JPH04160208A - Led driving circuit and position detector of hydraulic actuator using it - Google Patents

Abstract

PURPOSE:To enable lighting switching in a simple circuit by connecting plural LEDs different in forward voltage in parallel and lighting the LEDs corresponding to the difference in voltage value of driving voltage sources. CONSTITUTION:When a change-over switch 5 is opened and a power supply switch 7 is closed, an electric current from a driving voltage source 6 flows in a green LED 2 through a resistance 4 and does not flow through a red LED 3. Accordingly, only the green LED 2 can be lighted by closing the power supply switch 7. When the power supply switch 7 is closed and the change-over switch 5 is closed, an electric current from the driving voltage source 6 flows through the red LED 3 having smaller forward voltage through the resistance 4 according to the difference in the forward voltage, and does not flow through the green LED 2. Accordingly, only the red LED 3 can be lighted by closing the change-over switch 5 in addition to the power supply switch 7. Thus, lighting of the LEDs 2, 3 can be controlled by one change-over switch 5. Furthermore, the supply of driving voltage for a position detector of a hydraulic actuator can be confirmed using the LED driving circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application]
iode) Regarding drive circuits, in particular, it is possible to control the lighting and extinguishing of multiple LEDs connected in parallel, and it is also used in position detection devices for fluid pressure operated equipment, allowing for position detection and maintenance display of fluid pressure operated equipment. It is said that L
The present invention relates to a technology that is effective when applied to an ED drive circuit and a position pressure detection device for fluid pressure operated equipment using the same.

[Prior Art] Generally, as a position detection device for a fluid pressure operated device, for example, in order to detect the operating position of a piston, which is an operating member, a magnetic resistance element such as a magnetic resistance element that is sensitive to a permanent magnet built into the piston is used. A sensor equipped with a sensitive detection element is used.

The outline is, for example, a light source such as an LFD is provided inside the position detection device, and the LED is turned on and off in accordance with the operation of the detection element, and the detection of the piston's operating position is displayed by the lighting of the LED. It becomes.

[Problems to be Solved by the Invention] However, in the prior art as described above, although the detection of the piston's operating position can be confirmed by lighting up the LED, if all the LEDs are off, the piston is not detected. There is a problem in that it is not possible to distinguish between the current state and the state where the driving voltage is not supplied.

In addition, for example, as shown in FIG. 5, it is equipped with a two-color emitting LED,
A position detection device can be considered in which the closed circuit of each LED has a circuit configuration in which the logic is reversed, and one LED (G) lights up when driving voltage is supplied, and the other LED (R) lights up when the piston position is detected. In this case as well, there are problems in that the number of circuit elements increases and the position detection device becomes larger, and attachment to fluid pressure operated equipment is restricted.

Therefore, in a position detection device equipped with a two-color LED, it is possible to distinguish between supply of drive voltage and position detection, but there is a problem that it cannot be well applied to a position detection device that requires miniaturization.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an LED drive circuit that can control the lighting and extinguishing of a plurality of LEDs in response to differences in the voltage values of drive voltages.

Another object of the present invention is to provide a position detection device for fluid pressure operated equipment that is capable of displaying the supply state of drive voltage to the position detection device and the detection state of the operating position of the operating member. It is in.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for Solving the Problems] Among the inventions disclosed in this application, a brief overview of typical inventions is as follows.

That is, in the LED drive circuit of the present invention, a plurality of LEDs having different forward voltages are connected in parallel, and
D is turned on in accordance with the difference in the voltage value of the drive voltage source.

In this case, use multiple LEDs that emit light of different colors.
D.

Also, among the plurality of LEDs, one L with a large forward voltage
ED and other LEDs excluding this LED with large forward voltage
A switching means connected in series to D, the LED with a large forward voltage is turned on only when a closed circuit is formed with the drive voltage source, and other LEDs other than the LED with a large forward voltage are lit.
D is turned on only when the corresponding opening/closing means is closed and a closed circuit is formed with the drive voltage source.

Further, in the position detection device for a fluid pressure operated device using the LED drive circuit of the present invention, when a drive voltage is supplied to the position detection device for a fluid pressure operated device, the LED drive circuit of the present invention has a large forward voltage.
When the operating position of the actuating member is detected with D turned on, all other LEDs except the one with a large forward voltage turned off, and drive voltage being supplied to the position detection device of the fluid pressure operated device. , except for the LED with a large forward voltage, the corresponding other LEDs are turned on, and the LED with a large forward voltage is turned off.

[Function] According to the above-mentioned LED drive circuit, a plurality of LEDs with different forward voltages are connected in parallel, and the plurality of LEDs light up in accordance with the difference in the voltage value of the drive voltage source, thereby reducing the required minimum power. Multiple LEDs can be lit individually using limited parts. Thereby, lighting switching of the LED can be performed with a simple circuit configuration.

In this case, multiple LEDs are LEDs that emit light of different colors.
By setting it as D, it becomes clear whether the LED can be identified by the difference in the emitted light color.

Also, one of the plurality of LEDs has a large forward voltage.
The ED lights up only when a closed circuit is formed with the drive voltage source, and the other LEDs except the LED with a large forward voltage are closed with the drive voltage source when the corresponding opening/closing means connected in series are closed. By lighting only when a circuit is formed, only one LED with a large forward voltage is lit when the driving voltage is supplied, and when the driving voltage is being supplied and the opening/closing means is closed. Only other corresponding LEDs with lower forward voltages can be turned on. This makes it possible to confirm whether or not a drive voltage is being supplied to the LED drive circuit, and also to identify the open/closed state of the switching means connected in series with the LED.

Furthermore, according to the position detection device for a fluid pressure operated device using the above-described LED drive circuit, when a drive voltage is supplied to the position detection device for a fluid pressure operated device, the LED with a large forward voltage lights up, In addition, when the other LEDs except the LED with a large forward voltage are turned off and the drive voltage is supplied to the position detection device of the fluid pressure operated device and the operating position of the actuating member is detected, the LED with the large forward voltage An LED with a large forward voltage that lights up other corresponding LEDs except for
By turning off the light, only the LED with a large forward voltage is lit when the drive voltage is supplied to the position detection device, and only the other LEDs with a corresponding small forward voltage are lit when the position detection device is detecting the actuating member. can be lit. This makes it possible to confirm whether or not the drive voltage is being supplied to the position detection device, and also to identify the detection state of the actuating member by the position detection device.

[Example 1] Fig. 1 is a circuit diagram showing an LED driving circuit according to an embodiment of the present invention, and Fig. 2 is an explanatory diagram showing forward voltage-forward current characteristics in the LED driving circuit of this embodiment. .

First, the configuration of the LED drive circuit of this embodiment will be explained with reference to FIG.

The LED drive circuit of this embodiment is, for example, an LED drive circuit 1 having a two-color light emitting display function, and includes a green (G) LED 2 and a red (R) LED 3 having different forward voltages, and a current limiting resistor 4. , a changeover switch (opening/closing means) 5 that turns the red LED 3 on and off, a drive voltage source 6 for driving the circuit, and a power switch 7 that turns the drive voltage source 6 on and off. A resistor 4 is connected in series to the drive voltage source 6, a green LED 2 and a red LED 3 are connected in parallel, and a changeover switch 5 is connected in series to the red LED 3.

The green LED 2 is made of, for example, a GaP semiconductor material, and has operating characteristics of a rise voltage of 1.8 V and a forward voltage of approximately 1.9 V, as shown in FIG.
It has a larger forward voltage than ED2.

On the other hand, the red LED 3 is made of GaAsP semiconductor material, for example, and has a rising voltage of 1.6V as shown in FIG.
The forward voltage is approximately! , 7 V operating characteristics.

Next, the operation of this embodiment will be explained.

First, when the power switch 7 is closed while the selector switch 5 is open, current from the drive voltage source 6 flows through the resistor 4 to the green LED 2 . In this case, since the changeover switch 5 is open, no current flows through the red LED 3. Thereby, by closing the power switch 7, only the green LED 2 can be turned on.

Next, when the changeover switch 5 is further closed while the power switch 7 is closed, the current from the drive voltage source 6 flows through the resistor 4 to the red LED 3, which has a lower forward voltage due to the difference in forward voltage. . In this case, no current flows through the green LED 2 having a large forward voltage.

As a result, by closing the changeover switch 5 in addition to the power switch 7, the green LED 2 is turned off and the red LED is turned off.
Only ED3 can be lit.

Therefore, the LED drive circuit of this embodiment includes a green LED 2 and a red LED 3 with different forward voltages.
By connecting the changeover switch 5 in series with the red LED 3, which has a low forward voltage, only the green LED 2 lights up when the changeover switch 5 is open, and conversely, the red LED lights up when the changeover switch 5 is closed. Since only the LED 3 can be turned on, the lighting of the green LED 2 and the red LED 3 can be controlled by one changeover switch 5.

[Embodiment 2] FIG. 3 is a circuit configuration diagram showing a position detection device for a fluid pressure operated device using an LED dynamic circuit according to another embodiment of the present invention.

The position detection device using the LED drive circuit of this embodiment is, for example, a position detection device 11 that is attached to a fluid pressure operated device and has a two-color light emitting display function, and as shown in FIG. A sensor 12 that detects the operating position of the operating member, a signal processing circuit 13 that processes the detection signal of this sensor 12, and an L similar to the first embodiment that displays the detection state.
An ED drive circuit 1a, an output circuit 14 that outputs a detection state to the outside, and a drive voltage source circuit 1 that generates a voltage for driving the circuit.
It consists of 5.

The sensor 12 is composed of a bridge structure sensor in which magnetic resistance elements are incorporated on four sides, for example, and generates a minute voltage in response to the magnetic force of a permanent magnet (not shown) built into the operating member of the fluid pressure operated device. It is something that is generated.

The signal processing circuit 13 includes an amplifier section 16 that amplifies the detection signal.
, a comparator 17 that compares it with a predetermined reference voltage, and an oven collector buffer (opening/closing means) 18 that is turned on and off by the output of the comparator 17.The output voltage from the sensor 12 is amplified by an amplifier 16, and the comparator 17, the voltage is compared with a predetermined reference voltage, and when the voltage is higher than the reference voltage, that is, when the sensor 12 is in a detection state, the oven collector buffer 18 is operated.

The LED drive circuit 1a includes a green (G) LED 2a, a red (R) LED 3a, and a red (R) LED 3a for displaying the detection state as in the first embodiment.
It consists of a resistor 4a for current limiting, and a green LED.
The forward voltage of 2a and red LED 3a is different, and the green LED
D2a has a larger forward voltage than the red LED 3a. In conjunction with the operation of the oven collector buffer 18, the green LED 2a lights up when the sensor I2 is in a non-operating state, that is, when the sensor I2 is in a non-detecting state.
The red LED 3a lights up when the sensor is in the detection state.

The output circuit 14 includes a transistor I9 that outputs the detected state to the outside, and a current limiting resistor 20. When the sensor 12 is in the detected state, the transistor I9 is operated and outputted to the outside.

The drive voltage source circuit 15 includes a power supply section 21 such as a regulator that generates a constant voltage for driving the circuit.

In the circuit configuration as described above, the green LED 2a is
and red LED3a are connected in parallel, red LED3a
An oven collector buffer 18 is connected in series to .

Therefore, according to the LED drive circuit [position detection device using a] 1 of the present embodiment, when the drive voltage is supplied to the power supply terminal (+V) while the sensor 12 is in the non-detection state, the drive voltage source circuit 15 A current due to the constant voltage (Vcc) flows to the green LED 2a via the resistor 4a. In this case,
Since the oven collector buffer 18 is in an inactive state, no current flows to the red LED 3a. Thereby, only the green LED 2a can be turned on by supplying the drive voltage.

Furthermore, when the sensor 12 enters the detection state while the drive voltage is being supplied, the current due to the constant voltage (Vcc) flows through the resistor 4a to the red LED 3a, which has a smaller forward voltage due to the difference in forward voltage. . In this case, no current flows through the green LED 2a having a large forward voltage. As a result, when the operating position of the fluid pressure operated device is detected by the sensor 12 in the state where the drive voltage is supplied, the green LED 2a is turned off and the red LED 3a is turned off.
Only the light can be lit.

Therefore, according to the position detection device 11 for a fluid pressure operated device using the LED drive circuit 1a of this embodiment, the green LED 2a and the red LED 3a having different forward voltages are provided, and the sensor 12 is connected to the red LED 3a having a small forward voltage. By connecting the oven collector buffers 18 in series that operate in the detection state, it is possible to confirm that the sensor 12 is in the non-detection state and that the position detection device is in the operable state by lighting only the green LED 2a, and conversely, the red LED 2a lights up. It can be confirmed that the sensor I2 is in the detection state by lighting only the LED 3a.

[Embodiment 3] FIG. 4 is a circuit diagram showing a position detection device for a fluid pressure operated device using an LED drive circuit, which is still another embodiment of the present invention.

The position detection device using the LED drive circuit of this embodiment is, for example, a position detection device 11a that is attached to a fluid pressure operated device and has two sets of two-color light emitting display functions. A sensor 12a that detects the operating position of the operating member of the pressure-actuated device, a signal processing circuit 13a that processes the detection signal of this sensor 12a, and a green (G) LED 2b similar to Embodiments 1 and 2 that displays the detection state. Red (R
) The LED drive circuit 1b includes an LED 3b and a resistor 4b, an output circuit 14a that outputs the detected state to the outside, and a drive voltage source circuit 15a that generates a voltage for driving the circuit, which is different from the second embodiment. The points are two sets of sensors 12a,
By providing the signal processing circuit 13a, the LED drive circuit 1b, and the output circuit 14a, it is possible to display both detection ends of the actuating member, for example.

The sensor 12a is an optical sensor composed of, for example, a photodiode (not shown) that utilizes a photovoltaic effect, and a phototransistor, and the released light from the photodiode is incident on the phototransistor, and is converted into an electrical signal by charge conversion. It is now converted to . And, it is positioned and disposed at a predetermined operating position for detecting the operating member of the fluid pressure operated device.

That is, the circuit diagram of the position detection device 11a of this embodiment is as follows:
It almost corresponds to a circuit diagram concretely showing the circuit configuration diagram of the second embodiment, and for example, the comparing section 17 of the signal processing circuit 13 is replaced with a comparator 17a, the oven collector buffer 18 is replaced with a composite transistor (opening/closing means) 18a, and The circuit has a resistor and capacitor connected between each component and between constant voltage or ground.

Therefore, according to the position detection device 11a using the LED drive circuit ib of this embodiment, the two sets of two-color light emitting display functions enable position detection and display of both detection ends of the actuating member. Similarly, by lighting only the green LED 2b, it can be confirmed that the sensor 12a is in the non-detection state and the position detection device is in the operable state, and conversely, by lighting only the red LED 3b, it can be confirmed that the corresponding sensor 12a is in the detection state. can be confirmed.

As above, the invention made by the present inventor has been specifically explained based on Examples 1 to 3. However, the present invention is not limited to the above-mentioned Examples, and can be modified in various ways without departing from the gist thereof. It goes without saying that there is.

For example, the LED drive circuit l of Examples 1 to 3.

1a, 1b and position detection device 11. Regarding lla, green LEDs 2 and 2a have a large forward voltage.

Although a case has been described in which the circuit configuration is such that LEDs b and red LEDs 3.3a and 3.3b, which have a lower forward voltage than green LEDs 2.2a and b, are connected in parallel, the present invention is limited to each of the above embodiments. For example, it is widely applicable to circuit configurations in which one LED with a high forward voltage is connected in parallel with two or three or more LEDs with a lower forward voltage than this LED. The color of the emitted light is also not limited to green and red.

Furthermore, the position detection device II of Examples 2 and 3.

The circuit configuration of 11a is also not limited to the circuit configurations shown in FIGS. 3 and 4.

In the above description, the invention made by the present inventor will be mainly described as an LED drive circuit 1a used in a position detection device 11.11a of a fluid field operating device, which is the field of application thereof.
1b has been described, but the present invention is not limited thereto, and can be widely applied to, for example, devices capable of displaying light emitted by LEDs.

[Effects of the Invention] Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

(1) Multiple LEDs with different forward voltages are connected in parallel, and these multiple LEDs light up in response to the difference in the voltage value of the drive voltage source, making it possible to operate multiple LEDs with the minimum necessary components. Since it can be turned on individually, LE
The lighting switching of D can be performed with a simple circuit configuration.

(2) Since the plurality of LEDs are LEDs that emit light of different colors, the LEDs can be clearly identified by the difference in the emitted light colors.

(3) Among multiple LEDs, one LED with a large forward voltage and other LEDs other than this LED with a large forward voltage
The LED has a switching means connected in series to the ED, and the LED with a large forward voltage lights up only when a closed circuit is formed with the drive voltage source, and other LEDs other than the LED with a large forward voltage turn on.
By lighting up only when the corresponding opening/closing means is closed and a closed circuit is formed with the drive voltage source, only one LED with a large forward voltage is lit when the drive voltage is supplied, and When the driving voltage is supplied and the opening/closing means is closed, other corresponding LEs with small forward voltages
Since only D can be lit, it is possible to confirm whether or not a drive voltage is being supplied to the LED drive circuit, and it is also possible to identify the open/close state of the switching means connected in series with the LED.

(4) When an LED drive circuit is used as a position detection device of a fluid pressure operated device, and a drive voltage is supplied to the position detection device of a fluid pressure operated device, the LED with a large forward voltage lights up, and in this order When the operating position of the actuating member is detected with the directional voltage being large, the corresponding LEDs other than the ED being turned off, and the driving voltage being supplied to the position detecting device,
The other LEDs except the one with the higher forward voltage light up,
And by turning off the LED with a large forward voltage,
When the driving voltage is supplied to the position detection device, only the LED with a large forward voltage is turned on, and when the operating member is detected by the position detection device, the corresponding LED with a small forward voltage is turned on.
Since only the ED can be lit, it is possible to confirm whether or not the drive voltage is being supplied to the position detection device, and it is also possible to identify the detection state of the actuating member by the position detection device.

(5) According to (1) to (3) above, it is possible to obtain an LED drive circuit in which the lighting and extinguishing of a plurality of parallel-connected LEDs is controlled by a simple circuit configuration, and which enables miniaturization. .

(6), According to (4) above, it is possible to display the supply state of drive voltage to the position detection device and the detection state of the operating position of the operating member, and the maintenance display of the position detection device and the fluid pressure operated equipment. It is possible to obtain a position detection device for a fluid pressure operated device that is capable of displaying position detection.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an LED drive circuit according to the first embodiment of the present invention, FIG. 2 is an explanatory diagram showing forward voltage-forward current characteristics in the LED drive circuit according to the first embodiment, and FIG. 3 is a circuit diagram showing the LED drive circuit according to the first embodiment of the present invention. Embodiment 2 A circuit configuration diagram showing a position detection device for a fluid pressure operated device using an LED drive circuit, and FIG. A circuit diagram showing the device. FIG. 5 is a circuit diagram showing an LED driving circuit as an example of the prior art. 1, la, 1b - LED drive circuit, 2.2a, 2b - green LED (LED with large forward voltage), 3.3a, 3b - red LED (other LED), 4.
4a, 4b...Resistor, 5...Selector switch (opening/closing means), 6...Drive voltage source, 7...Power switch, 11.11a...Position detection device, 12.12a...・Sensor, 13.13a...signal processing circuit, 14.14a...output circuit, 15.15a...drive voltage source circuit, 16...amplifier section, 17...comparison section, 17a... Comparator, 18... Oven collector buffer (opening/closing means), 1
8a... Composite transistor (opening/closing means), 19... Transistor, 20... Resistor, 21... Power supply section. Patent applicant Koganei Seisakusho Co., Ltd. Representative Patent attorney Dai Tsutsui Sodo Patent attorney Toshio Nakano Figure 5

Claims (1)

[Claims] 1. A plurality of LEDs having different forward voltages are connected in parallel,
An LED drive circuit characterized in that the plurality of LEDs light up in response to differences in voltage values of drive voltage sources. 2. The LED drive circuit according to claim 1, wherein the plurality of LEDs are LEDs that emit light of different colors. 3. Among the plurality of LEDs, one LED with a large forward voltage and other LEDs other than the LED with a large forward voltage
D, the LED with a large forward voltage is lit only when a closed circuit is formed with the drive voltage source, and the other LEDs other than the LED with a large forward voltage are 3. The LED drive circuit according to claim 1, wherein the LED drive circuit lights up only when the corresponding opening/closing means is closed to form a closed circuit with the drive voltage source. 4. Using the LED drive circuit according to claim 1, 2 or 3, when a drive voltage is supplied to a position detection device of a fluid pressure operated device, the LED with a large forward voltage lights up, and When the operating position of the actuating member is detected with the other LEDs excluding the LED with a high voltage turned off and the drive voltage being supplied to the position detection device of the fluid pressure operated device, the forward voltage is high. The corresponding LED other than the LED lights up, and the LED has a large forward voltage.
A position detection device for a fluid pressure operated device, characterized in that the light turns off.