CN201689651U - Circuit capable of realizing the fixed frequency and adjusting the duty ratio by button - Google Patents
Circuit capable of realizing the fixed frequency and adjusting the duty ratio by button Download PDFInfo
- Publication number
- CN201689651U CN201689651U CN2010202224292U CN201020222429U CN201689651U CN 201689651 U CN201689651 U CN 201689651U CN 2010202224292 U CN2010202224292 U CN 2010202224292U CN 201020222429 U CN201020222429 U CN 201020222429U CN 201689651 U CN201689651 U CN 201689651U
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- circuit
- button
- comparer
- wave
- fixed frequency
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Abstract
The utility model provides a circuit which is capable of realizing the fixed frequency and adjusting the duty ratio by a button and is characterized by comprising a digital potentiometer, a square wave generator circuit, a square wave and triangle wave transferring circuit, and a comparator, wherein the digital potentiometer is connected with the comparator, the square wave generator circuit, the square wave and triangle wave transferring circuit and the comparator are connected in turn. The utility model is realized by adopting the pure hardware circuit, which solves the problem that the prior art depends on the software programming to realize the duty ratio adjusting mode.
Description
[technical field]
The utility model relates to a kind of liquid crystal display, particularly a kind of liquid crystal display backlight control circuit.
[background technology]
Development along with technology, the backlight control mode of liquid crystal display replaces traditional inverter dimming mode by the PWM mode, novel PWM transfers mode backlight adjustable extent backlight can be become wideer, and it is more stable, this novel PWM transfers mode backlight need be operated under certain fixed frequency condition, thereby the time by the adjustment high level changes its output voltage values, is dutycycle; At present on the market except realizing this mode by software is programmed, still not having other corresponding ready-made chips realizes, the bigger difficulty that has owing to software programming, cost is also higher, therefore be unfavorable for saving cost, need a kind of circuit that adopt pure hardware to realize the mode of this fixed frequency, adjustable dutycycle.
[utility model content]
The technical problems to be solved in the utility model, be to provide a kind of button to realize the circuit of fixed frequency, adjustable dutycycle, solve the mode that the programming of prior art depended software realizes EDM Generator of Adjustable Duty Ratio, adopt pure hardware circuit to realize, and can set the maximum or the minimum value of dutycycle.
The utility model is achieved in that the circuit of a kind of button realization fixed frequency, adjustable dutycycle, comprises that a digital regulation resistance, a square-wave generator circuit, a square wave change triangle wave circuit, and one first comparer; Described digital regulation resistance is connected with described first comparer with button respectively; Described square-wave generator circuit, described square wave change triangle wave circuit and described first comparer connects in turn.
It is the resistance capacitance charge-discharge circuit that described square wave changes triangle wave circuit, or the integrating circuit that adopts second comparer to be connected into.
Described digital regulation resistance is connected with the positive pole of described first comparer; Square wave changes triangle wave circuit and is connected with the negative pole of described first comparer.
Described digital regulation resistance is X9511 digital regulation resistance or ISL22511 digital regulation resistance; Described square-wave generator circuit is the NE555 square-wave generator; The LM358 chip comparator that described first comparer is a single supply.
Advantage of the present utility model is: adopt pure hardware circuit to realize, solved the mode of prior art depended software programming realization EDM Generator of Adjustable Duty Ratio; Can store adjusted dutycycle, and can set the maximum or the minimum value of dutycycle, power down is difficult for losing, automatically access adjusted duty electricity last time numerical value.
[description of drawings]
In conjunction with the embodiments the utility model is further described with reference to the accompanying drawings.
Fig. 1 is a circuit block diagram of the present utility model.
[embodiment]
See also shown in Figure 1ly, button of the present utility model is realized the circuit of fixed frequency, adjustable dutycycle, comprises that a digital regulation resistance 1, a square-wave generator circuit 2, a square wave change triangle wave circuit 3, and one first comparer 4; Described digital regulation resistance 1 is connected with described first comparer 4 with button 5 respectively; Described square-wave generator circuit 2, described square wave change triangle wave circuit 3 and described first comparer 4 connects in turn.During connection, described digital regulation resistance 1 can be connected with the positive pole of described first comparer 4; Square wave changes triangle wave circuit 3 and is connected with the negative pole of described first comparer 4, but is not limited thereto.
The function of the utility model each several part circuit is as follows:
Described digital regulation resistance 1: be used to store corresponding key information, by digital regulation resistance the touch-switch push button signalling is converted to adjustable level signal, this digital regulation resistance can select to use X9511 digital regulation resistance or ISL22511 digital regulation resistance, its adjustable accuracy can reach 32, promptly can produce 32 stepped voltages;
Described square-wave generator circuit 2: be used to realize fixed frequency, the fixing square wave of dutycycle, by disposing peripheral RC circuit, thereby realize the frequency that needs, generally select dutycycle to be fixed as 50% square wave generation circuit, as NE555 square-wave generator circuit;
Described square wave changes triangle wave circuit 3: the simplest implementation method is by resistance capacitance charge-discharge circuit (RC), utilization realizes the conversion of square wave-triangular wave to discharging and recharging of resistance capacitance charge-discharge circuit, also can adopt second comparer to be connected into complicated integrating circuit;
Described first comparer 4: be used for level signal and triangular wave that digital regulation resistance is realized are compared, can realize the circuit of fixed frequency, EDM Generator of Adjustable Duty Ratio, this first comparer can be selected the LM358 chip comparator of single supply.
Principle of work of the present utility model is as follows:
One branch road is by described digital regulation resistance 1 push button signalling of button 5 to be converted to adjustable level signal; Simultaneously another branch road produces dutycycles by described square-wave generator circuit 2 and is fixed as 50% square wave, and changes triangle wave circuit 3 by described square wave and convert triangular wave to; By described first comparer 4 described level signal and triangular wave are compared at last, can realize the fixed frequency backlight of liquid crystal display and the control of adjustable dutycycle.Because described digital regulation resistance 1 has memory function, thus the difficult mistake of power down, benefit from the result that this power down is difficult for mistake, the brightness of liquid crystal display all can keep the adjusted brightness of last user when starting shooting at every turn; Can set the maximum or the minimum value of dutycycle again by first comparer 4, can realize controlling the high-high brightness and the minimum brightness of liquid crystal display, to produce the PWM backlight control mode that is fit to present liquid crystal display (as the notebook liquid crystal display etc.) needs.
Claims (6)
1. a button is realized the circuit of fixed frequency, adjustable dutycycle, it is characterized in that: comprise that a digital regulation resistance, a square-wave generator circuit, a square wave change triangle wave circuit, and one first comparer; Described digital regulation resistance is connected with described first comparer with button respectively; Described square-wave generator circuit, described square wave change triangle wave circuit and described first comparer connects in turn.
2. a kind of button as claimed in claim 1 is realized the circuit of fixed frequency, adjustable dutycycle, it is characterized in that: it is the resistance capacitance charge-discharge circuit that described square wave changes triangle wave circuit, or the integrating circuit that adopts second comparer to be connected into.
3. a kind of button as claimed in claim 1 is realized the circuit of fixed frequency, adjustable dutycycle, and it is characterized in that: described digital regulation resistance is connected with the positive pole of described first comparer; Described square wave changes triangle wave circuit and is connected with the negative pole of described first comparer.
4. a kind of button as claimed in claim 1 is realized the circuit of fixed frequency, adjustable dutycycle, and it is characterized in that: described digital regulation resistance is the X9511 digital regulation resistance, or the ISL22511 digital regulation resistance.
5. a kind of button as claimed in claim 1 is realized the circuit of fixed frequency, adjustable dutycycle, and it is characterized in that: described square-wave generator circuit is the NE555 square-wave generator.
6. realize the circuit of fixed frequencies, adjustable dutycycle as claim 1 or 3 described a kind of buttons, it is characterized in that: the LM358 chip comparator that described first comparer is a single supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202224292U CN201689651U (en) | 2010-06-10 | 2010-06-10 | Circuit capable of realizing the fixed frequency and adjusting the duty ratio by button |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202224292U CN201689651U (en) | 2010-06-10 | 2010-06-10 | Circuit capable of realizing the fixed frequency and adjusting the duty ratio by button |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201689651U true CN201689651U (en) | 2010-12-29 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010202224292U Expired - Fee Related CN201689651U (en) | 2010-06-10 | 2010-06-10 | Circuit capable of realizing the fixed frequency and adjusting the duty ratio by button |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201689651U (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102635564A (en) * | 2012-02-27 | 2012-08-15 | 石家庄市公共交通总公司 | Air-conditioning blower control system of natural gas bus |
| CN102932981A (en) * | 2011-08-11 | 2013-02-13 | 原景科技股份有限公司 | Dimming device and signal adjustment device thereof |
| CN102968965A (en) * | 2012-12-14 | 2013-03-13 | 深圳市华星光电技术有限公司 | Direct type LED (Light-emitting Diode) backlight source |
| US9024532B2 (en) | 2012-12-14 | 2015-05-05 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Direct type LED backlight and liquid crystal display thereof |
| CN106817102A (en) * | 2013-11-12 | 2017-06-09 | 歌尔科技有限公司 | A kind of volume adjustment device, volume adjusting method and a kind of electronic equipment |
-
2010
- 2010-06-10 CN CN2010202224292U patent/CN201689651U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102932981A (en) * | 2011-08-11 | 2013-02-13 | 原景科技股份有限公司 | Dimming device and signal adjustment device thereof |
| CN102932981B (en) * | 2011-08-11 | 2016-01-20 | 原景科技股份有限公司 | Light modulating device and sig-nal-conditioning unit thereof |
| CN102635564A (en) * | 2012-02-27 | 2012-08-15 | 石家庄市公共交通总公司 | Air-conditioning blower control system of natural gas bus |
| CN102635564B (en) * | 2012-02-27 | 2014-12-10 | 于新泉 | Air-conditioning blower control system of natural gas bus |
| CN102968965A (en) * | 2012-12-14 | 2013-03-13 | 深圳市华星光电技术有限公司 | Direct type LED (Light-emitting Diode) backlight source |
| US9024532B2 (en) | 2012-12-14 | 2015-05-05 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Direct type LED backlight and liquid crystal display thereof |
| CN106817102A (en) * | 2013-11-12 | 2017-06-09 | 歌尔科技有限公司 | A kind of volume adjustment device, volume adjusting method and a kind of electronic equipment |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20101229 Termination date: 20120610 |