JP2008182801A - Charge controller, charge control method, and charge control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To elongate the life of a battery and improve the determination accuracy of the residual quantity of the battery. <P>SOLUTION: In circuit constitution where it is indispensable to actually apply charge voltage when detecting the charge residual quantity of a light emitting capacitor 7 which accumulates charge that makes a xenon tube 9 emit light, the target value of the charge voltage that a step-up circuit 2 should apply to the light emitting capacitor 7 is set to a first voltage value in specified detection timing so as to start charge operation, and then the accumulation state of the charge in the light emitting diode 7 at the beginning of start of the charge operation is checked. In the case where the checked accumulation state of the charge does not reach a specified reference level, the target value is switched into a second voltage value higher than the first voltage value, and the charge operation is continued. It mitigates the load of a battery 1 at the beginning of the detection start of the charge residual quantity of the light emitting capacitor 7, and also makes the number of times of battery voltage dropping largely into the minimum necessary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charge control device, a charge control method, and a charge control program for controlling a charging operation using a battery as a power source for a light emitting capacitor for accumulating charges for causing a light emitting element to emit light.

2. Description of the Related Art Conventionally, in a camera device such as a digital camera, for example, as described in Patent Document 1 below, the voltage of a battery housed in a camera body is boosted and charged to a large capacity light emitting capacitor. In addition, a built-in flash device (flash) that discharges and emits electric charge stored in the light-emitting capacitor according to the trigger signal is given to the discharge tube (xenon tube, etc.) via the trigger coil when shooting. Things are common. This type of camera device is usually configured to emit auxiliary light from the light emitting element when necessary exposure cannot be ensured even when the shutter speed and aperture value are controlled during shooting.
JP 2002-2327272 A

  In the camera device incorporating the flash device as described above, the light emitting capacitor is fixed at least to the extent that light can be emitted by a discharge tube (lamp) as a light emitting element so that auxiliary light can be used immediately when necessary for photographing. It is desirable to ensure the above charge amount regularly. For this reason, it is necessary to detect the remaining charge amount of the light emitting capacitor even when there is no shooting instruction by the shutter key, for example, at certain intervals or when the shutter key is half-pressed.

  However, when the circuit configuration in the camera device needs to actually charge the light-emitting capacitor when detecting the remaining charge amount of the light-emitting capacitor, there are the following problems. That is, when charging the light-emitting capacitor, it is necessary to flow a large current through the light-emitting capacitor, so that the load on the battery is large, and the battery voltage drops greatly each time the remaining charge is detected. Therefore, when the number of remaining charge detections increases, the battery life is shortened accordingly. In addition, there is a problem that the accuracy of determination of the remaining battery capacity decreases due to an increase in the number of times the battery voltage greatly drops.

  The present invention has been made in view of such conventional problems, and is intended to prolong the battery life and improve the determination accuracy of the remaining battery level, a charge control method, a charge control method, and a charge. An object is to provide a control program.

  In order to solve the above-described problem, the charge control device according to claim 1 is a charge control device that controls a charging operation using a battery as a power source for a light-emitting capacitor that accumulates electric charges for emitting light from an issuing element. A detecting means for detecting a charge accumulation state in the light emitting capacitor, and charging at a predetermined detection timing by setting a target voltage value of a charging voltage to be applied to the light emitting capacitor by the charging operation to a first voltage value When the charge accumulation state detected by the detection means at the beginning of the charge operation does not reach the predetermined first reference level, the target voltage value is higher than the first voltage value. And a control means for switching to the second voltage value to continue the charging operation.

  Further, in the charge control device according to claim 2, the control means switches the target voltage value to the second voltage value, and the charge accumulation state detected by the detection means is a predetermined second reference. The charging operation is stopped when the level is reached.

  Further, in the charge control device according to claim 3, when the charge accumulation state detected by the detection means at the beginning of the charging operation reaches the first reference level, the control means The charging operation is continued in a state where the target voltage value is set to a predetermined voltage value lower than the second voltage value.

  In the charging control device according to claim 4, the predetermined voltage value lower than the second voltage value is the first voltage value, and the control means is configured to start the charging operation at the beginning of the charging operation. When the accumulation state of the charges detected by the detection means has reached the first reference level, the charging operation is continued while the target voltage value is set to the first voltage value.

  Further, in the charging control device according to claim 5, the control means performs charging when the charge accumulation state detected by the detection means at the beginning of the charging operation has reached the first reference level. The operation is stopped.

  In the charging control device according to claim 6, the first voltage value is a voltage value set as the target voltage value by the control means only at the beginning of the charging operation at the predetermined detection timing. It is characterized by being.

  The charge control device according to claim 7 further includes setting means for setting the first or second reference level.

  The charge control method according to claim 8 is a charge control method for controlling a charging operation using a battery as a power source for a light emitting capacitor for accumulating electric charges for emitting light emitted from an issuing element, wherein a predetermined detection timing is set. And starting the charging operation by setting the target voltage value of the charging voltage to be applied to the light emitting capacitor to the first voltage value, and the charge accumulation state in the light emitting capacitor at the beginning of the charging operation And when the confirmed charge accumulation state does not reach a predetermined reference level, the target voltage value is switched to a second voltage value higher than the first voltage value to continue the charging operation. And a process.

  In the charging control program according to claim 9, the computer is configured to control the charging operation using a battery as a power source for the light emitting capacitor for accumulating the electric charge that causes the light emitting element to emit light. The procedure for setting the target voltage value of the charging voltage to be applied to the light emitting capacitor to the first voltage value and starting the charging operation, and the charge accumulation state in the light emitting capacitor at the beginning of the charging operation are confirmed. And a procedure for switching the target voltage value to a second voltage value higher than the first voltage value and continuing the charging operation when the confirmed charge accumulation state does not reach a predetermined reference level. It is made to perform.

  According to the present invention, while reducing the load on the battery at the beginning of detection of the remaining charge amount of the light emitting capacitor, the battery life is prolonged by minimizing the number of times the battery voltage greatly drops. Thus, it becomes possible to improve the determination accuracy of the remaining battery level.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing the main part of a digital camera with a built-in flash device, which mainly constitutes the flash device.

  As shown in the figure, the flash device of the present embodiment mainly includes a booster circuit 2 and a charge control IC 3 for boosting the voltage of a battery 1 that is a power source of a digital camera, and an output voltage after boosting by the booster circuit 2, that is, charging. Charge amount detection circuit 4 that converts the voltage into a low feedback voltage by so-called resistance division and feeds it back to the FB terminal of charge control IC 3, and applies the charge voltage via first and second backflow prevention diodes 5 and 6. The light emitting capacitor 7, the light emission control element 8, and the xenon tube 9 as the light emitting element are included.

  The charging voltage applied to the light emitting capacitor 7 is connected to the SW terminal in accordance with the result of comparison between the value of the feedback voltage input to the FB terminal by the charging control IC 3 and a reference voltage value stored in advance. The current to the booster circuit 2 is maintained at a predetermined target voltage value by duty control.

  In the present embodiment, the target voltage value is a first voltage value for low-speed charging or a second voltage value for high-speed charging that is higher than the voltage of the light-emitting capacitor 7 when fully charged (hereinafter referred to as the upper limit voltage). The first voltage value has a small difference from the upper limit voltage, and the light emitting capacitor 7 is charged at a low speed, and the second voltage value has a large difference from the upper limit voltage to the light emitting capacitor 7. This voltage is charged at high speed. The charge control IC 3 stores values corresponding to the two types of target voltage values, the reference voltage value corresponding to the upper limit voltage, and the duty control data as the reference voltage values.

  When the IGBT signal is output from the IGBT terminal of the charging control IC 3 at an arbitrary shooting timing, the light emission control element 8 boosts the voltage of the light emitting capacitor 7 to 2 KV or higher in response to the IGBT signal and triggers the light emission to the xenon tube 9. To give it a light emission (discharge).

  The operation of the charging control IC 3 is controlled by a CPU 10 that controls the overall operation of the digital camera. Specifically, the charging operation to the light-emitting capacitor 7 is started or terminated by the CHG signal sent from the CPU 10, and the charging voltage is set to the target voltage value indicated by the CURRNT-CHG signal during the charging operation. (First voltage value or second voltage value). When an IGBT-ON signal sent from the CPU 10 is sent, an IGBT signal is output to the light emission control element 8 in response thereto. When the value of the feedback voltage input to the FB terminal becomes the reference voltage value corresponding to the upper limit voltage, the charging control IC 3 outputs a CHG-END signal indicating that to the CPU 10.

  Further, between the first and second backflow prevention diodes 5 and 6 and the GND, the voltage of the light emitting capacitor 7, that is, the remaining charge, is divided by so-called resistance division as in the charge amount detection circuit 4. A remaining amount detection circuit 11 is provided that converts the amount (about 320 V at maximum) into a voltage level that can be detected by the CPU 10 and outputs the voltage level to the CPU 10. Thus, the CPU 10 can appropriately detect the remaining charge amount of the light emitting capacitor 7. That is, the remaining amount detection circuit 11 is the detection means of the present invention.

  In the circuit configuration described above, the second backflow prevention diode 6 is necessary to prevent the accumulated charge of the light emitting capacitor 7 from flowing to the GND. On the other hand, the second backflow prevention diode 6 Therefore, it is indispensable to actually apply the charging voltage in order to detect the remaining charge amount of the light emitting capacitor 7.

  On the other hand, the CPU 10 functions as a control unit of the present invention by performing charge control (described later) shown in FIG. 2 based on a program stored in a memory (not shown) of the camera device.

  FIG. 2 is a flowchart showing a processing procedure related to the charging control of the flash device that is executed at the operation timing of the so-called half shutter when the CPU 10 is operated to the half-pressed position for performing the shooting advance notice in the camera device. It is.

  In the following explanation, the CPU 10 starts processing in response to the half shutter operation, and first sends a CURRNT-CHG signal to the effect that the charging voltage should be set to the first voltage value (small voltage) described above to the charging control IC 3. (Step S1) Further, by sending a CHG signal for starting the charging operation, the charging control IC 3 starts the charging operation of the light emitting capacitor 7 with the first voltage value (Step S1). During the charging operation, the remaining charge amount of the light emitting capacitor 7 is confirmed based on the output voltage of the remaining amount detection circuit 11 (step S3).

  Subsequently, it is confirmed whether or not the confirmed remaining charge amount is a remaining charge amount that can emit light from the xenon tube 9 and is equal to or more than a predetermined reference charge remaining amount. Level) or higher (NO in step S4), the CURRNT-CHG signal indicating that the target voltage value of the charging voltage should be set to the above-described second voltage value (large voltage) at that point in time. To switch the charging voltage to the second voltage value (step S5).

  Thereafter, the charging operation with the second voltage value as a target is continued until the light emitting capacitor 7 is fully charged and a CHG-END signal indicating it is sent from the charging control IC 3 (NO in step S6). That is, the light emitting capacitor 7 is charged at high speed.

  When the light-emitting capacitor 7 is fully charged (second reference level) (YES in step S6), a CHG signal is sent to the charging control IC 3 to end the charging operation to the charging control IC 3. The charging operation of the light emitting capacitor 7 is terminated (step S7), and the process is completed.

  If the determination result in step S4 is YES and the remaining charge amount of the light-emitting capacitor 7 confirmed in response to the half shutter operation is equal to or greater than the reference charge remaining amount, the charge voltage is set to the second charge voltage. While maintaining the first voltage value without switching to the voltage value, the charging operation is continued until the light emitting capacitor 7 is fully charged (NO in step S6). That is, the light emitting capacitor 7 is charged at a low speed.

  When the light emitting capacitor 7 is fully charged (YES in step S6), the charging control IC 3 ends the charging operation of the light emitting capacitor 7 (step S7), and the process is completed.

  Here, for the sake of convenience, the description has been made assuming that the CPU 10 unconditionally detects the remaining charge amount of the light-emitting capacitor 7 in response to the half-shutter operation, but actually, the light-emitting capacitor 7 is fully charged at the time of the half-shutter operation. When in the charging state (when the CHG-END signal is sent from the charging control IC 3), the processing is immediately completed without detecting the remaining charge amount (starting the charging operation).

  As described above, in this embodiment, every time the shutter key is pressed halfway, the remaining charge amount of the light emitting capacitor 7 is detected, and when it does not reach the reference remaining charge amount, the light emitting capacitor 7 is quickly turned on. , The charged state of the light emitting capacitor 7 is restored to a state where the xenon tube 9 can emit light in a short time. As a result, the auxiliary light can be used immediately when necessary for photographing.

  On the other hand, in the charging operation accompanying the detection of the remaining charge amount, the charging voltage at the initial stage of the operation is always set to the first voltage value, so that the current flowing at the initial stage of the operation can be reduced. Therefore, as described above, even in the circuit configuration in which it is indispensable to actually apply the charging voltage in order to detect the remaining charge amount of the light emitting capacitor 7, for example, the charge voltage from the beginning of the detection of the remaining charge amount Compared with the case where is set to the second voltage value for quick charging, the load on the battery at the beginning of detection can be reduced.

  In other words, in situations where the remaining charge level at the start of detection is greater than or equal to the reference remaining charge level, it is possible to avoid wasteful power consumption of the battery. It is also possible to minimize the number of times of significant descent below that. Therefore, it is possible to extend the battery life and improve the accuracy of determining the remaining battery level.

  Here, in this embodiment, for the purpose of detecting the remaining charge amount of the light-emitting capacitor 7, the description has been given of the case where the remaining amount detection circuit 11 is provided separately from the charge amount detection circuit 4. It has the same function in that it detects the voltage of the light emitting capacitor 7 in a state where the current flows. Therefore, the remaining amount detection circuit 11 may be eliminated and the detection result of the charge amount detection circuit 4 may be sent to the CPU 10. However, in this case, the circuit configuration of the charge amount detection circuit 4 needs to be a configuration that can convert the detection result into a voltage level that can be detected by the CPU 10. Furthermore, the above-described charging control by the CPU 10 may be configured to be performed by the charging control IC 3, and in this case, a timing signal indicating the timing when the half shutter is operated may be output from the CPU 10 to the charging control IC 3.

  Further, the timing for detecting the remaining charge amount of the light emitting capacitor 7 is the timing at which the half shutter is operated. However, the detection timing of the remaining charge amount may be repeated every predetermined time if it is a predetermined timing. I do not care. Even in that case, as described above, under the situation where the remaining charge amount is equal to or greater than the reference remaining charge amount, the load on the battery 1 is light and unnecessary power consumption can be avoided. In other words, even if detection of the remaining charge is repeated at regular intervals, the battery 1 is not consumed so that a charge amount that is at least a certain level at which the xenon tube 9 can emit light is maintained while maintaining the battery life. The light emitting capacitor 7 can be constantly secured.

  Further, in the present embodiment, when the remaining charge amount of the light emitting capacitor 7 is detected, the light emitting capacitor 7 is always fully charged regardless of the remaining charge amount (except when fully charged). The case where the charging operation is continued until the above is described. For example, when detecting the remaining charge at the half shutter operation timing described above, the charge target is lower than the full charge with the reference remaining charge as the lower limit. It may be in a charged state.

  In other words, when the charging operation is actually performed at the half shutter operation timing or the like, the charging operation may be stopped at a stage before the light emitting capacitor 7 is fully charged. Is the reference charge remaining amount, that is, when the remaining charge amount of the light emitting capacitor 7 is equal to or greater than the reference charge remaining amount, the charging operation for the purpose of detecting the remaining charge amount may be immediately stopped. Absent. In short, it is sufficient that the remaining charge amount of the light emitting capacitor 7 can be maintained at least in a charged state in which the xenon tube 9 can emit light (including a state in which light can be emitted only once).

  In the present embodiment, when the first voltage value initially set as the target voltage value is a voltage value for low-speed charging in order to enable detection of the remaining charge amount of the light emitting capacitor 7 in the above-described charging control. However, the first voltage value may not be used in the actual charging operation, but may be a voltage value used only for detecting the remaining charge amount. In that case, in the configuration in which the charging operation in the different modes of the low speed charge and the high speed charge is performed according to the remaining charge amount of the light emitting capacitor 7 as described above, it is larger than the first voltage value during the low speed charge, In addition, a voltage value smaller than the voltage value set at the time of high-speed charging is set.

  Further, the first voltage value may be the lowest voltage value that can ensure the above-described reference charge remaining amount in the light emitting capacitor 7, that is, the charge accumulation state can be set to a predetermined reference level. In that case, in step S4 in the above-described charging control, it is confirmed whether or not the remaining charge amount of the light emitting capacitor 7 can be detected. If not detected (no current flows), the remaining charge amount is the reference charge. If it is determined that the remaining charge is equal to or greater than the remaining charge, and if it can be detected (current flows), it is determined that the remaining charge is not equal to or greater than the reference remaining charge and the subsequent processing may be performed.

  Further, in the present embodiment, the case where the charging operation is performed in the two types of the low-speed charging mode and the high-speed charging mode according to the remaining charge amount of the light-emitting capacitor 7 has been described. Three or more types of modes may be prepared, and the charging operation may be performed in a mode in which the charging speed is faster as the remaining charge amount of the light emitting capacitor 7 decreases.

  In that case, two or more types of reference charge remaining amounts having different levels are determined as the reference charge remaining amount described above, and a plurality of voltage values corresponding to the first voltage value correspond to each reference charge remaining amount. When the remaining charge amount is detected at a predetermined timing such as the half shutter operation timing, the above-described processing is repeated while sequentially switching the reference remaining charge amount and the first voltage value. Good.

  Furthermore, as described above, the reference charge remaining amount described above is included, including the case where two or more types of reference charge remaining amount are determined as the reference charge remaining amount (three or more types of charging operation types are prepared). The amount may be variable. That is, the CPU 10 may function as the setting unit of the present invention, and the reference charge remaining level may be set (changed) according to a predetermined operation by the user.

  Further, the CPU 10 may automatically set the reference remaining charge level to a different level according to the operating condition of the camera device. For example, when the power saving mode is set for the camera device, the reference remaining charge level is set to a lower level than when the power saving mode is not set, or multiple shootings are performed with a single shutter operation as a shooting mode. When the continuous shooting mode is set, that is, when there is a high possibility that the auxiliary light will be emitted continuously, the reference charge remaining level is higher than when the normal shooting mode is set. Or may be set to

  Further, the reference charge remaining amount may be automatically set to a different level according to an external shooting environment such as the brightness of the subject.

It is a circuit diagram showing a portion corresponding to a flash device of a digital camera, showing a preferred embodiment of the present invention. It is the flowchart which showed the process sequence regarding the charge control performed by the operation timing of a half shutter.

Explanation of symbols

1 battery 2 step-up transformer 3 charge control IC
DESCRIPTION OF SYMBOLS 4 Charge amount detection circuit 5 1st backflow prevention diode 6 2nd backflow prevention diode 7 Light emission capacitor 8 Light emission control element 9 Xenon tube 10 CPU
11 Remaining amount detection circuit

Claims (9)

A charge control device for controlling a charging operation using a battery as a power source for a light emitting capacitor that accumulates electric charges for emitting light from a light emitting element,
Detecting means for detecting a charge accumulation state in the light emitting capacitor;
At a predetermined detection timing, the target voltage value of the charging voltage to be applied to the light emitting capacitor by the charging operation is set to the first voltage value to start the charging operation, and at the beginning of the charging operation, the detecting means Control means for switching the target voltage value to a second voltage value higher than the first voltage value and continuing the charging operation when the accumulated state of the detected charge does not reach a predetermined first reference level; A charge control device comprising: The control means stops the charging operation when the charge accumulation state detected by the detection means reaches a predetermined second reference level after switching the target voltage value to the second voltage value. The charge control device according to claim 1, wherein   The control means sets the target voltage value to a predetermined value lower than the second voltage value when the charge accumulation state detected by the detection means at the beginning of the charging operation has reached the first reference level. The charging control device according to claim 1, wherein the charging operation is continued in a state where the voltage value is set. The predetermined voltage value lower than the second voltage value is the first voltage value,
The control means maintains the target voltage value at the first voltage value when the accumulation state of the charge detected by the detection means at the beginning of the charging operation has reached the first reference level. The charging control device according to claim 3, wherein the charging operation is continued.   2. The control unit according to claim 1, wherein the control unit stops the charging operation when an accumulation state of charges detected by the detecting unit at the beginning of the charging operation has reached the first reference level. 3. Charge control device.   2. The charge control device according to claim 1, wherein the first voltage value is a voltage value set as the target voltage value by the control means only at the beginning of a charging operation at the predetermined detection timing. .   7. The charging control apparatus according to claim 1, further comprising setting means for setting the first or second reference level. A charge control method for controlling a charging operation using a battery as a power source for a light emitting capacitor that accumulates electric charges for emitting light from a light emitting element,
A step of setting a target voltage value of a charging voltage to be applied to the light emitting capacitor to a first voltage value at a predetermined detection timing and starting a charging operation;
A step of confirming a charge accumulation state in the light emitting capacitor at the beginning of the charging operation;
A step of switching the target voltage value to a second voltage value higher than the first voltage value and continuing a charging operation when the confirmed charge accumulation state does not reach a predetermined reference level. A charge control method characterized. On the computer,
When controlling a charging operation using a battery as a power source for a light emitting capacitor that accumulates charges for emitting light from the light emitting element,
A procedure for starting a charging operation by setting a target voltage value of a charging voltage to be applied to the light emitting capacitor to a first voltage value at a predetermined detection timing;
A procedure for confirming a charge accumulation state in the light emitting capacitor at the beginning of the charging operation;
A step of switching the target voltage value to a second voltage value higher than the first voltage value and continuing the charging operation when the confirmed charge accumulation state does not reach a predetermined reference level; A charge control program characterized by this.

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