JPH1056367A - Voltage controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage controller which can control a voltage irrelevantly to whether the controlled voltage is plus or minus. SOLUTION: The voltage controller constituted by connecting resistance 30 and 32 in series between a voltage input terminal 40 and the ground, connecting a voltage output terminal 41 between the resistors 30 and 32, and further connecting a resistor 31 for a switch and a 1st switch element 20 based upon a control signal in series between a voltage output terminal 41 and the ground has a photo-MOS relay 1a, having a 2nd switch element 7a which is equipped with two terminals 60a and 60b for input and two terminals 61a and 61b for the switch and makes the terminals 61a and 61b for the switch open and closed and allows a current to flow in both directions between the terminals 61a and 61b when the terminals 61a and 61b are closed, arranged between the 1st switch element 20 and resistor 31 for the switch. The input terminal has its plus terminal 60a connected to a power source Vcc for element driving and its negative terminal 60b connected to the 1st switch element 20; and one switch terminal 61a is connected to the resistor 31 for the switch and the other terminal 61b is grounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control device for controlling the contrast voltage of an LCD (Liquid Crystal Display) based on a control signal to change the contrast of the LCD.

[0002]

2. Description of the Related Art In order to obtain a predetermined voltage stepped down from a power supply voltage of a DC power supply or an AC power supply, a plurality of resistors (3) are connected between a voltage input terminal (40) to which the power supply voltage is applied and ground.
0) and (32) may be connected in series, and a voltage output terminal (41) may be connected between the resistors (30) and (32). The ratio of the voltage at the voltage input terminal (40) to the voltage at the voltage output terminal (41) is determined by the total resistance between the voltage input terminal (40) and ground and the voltage output terminal (41).
And the ratio of the total resistance between the ground and the ground.
The voltage at (40) can be reduced at the voltage output terminal (41).
Further, when the output voltage from the voltage output terminal (41) needs to be changed continuously or discretely, a resistor (32) disposed between the voltage output terminal (41) and the ground is used as a variable resistor. Or, as shown in FIG.
A new switch resistor (31) and switch means (2) may be connected in series between 1) and ground. At this time, since the total resistance between the voltage output terminal (41) and the ground changes due to the change in the resistance value of the variable resistor or the opening and closing of the switch means (2), the output voltage from the voltage output terminal (41) also increases. Can change.

[0003] Based on control signals, especially digital signals,
To control the opening and closing of the switch means (2), a digital circuit element such as a TTL (transistor-transistor logic circuit) is used as the switch means (2). Hereinafter, the digital circuit element functioning as the switch means (2) is referred to as a first switching element (20). For example, as shown in FIG. 5, as the first switching element (20), an open collector TTL (21) such as 7406 in 74 series which is a unified standard in the TTL is used, and the TTL (21) is A control signal input terminal (5) for receiving a digital signal is connected to the input side, and a switch resistor (31) is connected to the output side of the TTL (21).
Is connected. At this time, when the digital signal applied to the input terminal (5) is at an H (high) level, the TTL (21) is turned on, and the switch resistor connected to the TTL (21) is turned on.
(31) is electrically connected to the ground. Also, if the digital signal is L
In the case of the (low) level, the TTL (21) is turned off, the switch resistor (31) does not conduct, and the high potential is maintained. Therefore, the open collector type TTL (21) functions as the first switching element (20).

[0004]

The driving voltage of the LCD may be a positive voltage higher than the ground potential or a negative voltage lower than the ground potential depending on the method or specifications. Sometimes used. However, the voltage control device using the TTL (21) does not function as the first switching element (20) unless the output side potential of the TTL (21) is higher than the ground potential. Therefore, if the driving voltage of the LCD is negative, it cannot be used. In this case, the TTL (21) and the switch resistor (31)
Between the TTL (21) and the switch resistor (3
1) is electrically insulated, and only the control signal is delivered, and the second switch means opens and closes between the switch resistor (31) and the ground. However, the additional arrangement of the photocoupler, the amplifier circuit and the second switch means increases the size of the device and increases the cost. Therefore, it has been impossible to share the circuit configuration of the voltage control device when the voltage applied to the voltage input terminal (40) is a positive voltage and the circuit configuration when the voltage is a negative voltage.

Recently, from the viewpoint of miniaturization and weight reduction, the photocoupler, the amplifier circuit and the second switch are being replaced by a photo MOS relay (1). As shown in FIG. 6, the known photo MOS relay (1) has, as a basic configuration, two terminals (60a) and (60b) for input and two terminals for switch.
(61a) and (61b), and two terminals for the input (60a) (60b)
And a light emitting element (10) such as a light emitting diode (LED) that converts electric energy into light energy, and is disposed at a position where the light of the light emitting element (10) irradiates to convert light energy into electric energy. Photovoltaic elements such as solar cells (11)
And the photoelectric element (11) and the switch terminal (61a) (61b)
, Power MOS-FET that opens and closes between the switch terminals (61a) (61b) based on the electromotive force of the photoelectric element (11)
And a second switching element (7). When a current flows from the input terminal to the light emitting element (10), the light emitting element (10) emits light, and the light is received by the photoelectric element (11) and converted into electric energy. The second switching element (7) is a power MOS-FE
If T, the electromotive force of the photoelectric element (11) is applied to the gate G, so that current flows from the drain D to the source S, and the current flows from the output terminal (61a) to the terminal (61b). Can flow. Next, when the current of the light emitting element (10) is stopped, the light emitting element (10) stops emitting light, the electromotive force of the photoelectric element (11) becomes zero, the gate voltage of the power MOSFET falls, and the drain D The source S is shut off, and the output-side two terminals (61a, 61b) are shut off. Since the photo MOS relay (1) does not require an amplification circuit, the number of components can be reduced, and thus the light emitting element (10), the photoelectric element (11) and the second switching element (7) are integrated into one. Can be formed into parts.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a voltage control device which can control whether a power supply voltage is a positive potential or a negative potential with respect to a ground voltage by using the photo MOS relay. .

[0007]

Means for Solving the Problems The present invention is configured as follows to solve the above-mentioned problems. A plurality of resistors are connected in series between the voltage input terminal and the ground, a voltage output terminal is connected between the plurality of resistors, and a switch resistor is provided between the voltage output terminal and the ground. In a voltage control device in which first switching elements that open and close based on a control signal are connected in series, a photo MOS relay having two input terminals and two switch terminals is provided.
A light-emitting element that is connected to a terminal and converts electric energy into light energy, a photoelectric element that is provided at a position where the light of the light-emitting element is irradiated, and converts light energy into electric energy; and a photoelectric element and the switch. Connected between the switch terminals based on the electromotive force of the photoelectric element, and capable of flowing a current in any direction between the switch terminals when the switch terminals are closed. 2
A photo MOS relay integrally including a switching element is provided between the first switching element and the switching resistor. The photoMOS relay has a positive terminal connected to an element driving power supply Vcc among two input terminals,
The negative terminal is connected to the first switching element, one of the two terminals for the switch is connected to the switch resistor, and the other terminal is connected to the ground.

[0008]

When the connection between the output terminal of the first switching element (20) and the ground is closed by the control signal applied to the control signal input terminal (5), the photo MOS relay (1a)
A current flows through the light emitting element (10) to emit light. Photoelectric device (11)
Converts the light from the light emitting element (10) into electric energy and applies the electromotive force to the second switching element (7a). The second switching element (7a) closes between the two switching terminals (61a) (61b) based on the applied voltage, a current flows through the switching resistor (31), and the voltage output terminal (41 ) And the ground, the output voltage of the voltage output terminal (41) changes. Next, when the output terminal of the first switching element (20) and the ground are opened by the control signal applied to the control signal input terminal (5), current is applied to the light emitting element (10) of the photo MOS relay (1a). Stops flowing and the light emission stops. At this time, the photoelectric element (11) is a second switching element.
The voltage applied to (7a) also stops, and the switch terminal (61a)
(61b) Open the space. Therefore, no current flows through the switch resistor (31), the total resistance value between the voltage output terminal (41) and the ground returns to the original value, and the output voltage of the voltage output terminal (41) returns to the original value.

[0009]

In the above photo MOS relay (1a), the second switching element (7a) is a two-terminal switch (61a) (61b).
When the space is closed, a current can flow in any direction between the two terminals (61a) (61b). Therefore, the conventional voltage control device that can only control the positive voltage has the above-mentioned photo MOS.
By simply adding the relay (1a), it is possible to realize a voltage control device that can control whether the voltage applied to the voltage input terminal (40) is either a positive voltage or a negative voltage. ) Can have a common circuit configuration of voltage control devices having different polarities of voltages applied to the voltage control devices.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) As shown in FIG. 1, a voltage control device according to this embodiment includes two resistors (3) between a voltage input terminal (40) and ground.
0) and (32) are connected in series, and a voltage output terminal (41) is connected between the resistors (30) and (32). Further, a switch resistor (31) is connected between the resistors (30) and (32), and the switch resistor (3
1) is connected to a photo MOS relay (1a), and
The first switching element (20) is connected to the OS relay (1a). The first switching element (20) is a control signal input terminal
(5) Opening and closing between the output terminal and the ground based on the control signal applied to (5). As the first switching element (20) in the present embodiment, an open collector type TTL (21) such as 7406 in the 74 series is used. The input terminal of the TTL (21) is connected to the control signal input terminal (5), and the output terminal is connected to the photo MOS relay (1a).

As shown in FIG. 2, the photo MOS relay (1a) has two input terminals (60a) (60b) and two switch terminals (6
1a) and (61b) are provided. Also, the photo MOS relay (1a)
A light emitting element (10) that is connected between the input terminals (60a) and (60b) and converts electric energy to light energy, and is disposed at a position where the light of the light emitting element (10) is irradiated with light, and converts the light energy. A photoelectric element (11) for converting to electric energy, connected to the photoelectric element (11) and the switch terminals (61a) (61b),
Switch terminal (61a) based on electromotive force of photoelectric element (11)
A second switching element (7a) that opens and closes between (61b) and allows current to flow in any direction between the terminals (61a) and (61b) when the terminals (61a) and (61b) are closed. And one in one. Of the input terminals (60a) (60b), the positive terminal (60a)
It is connected to an element driving power supply Vcc via an adjusting resistor (8) for adjusting the current and voltage flowing through the light emitting element (10), and the negative terminal (60b) is an output terminal of the first switching element (20). Connected to. One of the switch terminals (61a) (61b) is connected to the switch resistor (31),
The other terminal (61b) is connected to the ground.

In this embodiment, the photo MOS relay (1a)
In, the LED as the light emitting element (10), photoelectric element (11)
Each uses a solar cell. The second switching element (7a) includes two N-channel power MOSFs.
ET (70a) (70b) and two diodes (71a) (71b). In the power MOSFETs (70a) and (70b), each gate G is connected to the positive electrode of the photoelectric element (11), each source S is connected to each other, and each drain D is connected to each switch terminal (61a) (61b). Connected. Each power MOSFET (70a) (70b)
Between the source S and the drain D of the diode (7
1a) and (71b) are connected. The direction of current flow in each diode (71a) (71b) depends on the power MOSFET (7
0a) It is opposite to the direction in which the current flows in (70b). That is, the anode A of each diode (71a) (71b) is
(70a) Connected to the source S of (70b), each diode (71a)
The cathode K of (71b) is the drain D of each of the FETs (70a) and (70b).
Connected to each other. The second switching element (7a)
The gate G of each power MOSFET (70a) (70b)
Is applied from the drain D to the source S
Current can be passed through. At this time, the upper switch terminal (61a) with respect to the lower switch terminal (61b) in FIG.
If the voltage is positive, the upper switch terminal (61a)
Then, a current flows through the FET (70a) and the diode (71b) to the lower switch terminal (61b). Conversely, the upper switch terminal for the lower switch terminal (61b)
If the voltage of (61a) is negative, the lower switch terminal
A current flows from (61b) to the upper output terminal (61a) through the FET (70b) and the diode (71a).

When a high-level signal is input to the control signal input terminal (5), the open collector TT
The connection between the output terminal at L (21) and the ground is closed, and a current flows from the element driving power supply Vcc to the adjusting resistor (8) and the light emitting element (10). At this time, a desired current flows through the light emitting element (10) via the adjusting resistor (8) to emit light.
The emitted light irradiates the photoelectric element (11), and the photoelectric element (11)
Converts the irradiated light into electric energy and applies a positive voltage to the gate G of each power MOSFET (70a) (70b). When a positive voltage is applied to the gate G, a current can flow from the drain D to the source S in each of the power MOSFETs (70a) (70b), and between the switch terminals (61a) (61b), FET (70a) and diode (71b)
Alternatively, current flows through the FET (70b) and the diode (71a). As a result, the switch resistor (31) conducts to the ground and current flows, so that the total resistance value between the voltage output terminal (41) and the ground changes, and the output voltage at the voltage output terminal (41) changes. it can. Next, the control signal input terminal (5)
Then, when a signal having a voltage of L level is inputted, the output terminal of the open collector type TTL (21) and the ground are opened, and no current flows through the light emitting element (10), and the light emitting element (10) stops emitting light. Then, the voltage applied by the photoelectric element (11) to the gate G of each FET (70a) (70b) also becomes zero, and each FET (70
a) No current flows from the drain D to the source S in (70b). Therefore, no current flows through the switch resistor (31), the total resistance value between the voltage output terminal (41) and the ground returns to the original value, and the output voltage of the voltage output terminal (41) returns to the original value.

Therefore, a current can flow in any direction from the switch resistor (31) to the ground or from the ground to the switch resistor (31). As a result, the voltage applied to the voltage input terminal (40) can be increased by simply adding the photoMOS relay (1a) and the adjusting resistor (8) to the conventional voltage control device that can only control the positive voltage. Voltage control device that can control whether the applied voltage is either a positive voltage or a negative voltage.As a result, the circuit configuration of the voltage control device having different polarities of the voltage applied to the voltage input terminal (40) can be manufactured. Can be shared without significantly increasing costs.

(Embodiment 2) As shown in FIG. 3, the voltage control device of this embodiment includes a switch resistor (31), a photo
The number of the S relay (1a), the adjusting resistor (8), the first switching element (20), and the control signal input terminal (5) has been increased from one in the first embodiment to three. . The voltage control device of the present embodiment, for example, based on a control signal,
It is used to control the LCD contrast voltage to change the LCD contrast. The contrast voltage of the LCD varies depending on the type or specification of the LCD. For example, in a color STN (super twisted nematic) type LCD, the contrast voltage is +27 V ± 2 V,
Some N-type LCDs have a voltage of -24V ± 2V. For this reason, the conventional voltage control device for controlling the contrast voltage of the LCD uses a different circuit configuration depending on the method or specification. Therefore, if the voltage control device of the present embodiment is used, both the positive and negative voltages can be controlled, so that the circuit configuration can be made common and the manufacturing cost can be reduced. Also, by inputting three control signals, the total resistance value between the voltage output terminal (41) and the ground is
It can be changed to 2 ³ = 8 ways. Therefore, the output voltage of the voltage output terminal (41) can be changed in eight steps.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. or,
The configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims. For example, in this embodiment, an open collector TTL (21) is used as the first switching element (20).
Was used, but this was replaced with an open drain type CMOS, etc.
Other digital circuit elements can be used. Similarly, other circuits can be arbitrarily selected as long as the above effects and effects can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a voltage control device according to the present invention.

FIG. 2 is a circuit diagram illustrating a photo MOS relay according to the first embodiment.

FIG. 3 is a circuit diagram showing a second embodiment of the voltage control device according to the present invention.

FIG. 4 is a circuit diagram showing the principle of the voltage control device.

FIG. 5 is a circuit example showing a conventional voltage control device for controlling a positive voltage.

FIG. 6 is a circuit diagram showing a basic configuration of a photo MOS relay.

[Explanation of symbols]

 (1), (1a) Photo MOS relay (5) Control signal input terminal (7), (7a) Second switching element (20) First switching element (30), (31), (32) Resistor (40 ) Voltage input terminal (41) Voltage output terminal

Claims (3)

[Claims] 1. A plurality of resistors (30) and (32) are connected in series between a voltage input terminal (40) and ground, and a voltage output terminal (41) is connected between the resistors (30) and (32). And the voltage output terminal
In a voltage control device in which a switch resistor (31) and a first switching element (20) that opens and closes based on a control signal are connected in series between (41) and ground, two input terminals (60a ) (60b) and 2 terminals for switch (61a)
(61a) a relay comprising the input two terminals (60a).
(60b), a light emitting element (10) for converting electric energy to light energy, and a photoelectric element (11) disposed at a position where the light of the light emitting element (10) is irradiated with light to convert light energy to electric energy. ), Connected to the photoelectric element (11) and the switch terminals (61a) (61b), and opens and closes the switch terminals (61a) (61b) based on the electromotive force of the photoelectric element (11), And a photo MOS integrally provided with a second switching element (7a) capable of flowing a current in any direction between the terminals (61a) and (61b) when the terminals (61a) and (61b) are closed. Relay (1a)
Is disposed between the first switching element (20) and the switching resistor (31), and the positive terminal (60a) of the input terminals (60a) (60b) in the photoMOS relay (1a) is provided. ) Is connected to the element driving power supply Vcc, the negative terminal (60b) is connected to the first switching element (20), and the switch terminal (61a) is connected.
(61b), one terminal (61a) is a switch resistor (31)
And the other terminal (61b) is connected to ground. 2. The second switching element (7a) comprises two N
A power MOSFET (70a) (70b) and two diodes (71a) (71b);
a) (70b), each gate G is connected to the positive electrode of the photoelectric element (11), each source S is connected to each other, each drain D is connected to each switch terminal (61a) (61b), In the diodes (71a) and (71b), each anode A is connected to the FET (70a) (70
b), and each cathode K is connected to each FET (70
a) connected to the drain D of (70b) respectively.
3. The voltage control device according to claim 1. 3. A switch resistor (31) connected to a voltage output terminal (41), a photo MOS relay (1a) connected to the switch resistor (31), and a photo MOS relay (1a). )
A plurality of electric circuits each comprising a first switching element (20) connected to the first switching element (20) and a control signal input terminal (5) connected to the first switching element (20). The voltage control device according to claim 1 or 2.