JP2013125112A - Shutter control device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shutter control device capable of suppressing power consumption when the power residual quantity of a battery becomes small.SOLUTION: A shutter control device 10 includes: a motor 12M for driving an electronic control type mechanical shutter 12 for controlling the exposure time of an imaging portion 13 from an exposure completing state to a state before an exposing action; and control portions 15 and 14 detecting the power residual quantity of a battery 20 for supplying power to the motor 12M, and controlling the motor 12M so as to move the mechanical shutter 12 from the exposure completing state to the state before the exposure action at moving speed different according to the detected power residual quantity.

Description

  The present invention relates to a shutter control device and an imaging device.

  An imaging device driven by a battery suddenly becomes inoperable when the remaining battery level falls below a predetermined level, and there is a possibility of missing a photo opportunity. For this reason, conventionally, there is an image pickup apparatus that reduces the drive accuracy of a cover provided on the subject side of the image pickup unit from a normal state when the remaining amount of the battery becomes a predetermined level or less. This suppresses power consumption when the remaining amount of the battery is low (see, for example, Patent Document 1).

JP 2004-153475 A

  An object of the present invention is to provide a shutter control device and an imaging device that can further suppress power consumption when the remaining amount of power of a battery decreases.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

According to the first aspect of the present invention, there is provided a motor (12M) for driving an electronically controlled mechanical shutter (12) for controlling an exposure time of the imaging unit (13) from an exposure completion state to a state before an exposure operation, and the motor The remaining power of the battery (20) that supplies power to (12M) is detected, and the mechanical shutter (12) is moved from the exposure completion state to the state before the exposure operation at different moving speeds depending on the detected remaining power. And a control unit (15, 14) for controlling the motor (12M) so as to move to the shutter control device (10).
Invention of Claim 2 is the shutter control apparatus (10) of Claim 1, Comprising: The said control part (15,14) makes the said moving speed slow, when the said moving speed is below a threshold value. This is a shutter control device (10).
A third aspect of the present invention is the shutter control device (10) according to the second aspect, wherein the control unit (15, 14) pulses the motor (12M) when the moving speed is decreased. The shutter control device (10) is characterized by being controlled by a width modulation method.
A fourth aspect of the present invention is the shutter control device (10) according to the third aspect, wherein the control unit (15, 14) sets the duty ratio of the pulse width modulation method to the battery (20). The shutter control device (10) is characterized in that it is changed on the basis of the remaining amount.
A fifth aspect of the present invention is the shutter control device (10) according to any one of the first to fourth aspects, wherein the control unit (15, 14) starts to move the mechanical shutter (12). Immediately after, immediately before the end of movement, and between the time immediately after the start of movement and immediately before the end of movement, the moving speed of the mechanical shutter (12) immediately after the start of movement is made the fastest, and the movement The shutter control device (10) is characterized in that the moving speed immediately before the end is made slowest.
A sixth aspect of the present invention is the shutter control device (10) according to any one of the first to fifth aspects, wherein the remaining power of the battery (20) is used as a reference for changing the moving speed. The shutter control device (10) is characterized in that the amount varies depending on the temperature in the vicinity of the motor (12M).
A seventh aspect of the present invention is an imaging apparatus (1) comprising the shutter control device (10) according to any one of the first to sixth aspects.
Note that the configuration described with reference numerals may be modified as appropriate, and at least a part of the configuration may be replaced with another component.

  ADVANTAGE OF THE INVENTION According to this invention, the shutter control apparatus and imaging device which can suppress electric power consumption when the electric power remaining of a battery decreases can be provided.

It is a block diagram which shows the schematic structure of the camera provided with the shutter control apparatus which concerns on this invention. It is a flowchart of shutter drive mode setting control by a microcomputer. FIG. 7 is a sequence diagram illustrating an operation of a shutter during shooting in a low power consumption mode. FIG. 6 is a sequence diagram illustrating an operation of a shutter at the time of shooting in a normal mode. It is a figure which shows the example which changes the duty ratio of the drive signal of a charge motor at the time of shutter charge.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a camera 1 which is an imaging apparatus provided with a shutter control device 10 according to the present invention.
The camera 1 is a so-called digital camera that takes an image by converting an image into an electrical signal. The camera 1 includes a lens 11, a shutter 12, an image sensor 13, a shutter control device 10, an operation member 16, a display unit 17, a memory 18, and the like. Moreover, the camera 1 is equipped with the battery 20 which supplies drive electric power so that attachment or detachment is possible.

The lens 11 is an imaging optical system that forms an image of a photographing light beam from a subject on the imaging surface of the imaging device 13. The lens 11 may be either detachable (lens interchangeable) or fixed.
Although not shown in detail, the shutter 12 is an electronically controlled mechanical plane shutter having a front curtain and a rear curtain. The shutter 12 is controlled by the shutter control device 10 to define an exposure time (exposure) by opening and closing an optical path from the lens 11 to the image sensor 13 by opening traveling of the front curtain and closing traveling of the rear curtain.
The imaging element 13 is a photoelectric conversion element such as a CCD, for example, and receives the subject image formed by the lens 11 and converts it into an electrical signal, which is output to the microcomputer 14.

The shutter control device 10 includes a motor 12M, a shutter motor driver 15, and a microcomputer 14.
The motor 12M charges the front curtain and rear curtain of the shutter 12 to the standby position.
The shutter motor driver 15 generates a drive signal for the charge motor 12M that charges the front curtain and the rear curtain in the shutter 12 based on a command from the microcomputer 14, and drives the charge motor 12M with this drive signal.

  The microcomputer 14 includes a CPU and the like, and comprehensively controls the operation of each functional unit related to shooting in the camera 1 including the shutter 12. The signal output from the image sensor 13 and A / D converted is subjected to known image processing, and the processed signal is output to the display unit 17 to display an image and stored in the memory 18. The operation of the microcomputer 14 as a shutter control device that controls the opening and closing of the shutter 12 and the charging operation of the front curtain and rear curtain via the shutter motor driver 15 described later will be described in detail later.

The operation member 16 is a setting button for setting various conditions relating to photographing, a release button, or the like, and outputs an operation input by the user to the microcomputer 14 as an electric signal.
The display unit 17 includes a display panel made of liquid crystal or the like, and displays a captured image image-processed by the microcomputer 14 and a screen for setting operation conditions on the display panel.

And the camera 1 acts as follows at the time of imaging | photography.
When the release button on the operation member 16 is pressed (release operation), the microcomputer 14 opens and closes the shutter 12 via the shutter motor driver 15 to cause the image sensor 13 to expose subject image light for a predetermined time. The image sensor 13 converts subject image light into an electrical signal, which is processed by the microcomputer 14 and displayed on the display unit 17, and stored in the memory 18. Power for the camera 1 is supplied from the battery 20.

  In the camera 1 according to the present embodiment, the shutter 12 is opened during shooting standby when the main switch is turned on, and an image captured by the image sensor 13 is displayed on the display unit 17 in real time. That is, composition determination can be performed by so-called live view.

Next, the drive control of the shutter 12 by the microcomputer 14 will be described with reference to FIGS. 2 to 4 in addition to FIG. 1 described above. FIG. 2 is a flowchart of shutter drive mode setting control. 3 and 4 are sequence diagrams of the shutter 12 during photographing.
As described above, the shutter 12 is a focal plane shutter having a front curtain and a rear curtain, and the front curtain and the rear curtain are charged to a standby position by a charge motor 12M which is a DC motor.

Here, the microcomputer 14 has two drive modes, a normal mode and a low power consumption mode, for controlling the operation of the shutter 12, and shutter drive for switching between these drive modes in accordance with the remaining power of the battery 20. Perform mode setting control.
FIG. 2 is a flowchart of this shutter drive mode setting control. In FIG. 2 and the following description, step is also abbreviated as “S”.

In the shutter drive mode setting control, first, a voltage is measured (battery check) as an index of the remaining power of the battery 20 (S201).
Then, the measured voltage value of the battery 20 is compared with a predetermined value (threshold value) set in advance (S202).

If it is determined in step 202 that the measured voltage value is equal to or less than the predetermined value (Yes), the drive mode is set to the low power consumption mode (S203).
On the other hand, when it is determined in step 202 that the measured voltage value exceeds the predetermined value (No), the drive mode is set to the normal mode (S204).
That is, the shutter drive mode setting control is performed in the normal mode when the battery 20 has sufficient power, and is controlled in the low power consumption mode when the remaining power is low.
The setting of the low power consumption mode may be performed by the user using the operation member 16.

  Next, the operation of the shutter 12 at the time of shooting in each drive mode will be described with reference to FIGS. FIG. 3 is a sequence diagram illustrating the operation of the shutter 12 during shooting in the low power consumption mode, and FIG. 4 is a sequence diagram illustrating the operation of the shutter 12 during shooting in the normal mode.

The basic operation of the shutter 12 common to each drive mode is shown below. Note that (1) to (6) are also shown in FIGS.
(1) When the release button on the operation member 16 is pressed, the magnets of the front curtain and the rear curtain are energized so that the curtain can be held. Before the release, both the first and second curtains are open. The rear curtain is held open by the rear curtain magnet.
(2) The charge motor 12M (see FIG. 1) is driven to close the front curtain, and the front curtain is held by the front curtain magnet.
(3) Turn off the energization of the front curtain magnet. As a result, the front curtain travels from the closed state to the open state.
(4) The energization of the trailing curtain magnet is turned off after a predetermined time from the start of the leading curtain travel ((3)). As a result, the rear curtain travels from the open state to the closed state, and exposure is performed between the front curtain and the rear curtain.
(5) After the rear curtain is closed and the exposure is completed, the charge motor 12M is driven to start shutter charging for returning the closed rear curtain to the open state.
(6) The rear curtain is opened and the shutter charge is completed.

Here, the drive control of the charge motor 12M (see FIG. 1) at the time of shutter charging according to the above (5) to (6) differs between the low power consumption mode and the normal mode.
At the time of photographing in the normal mode shown in FIG. 4, the charge motor 12M is controlled at a constant voltage. On the other hand, in the low power consumption mode shown in FIG. 3, the charge motor 12M is driven by PWM (pulse width modulation) control, and the average voltage is set low.

  As a result, in the low power consumption mode, the shutter charge operation is slower than in the normal mode and requires time to complete the shutter charge. However, the power consumption per unit time can be reduced, and the life of the battery 20 can be reduced. Can be extended. The shutter charge operation is between frames in shooting and does not affect shooting.

In addition, when the charge motor 12M that is being driven is stopped when the shutter charge is completed, both ends of the motor electrodes are short-circuited and the brake is applied. Can be reduced from time. This can also reduce power consumption.
Further, by adopting PWM control as the drive control of the charge motor 12M, there is no loss related to a voltage drop as in the case of lowering the applied voltage by constant voltage control, and the power at the LOW level can be effectively reduced.

Here, the PWM control of the charge motor 12M at the time of shutter charging in the low power consumption mode is effective even when driven at a constant duty ratio as shown in FIG. 3, but the duty ratio is changed according to the conditions. May be.
FIG. 5 shows an example of changing the duty ratio of the drive signal of the charge motor 12M during shutter charging.
FIG. 5A shows an example in which the duty ratio is changed in three stages during shutter charging. That is, the duty ratio is set large at the start of shutter charge, and the duty ratio is set small near the completion of shutter charge. The intermediate section has a duty ratio intermediate between the two. As a result, it is possible to increase the torque at the start of charge driving and drive it quickly and efficiently, and reduce the torque near the completion of shutter charging to improve the power consumption reduction effect during braking. Note that the change in the duty ratio is not limited to three stages, and may be made finer or continuously variable.

FIG. 5B is an example in which three different types of duty ratio patterns are prepared and applied according to the voltage (remaining power) of the battery 20.
That is, based on a constant duty ratio pattern as in the above-described embodiment (FIG. 3) shown in FIG. 5 (b-2), the duty ratio is increased at the start of shutter charge as shown in FIG. 5 (b-1). The duty ratio pattern thus prepared and a duty ratio pattern in which the vicinity of the shutter charge completion is low as shown in FIG. 5B-3 are prepared. Then, the applied duty ratio pattern is changed to (b-1) to (b-3) as the voltage (remaining power) of the battery 20 decreases.
As a result, the power consumption can be reduced more finely according to the voltage (remaining power) of the battery 20, and the number of images that can be shot when the voltage of the battery 20 decreases can be further increased.

As described above, this embodiment has the following effects.
(1) The camera 1 controls the charge motor 12M of the shutter 12 in the low power consumption mode when the remaining power of the battery 20 is low. In the low power consumption mode, the charge motor 12M is driven by PWM control, and the average voltage is set low. As a result, the power consumption related to the shutter charge can be reduced, and the life of the battery 20 can be extended.

(2) When the charge motor 12M that is being driven is stopped when the shutter charge is completed, both ends of the motor electrode are short-circuited and the brake is applied. However, in the low power consumption mode, the operation is slowed down. The power consumed during braking can also be reduced compared to the normal time. This can also reduce power consumption.
(3) Further, by adopting PWM control as the drive control of the charge motor 12M, there is no loss related to voltage drop as in the case of lowering the applied voltage by constant voltage control, and power at the LOW level can be effectively reduced. .

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
(1) In the low power consumption mode of the shutter in the present embodiment, the shutter charge operation is performed at a lower speed than in the normal mode, and it takes time to complete the shutter charge. For this reason, single shooting (single shot) is good, but continuous shooting affects the continuous shooting speed. For this reason, when the low power consumption mode is set, it may be configured such that continuous shooting cannot be set. Alternatively, when continuous shooting is set, switching to the low power consumption mode may not be performed.

(2) In the shutter drive mode setting control in the present embodiment, switching to the low power consumption mode is performed based on the voltage of the battery 20. However, a configuration may be adopted in which other information is added to the voltage of the battery 20 to determine the switching to the low power consumption mode and the control content. For example, the temperature of the charge motor 12M or the battery 20 that greatly affects the power consumption or the battery 20 life is detected by a temperature sensor or the like, and the determination of switching to the low power consumption mode and the control content are changed in consideration of the temperature information. You may comprise as follows.

(3) The low power consumption mode of the shutter in the present embodiment may be configured to be used in combination with a low power consumption measure (for example, luminance suppression of display liquid crystal) for other components in the camera 1.
(4) In the present embodiment, the so-called normally open shutter operation in which the shutter is normally opened has been described. However, the present invention can also be applied to a normally closed shutter in which the shutter is normally closed. is there.
(5) In this embodiment, the present invention is applied to the charge of the focal plane shutter, but may be applied to the shutter charge in the lens shutter.

  In addition, although embodiment and a deformation | transformation form can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

  1: Camera, 12: Shutter, 12M: Charge motor, 13: Image sensor, 14: Microcomputer, 15: Shutter motor driver, 20: Battery

Claims (7)

A motor that drives an electronically controlled mechanical shutter that controls the exposure time of the imaging unit from an exposure completion state to a state before the exposure operation;
The motor detects power remaining in a battery that supplies power to the motor, and moves the mechanical shutter from the exposure completion state to the state before the exposure operation at a moving speed that differs depending on the detected remaining power. A control unit for controlling
A shutter control device. The shutter control device according to claim 1,
The controller is
If the moving speed is less than or equal to a threshold, slow down the moving speed;
A shutter control device. The shutter control device according to claim 2,
The controller is
When slowing down the moving speed, controlling the motor by a pulse width modulation method,
A shutter control device. The shutter control device according to claim 3,
The control unit changes the duty ratio of the pulse width modulation method based on the remaining amount of the battery,
A shutter control device. The shutter control device according to any one of claims 1 to 4,
The controller controls the moving speed of the mechanical shutter immediately after the start of movement between immediately after the start of movement of the mechanical shutter, immediately before the end of movement, and between the time immediately after the start of movement and immediately before the end of movement. Fastest and slow down the moving speed just before the end of the movement,
A shutter control device. The shutter control device according to any one of claims 1 to 5,
The remaining power level of the battery as a reference for changing the moving speed is different depending on the temperature in the vicinity of the motor;
A shutter control device.   An imaging apparatus comprising the shutter control device according to claim 1.

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