JPH0961894A - Lighting control circuit for light emitting diode and strobe device including this circuit - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a notification configuration for directly controlling a lighting operation of a light emitting diode by directly connecting a CMOS output terminal of a central processing unit and a cathode of at least one light emitting diode. (EN) Provided are a lighting control circuit for a light emitting diode and a strobe device equipped with this circuit, which can reduce current consumption when the arithmetic processing unit is in a standby state in which drive power is supplied but no operation is performed. With the goal. A lighting control circuit for a light emitting diode according to the present invention and a strobe device equipped with this circuit are provided when a central processing unit is placed in a standby state in which no operation is performed.
It is configured to include a control element that controls an electrical connection state between at least one light emitting diode and its driving power supply to a non-connection state.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric device equipped with a central processing unit (hereinafter simply referred to as "CPU") and at least one light emitting diode whose operation is controlled by the CPU for notifying various information. The present invention relates to a lighting control circuit for the light emitting diode and a strobe device including the lighting control circuit.

2. Description of the Related Art Conventionally, an electric device equipped with at least one light emitting diode whose operation is controlled by the above-mentioned CPU for notifying various information is well known, and as one of such electric devices, when taking a picture, For example, a strobe device that is useful as an auxiliary light source is well known at night or when the ambient brightness of a subject such as indoors is low, and such strobe device exchanges various photographing information with a mounted camera. It is well known that there are so-called dedicated strobe devices that can be used, as well as so-called general-purpose strobe devices that cannot perform such replacement, or so-called built-in strobe devices that are built into the camera. By the way, the strobe device is provided with a power source section for charging the main capacitor, a flash discharge tube for consuming the charge charged in the main capacitor to emit light, and is well known to be output in response to, for example, a shutter release operation of a camera. Is a device whose basic operation is to supply the charge charged in the main capacitor to the flash discharge tube in response to a so-called light emission start signal such as the synchro signal. However, recent strobe devices, for example, exchange shooting information such as aperture value information and guide number information with a mounted camera,
Alternatively, the functions of the power supply unit and the light emitting operation of the flash discharge tube are controlled in various forms, and so on.
An apparatus including a CPU and having the above-mentioned photographing information exchange configuration and operation control configuration by the CPU is becoming common. On the other hand, conventionally, the strobe device is provided with an appropriate informing configuration for informing the so-called own operating state such as whether or not the charging state of the main capacitor and the operating state capable of controlling the light emission amount are almost indispensable. Has been
Of course, the above-mentioned device with built-in CPU is no exception,
Further, a device that employs the light emitting diode as described at the beginning as its notification element is also well known. FIG. 2 is provided with a CPU that configures a configuration for exchanging shooting information such as aperture value information with a mounted camera, and employs a light emitting diode as a notification element that notifies the operating state of itself, FIG. 9 is a schematic electrical circuit diagram of essential parts showing a conventional light emitting diode lighting control circuit in which the CPU controls the notification operation by the light emitting diode and an example of a strobe device provided with this circuit. The CPU 1 constitutes at least a part of the strobe device and constitutes a configuration for exchanging photographing information such as aperture value information with a mounted camera and the like, and outputs a first voltage (not shown). The first voltage is supplied as a driving power supply via a first power supply terminal 2 connected to one power supply. The cathodes of the plurality of light emitting diodes 3, 4 and 5 are respectively connected to the CMOS output terminals 1a, 1b and 1 of the CPU 1.
The limiting resistors 6, 7 and 8 are connected to c and have their resistance values appropriately set in consideration of the lighting current, which is generally known to differ depending on the color of the emitted light.
It is connected to a second power supply terminal 9 connected to a second power supply (not shown) that outputs a second voltage via. Therefore,
In a state where the first and second power supplies (not shown) output the first and second voltages and both voltages are supplied to the first power supply terminal 2 and the second power supply terminal 9, for example, C
When the CMOS output terminal 1a of PU1 outputs a low-level signal, the second power source outputs the second power source via the second power source terminal 9 and the limiting resistor 6 to the light emitting diode 3 whose cathode is connected to the CMOS output terminal 1a. When the voltage is supplied and applied, the light emitting diode 3 emits light to perform a desired notification operation. When the other CMOS output terminals 1b and 1c output a low level signal, the light emitting diodes 4 and 5 whose cathodes are connected to the respective terminals emit light, and a notification operation is performed according to the respective light emitting diodes 4 and 5. It will be.

As described above, the conventional device shown in FIG. 2 is provided with a plurality of light emitting diodes whose cathodes are connected to the CMOS output terminals of the CPU.
A plurality of notification operations can be performed by controlling the output state of the S output terminal. However, focusing on the current flowing through the light emitting diode, for example, when it is not possible to confirm the use of the strobe device for a predetermined period in a state in which the strobe device is in an operating state by starting the supply of power,
Is configured to prevent waste of the power source by changing the active state in which the desired operation can be performed to the standby state in which no operation is performed, the first power source and the second power source output the first power source. Depending on the voltage value of the voltage and the second voltage, etc., there is a risk of causing the following inconveniences. For example, the voltage values of the first voltage and the second voltage output from the first power supply and the second power supply are the voltage values of the first voltage and the second voltage, respectively. It is set in consideration of the voltage value that can normally light the light emitting diode. Specifically, the voltage value of the first voltage is up to several volts, and the voltage value of the second voltage is Although it depends on the emission color, in the case of a notification structure including green, it is generally set to several volts or more. That is, the first power source and the second power source are, in addition to the above-mentioned difference in the operating voltage values of the CPU and the light emitting diode, a driving operation with a very stable constant voltage in order to ensure a normal driving operation of the CPU. In consideration of the necessity of the above, the second power source is usually configured as a separate power source so as to be a power source that outputs a high voltage. Therefore, as described above, for example, the CPU
Even when the power supply is prevented from being wasted by setting the first voltage in the standby state under appropriate conditions, the conventional example shown in FIG. A leak current based on a potential difference between the second voltage and the like flows through the light emitting diode and the CMOS output terminal of the CPU, and as a result, the current consumption cannot be reduced to some extent or more. .
That is, as described above, not only when there is a difference between the first and second voltages, but also when the potential difference between the two power supplies is eliminated by sharing the first power supply and the second power supply, for example. ,
When the light emitting diode is irradiated with light from the outside, a leak current similar to the leak current based on the potential difference is generated. The present invention has been made in consideration of the above-mentioned inconveniences, and the cathode of the light emitting diode is connected to the C of the CPU.
In the configuration for controlling the lighting operation of the light emitting diode by directly connecting to the MOS output terminal, the CPU
Is capable of preventing the generation of a leak current through the light emitting diode and the CMOS output terminal when in a standby state where no operation is performed, and further reducing the current consumption in the standby state. It is an object of the present invention to provide a lighting control circuit and a strobe device equipped with this circuit.

In a lighting control circuit for a light emitting diode according to the present invention, a CMOS of a central processing unit to which a first power source for outputting a first voltage is supplied as a driving power source.
It has at least one light-emitting diode whose cathode is connected to the output terminal, one end connected to the anode of the light-emitting diode through a limiting resistor, and the other end connected to a second power supply that outputs a second voltage, When the central processing unit is in an active state in which it can perform a predetermined operation, the second power supply and the light emitting diode are connected to each other, and the central processing unit is in a standby state in which no operation is performed. And a control element for disconnecting the second power source and the light emitting diode from each other. The strobe device according to the present invention is a CM of a central processing unit to which a first power supply for outputting a first voltage is supplied as a driving power supply.
It has at least one light emitting diode whose cathode is connected to the OS output terminal, one end which is connected to the anode of the light emitting diode through a limiting resistor, and the other end which is connected to a second power source that outputs a second voltage. When the central processing unit is in an active state capable of performing a predetermined operation, the second power supply and the light emitting diode are connected to each other, and the central processing unit is in a standby state in which no operation is performed. The light emitting diode lighting control circuit including the second power source and the control element for disconnecting the second light source from the light emitting diode is provided.

Since the lighting control circuit of the light emitting diode and the strobe device including the circuit according to the present invention have the above-mentioned configuration, at least one light emitting diode is provided when the CPU is in an active state where it can perform a desired operation. The anode is electrically connected to the second power supply through the limiting resistance and the control element, and accordingly, an appropriate notification operation is performed in response to the output state of the CMOS output terminal of the CPU to which the cathode is connected. Will be done. On the other hand, C
When the PU is placed in a standby state where it does not perform any operation, unlike the above case, the electrical connection between the anode of the at least one light emitting diode and the second power source is blocked by the control element. Become. Therefore, the second
No leak current flows from the power supply through the CMOS output terminal of the CPU to which the light emitting diode and the cathode thereof are connected, and the current consumption of the device in the standby state can be further reduced.

1 is an electric circuit diagram of a main part showing an embodiment of a lighting control circuit for a light emitting diode according to the present invention and a strobe device equipped with this circuit. In FIG. Indicate the same functional component. Code 10
Has CMOS output terminals 10a, 10b, 10c connected to the first power supply terminal 2 and to the cathodes of the plurality of light emitting diodes 3 to 5, that is, similar to the CPU shown by reference numeral 1 in FIG. A control for controlling the operation of a control element, which will be described later, showing a CPU, and different output signals in response to whether the CPU 10 is in an active state in which it performs a desired operation or in a standby state in which no operation is performed. Status output terminal 10 for outputting as a signal
d. Reference numeral 11 is connected to one end of each of the plurality of light emitting diodes 3 to 5 connected to each anode via limiting resistors 6 to 8, and to a second power supply terminal 9 connected to a second power supply (not shown). Has a control pole connected to the state output terminal 10d of the CPU 10 via the other end and the resistor 12, and has the plurality of light emitting diodes 3 to 5 and the second light emitting diode 3-5.
The control element which controls the electrical connection state between power supplies is shown. In this embodiment, the control element 11 is a collector connected to the respective anodes of the plurality of light emitting diodes 3 to 5 through limiting resistors 6 to 8, and a second power supply terminal 9
CPU1 via an emitter connected to
P having a base connected to the 0 state output terminal 10d
The NP transistor is adopted. The operation of one embodiment of the lighting control circuit for a light emitting diode according to the present invention having the above-described configuration of the main part and the strobe device equipped with this circuit will be described below. In this embodiment, a PNP transistor is used as the control element 11. Since it is an example adopted,
The CPU 10 outputs a low-level output signal from the state output terminal 10d to the control element 11 when it is in an active state where a predetermined operation can be performed and when it is in a standby state where no operation is performed. It is assumed that the PNP transistor is configured to output as a control signal. Therefore, in the light-emitting diode lighting control circuit according to the present invention and the strobe device including this circuit, when the CPU 10 provided now is in an active state in which desired operation can be performed, the CPU 10 outputs the state output terminal 10d.
It outputs a lower level control signal to control the PNP transistor, which is the control element 11, to the conductive state.
As a result, electrical connection is established between the second power supply terminal 9 and the limiting resistors 6-8. That is, the anodes of the plurality of light emitting diodes 3 to 5 are electrically connected to the second power source (not shown) through the limiting resistors 6 to 8, the control element 11, and the second power source terminal 9. Become. As a result, the plurality of light emitting diodes 3 to 5 perform appropriate notification operations in response to the output states of the CMOS output terminals 10a to 10c of the CPU 10 to which the respective cathodes are connected. On the other hand, when the provided CPU 10 is placed in a standby state in which no operation is performed, the CPU 10 outputs a high-level control signal from the state output terminal 10d, unlike the above case, and the PNP that is the control element 11 is provided.
The transistor is controlled to be in a non-conducting state, whereby the electrical connection between the second power supply terminal 9 and the limiting resistors 6 to 8 is released. That is, the respective anodes of the plurality of light emitting diodes 3 to 5 are not electrically connected to the second power source (not shown), and as a result, the plurality of light emitting diodes 3 to 5 are appropriately notified. Never do. In addition, the first power supply and the second power supply (not shown) output, and the first power supply terminal 2 and the second power supply terminal 9
Even if there is a potential difference between the first voltage and the second voltage supplied to and applied to, the electrical connection between the second power supply terminal 9 and the limiting resistors 6 to 8 is released as described above. Therefore, a leak current does not flow through the plurality of light emitting diodes 3 to 5 and the CMOS output terminals 10a to 10c of the CPU 10.

The lighting control circuit for a light emitting diode according to the present invention and the strobe device equipped with this circuit can establish an electrical connection state between at least one light emitting diode and its driving power source according to the state of the CPU provided. When the CPU is in the standby state, the control element for controlling is provided to control the electrical connection state between the plurality of light emitting diodes and the driving power source thereof to the non-connection state. No leak current flows through the output terminal or the like, and as a result, the current consumption in the standby state of the CPU can be further reduced.

[Brief description of drawings]

FIG. 1 is a main part electric circuit diagram showing an embodiment of a lighting control circuit of a light emitting diode according to the present invention and a strobe device equipped with this circuit.

FIG. 2 is a schematic electric circuit diagram of a main part showing a conventional lighting control circuit of a light emitting diode and an example of a strobe device provided with this circuit.

[Explanation of Codes] 1 Central Processing Unit (CPU) 2 First Power Supply Terminal 3 Light Emitting Diode 4 Light Emitting Diode 5 Light Emitting Diode 6 Limiting Resistor 7 Limiting Resistor 8 Limiting Resistor 9 Second Power Supply Terminal 10 CPU (Central Processing Unit) 11 Control element 12 Resistance

Claims (6)

[Claims] 1. At least one light emitting diode having a cathode connected to a CMOS output terminal of a central processing unit to which a first power source for outputting a first voltage is supplied as a driving power source, an anode of the light emitting diode, and a limiting resistor. The second power supply when the central processing unit is in an active state in which it can perform a predetermined operation, and has one end connected via the second power supply and a second power supply outputting the second voltage. And a control element for connecting the second power supply and the light emitting diode when the central processing unit is in a standby state in which the central processing unit does not perform any operation. Lighting LED lighting control circuit. 2. The lighting control circuit for a light emitting diode according to claim 1, wherein the control element is a switch element which is turned on in an active state and turned off in a standby state. 3. A central processing unit to which a first power supply for outputting a first voltage is supplied as a driving power supply, and at least one light emitting diode whose cathode is connected to a CMOS output terminal of the central processing unit, A limiting resistor connected to the anode of the light emitting diode, and a collector connected to the anode of the light emitting diode via the limiting resistor;
A low-level output signal is output when the emitter connected to the second power supply that outputs a voltage and the central processing unit are in an active state where they can perform a predetermined operation, and the central processing unit does not perform any operation. A lighting control circuit for a light emitting diode, comprising a control element, which is a PNP transistor composed of a base connected to a status output terminal of the central processing unit, which outputs a high-level output signal when in a standby state . 4. At least one light emitting diode having a cathode connected to a CMOS output terminal of a central processing unit to which a first power source for outputting a first voltage is supplied as a driving power source, an anode of the light emitting diode, and a limiting resistor. The second power supply when the central processing unit is in an active state in which it can perform a predetermined operation, and has one end connected via the second power supply and a second power supply outputting the second voltage. And a control element for connecting the second light source and the light emitting diode when the central processing unit is in a standby state in which the central processing unit does not perform any operation. A strobe device equipped with a lighting control circuit for a light emitting diode. 5. The strobe device according to claim 4, wherein the control element is a switch element which is turned on in an active state and turned off in a standby state. 6. A central processing unit to which a first power source for outputting a first voltage is supplied as a driving power source, and at least one light emitting diode whose cathode is connected to a CMOS output terminal of the central processing unit, A limiting resistor connected to the anode of the light emitting diode, and a collector connected to the anode of the light emitting diode via the limiting resistor;
A low-level output signal is output when the emitter connected to the second power supply that outputs a voltage and the central processing unit are in an active state where they can perform a predetermined operation, and the central processing unit does not perform any operation. A lighting control circuit for a light emitting diode, which includes a control element which is a PNP transistor including a base connected to a state output terminal of the central processing unit that outputs a high-level output signal when in a standby state where no operation is performed. Equipped with strobe device.