JPH0342421Y2 - - Google Patents

Description

[Detailed description of the invention] The invention consists of a booster circuit that boosts the battery voltage by applying battery voltage from the battery, and an exposure control that controls photometry and exposure by applying the boosted voltage from the booster circuit. This invention relates to an improvement in an electronic circuit for controlling exposure of a camera, which is equipped with a circuit, and more specifically, it relates to an improvement in an electronic circuit for controlling exposure of a camera, which is equipped with an electronic circuit for controlling exposure of a camera. This invention relates to a camera power supply voltage detection circuit that can accurately detect the battery voltage of a battery.

Conventionally, for example, the exposure control electronic circuit of a camera has a booster circuit that boosts the battery voltage by applying battery voltage from the battery, and a booster circuit that boosts the battery voltage by applying the boosted voltage from the booster circuit to control photometry and exposure. There are known devices that are equipped with an exposure control circuit for controlling exposure electronically. The exposure control electronic circuit of this camera has a built-in applied voltage detection circuit for detecting the boosted voltage applied to the exposure control circuit, and the exposure control circuit is used for photometry and exposure. The boosted voltage applied to the exposure control circuit is a voltage that allows normal photometry and exposure control. It is now possible to confirm whether or not the system is maintained.

By the way, cameras are also required to detect whether or not the battery voltage is maintaining a predetermined voltage.
In that case, applying the boosted battery voltage via the booster circuit to the applied voltage detection circuit to measure the battery voltage would not be able to accurately measure the battery voltage. Separately from the applied voltage detection circuit, a battery voltage detection circuit as a power supply voltage detection circuit of the camera is provided exclusively to detect the battery voltage, but with this configuration, The circuit configuration of the camera becomes complicated.

The present invention was devised in view of the problems of the prior art described above, and its purpose is to provide a camera voltage switching device suitable for accurately detecting battery voltage using an applied voltage detection circuit. Our goal is to provide the following.

The configuration of the present invention includes a booster circuit that boosts the battery voltage by applying battery voltage from the battery by operating a power switch, and a booster voltage on/off switch that turns on and off the boosted voltage from the booster circuit. a circuit, an applied voltage detection circuit to which the boosted voltage can be applied and the battery voltage can be applied via the boosted voltage on/off circuit, and a changeover switch, and when the changeover switch is on, the boosted voltage is applied. The voltage on/off circuit is turned off to cut off the boosted voltage from being applied to the applied voltage detection circuit, and the battery voltage is applied to the applied voltage detection circuit, and when the changeover switch is off, the battery voltage is an applied voltage switching circuit that cuts off application of the boosted voltage to the applied voltage detection circuit, turns on the boosted voltage on/off circuit, and applies the boosted voltage to the applied voltage detection circuit. This is a power supply voltage detection circuit for a camera.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply voltage detection device for a camera according to the present invention will be described below with reference to the drawings.

In the figure, 1 is a battery, 2 is a power switch, and 3 is a battery.
is GND, power switch 2 is composed of contact 4 and terminal 5, and the negative side of battery 1 is
Connected to GND3, the positive side of battery 1 is contact 4
It is connected to the. And the terminal 5 is the booster circuit 6
The battery voltage V ₁ of the battery 1 is applied to the booster circuit 6 via the power switch 2 . Further, the booster circuit 6 boosts the battery voltage _V1 and transfers this boosted voltage to the boosted voltage on/off circuit 7.
The boosted voltage on/off circuit 7 has the function of applying voltage to the exposure control circuit 8 via the voltage dividing circuit 9.
and a transistor 10. The voltage divider circuit 9 has a series circuit configuration consisting of a resistor 11 and a resistor 12, an NPN type transistor is used as the transistor 10, and one end of the resistor 11 connects the output terminal 6a of the booster circuit and the collector of the transistor 10. One end of the resistor 12 is connected to GND3. Further, the base of the transistor 10 is connected to the other end of the resistor 11 and the other end of the resistor 12,
The emitter of the transistor 10 is connected to the power supply terminal 8a of the exposure control circuit 8 and one end of the resistor 13. The exposure control circuit 8 has an applied voltage detection circuit 14 built therein, and has the function of controlling photometry and exposure as well as detecting the applied voltage applied to the power supply terminal 8a.

The applied voltage detection circuit 14 is roughly composed of a voltage dividing circuit 15 and a transistor 16. The transistor 16 is of an NPN type, and the voltage dividing circuit 15 has a series configuration of a resistor 17 and a resistor 18. One end of the resistor 17 is connected to the power supply terminal 8a, and one end of the resistor 18 is connected to the GND terminal 8b of the exposure control circuit 8. Further, the other end of the resistor 17 and the other end of the resistor 18 are connected to the base of the transistor 16, and the emitter of the transistor 16 is connected to the base of the transistor 16.
Connected to GND terminal 8b. Further, the collector of the transistor 16 is connected to the applied voltage detection terminal 8c of the exposure control circuit 8, and the collector of the transistor 16 is connected to the applied voltage detection terminal 8c of the exposure control circuit 8.
c is a light emitting diode element 19 for displaying detected voltage;
connected to the cathode side of the light emitting diode element 1
The anode side of the resistor 9 is connected to the other end of the resistor 13.

When the power switch ₂ is closed, a boosted voltage V2 is generated at the output terminal 6a of the booster circuit 6, and a divided voltage obtained by dividing the boosted voltage _V2 is generated at the base of the transistor 10. V ₃ is applied, and the transistor 10 is connected to the power switch 2
When closed, a reverse voltage is applied between its base and collector, and a forward voltage is applied between its base and emitter. On the other hand, the exposure control circuit 8
A boosted voltage _V4 obtained by subtracting the base-emitter voltage of the transistor ₁₀ from the divided voltage V3 is applied to the power supply terminal _8a of the exposure control circuit 8. Therefore, photometry and exposure control are now performed. Then, a reverse voltage is applied between the collector and the base of the transistor 16, and a forward voltage is applied between the emitter and the base of the transistor 16, turning on the transistor 16, energizing the light emitting diode element 19, and applying the voltage to the exposure control circuit 8. boosted voltage
It is now possible to check whether _V4 is maintained at a predetermined value or higher.

The transistor 10 is in an off state when detecting the battery voltage, and the transistor 10 is in an off state when detecting the battery voltage.
The base of 0 is connected to the anode of a diode 21 that forms part of the applied voltage switching circuit 20. The applied voltage detection circuit 20 includes a transistor 2
2, a changeover switch 23, and a resistor 24, and the changeover switch 23 has a contact 25 and a terminal 26.
It is composed of. The contact 25 is connected to GND3, the terminal 26 is connected to the cathode side of the diode 21 and one end of the resistor 24, and the transistor 2
2 is a PNP type. The emitter of this transistor 22 is connected to the positive side of the battery 1, the base of the transistor 22 is connected to the other end of the resistor 24, and the collector of the transistor 22 is connected to one end of the resistor 13 and the power supply terminal 8a of the exposure control circuit 8. The changeover switch 23 has the function of turning off the transistor 10 and the function of turning on and off the transistor 22. For this reason,
When the changeover switch 23 is closed, the transistor 1
0 is turned off, and at the same time, a forward voltage is applied between the emitter and base of the transistor 22, turning the transistor 22 on. In addition, the exposure control circuit 8
When the transistor 22 is turned on, the voltage on the collector side of the transistor 22 is applied to the power supply terminal 8a.
When _V5 is applied as the battery voltage and the battery voltage is maintained at a predetermined value or higher, the transistor 16 is turned on to energize the light emitting diode element 19, and the battery voltage is maintained at a predetermined value or higher. It is now possible to check whether there is a person or not.

In the circuit having this configuration, even if the changeover switch 23 is closed while the power switch 2 is open, the transistor 22 is not turned on.

In the embodiments described above, a transistor is used as an applied voltage detection circuit for switching the applied voltage applied to the exposure control circuit 8, but other semiconductor switches may also be used.

The camera voltage switching device according to the present invention is
With the configuration as described above, the battery voltage can be accurately detected using the applied voltage detection circuit, contributing to the simplification of the circuit configuration.

[Brief explanation of drawings]

The figure is an overall configuration diagram of a power supply voltage detection circuit for a camera according to the present invention. DESCRIPTION OF SYMBOLS 1... Battery, 2... Power switch, 6... Boost circuit, 7... Boosted voltage on/off circuit, 8... Exposure control circuit, 14... Applied voltage detection circuit, 19...
...Light emitting diode element, 20... Applied voltage switching circuit, 23... Changeover switch, V ₁ ... Battery voltage, V ₂ ... Boost voltage.

Claims (1)

[Claims for Utility Model Registration] A booster circuit that boosts the battery voltage when battery voltage from the battery is applied by operating a power switch;
A boosted voltage on/off circuit that turns off, an applied voltage detection circuit to which the boosted voltage can be applied and the battery voltage can be applied via the boosted voltage on/off circuit, and a changeover switch. When the switch is on, the boost voltage is on.
The off circuit is turned off to cut off the boosted voltage from being applied to the applied voltage detection circuit, and the battery voltage is applied to the applied voltage detection circuit, and when the changeover switch is off, the battery voltage is applied to the applied voltage detection circuit. An applied voltage switching circuit that cuts off the applied voltage to the voltage detection circuit, turns on the boosted voltage on/off circuit, and applies the boosted voltage to the applied voltage detection circuit. power supply voltage detection circuit.