JP2006060900A - Electronic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit wherein supply voltage to a control circuit, such as CPU, can be ensured with stability and the operation of a boosting circuit for high voltage, such as a DC/DC converter, can be controlled with higher efficiency. <P>SOLUTION: The electronic circuit includes: the boosting circuit 1 for high voltage that boosts battery voltage; a control circuit 4 that on/off controls the boosting circuit 1 for high voltage; a boosting circuit 6 for control that boosts the battery voltage for ensuring the operating voltage of the control circuit 4; and a constant-voltage circuit 5 that generates the operating voltage of the control circuit 4 from the output voltage of the boosting circuit 6 for control. The control circuit 4 on/off controls the boosting circuit 1 for high voltage based on the value of the output voltage of the boosting circuit 6 for control. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic circuit, and more particularly to an electronic circuit including a high-voltage boosting circuit that is a DC / DC converter that boosts a battery voltage.

  For example, a strobe device includes a booster circuit (DC / DC converter) that boosts a supply voltage (battery voltage) from a battery to a DC high voltage, and is required for strobe light emission by the DC high voltage. A high load current is accumulated (charged) in the main capacitor, and strobe light emission is performed by consuming this accumulated charge.

  By the way, in recent years, multi-functionality and high performance of strobe devices have progressed, and it is not uncommon for a strobe device to have a microcomputer (control circuit) such as a CPU, thereby controlling the entire device.

  In this type of strobe device, it is necessary to supply a predetermined voltage (control voltage) to the control circuit for stable control of the entire circuit. In particular, when the booster circuit is turned on, the battery voltage rapidly decreases. Therefore, even in such a case, a measure for securing the control voltage is essential.

Various proposals have been made for securing such a control voltage (for example, Patent Document 1, Patent Document 2, etc.).
A conventional control voltage securing method will be described with reference to FIG. FIG. 3 is a block diagram showing a general circuit configuration of a strobe device including a control circuit such as a CPU.

  The strobe device circuit shown in FIG. 3 includes a power supply battery E, a high-voltage booster circuit 1 that boosts a supply voltage from the battery E to a DC high voltage, and a main capacitor 2 that accumulates (charges) charges by the DC high voltage. A flash discharge tube 3 such as a xenon tube that emits light by consuming stored charge of the main capacitor 2, an IGBT (insulated gate bipolar transistor) that controls the light emission operation of the flash discharge tube 3 by a switching operation, and a high voltage booster circuit 1 on / off control, control circuit 4 for controlling the entire strobe device, operating voltage (control voltage) V3 for generating and outputting the operating voltage (control voltage) V3 of the control circuit 4, and supply voltage from battery E Is provided with a control boosting circuit 6 that constantly boosts the voltage V2 to a voltage V2 exceeding V3, a voltage detection circuit 7 that detects the battery voltage V1, and adjustment resistors R3 and R4.

  The control related to securing the control voltage of the conventional strobe device will be described. FIG. 4 is a graph showing voltage fluctuations at the main points of the circuit. The graph showing the battery voltage V1, the output voltage V2 of the control booster circuit, and the control voltage V3 corresponds to the voltage value on the left vertical axis. First, when the high-voltage booster circuit 1 is turned on (t0) while the main capacitor 2 is empty (V4 is 0), the battery voltage V1 rapidly decreases. At this time, charging of the main capacitor 2 is started.

  The fluctuation of the battery voltage V <b> 1 is transmitted to the control circuit 4 through the voltage detection circuit 7. The control circuit 4 turns off the high voltage booster circuit 1 when V1 falls below a predetermined voltage (for example, 2 V) for the reason of securing the control voltage V3. When the high voltage booster circuit 1 is turned off, V1 rises. When this voltage exceeds 2V, the high voltage booster circuit 1 is turned on. The on / off of the high voltage booster circuit 1 is repeated until the power supply voltage V1 does not fall below 2V (between t0 and t3). During this time, the voltage V4 of the main capacitor 2 slightly increases (in order to facilitate understanding, the increase in the voltage V4 between t0 and t3 is expressed in a rough manner in FIG. 4).

  Then, the voltage V4 of the main capacitor 2 starts to increase greatly from the time (t3) when V1 does not fall below 2V. In addition, the graph which shows V4 respond | corresponds to the voltage value of the vertical axis | shaft of the right side of FIG.

  As the voltage V4 increases, the battery voltage V1 also increases (recovers) (that is, the voltage does not decrease even when the high voltage booster circuit 1 is on). Further, the output voltage V2 of the control booster circuit 6 is kept constant (for example, 5.5V). This is because the control booster circuit 6 can boost the voltage up to 5.5V if V1 can be maintained at about 2V or higher.

In the electronic circuit (high voltage booster circuit, control circuit such as CPU, constant voltage circuit, control booster circuit and voltage detection circuit) included in the above conventional strobe device, the control circuit monitors the battery voltage and uses it for high voltage. Whether the booster circuit is turned on or off is controlled based on the value of the battery voltage, and the operating voltage (control voltage) of the control circuit is secured. Therefore, even when there is a sudden voltage drop when the high voltage booster circuit is turned on when the main capacitor is empty, the entire circuit including the electronic circuit (for example, a strobe device) can be stably operated.
Japanese Patent Laid-Open No. 1-138544 JP-A-10-94183

  However, in the above-described conventional electronic circuit, the on / off control of the high voltage booster circuit is performed based on the detected value of the battery voltage, and therefore there is a tendency that the on / off switching is given up quickly. Generally, since the battery voltage switching reference value (for example, 2V) has a margin (for example, about 0.5V), the high voltage booster circuit is turned on when there is a sufficient margin for securing the control voltage. To OFF (between t0 and t3 in FIG. 4). Then, the high voltage booster circuit is turned on / off unnecessarily, so that the operation efficiency is deteriorated and the capacity of the battery serving as a power source cannot be sufficiently exhibited.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an electronic circuit that can stably secure a supply voltage to a control circuit and can more efficiently control the operation of a high-voltage booster circuit. And

  The electronic circuit of the present invention includes a first booster circuit that boosts the battery voltage, a control circuit that controls switching of the operation of the first booster circuit, and the battery voltage for securing the operating voltage of the control circuit. And a constant voltage circuit for generating an operating voltage of the control circuit from the output voltage of the second booster circuit, the control circuit including an output voltage of the second booster circuit The switching control of the operation of the first booster circuit is performed based on the value.

  According to the electronic circuit having the above configuration, since the switching control of the operation of the first booster circuit is performed based on the output voltage value of the second booster circuit (that is, the input voltage value of the constant voltage circuit), more precise control is possible. Thus, the first booster circuit can be efficiently operated while supplying a stable voltage to the control circuit, and the capacity of the battery serving as a power source can be fully utilized.

  Further, the voltage boosted by the first booster circuit is supplied to the main capacitor for storing the electric charge for strobe light emission, so that the effect of shortening the charging time can be expected. It can be said that this is a preferred embodiment.

  As described above, the electronic circuit of the present invention serves as a power source because it can efficiently operate the high-voltage booster circuit for charging the main capacitor while ensuring the operating voltage of the control circuit such as the CPU safely. The battery capacity can be fully utilized.

  Hereinafter, an electronic circuit according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a general circuit configuration of a strobe device including an electronic circuit according to the present embodiment.

  The strobe device circuit shown in FIG. 1 includes a power supply battery E, a high voltage booster circuit 1 (first booster circuit) that is a so-called DC / DC converter that boosts a supply voltage from the battery E to a DC high voltage, The main capacitor 2 that accumulates (charges) charges by DC high voltage, the flash discharge tube 3 such as a xenon tube that emits light by consuming the accumulated charge of the main capacitor 2, and the flash operation of the flash discharge tube 3 by switching operation. In addition to the on / off control of the IGBT (insulated gate bipolar transistor) to be controlled and the high voltage booster circuit 1, the control circuit 4 for controlling the entire strobe device and the operating voltage (control voltage) V3 of the control circuit 4 are generated. In addition, the control is a so-called DC / DC converter that constantly boosts the output voltage from the constant voltage circuit 5 and the battery E to a voltage V2 exceeding V3. Use the boosting circuit 6 (second booster circuit), and a voltage detection circuit 7 and a resistor for adjustment R1, R2 for detecting the output voltage V2 of the control step-up circuit 6.

  In the present embodiment, the high voltage booster circuit 1, the control circuit 4 (including the voltage detection circuit 7, resistors R3 and R4), the control booster circuit 6 and the constant voltage circuit 5 constitute an electronic circuit according to the present invention. To do.

  The circuit configuration of the strobe device of FIG. 1 is different from the circuit configuration of the conventional strobe device (FIG. 3) in that the voltage detection point of the voltage detection circuit 7 is changed. Such a point is a feature of the electronic circuit of the present invention. The operation will be described below.

  FIG. 2 is a graph showing voltage variations at the main points of the circuit of FIG. The graph showing the battery voltage V1, the output voltage V2 of the control booster circuit, and the control voltage V3 corresponds to the voltage value on the left vertical axis, and the graph showing the voltage V4 corresponds to the voltage value on the right vertical axis. ing. First, when the high-voltage booster circuit 1 is turned on with the main capacitor 2 being empty (V1 is 0) (t0), the battery voltage V1 rapidly decreases. At this time, charging of the main capacitor 2 is started.

  When V1 falls below a predetermined voltage (2 V in this embodiment), the output voltage V2 of the control booster circuit 6 starts to drop. If the input voltage (that is, the battery voltage V1) is 2V or higher, the control booster circuit 6 can boost the voltage to a predetermined voltage (5.5V in the present embodiment) and output it, but V1 falls below 2V. And V2 falls. And if V1 falls to about 1.5V, V2 will fall to about 5V.

  The control circuit 4 secures the control voltage V3 (the output voltage of the constant voltage circuit 5; in this embodiment, 4.8 V), and when the voltage V2 falls below 5 V, the high voltage booster circuit 1 is used. Turn off. When the high voltage booster circuit 1 is turned off, V1 and V2 rise. When V2 exceeds 5V, the control circuit 4 turns on the high voltage booster circuit 1 again. Thereafter, the control circuit 4 repeatedly turns on / off the high voltage booster circuit 1 until V2 does not fall below 5V (between t1 and t2). During this time, the voltage V4 of the main capacitor 2 slightly increases (in order to facilitate understanding, the increase in the voltage V4 between t0 and t2 is expressed roughly in FIG. 2). The increase rate of V4 between t0 and t2 in FIG. 2 is larger than the increase rate of V4 between t0 and t3 in FIG. However, the voltage value of V4 at t2 in FIG. 2 is lower than the voltage value of V4 at t3 in FIG.

  Then, the voltage V4 of the main capacitor 2 starts to increase greatly from the time (t2) when V2 does not fall below 5V. At the same time, V1 and V2 also rise (recover).

  As described above, according to the electronic circuit of this embodiment, on / off switching of the high voltage booster circuit is performed based on the input voltage of the constant voltage circuit that generates the control voltage (that is, the output voltage of the control booster circuit). Therefore, more precise control is possible compared to a conventional electronic circuit that performs similar control based on the battery voltage, and as a result, the high-voltage booster circuit can be operated efficiently. Therefore, the capacity of the battery serving as a power source can be sufficiently exerted (the range indicated by the hatched area in FIG. 2 indicates a portion that is more effectively used than in the past). Moreover, in the strobe device provided with the electronic circuit of the present embodiment, the charging speed of the main capacitor can be increased as compared with the conventional example (because the operating efficiency of the high-voltage booster circuit is improved). Shortening can be achieved.

  The electronic circuit according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the electronic circuit of the present invention is applied to the strobe device, and the voltage boosted by the high voltage booster circuit is supplied to the main capacitor that stores the charge for strobe light emission. However, the present invention can be applied to other devices (for example, an actuator driving device) including a main capacitor other than the strobe device.

  The electronic circuit of the present invention can also be applied to a device that does not use the boosted voltage from the high-voltage booster circuit for charging the main capacitor but uses it as an operating voltage for other circuits in the subsequent stage.

  The electronic circuit according to the present invention can stably supply an operating voltage to a control circuit such as a CPU, and can improve the operating efficiency of a high-voltage boosting circuit that is a DC / DC converter. Then, shortening of the charging time of the main capacitor can be expected.

1 is a block diagram showing a circuit configuration of a strobe device including an electronic circuit according to an embodiment of the present invention. In FIG. 1, a graph showing voltage fluctuations at main points Block diagram showing the circuit configuration of a strobe device containing a conventional electronic circuit In FIG. 3, a graph showing voltage fluctuations at main points

Explanation of symbols

1 Booster circuit for high voltage 4 Control circuit 5 Constant voltage circuit 6 Booster circuit for control 7 Voltage detection circuit

Claims (3)

A first booster circuit for boosting the battery voltage;
A control circuit for performing switching control of the operation of the first booster circuit;
A second booster circuit for boosting the battery voltage to ensure an operating voltage of the control circuit;
A constant voltage circuit that generates an operating voltage of the control circuit from an output voltage of the second booster circuit,
The electronic circuit according to claim 1, wherein the control circuit performs switching control of operation of the first booster circuit based on an output voltage value of the second booster circuit.   2. The electronic circuit according to claim 1, wherein the voltage boosted by the first booster circuit is supplied to a main capacitor that accumulates electric charges for strobe light emission. The electronic circuit according to claim 1, wherein the control circuit performs on / off control of the first booster circuit based on an output voltage value of the second booster circuit.

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