of the urging spring.

  The charge pump circuit 31 is a circuit for accumulating the current of the drive motor during braking operation in a charge capacitor described later and boosting the accumulated voltage. As shown in FIG. 5, the control signals Sf, Sg, Sh, SW 41, SW 42, SW 43, SW 44 as a changeover switch group that is controlled to be turned on / off by Si, and the drive motor current I at the time of motor braking are taken in and stored as electric charges, and further, power is supplied to the regulator circuit 32 during the bias spring charging operation A charging capacitor C45 as an electric energy storage and supply unit and a capacitor residual charge discharging resistor R46 are provided.

Note that the voltage Vref of the charge pump circuit 31 is Vc when the voltage across the capacitor C45 is Vc and the drop voltage of the regulator circuit 32 is Vr.
Vc + Vref-Vr = Vbat
Is adjusted in advance so that

  The regulator circuit 32 has a function of aligning the output voltage V of the charge pump circuit 31 with the battery supply voltage Vbat.

  The charging drive motor 107 is applied with the battery supply voltage Vbat of the mirror control unit 112 superimposed on the output of the regulator circuit 32, and through the reduction gear 107b, the biasing spring A103a for driving the main mirror 103 up, and the down The drive biasing spring B103b is charged. Note that the output signal of the PI 107a that detects the rotational position of the output shaft of the reduction gear 107b is input to the control CPU 10B.

  The biasing spring A103a and the biasing spring B103b driven to be charged by the drive motor 107 are released from the charged state by the electromagnetic switches 17 and 18 that are on / off controlled by the control signal Sd of the control CPU 10B, and the biasing springs 103a and 103b The main mirror 103, which is a quick return mirror, is rotationally driven from the entry position P1 to the retracted position P2 that is the second position, or from the retracted position P2 to the entry position P1 that is the first position by the urging force.

  The main mirror up / down control operation by the mirror control unit 112B having the above-described configuration will be described with reference to the time chart of FIG.

  When charging the urging spring A103a, the SW43 is turned on when the switches 41 and 42 are off, and the voltage V due to the charge accumulated in the capacitor C45 is superimposed on the battery supply voltage Vbat via the regulator circuit 32. High-speed driving of the drive motor is started (elapsed time t11).

  After a certain time from the start of the spring charge (elapsed time t12), the SW43 is turned off and the SW44 is turned on to discharge the remaining charge of the capacitor C45. When the spring charge end rotation position of the drive motor 107 is detected by the detection signal of the PI 107a (elapsed time t13), SW41 and SW42 are turned on and the drive motor 107 is braked. Electric energy generated by the drive motor 107 is stored in the capacitor C45.

  Subsequent operations are the same as the control operations in the first embodiment.

  According to the mirror control unit 112B of the single-lens reflex camera of the present embodiment described above, the same effect as when the mirror control unit 112A of the first embodiment is applied, and the electric power during motor braking accumulated in the capacitor C45 is obtained. Is superimposed on the battery supply power, so that the power consumption of the battery can be suppressed.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

  The quick return mirror driving device according to the present invention can be used as a quick return mirror driving device that enables high-speed driving of a mirror and can realize low power consumption.

It is a figure which shows the structure of the single-lens reflex camera to which 1st embodiment of this invention is applied. It is a block block diagram of the mirror control part and main mirror drive part of the single-lens reflex camera of FIG. 2 is a time chart showing a change in drive current of a drive motor, an on / off state of a control changeover switch group, and a change in main mirror position when the main mirror is driven in the single-lens reflex camera of FIG. It is a block block diagram of the mirror control part and the main mirror drive part in the single-lens reflex camera of 2nd embodiment of this invention. 5 is a block configuration of a charge pump circuit built in the mirror control unit of FIG. 4. 5 is a time chart showing a change in drive current of a drive motor and a change in on / off state of a control switch group during an urging spring charging operation in the single-lens reflex camera of FIG. 4. It is a figure which shows the structure of the conventional single-lens reflex camera. 8 is a time chart showing changes in the drive current of the drive motor and the position of the main mirror in the rotation control of the main mirror in the conventional single-lens reflex camera system of FIG.

Explanation of symbols

C24, C45 ... Capacitors (electric energy storage and supply unit)
101 ... Interchangeable lens (imaging optical system)
103 ... Main mirror (quick return mirror)
107: driving motor P1: entry position (first position)
P2 ... Retraction position (second position)

Claims (1)

A quick return mirror that moves between a first position for focus adjustment that falls on the optical path of the imaging optical system and a second position for imaging that retracts from the optical path of the imaging optical system;
A drive motor for driving the quick return mirror unit;
A power supply for supplying power to the drive motor;
The electric energy generated when the drive motor that is driving the quick return mirror unit is stopped is accumulated. When the drive motor is driven again after the stop, the electric energy accumulated together with the power source unit is accumulated. An electrical energy storage and supply unit for supplying to
A quick return mirror driving device comprising:

Images