Temperature compensation voltage-generating circuit

• US 5,621,306 A
• Filed: 10/18/1994
• Issued: 04/15/1997
• Est. Priority Date: 11/18/1993
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ise, Masahiro
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/323,681
• Time in Patent Office: 910 Days
• Field of Search: 323/313, 323/907, 323/273, 323/275, 323/280, 323/281, 323/349, 323/350
• US Class Current: 323/313
• CPC Class Codes: G05F 1/463 Sources providing an output which depends on temperature
• CPC Class Codes: Y10S 323/907 Temperature compensation of semiconductor

Abstract

The invention provides a voltage-generating circuit in which the characteristic of the output voltage in response to the ambient temperature is represented by a predetermined line. A temperature sensor outputs a voltage in proportion to the ambient temperature, and the voltage is inversely amplified by an operational amplifier. An optimum operating voltage V_op for a liquid crystal is output from an output terminal of a variable voltage regulator, in response to the voltage output ted from the operational amplifier.

Claims

1. A temperature compensation voltage-generating circuit for supplying an operating voltage to a load such that an optimum operating voltage varies linearly with change in temperature, the circuit comprising:

a temperature sensor whose output changes linearly in response to the temperature;

a voltage regulator with a control terminal, which outputs an output voltage in response to an electrical signal level fed to the control terminal;

an amplification network which receives the output from the temperature sensor and which amplifies at a gain set so as to vary the output voltage of the voltage regulator with a predetermined gradient, the amplification network comprising;

an operational amplifier whose negative terminal receives the output of the temperature sensor,

a first resistance element which is interposed between the negative terminal and an output terminal of the temperature sensor, and

a second resistance element which is connected between the negative terminal and an output terminal of the operational amplifier; and

a level setting network for adjusting an output level from the amplification network and feeding the adjusted output level to the control terminal of the voltage regulator.

2. The circuit of claim 1, wherein the output of the temperature sensor linearly increases in response to increase in temperature.

3. The circuit of claim 1, wherein the second resistance element )s a variable resistance element.

4. The circuit of claim 1, wherein the load is such that the optimum operating voltage linearly decreases with increase in temperature.

5. The circuit of claim 4, wherein the load is a liquid crystal.

6. The circuit of claim 1, wherein a voltage smoothing condenser is connected to at least one of the input terminal and output terminal of the voltage regulator.

7. A temperature compensation voltage-generating circuit for supplying an operating voltage to a load such that an optimum operating voltage varies linearly with change in temperature, the circuit comprising;

a temperature sensor whose output changes linearly in response to the temperature;

a voltage regulator with a control terminal, which outputs an output voltage in response to an electrical signal level fed to the control terminal;

an amplification network which receives the output from the temperature sensor and which amplifies at a gain set so as to vary the output voltage of the voltage regulator with a predetermined gradient;

a level setting network for adjusting an output level from the amplification network and feeding the adjusted output level to the control terminal of the voltage regulator;

wherein the level setting network comprises;

a resistance element interposed between the output terminal of the amplification network and the control terminal of the voltage regulator, and

a resistance element connected between the output terminal and control terminal of the voltage regulator.

8. The circuit of claim 7, wherein the resistance element interposed between the output terminal of the amplification network and the control terminal of the voltage regulator is a variable resistance element.

9. The circuit of claim 7, wherein the amplification network comprises:

an operational amplifier whose negative terminal receives the output of the temperature sensor,

a first resistance element which is interposed between the negative terminal and an output terminal of the temperature sensor, and

a second resistance element which is connected between the negative terminal and an output terminal of the operational amplifier.