# US 10,320,286 B2 · Absorption circuit, feed circuit and liquid crystal display

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- Number: US 10,320,286 B2
- Document ID: US10320286B2
- Status: Granted
- Kind: B2
- Application number: 15/327,612
- Filed: 2016-12-22
- Published: 2018-08-02
- Granted: 2019-06-11
- Earliest claimed: 2016-09-20
- Assignees: Shenzhen China Star Optoelectronics Technology Co., Ltd.
- Applicants: Shenzhen China Star Optoelectronics Technology Co., Ltd.
- Inventors: Dan Cao
- Web page: https://patentgrep.com/patent/US10320286B2

## CPC

- H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
- G09G 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters}
- G09G 3/36: using liquid crystals
- H02M 3/145: using devices of a triode or transistor type requiring continuous application of a control signal
- H02M 3/335: using semiconductor devices only
- G09G 2330/02: Details of power systems and of start or stop of display operation
- G09G 2330/021: Power management, e.g. power saving
- G09G 2330/06: Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
- H02M 1/0038: {Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control}
- H02M 1/0048: {Circuits or arrangements for reducing losses (using snubbers H02M1/34)}
- H02M 1/0064: {Magnetic structures combining different functions, e.g. storage, filtering or transformation}
- H02M 1/344: {Active dissipative snubbers}
- H02M 1/348: {Passive dissipative snubbers}
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

The absorption circuit of the present invention is applied in a feed circuit, wherein the absorption circuit comprises a comparison unit and a regulation unit, and the comparison unit is employed to receive a voltage of a transformer primary dotted terminal of the feed circuit, and to compare the voltage with a first preset voltage and a second preset voltage and to output a comparison result, and the regulation unit is employed to regulate a resistor and a capacitor coupled to the transformer according to the comparison result, wherein the first preset voltage is larger than the second preset voltage. Therefore, the present invention can control the resistor and the capacitor coupled to the transformer according to the leakage inductance (i.e. the voltage) of the transformer, and then to adaptively restrain the corresponding voltage peak and EMI.

## Claims

### Claim 1

An absorption circuit, applied in a feed circuit, wherein the absorption circuit comprises a comparison unit and a regulation unit, and the comparison unit is employed to receive a voltage of a transformer primary dotted terminal of the feed circuit, and to compare the voltage with a first preset voltage and a second preset voltage and to output a comparison result, and the regulation unit is employed to regulate a resistor and a capacitor coupled to the transformer according to the comparison result, wherein the first preset voltage is larger than the second preset voltage.

### Claim 2 (depends on 1)

The absorption circuit according to claim 1, wherein the comparison unit comprises a first comparator, a second comparator, a first electric switch and a first resistor, and a non inverting input terminal of the first comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an inverting input terminal of the first comparator receives the first preset voltage, and an output terminal of the first comparator is coupled to the regulation circuit, and a non inverting input terminal of the second comparator receives the second preset voltage, and an inverting input terminal of the second comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an output terminal of the second comparator is coupled to a control terminal of the first electrical switch, and a first terminal of the first electrical switch is coupled to a voltage terminal through the first resistor and coupled to the regulation unit, and a second terminal of the first electrical switch is grounded.

### Claim 3 (depends on 2)

The absorption circuit according to claim 2, wherein the regulation unit comprises a second electrical switch, a third electrical switch, a fourth electrical switch, a fifth electrical switch, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a third capacitor, and a diode, a control terminal of the second electrical switch is coupled to an output terminal of the first comparator, and a first terminal of the second electrical switch is coupled to a transformer primary homonymous terminal through the second resistor, and a second terminal of the second electrical switch is coupled to a cathode of the diode, and an anode of the diode is coupled to the transformer primary dotted terminal, and a control end of the third electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the third electrical switch is coupled to the transformer primary homonymous terminal, and is also coupled to the cathode of the diode through the third resistor, and a second terminal of the third electrical switch is coupled to the cathode of the diode, and a control terminal of the fourth electrical switch is coupled to the output terminal of the first comparator, and a first terminal of the fourth electrical switch is coupled to the transformer primary homonymous terminal through the first capacitor, and a second terminal of the fourth electrical switch is coupled to the cathode of the diode, and a control terminal of the fifth electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the fifth electrical switch is coupled to the transformer primary homonymous terminal through the second capacitor, and is also coupled to the cathode of the diode through the third capacitor, and a second terminal of the fifth electrical switch is coupled to the cathode of the diode.

### Claim 4 (depends on 3)

The absorption circuit according to claim 3, wherein the first electrical switch to the fifth electrical switch are NPN type field effect transistors, and control terminals, first terminals and second terminals of the first electrical switch to the fifth electrical switch respectively are gates, drains and sources of the field effect transistors.

### Claim 5

A feed circuit, comprising a transformer and an absorption circuit, wherein the absorption circuit comprises a comparison unit and a regulation unit, and the comparison unit is employed to receive a voltage of a transformer primary dotted terminal of the feed circuit, and to compare the voltage with a first preset voltage and a second preset voltage and to output a comparison result, and the regulation unit is employed to regulate a resistor and a capacitor coupled to the transformer according to the comparison result, wherein the first preset voltage is larger than the second preset voltage.

### Claim 6 (depends on 5)

The feed circuit according to claim 5, wherein the comparison unit comprises a first comparator, a second comparator, a first electric switch and a first resistor, and a non inverting input terminal of the first comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an inverting input terminal of the first comparator receives the first preset voltage, and an output terminal of the first comparator is coupled to the regulation circuit, and a non inverting input terminal of the second comparator receives the second preset voltage, and an inverting input terminal of the second comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an output terminal of the second comparator is coupled to a control terminal of the first electrical switch, and a first terminal of the first electrical switch is coupled to a voltage terminal through the first resistor and coupled to the regulation unit, and a second terminal of the first electrical switch is grounded.

### Claim 7 (depends on 6)

The feed circuit according to claim 6, wherein the regulation unit comprises a second electrical switch, a third electrical switch, a fourth electrical switch, a fifth electrical switch, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a third capacitor, and a diode, a control terminal of the second electrical switch is coupled to an output terminal of the first comparator, and a first terminal of the second electrical switch is coupled to a transformer primary homonymous terminal through the second resistor, and a second terminal of the second electrical switch is coupled to a cathode of the diode, and an anode of the diode is coupled to the transformer primary dotted terminal, and a control end of the third electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the third electrical switch is coupled to the transformer primary homonymous terminal, and is also coupled to the cathode of the diode through the third resistor, and a second terminal of the third electrical switch is coupled to the cathode of the diode, and a control terminal of the fourth electrical switch is coupled to the output terminal of the first comparator, and a first terminal of the fourth electrical switch is coupled to the transformer primary homonymous terminal through the first capacitor, and a second terminal of the fourth electrical switch is coupled to the cathode of the diode, and a control terminal of the fifth electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the fifth electrical switch is coupled to the transformer primary homonymous terminal through the second capacitor, and is also coupled to the cathode of the diode through the third capacitor, and a second terminal of the fifth electrical switch is coupled to the cathode of the diode.

### Claim 8 (depends on 7)

The feed circuit according to claim 7, wherein the first electrical switch to the fifth electrical switch are NPN type field effect transistors, and control terminals, first terminals and second terminals of the first electrical switch to the fifth electrical switch respectively are gates, drains and sources of the field effect transistors.

### Claim 9

A display device, comprising a display unit and a feed circuit, and the feed circuit applying power to the display unit, and the feed circuit comprising a transformer and an absorption circuit, wherein the absorption circuit comprises a comparison unit and a regulation unit, and the comparison unit is employed to receive a voltage of a transformer primary dotted terminal of the feed circuit, and to compare the voltage with a first preset voltage and a second preset voltage and to output a comparison result, and the regulation unit is employed to regulate a resistor and a capacitor coupled to the transformer according to the comparison result, wherein the first preset voltage is larger than the second preset voltage.

### Claim 10 (depends on 9)

The display device according to claim 9, wherein the comparison unit comprises a first comparator, a second comparator, a first electric switch and a first resistor, and a non inverting input terminal of the first comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an inverting input terminal of the first comparator receives the first preset voltage, and an output terminal of the first comparator is coupled to the regulation circuit, and a non inverting input terminal of the second comparator receives the second preset voltage, and an inverting input terminal of the second comparator is coupled to the transformer primary dotted terminal to receive the voltage, and an output terminal of the second comparator is coupled to a control terminal of the first electrical switch, and a first terminal of the first electrical switch is coupled to a voltage terminal through the first resistor and coupled to the regulation unit, and a second terminal of the first electrical switch is grounded.

### Claim 11 (depends on 10)

The display device according to claim 10, wherein the regulation unit comprises a second electrical switch, a third electrical switch, a fourth electrical switch, a fifth electrical switch, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a third capacitor, and a diode, a control terminal of the second electrical switch is coupled to an output terminal of the first comparator, and a first terminal of the second electrical switch is coupled to a transformer primary homonymous terminal through the second resistor, and a second terminal of the second electrical switch is coupled to a cathode of the diode, and an anode of the diode is coupled to the transformer primary dotted terminal, and a control end of the third electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the third electrical switch is coupled to the transformer primary homonymous terminal, and is also coupled to the cathode of the diode through the third resistor, and a second terminal of the third electrical switch is coupled to the cathode of the diode, and a control terminal of the fourth electrical switch is coupled to the output terminal of the first comparator, and a first terminal of the fourth electrical switch is coupled to the transformer primary homonymous terminal through the first capacitor, and a second terminal of the fourth electrical switch is coupled to the cathode of the diode, and a control terminal of the fifth electrical switch is coupled to the first terminal of the first electrical switch, and a first terminal of the fifth electrical switch is coupled to the transformer primary homonymous terminal through the second capacitor, and is also coupled to the cathode of the diode through the third capacitor, and a second terminal of the fifth electrical switch is coupled to the cathode of the diode.

### Claim 12 (depends on 11)

The display device according to claim 11, wherein the first electrical switch to the fifth electrical switch are NPN type field effect transistors, and control terminals, first terminals and second terminals of the first electrical switch to the fifth electrical switch respectively are gates, drains and sources of the field effect transistors.