JP4211876B2 - camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera having an electromagnetically driven shutter, and more particularly to a camera having an electromagnetically driven shutter that uses electrical energy stored in a capacitor.
[0002]
[Prior art]
For the charging control of the electromagnetically driven shutter capacitor as described above, the charging of the capacitor is started by the first stroke operation of the release button, the charging is stopped before the shutter travels, and then the front curtain is traveled until the rear curtain travels. In some cases, charging is performed again during this period and then the trailing curtain is controlled.
[0003]
And normally, when the voltage to charge is higher than a battery voltage, a DC / DC converter is used.
[0004]
[Problems to be solved by the invention]
However, in the case of performing the charge control as described above, the DC / DC converter is always operated even after the capacitor is completely charged in a state in which a sequence other than the exposure operation is executed, so that the naturally discharged charge is replenished. If this is continued, the current consumption during the operation of the DC / DC converter is wasted.
[0005]
In the special shooting mode such as the long exposure mode (BULB mode), the timing of the rear curtain travel is the time when the photographer releases the release button. A time lag occurs.
[0006]
The present invention has the purpose of charging the capacitors it is possible to prevent wasteful current consumption in DC / DC converter for capacitor charging after completion, to provide a camera which is to allow a reliable shutter drive Yes.
[0011]
In the present invention, a shutter that operates using electric energy stored in a capacitor, opens when the release switch means is turned on, and closes when the release switch means is turned off, and charging that performs an operation for charging the capacitor When the passage of a predetermined time is repeated before the closing operation of the shutter when the voltage of the capacitor is equal to or lower than the predetermined value during the period from the opening operation to the closing operation of the shutter. Control means for operating the charging means at every elapse of a predetermined time is provided.
[0012]
Thereby , for example, when shooting in the long exposure (BULB) mode , the charging means is operated when the capacitor voltage becomes a predetermined value or less between the time when the shutter is opened and the time when the shutter is closed. By charging the capacitor, it is possible to realize a camera capable of preventing wasteful current consumption as in the case of operating the charging means regardless of the capacitor voltage and performing a reliable shutter operation.
[0013]
In the present invention, in the configuration in which the electrical energy stored in the capacitor is also supplied to the operating means other than the shutter, when operating the charging means, the supply of electrical energy from the capacitor to the operating means is restricted. The capacitor may be charged quickly.
[0014]
Further, when supplying the electric energy to the actuating means from the capacitor, so as to regulate the operation of the charging means, so small DC / DC converter can be used, the aim of the camera size and energy saving Also good.
[0015]
The present invention, shutter a focal plane shutter having a front and rear curtains, particularly suitable for a camera that capacitors are provided separately as a drive of the front curtain and the rear curtain.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a control circuit of a single-lens reflex camera according to the first embodiment of the present invention. In this figure, reference numeral 1 denotes a main microcomputer for controlling the operation of the camera (hereinafter referred to as main microcomputer: corresponding to the control means in the claims), ROM, RAM, A / D converter, D / A converter, This is a single-chip microcomputer including peripheral circuits such as a PWM circuit.
[0017]
Reference numeral 2 denotes a sub-microcomputer (hereinafter referred to as a sub-microcomputer) that performs autofocus control, which also includes peripheral circuits similar to those of the main microcomputer 1.
[0018]
Reference numeral 3 denotes a focus detection unit including an image sensor or the like. Reference numeral 4 denotes a three-terminal regulator for generating a low voltage from a high voltage. In this embodiment, a voltage of 10 V is generated.
[0019]
Reference numeral 5 denotes a semiconductor switch composed of a transistor for supplying power to the sub-microcomputer 2 and is turned on when a special function of the sub-microcomputer 2 is used.
[0020]
Reference numeral 6 denotes a DC / DC converter (charging means referred to in the claims), which produces various power supply voltages for the main microcomputer, the sub microcomputer, and the shutter.
[0021]
7 is a battery as a system power supply, 8 is a shutter control circuit, 9 is a feeding control circuit for controlling the film, 10 is a mirror control circuit for raising and lowering the mirror, and 11 is measuring the brightness of the subject. This is a photometric circuit.
[0022]
Reference numeral 12 denotes a switch sense circuit for detecting the state of a switch existing inside and outside the camera. The switch sense circuit 12 is turned on by a first stroke operation of the release button, and is a switch SW1 (exposure preparation operation switch referred to in the claims), which is a switch for starting photographing preparation operations such as photometry and focus detection , and a release button. SW2 (exposure operation switch as claimed in the claims) that is turned on by the second stroke operation to start the exposure operation, the mode setting switch MODE, and the state of the switch LOCK for performing the release lock are detected. To do.
[0023]
Reference numeral 13 denotes a liquid crystal display circuit for displaying the mode and state of the camera, 14 is a strobe control circuit for performing communication and control with an external strobe, and 15 is a lens communication circuit for performing communication with the lens.
[0024]
FIG. 2 shows a circuit configuration of the shutter control circuit 8. MG3-1 is a front curtain magnet for releasing the tension of the front curtain, MG3-2 is a rear curtain magnet for releasing the tension of the rear curtain, and CMG3-1 is a front curtain capacitor for driving the front curtain magnet MG3-1. (Capacitor in claims), CMG3-2 is a rear curtain capacitor (capacitor in claims) for driving the rear curtain magnet MG3-2.
[0025]
DMG31 and DMG32 are diodes for preventing backflow of current, RMG31, RMG32, RMG33, and RMG34 are resistors, TRMG31 is a front-curtain transistor for controlling energization to the front-curtain magnet MG3-1 , and TRMG32 is a rear-curtain magnet MG3- 2 is a rear-curtain transistor for controlling energization to 2.
[0026]
V3 is a power source and is supplied from the DC / DC converter 6. The bases of the transistors TRMG31 and 32 are connected to the main microcomputer 1 via resistors and controlled by a program.
[0027]
FIG. 3 shows the configuration of the DC / DC converter 6. The DC / DC converter 6 includes two DC / DC converter parts A and B.
[0028]
The DC / DC converter section A generates a voltage of 5V, which is the main power source of the camera, from the voltage (BATT) input from the battery. The DC / DC converter unit A is controlled to be turned on / off by a V2ON signal from the main microcomputer 1. The DC / DC converter unit B generates a voltage (V3) of 12V that is a shutter voltage from a voltage (BATT) input from the battery. The DC / DC converter B is controlled to be turned on / off by the V3ON signal from the main microcomputer 1.
[0029]
DV1 and DBATT are diodes that output the higher voltage of the output of the DC / DC converter A or the voltage input from the battery as V1, and serve as a power source for the main microcomputer 1. DV2 is a diode and supplies the output of the DC / DC converter unit A to the sub-microcomputer 2 as V2. CV3 is a capacitor and smoothes the boosted voltage of V3.
[0030]
Although not shown in the figure, in an actual circuit, a three-terminal regulator is inserted between the battery ( BATT ) and the diode DBATT so that a voltage difference between V1 and V2 does not occur even when the battery voltage is high. The
[0031]
FIG. 4 is a part of the photometry sequence of the camera, and is a subroutine executed at a cycle of 62.5 mS when SW1 is turned on and the photometry operation or mode is being set.
[0032]
First, the voltage V3 is read by the A / D converter of the main microcomputer 1 (step 401). Then, it is checked whether or not this voltage is equal to or higher than a predetermined voltage (in this embodiment, this voltage is set to 10.6 V ) that can be released (the front curtain and the rear curtain can travel) (step 402). If it is determined that the voltage is low and release is impossible, the process proceeds to step 405, where the V3ON signal is output to the DC / DC converter 6 (DC / DC converter section B) to output the leading curtain capacitor CMG3-1 and the trailing curtain. Charging of the capacitor CMG3-2 is started. At this time, the DC / DC converter 6 is turned off so that V3 is not supplied to other loads (such as the sub-microcomputer 2) in order to finish charging quickly, and this subroutine program is terminated.
[0033]
On the other hand, if there is a sufficient voltage when the voltage is checked in step 402 (if the voltage is equal to or higher than the predetermined voltage) , the process proceeds to step 403 to check whether the release button is half pressed (SW1 is on). . If it is on, the process proceeds to step 405. If it is off, the process proceeds to step 404 to stop charging the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2, and this subroutine program is terminated.
[0034]
Thus, according to this subroutine program, when the voltages of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 are lower than a predetermined voltage or when SW1 is on, the DC / DC converter 6 is operated ( V3ON), charging is continued as it is, and replenishment of charges by natural discharge is performed. On the other hand, when the voltages of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 are higher than a predetermined voltage and SW1 is turned off, charging is stopped and unnecessary current consumption is suppressed. Thus, a reliable shutter operation is ensured while saving energy. Here, FIG. 8 shows voltage changes of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 by the subroutine program. When charging is stopped at time Ta, the voltage decreases with time. When the voltage reaches a predetermined voltage (= 10.6 V) at time Tb, charging starts again, and time Tc after 62.5 mS (subroutine cycle shown in FIG. 4). Charging stops.
[0035]
FIG. 5 shows an exposure control routine executed when the SW2 of the camera is turned on.
[0036]
When SW2 is turned on, charging of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 is first started (step 501). Then, the main mirror is raised (step 502), and the lens diaphragm is driven simultaneously. When the driving of the main mirror is completed, charge control of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 is performed (step 503).
[0037]
Here, the details of step 503 (capacitor charging control) will be described with reference to FIG. First, a timer is started (step 601).
[0038]
Then, charging of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 is started (step 602). Next, A / D conversion of the voltage ( capacitor voltage ) of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 is performed (step 603), and comparison with a predetermined voltage is performed (step 604). If the capacitor voltage has not reached the predetermined voltage, the process proceeds to step 605, and it is checked whether or not the timer started in step 601 has expired (in this embodiment, 100 mS).
[0039]
If the time is up, the process proceeds to error processing and the shutter exposure operation is restricted. When the time is not up, the process returns to step 603 to perform A / D conversion of the capacitor voltage again. This process is repeated in steps 603 → 604 → 605 → 603 until the capacitor voltage reaches a predetermined value. If the time is up, error processing is performed. If the predetermined voltage is reached, the process proceeds to step 606 to stop charging and return. .
[0040]
In step 504 of FIG. 5, a process of charging again is performed when the exposure time is longer than a predetermined time. Note that BULB (long exposure) control as one of the processes will be described later.
[0041]
When the exposure control in step 504 ends, the process proceeds to step 505, and charging of the front curtain capacitor CMG3-1 and the rear curtain capacitor CMG3-2 is started for the next exposure.
[0042]
Finally, the main mirror is lowered, the shutter mechanism is charged, and the film is fed (step 506).
[0043]
FIG. 7 shows a flowchart of the BULB exposure control. This flowchart is executed when the BULB control mode is set at the time of execution of step 504 described above.
[0044]
First, the front curtain magnet MG3-1 is energized (step 701). The TRMG 31 is turned on by the MG31 ON signal from the main microcomputer 1 , the current flows from the front curtain capacitor CMG3-1 to the front curtain magnet MG3-1, the front curtain is driven, and exposure is started. Thereafter, after waiting for 10 ms (step 702), the energization to the front curtain magnet MG3-1 is stopped (step 703).
[0045]
Next, V2ON (FIG. 3) is controlled to turn off the sub-microcomputer 2 (step 704). At this time, power is continuously supplied to the main microcomputer 1 by DBATT (FIG. 3), and step 705 is executed. In step 705, for example, a timer for charging the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 is started every 4 minutes.
[0046]
Next, SW1 is checked (step 706). If SW1 is on, the process proceeds to step 707 and the timer time is checked. When the timer time has not elapsed, the process returns to step 706, and step 706 and step 707 are repeatedly executed.
[0047]
If the timer time has elapsed in step 707, the process proceeds to step 708, and the capacitor charging control described in FIG. 6 is performed. When this is finished, the process returns to step 705 to restart the timer.
[0048]
In this way, the first-curtain capacitor CMG3-1 and the second-curtain capacitor CMG3-2 are charged every 4 minutes and wait for the SW1 to be turned off. When SW1 is turned off, the process proceeds to step 709, where V2ON is operated to resume power supply to the sub-microcomputer 2.
[0049]
Next, the front curtain capacitor CMG3-1 and the rear curtain capacitor CMG3-2 are charged (step 710), and the rear curtain magnet MG3-2 is energized (step 711). Thereby, TRMG32 is turned on by the MG32ON signal from the main microcomputer 1 , current flows from the rear curtain capacitor CMG3-2 to the rear curtain magnet MG3-2, and the rear curtain is driven. Thereafter, after waiting for 10 mS (step 712), the energization of the trailing curtain magnet MG3-2 is stopped (step 713).
[0050]
Thus, according to the present BULB control, during the execution of the BULB control mode, when the voltages of the leading curtain capacitor CMG3-1 and the trailing curtain capacitor CMG3-2 are lower than a predetermined voltage, these charges are performed. It is possible to achieve both good response at the end of BULB and energy saving.
[0051]
Note that the set times and voltages described in the present embodiment are merely examples, and can be changed to conditions optimal for the system when applied to an actual system.
[0054]
According to the present invention , for example, when shooting in the long exposure (BULB) mode , the charging unit is operated when the capacitor voltage is equal to or lower than a predetermined value between the time when the shutter is opened and the time when the shutter is closed. since so as to charge the capacitor Te, it can be realized camera capable of performing it is not possible to unnecessary current consumption, and reliable shutter operation as in the case of operating the charging means regardless of the capacitor voltage. In the BULB mode , the response at the end of this mode can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control circuit of a single-lens reflex camera according to a first embodiment of the present invention.
FIG. 2 is a detailed diagram of a shutter control circuit of the camera.
FIG. 3 is a detailed block diagram of a DC / DC converter which is a charging circuit of the camera.
FIG. 4 is a flowchart of a charging sequence during photometry of the camera.
FIG. 5 is a flowchart of an exposure control routine of the camera.
FIG. 6 is a flowchart of a charging sequence immediately before exposure of the camera.
FIG. 7 is a flowchart of a charging sequence when the camera is in a BULB control mode.
FIG. 8 is a voltage waveform diagram of a capacitor of the camera.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Main microcomputer 2 Sub microcomputer 3 Focus detection unit 4 Regulator 5 Switch 6 DC / DC converter 7 Battery 8 Shutter control circuit 9 Film feed control circuit 10 Mirror control circuit 11 Photometry circuit 12 Switch sense circuit 13 Liquid crystal display circuit 14 Strobe Communication control circuit 15 Lens communication control circuit SW1 Metering start switch SW2 Exposure start switch MG3-1 Shutter front curtain magnet MG3-2 Shutter rear curtain magnet CMG3-1 Front curtain capacitor CMG3-2 Rear curtain capacitor

Claims (4)

A shutter that operates using electrical energy stored in a capacitor, opens when the release switch means is turned on, and closes when the release switch means is turned off; and charging means that performs an operation for charging the capacitor A camera having
When the passage of the predetermined time is repeated before the closing operation of the shutter when the voltage of the capacitor is equal to or lower than the predetermined value between the opening of the shutter and the closing operation, And a control means for operating the charging means. The electric energy stored in the capacitor is also supplied to an operating means different from the shutter,
Wherein, when operating the charging means, a camera according to claim 1, characterized in that to regulate the supply of electrical energy to said actuating means from said condenser. The electric energy stored in the capacitor is also supplied to an operating means different from the shutter,
The camera according to claim 1 , wherein the control unit regulates an operation of the charging unit when electric energy is supplied from the capacitor to the operating unit. The shutter is a focal plane shutter having a front curtain and a rear curtain;
Said capacitor, said curtain and camera according to claim 1, any one of 3, characterized in that are provided separately for the driving of the rear curtain.

Images