JP6021453B2 - LIGHT EMITTING DEVICE, ITS CONTROL METHOD, AND CONTROL PROGRAM - Google Patents

Description

  The present invention relates to a light emitting device such as a strobe device, and more particularly to a light emitting device that reduces a leakage current of a main capacitor, a control method thereof, and a control program.

  Generally, in a light emitting device such as a strobe device, light is emitted by electrical energy stored in a charging unit such as a main capacitor. In such a light emitting device, it is necessary to detect the charging voltage of the main capacitor when emitting light.

  Conventionally, when detecting the charging voltage of the main capacitor, a plurality of impedance elements such as resistors are connected in series in parallel with the main capacitor to detect the divided voltage by the impedance element. Then, the completion of charging and the full charging voltage are determined according to the detection result, and light emission control and the like are performed.

  As a light-emitting device that performs light emission control by detecting the charging voltage of the main capacitor, for example, there is one that detects the voltage of the main capacitor again immediately after the completion of charging and immediately before the start of the photographing operation by the imaging device (See Patent Document 1). Here, if the detection voltage is lower than a predetermined voltage due to the voltage detection again, the photographing operation by the imaging device is not permitted, and the charging operation by the light emitting device is resumed. As a result, good flash photography (flash photography) can be performed.

  By the way, if the electric charge charged in the main capacitor leaks through a resistor or the like constituting the voltage detection circuit, the voltage drop of the main capacitor is large. For this reason, the recharging must be performed frequently, and the battery used for charging the main capacitor is quickly consumed.

  For this reason, a light emitting device is known in which a diode is arranged on the current supply side (for example, the DC / DC converter side) of the main capacitor so that the current does not flow into the voltage detection circuit after the main capacitor is completely charged. (See Patent Document 2).

Japanese Patent Laid-Open No. 7-20543 JP-A-2-193131

  As described above, in the light emitting device described in Patent Document 1, the current leaks from the main capacitor via the voltage detection circuit because the charging voltage of the main capacitor is always detected.

  On the other hand, in the light emitting device described in Patent Document 2, the charging voltage of the main capacitor cannot be detected while charging is stopped. For this reason, it is difficult to perform control that always needs to detect the charging voltage, such as light emission control and control for maintaining the charging voltage at a predetermined voltage.

  Accordingly, an object of the present invention is to provide a light emitting device capable of reducing leakage current from energy storage means such as a main capacitor and detecting the voltage of the main capacitor, its control method, and a control program. .

  In order to achieve the above object, a light-emitting device according to the present invention is a light-emitting device that includes an energy storage unit that stores electrical energy, and that causes a light-emitting unit to emit light using the electrical energy stored in the energy storage unit. A charging unit for charging the energy storage unit; a detection unit for detecting a voltage in the energy storage unit; and a current flowing from the energy storage unit to the detection unit when charging by the charging unit is stopped. A first voltage detection control for causing the detection means to detect a voltage in the energy storage means as a first detection voltage at a predetermined first interval when the blocking means and the energy storage means are being charged; When the first detection voltage reaches a preset first voltage, the energy by the charging means is -When charging of the storage means is stopped and charging of the energy storage means is stopped, the energy storage means is charged by the charging means for a predetermined time, and the detection means in the energy storage means And control means for obtaining a second detection voltage by performing second voltage detection control for detecting a voltage at a second interval longer than the first interval.

  The control method according to the present invention includes an energy storage unit that stores electrical energy, a charging unit that charges the energy storage unit, a detection unit that detects a voltage in the energy storage unit, and charging by the charging unit is stopped. And a blocking means for blocking current flowing from the energy storage means to the detection means, and a method of controlling the light emitting device that causes the light emitting portion to emit light by the electrical energy stored in the energy storage means, When the energy storage means is being charged, a first voltage detection control is performed to cause the detection means to detect a voltage at the energy storage means as a first detection voltage at a predetermined first interval. Control step, and when the first detection voltage reaches a preset first voltage, the charging means A second control step for stopping the charging of the energy storage means; and when the charging of the energy storage means is stopped, the energy storage means is charged by the charging means for a predetermined time, and the detection means And a third control step of performing a second voltage detection control for detecting a voltage in the energy storage means at a second interval longer than the first interval.

  The control program according to the present invention includes an energy storage unit that stores electrical energy, a charging unit that charges the energy storage unit, a detection unit that detects a voltage in the energy storage unit, and charging by the charging unit is stopped. A control program for use in a light-emitting device that emits light from a light-emitting unit by means of electrical energy stored in the energy storage means. When the energy storage unit is being charged, the computer included in the light emitting device causes the detection unit to detect the voltage in the energy storage unit as the first detection voltage at a predetermined first interval. A first control step for performing a first voltage detection control; and the first detection voltage. A second control step of stopping charging of the energy storage means by the charging means when reaching a preset first voltage; and when charging of the energy storage means is stopped, a predetermined time, A third voltage detection control for charging the energy storage unit by the charging unit and causing the detection unit to detect a voltage in the energy storage unit is performed at a second interval longer than the first interval. These control steps are executed.

  According to the present invention, the voltage in the energy storage means such as the main capacitor can be detected at a predetermined timing, and the energy storage means can be charged according to the detection result. Furthermore, it is possible to reduce the leakage current from the energy storage means when charging is stopped.

It is a block diagram which shows the structure about an example of the light-emitting device by embodiment of this invention. It is a figure which shows the relationship between the voltage of the main capacitor | condenser shown in FIG. 1, and the voltage concerning the input terminal AN of a microcomputer. 2 is a timing chart for explaining the operation of the booster circuit and the operation of the A / D converter shown in FIG. 1, (a) is a diagram showing charge control and A / D conversion in a charge completion period, and (b) is a diagram. The figure which shows the 1st example when the light emission process is performed in the charge completion period, (c) is the figure which shows the 2nd example when the light emission process is performed in the charge completion period, (d) is the charge completion It is a figure which shows the 3rd example when the light emission process is performed in the period. It is a flowchart for demonstrating the charge process in the flash device shown in FIG. It is a flowchart for demonstrating the A / D conversion process by charge shown in FIG. 3 is a flowchart for explaining light emission processing in the strobe device shown in FIG. 1.

  Hereinafter, an example of a light emitting device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of an example of a light emitting device according to an embodiment of the present invention.

  The illustrated light emitting device (hereinafter referred to as a strobe device) is used together with an imaging device such as a digital camera, for example. The strobe device includes a microcomputer 100. The microcomputer 100 is a microcomputer that controls the operation of the strobe device. The microcomputer 100 stores a program for performing light emission processing and adjustment values for performing various controls, and includes an AD converter and the like.

  A constant voltage circuit (hereinafter also referred to as a regulator circuit) 102 receives the voltage of the battery 101 as a power source, generates a constant voltage, and applies these constant voltages to the power supply terminal Vcc and the reference voltage AVcc of the microcomputer 100. The booster circuit 103 operates by receiving a control signal from the CHG terminal of the microcomputer 100 and boosts the voltage of the battery 101 to several hundred volts. The diode 104 rectifies the current output from the booster circuit 103.

  The main capacitor 105 (energy storage means) stores electrical energy that is the output of the booster circuit 103. The capacitor 106 is a noise absorbing capacitor. The voltage dividing resistors 107 and 108 are resistors for dividing the voltage of the main capacitor 105 at a predetermined ratio, and are connected to an input terminal AN connected to an AD converter built in the microcomputer 100.

  The diode 109 has a voltage dividing resistor 107 connected to the anode side and a main capacitor 105 connected to the cathode side. The diode 109 is an element for preventing leakage current from the main capacitor 105 and suppressing power consumption. The trigger circuit 110 receives a trigger signal from the trigger terminal TRG of the microcomputer 100 when performing light emission processing, and excites a light emitting unit such as the xenon tube 111.

  The light control circuit 112 includes a photodiode (not shown) as a light receiving sensor, and monitors the light output of the xenon tube 111. The dimming circuit 112 transmits and receives light emission information to and from the microcomputer 100 via the S1 and S2 terminals.

  As shown in the figure, a light emission control circuit 113 is connected to the CTR terminal and the light control circuit 112 of the microcomputer 100, and the light emission control circuit 113 is controlled by the light control circuit 112 and the microcomputer 100 as described later.

  FIG. 2 is a diagram showing the relationship between the voltage of main capacitor 105 shown in FIG. 1 and the voltage applied to input terminal AN of microcomputer 100.

  During the charging period Ta in which the main capacitor 105 is charged, a voltage corresponding to one tenth of the voltage of the main capacitor 105 appears at the input terminal AN due to the voltage dividing resistors 107 and 108. The microcomputer 100 converts this input voltage into digital data by an AD converter and detects the voltage of the main capacitor 105. That is, the microcomputer 100 detects that the voltage corresponding to ten times the voltage indicated by the digital data is the voltage of the main capacitor 105.

  The voltage V0 is a voltage at which the xenon tube 111 can emit light (light emission possible voltage). When the voltage of the main capacitor 105 reaches the voltage V0, the microcomputer 100 can output a trigger signal to the trigger circuit 110. .

  The voltage V1 is an upper limit voltage (first voltage) at which the main capacitor 105 can be charged. When the voltage of the main capacitor 105 reaches the upper limit voltage V1, the microcomputer 100 stops the control signal sent to the booster circuit 103 and boosts the voltage. The charging of the main capacitor 105 by the circuit 103 is terminated. Then, the microcomputer 100 shifts to the charging completion period Tb.

  In the charging completion period Tb, the microcomputer 100 always detects the voltage of the main capacitor 105 and controls charging and stopping charging in order to keep the voltage of the main capacitor 105 close to the upper limit voltage. When charging is stopped by the microcomputer 100, the main capacitor 105 and the voltage detection circuit side (that is, the microcomputer 100) are electrically disconnected by the diode 109.

  As a result, the capacitor 106 to the A / D converter instantaneously discharges and the voltage at the input terminal AN becomes 0 V, so that the voltage of the main capacitor 105 cannot be detected.

  When charging of the main capacitor 105 stops, the voltage gradually decreases due to spontaneous discharge. For this reason, the microcomputer 100 instantaneously charges until the voltage at the input terminal AN rises to a voltage (V1 / 10) corresponding to one-tenth of the upper limit voltage V1 of the main capacitor 105 at every predetermined period TAD. After that, the control to stop charging is repeated.

  The voltage V2 is a voltage provided with hysteresis with respect to the upper limit voltage V1, and is a threshold voltage (second voltage) at which charging needs to be restarted because the voltage of the main capacitor 105 has decreased. When detecting that the voltage of the main capacitor 105 has dropped below the threshold voltage V2, the microcomputer 100 operates the booster circuit 103 again and performs recharging until the voltage of the main capacitor 105 reaches the upper limit voltage V1 again.

  FIG. 3 is a timing chart for explaining the operation of the booster circuit 103 and the operation of the A / D converter shown in FIG. FIG. 3A is a diagram showing charging control and A / D conversion in the charging completion period, and FIG. 3B is a diagram showing a first example when the light emission process is performed in the charging completion period. It is. FIG. 3C is a diagram showing a second example when the light emission process is performed during the charging completion period, and FIG. 3D is a third example when the light emission process is performed during the charging completion period. It is a figure which shows the example of.

  In FIG. 3A, when the control signal output from the control terminal CHG of the microcomputer 100 is at a high (H) level, the booster circuit 103 is boosted and performs a boosting operation. On the other hand, when the control signal is at a low (L) level, boosting is turned off and the booster circuit 103 stops the boosting operation.

  The A / D converter built in the microcomputer 100 performs A / D conversion of the input voltage applied to the input terminal AN, and outputs digital data corresponding to the voltage of the main capacitor 105. That is, the A / D converter outputs digital data when a boosting operation (that is, charging operation: boosting ON) is performed. As a result, the microcomputer 100 performs the first voltage detection control for detecting the voltage of the main capacitor 105 (this voltage is the first detection voltage) only when the charging operation is being performed.

  In FIG. 3A, until time t1, the microcomputer 100 continuously turns on the booster circuit 103 to charge the main capacitor 105. As a result of continuous charging, a voltage obtained by dividing the voltage of the main capacitor 105 always appears at the input terminal AN. At this time, the microcomputer 100 performs A / D conversion at a predetermined A / D conversion cycle T1 (first interval, for example, 1 ms).

  When the detected voltage reaches the upper limit voltage V1 (that is, V1 / 10) (time t1), the microcomputer 100 turns off the boost to stop charging the main capacitor 105. As a result, the input terminal AN is electrically disconnected from the main capacitor 105 by the diode 109, and the capacitor 106 is discharged, so that the input voltage at the input terminal AN becomes 0V. As a result, the microcomputer 100 cannot detect the voltage of the main capacitor 105.

  On the other hand, the voltage of main capacitor 105 decreases due to natural discharge. Therefore, when a predetermined A / D conversion cycle T2 (second interval, for example, 2 sec) elapses, the microcomputer 100 sets the boost ON to detect the voltage of the main capacitor 105 at time t2, and the boost ON until time t3. The second voltage detection control is performed. Between time t2 and time t3, that is, a predetermined time t (for example, 10 ms) for boosting ON is a time required for A / D conversion, and the voltage of the input terminal AN corresponds to the voltage of the main capacitor 105. This is the time required for the voltage to rise (that is, one-tenth voltage).

  In the example shown in FIG. 3A, the voltage of the main capacitor 105 (this voltage is the second detection voltage) detected by the boost ON from time t2 to time t3 is equal to or higher than the threshold voltage V2 (see FIG. 2). Therefore, the microcomputer 100 determines that recharging is not necessary. Then, when the cycle T2 elapses again, the microcomputer 100 detects the voltage of the main capacitor 105 from time t4 to time t5 (predetermined time t) as boosting ON. At time t5, the microcomputer 100 turns off the boost. Thereby, as described above, the voltage of the input terminal AN becomes 0V.

  In the example shown in FIG. 3A, since the voltage of the main capacitor 105 detected by boost ON from time t4 to time t5 is less than the threshold voltage V2, the microcomputer 100 determines that recharging is necessary. At time t6, the microcomputer 100 starts to charge the main capacitor 105 with the boost ON. However, while the main capacitor 105 is being charged, AD conversion is performed in the AD conversion cycle T1, but the charging is temporarily stopped immediately before that, so that the microcomputer 100 is in a predetermined time t (in the illustrated example, time (Up to t7) A / D conversion is prohibited.

  If the boost is turned on for a predetermined time t, the main capacitor 105 is charged, so that the discharge amount during the A / D conversion period T2 is larger than the charge amount during the predetermined time t. In addition, the A / D conversion cycle T2 is set.

  After time t7, the microcomputer 100 boosts the voltage until the detected voltage (that is, the voltage of the main capacitor 105) reaches the upper limit voltage V1 (that is, V1 / 10). When the detected voltage reaches the upper limit voltage V1, the microcomputer 100 stops charging by setting the boost to OFF. Thereafter, as described above, the microcomputer 100 repeats the boost ON and the boost OFF.

  Here, the charging process when the light emission process is performed in the charging completion period Tb (that is, during the charging stop) will be described.

  In FIG. 3B, it is assumed that strobe light emission is performed at time t1-1 to time t1-2 between current times t1 and t2. This strobe emission consumes electrical energy accumulated in the main capacitor 105, and as a result, the voltage of the main capacitor 105 is greatly reduced. For this reason, the microcomputer 100 detects the voltage of the main capacitor 105 by setting the boost to ON for a predetermined time t from the light emission end time t1-2 even during the charging stop period.

  Here, since the voltage of the main capacitor 105 is less than the threshold voltage V2, the microcomputer 100 sets the boost ON at time t1-3. At this time, as described above, A / D conversion is prohibited for a predetermined time t. Then, the microcomputer 100 boosts the voltage until the voltage of the main capacitor 105 reaches the upper limit voltage V1.

  When the light emission process is performed when the main capacitor voltage is equal to or higher than the light emission possible voltage V0 in the charging period Ta illustrated in FIG. 2, the microcomputer 100 performs the charging process as described with reference to FIG. In the light emission process, the microcomputer 100 emits light after stopping charging.

  Next, a charging process in the case where the light emission process is performed during the boost ON at times t2 to t3 illustrated in FIG.

  In FIG. 3C, it is assumed that the light emission process is started at time t2-1 between time t2 and time t3 shown in FIG. The microcomputer 100 starts the light emission process after stopping the charging, that is, when the boosting is turned off. For this reason, charging is stopped before the input voltage at the input terminal AN rises to a voltage corresponding to the voltage of the main capacitor 105. Therefore, the microcomputer 100 does not execute A / D conversion at time t3 shown in FIG. Then, the microcomputer 100 detects the voltage of the main capacitor 105 by turning on the voltage for a predetermined time t immediately after the light emission end time t2-2.

  At this time, since the voltage of the main capacitor 105 is lower than the threshold voltage V2, the microcomputer 100 charges the main capacitor 105 with the boost ON as described with reference to FIG.

  Next, the charging process when the light emission process is continuously performed in the charging completion period Tb (that is, when charging is stopped) will be described.

  In FIG. 3D, the light emission process is continuously performed while the charging is stopped, and the light emission interval is shorter than the predetermined time t. Here, the first light emission process starts at time t1'-1, and ends at light emission end time t1'-2. The microcomputer 100 starts the detection of the voltage of the main capacitor 105 immediately after the light emission end time t1′-2 and starts to detect the voltage of the main capacitor 105, but before the voltage of the input terminal AN becomes a voltage corresponding to the voltage of the main capacitor 105, the microcomputer 100 Is started at time t1′-3.

  In this case, that is, when the time from the end of the first light emission process to the start of the second light emission process is less than the predetermined time t, the microcomputer 100 calculates the post-light emission voltage Va according to the following equation (1). A voltage calculation process is performed.

Voltage after light emission Va = voltage before light emission Vb−fixed voltage Vx (1)
Here, when obtaining the first post-light emission voltage Va, the pre-light emission voltage Vb is the voltage of the main capacitor 105 detected at time t1 shown in FIG. Further, when obtaining the second post-light emission voltage Va, the pre-light emission voltage Vb is the first post-light emission voltage. The fixed value voltage Vx is a voltage value stored in a ROM area provided in the microcomputer 100 according to the light emission amount.

  In particular, when the first light emission process is a so-called pre-light emission process and the second light emission process is a so-called main light emission process, the main capacitor 105 is calculated based on the equation (1) in order to appropriately calculate the main light emission amount. Needs to be calculated. When the voltage of the main capacitor 105 is equal to or higher than the light emission possible voltage V0 in the charging period Ta shown in FIG. 2, the post-light emission voltage Va according to the equation (1) even when the light emission process is continuously performed. Is calculated.

  Immediately after the light emission end time t1′-2 at which the first light emission process is completed, the microcomputer 100 turns on the boost to detect the voltage of the main capacitor 105, but before the predetermined time t elapses, the second light emission. Since the process is performed, the charging is stopped (the boost is turned off). And according to said Formula (1), the microcomputer 100 calculates | requires the voltage Va after the 1st light emission.

  Even if the first light emission voltage Va is less than the threshold voltage V2, the microcomputer 100 permits the second light emission if the light emission possible voltage V0 or more. In the example shown in FIG. 3D, since the first light emission voltage Va is equal to or higher than the light emission possible voltage V0, the microcomputer 100 permits the second light emission.

  Immediately after the light emission end time t1'-4 when the second light emission process is completed, the microcomputer 100 turns on the voltage boost to detect the voltage of the main capacitor 105. Then, the microcomputer 100 detects the voltage of the main capacitor 105 as described above. In the example shown in FIG. 3D, since the third strobe light emission is not performed, the microcomputer 100 detects the voltage of the main capacitor 105 by boosting ON. If the third strobe light emission is performed within the predetermined time t after the second strobe light emission, the microcomputer 100 obtains the second post-light emission voltage Va based on the equation (1).

  Here, since the voltage of the main capacitor 105 after the second light emission is less than the threshold voltage V2, the microcomputer 100 charges the main capacitor 105 as step-up ON as described with reference to FIG. Become.

  FIG. 4 is a flowchart for explaining a charging process in the strobe device shown in FIG.

  When the power of the strobe device is turned on, the microcomputer 100 determines whether or not the main capacitor 105 is being charged (step S100). Here, the microcomputer 100 determines that charging is being performed if the boost is ON. If it is determined that charging is in progress (YES in step S100), microcomputer 100 starts counting by the built-in A / D conversion cycle timer (step S101). Then, the microcomputer 100 monitors whether or not the count value of the A / D conversion cycle timer is equal to or greater than the A / D conversion cycle T1 (step S102).

  If the count value of the A / D conversion cycle timer is less than A / D conversion cycle T1 (NO in step S102), microcomputer 100 counts up the A / D conversion cycle timer (step S103), and in step S102 Return to processing.

  When the count value of the A / D conversion cycle timer reaches A / D conversion cycle T1 (YES in step S102), microcomputer 100 determines whether or not the count value of an A / D prohibition timer described later has reached a predetermined time t or more. Is monitored (step S104). If the count value of the A / D prohibition timer is less than predetermined time t (NO in step S104), microcomputer 100 proceeds to the process of step S103 and counts up the A / D prohibition timer.

  When the count value of the A / D inhibition timer reaches predetermined time t (YES in step S104), microcomputer 100 A / D converts the voltage at input terminal AN to obtain digital data (step S105). Then, the microcomputer 100 determines whether or not the voltage indicated by the digital data, that is, the voltage of the main capacitor 105 is equal to or higher than the upper limit voltage V1 (step S106).

  If the voltage of main capacitor 105 is upper limit voltage V1 (YES in step S106), microcomputer 100 stops boosting and stops charging of main capacitor 105 (step S107). Although not shown in FIG. 1, the microcomputer 100 is in a low battery state where the power button (not shown) is turned off or the voltage of the battery 101 is lower than the voltage required for the strobe operation. It is determined whether or not there is (step S108).

  If the power button is turned off or battery 101 is in the LOW Battery state (YES in step S108), microcomputer 100 cuts off the output of constant voltage circuit 102 and stops the operation of the strobe device. On the other hand, if the power button is not turned off and battery 101 is not in the LOW Battery state (NO in step S108), microcomputer 100 returns to the process in step S100.

  If the voltage of main capacitor 105 is less than upper limit voltage V1 in step S106 (NO in step S106), the process proceeds to microcomputer 100 step S108.

  In step S100, if charging is not in progress (NO in step S100), the microcomputer 100 starts counting by the A / D conversion cycle timer (step S109). Then, the microcomputer 100 monitors whether or not the count value of the A / D conversion cycle timer is equal to or greater than the A / D conversion cycle T2 (step S110).

  If the count value of the A / D conversion cycle timer is less than A / D conversion cycle T2 (NO in step S110), microcomputer 100 counts up the A / D conversion cycle timer (step S111), and in step S110 Return to processing.

  When the count value of the A / D conversion cycle timer reaches the A / D conversion cycle T2 (YES in step S110), the microcomputer 100 performs AD conversion processing by charging described later (step S112). Thereafter, the microcomputer 100 determines whether or not the voltage of the main capacitor 105 is less than the threshold voltage V2 (less than the second voltage) (step S113). If the voltage of main capacitor 105 is equal to or higher than threshold voltage V2 (NO in step S113), microcomputer 110 proceeds to the process of step S108.

  On the other hand, if the voltage of main capacitor 105 is less than threshold voltage V2 (YES in step S113), microcomputer 110 restarts charging main capacitor 105 with step-up ON (step S114). Subsequently, in order to monitor the voltage at the input terminal AN, the microcomputer 100 starts counting the AD prohibition timer (step S115), and proceeds to the process of step S108.

  FIG. 5 is a flowchart for explaining the A / D conversion processing by charging in step S112 shown in FIG.

  When the A / D conversion process by charging is started, the microcomputer 100 starts charging with the boosting ON (step S200). Then, the microcomputer 100 waits for the predetermined time t to elapse (step S201). When the predetermined time t has elapsed, the microcomputer 100 performs A / D conversion by the A / D converter to obtain digital data corresponding to the voltage at the input terminal AN (step S202).

  Thereafter, the microcomputer 100 sets the boost to OFF and stops charging (step S203), and proceeds to the process of step S113 shown in FIG.

  FIG. 6 is a flowchart for explaining light emission processing in the strobe device shown in FIG.

  The light emission process is an interrupt process, and as described with reference to FIG. 3, when this interrupt process occurs, the microcomputer 100 stops the charge by setting the boost to OFF when charging is in progress (step S300). Then, the microcomputer 100 determines whether or not the A / D conversion process is being performed by charging (step S301).

  If the A / D conversion process by charging is in progress (YES in step S301), the microcomputer 100 determines that a normal A / D conversion result cannot be obtained when the light emission process is performed. Is forcibly stopped on the way (step S302).

  Subsequently, the microcomputer 100 controls the trigger circuit 110 and the light emission control circuit 113 to emit light from the xenon tube 111 (step S303). Then, the microcomputer 100 determines that it is necessary to detect the voltage of the main capacitor 105 because the voltage of the main capacitor 105 has decreased due to light emission, and performs the A / D conversion process by charging described in FIG. Step S304). The process returns to the step before the occurrence of the light emission process as the interrupt process. If the A / D conversion process by charging is not in progress (NO in step S301), the microcomputer 100 proceeds to the process of step S303 to emit light.

  As described above, in the embodiment of the present invention, charging is performed only for a predetermined time while charging is stopped. Therefore, the voltage of the main capacitor can be detected at a predetermined timing, and the detection result is determined according to the detection result. The main capacitor can be charged. As a result, the light emission control and the charge control in the light emitting device can always be performed satisfactorily. During the charging stop, the diode 109 can reduce the leakage current from the main capacitor.

  As is clear from the above description, in the example shown in FIG. 1, the battery 101, the constant voltage circuit 102, and the booster circuit 103 function as charging means. Furthermore, the resistor 107, the resistor 108, and the microcomputer 100 function as a detection unit, and the diode 109 functions as a blocking unit. The microcomputer 100 functions as control means.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above embodiment may be used as a control method, and this control method may be executed by the light emitting device. In addition, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the light emitting device. The control program is recorded on a computer-readable recording medium, for example.

  Each of the control method and the control program has at least a first control step, a second control step, and a third control step.

  The present invention can also be realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or apparatus via a network or various recording media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

DESCRIPTION OF SYMBOLS 100 Microcomputer 101 Battery 102 Constant voltage circuit 103 Booster circuit 104,109 Diode 105 Main capacitor 107,108 Resistance 110 Trigger circuit 112 Light control circuit 113 Light emission control circuit

Claims (9)

A light-emitting device that includes an energy storage unit that stores electrical energy, and causes a light-emitting unit to emit light by the electrical energy stored in the energy storage unit;
Charging means for charging the energy storage means;
Detecting means for detecting a voltage in the energy storage means;
Blocking means for blocking current flowing from the energy storage means to the detection means when charging by the charging means is stopped;
When the energy storage means is being charged, performing a first voltage detection control for causing the detection means to detect the voltage in the energy storage means as a first detection voltage at a predetermined first interval, When the first detection voltage reaches a preset first voltage, charging of the energy storage unit by the charging unit is stopped, and when charging of the energy storage unit is stopped, a predetermined time The second voltage detection control for charging the energy storage means by the charging means and causing the detection means to detect the voltage in the energy storage means is performed at a second interval longer than the first interval, And a control means for obtaining a second detection voltage.   The said control means charges the said energy storage means with the said charging means, when the said 2nd detection voltage becomes less than the 2nd voltage lower than the said 1st voltage. Light-emitting device.   3. The discharge amount from the energy storage unit in the second interval is larger than the charge amount of the energy storage unit in the predetermined time in the second interval. Light emitting device.   The light-emitting device according to claim 1, wherein the predetermined time is shorter than the second interval.   The light-emitting device according to claim 1, wherein the predetermined time is longer than the first interval.   6. When charging the energy storage means after stopping charging, the control means prohibits execution of voltage detection by the detection means for at least the predetermined time. 2. The light emitting device according to item 1.   The light emission according to any one of claims 1 to 6, wherein when a light emission process for causing the light emitting unit to emit light occurs, the control unit performs control to forcibly stop charging the energy storage unit. apparatus. An energy storage means for storing electrical energy; a charging means for charging the energy storage means; a detection means for detecting a voltage in the energy storage means; and when the charging by the charging means is stopped, the energy storage. A light-emitting device control method for causing a light-emitting portion to emit light by means of electrical energy stored in the energy storage means,
When the energy storage means is being charged, a first voltage detection control is performed to cause the detection means to detect a voltage at the energy storage means as a first detection voltage at a predetermined first interval. Control steps of
A second control step of stopping charging of the energy storage means by the charging means when the first detection voltage reaches a preset first voltage;
A second voltage detection control for charging the energy storage means by the charging means for a predetermined time and causing the detection means to detect a voltage in the energy storage means when charging of the energy storage means is stopped; And a third control step of performing at a second interval longer than the first interval. An energy storage means for storing electrical energy; a charging means for charging the energy storage means; a detection means for detecting a voltage in the energy storage means; and when the charging by the charging means is stopped, the energy storage. A control program for use in a light emitting device that emits light from a light emitting portion by means of electrical energy stored in the energy storage means, and a blocking means for blocking current flowing from the means to the detection means,
In the computer provided in the light emitting device,
When the energy storage means is being charged, a first voltage detection control is performed to cause the detection means to detect a voltage at the energy storage means as a first detection voltage at a predetermined first interval. Control steps of
A second control step of stopping charging of the energy storage means by the charging means when the first detection voltage reaches a preset first voltage;
A second voltage detection control for charging the energy storage means by the charging means for a predetermined time and causing the detection means to detect a voltage in the energy storage means when charging of the energy storage means is stopped; And a third control step for executing at a second interval longer than the first interval.

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