CN102543021A - Full-temperature-section liquid crystal temperature compensating circuit - Google Patents
Full-temperature-section liquid crystal temperature compensating circuit Download PDFInfo
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- CN102543021A CN102543021A CN2011104531434A CN201110453143A CN102543021A CN 102543021 A CN102543021 A CN 102543021A CN 2011104531434 A CN2011104531434 A CN 2011104531434A CN 201110453143 A CN201110453143 A CN 201110453143A CN 102543021 A CN102543021 A CN 102543021A
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Abstract
The invention mainly discloses a full-temperature-section liquid crystal temperature compensating circuit which comprises a temperature sampling branch circuit, a single chip microcomputer, a compensating output circuit and a liquid crystal display. An environmental temperature signal of an instrument is acquired and inputted into the single chip microcomputer by the temperature sampling branch circuit; a compensating signal is outputted by an internal program of the single chip microcomputer according to the temperature signal; and the compensating signal is processed by the compensating output circuit to form a driving signal so as to drive the liquid crystal display to work. According to the invention, the cost is reduced, the performance of the automobile instrument is improved, the temperature compensation can be realized, the compensation of the full temperature section can be carried out, and the instrument can be ensured to still normally work at the limiting working temperature of a vehicle.
Description
Technical field
The present invention relates to automobile instrument lattice lcd technique for temperature compensation field, relevant with a kind of full temperature section liquid crystal temperature compensating circuit especially.
Background technology
At present, the lattice lcd that the automobile instrument use cost is expensive, and lattice lcd can unclear contrast to occur at high temperature or low temperature environment clear, cross effect appears, influenced visual effect.Present domestic lattice lcd is not also accomplished under-30 ℃ ~ 80 ℃ environment, can normally show.In order to overcome above problem, with liquid crystal integrated temperature compensation function, but cost is expensive.Bring huge cost pressure to instrument industry and car load factory.
Given this, the inventor has designed the temperature-compensation circuit of a full temperature section, has satisfied the working environment and the customer demand of liquid crystal-30 ℃ ~ 80 ℃, greatly reduces cost again, and this case produces thus.
Summary of the invention
Fundamental purpose of the present invention provides and a kind ofly can reduce cost, increases the circuit of automobile instrument performance, and this circuit can be realized temperature compensation, and can carry out the compensation of full temperature section, guarantees that instrument can also carry out operate as normal under the ultimate temperature of automobile work.
In order to achieve the above object, the present invention realizes through following technical scheme:
Full temperature section liquid crystal temperature compensating circuit comprises temperature sampling branch road, single-chip microcomputer, compensation output circuit, LCD; Temperature sampling branch road acquisition instrument ambient temperature signal, and this signal inputed in the single-chip microcomputer, the single-chip microcomputer internal processes is exported compensating signal according to temperature signal, and compensating signal forms drive signal through the over-compensation output circuit, the work of driving liquid crystal device.
Described temperature sampling branch road comprises power supply, pull-up resistor R115, thermistor R116, current-limiting resistance R9, and power supply and pull-up resistor R115 and thermistor R116 are connected serially to earth terminal; Current-limiting resistance R9 one end connects pull-up resistor R115 and thermistor R116, and the other end is connected to single-chip microcomputer.
Described compensation output circuit comprises ripple circuit, voltage follower, negative voltage transition circuit; The ripple circuit connects the pulse signal of single-chip microcomputer output, converts this pulse signal near direct current signal; Voltage follower is a discharge circuit, increases the driving force of ripple circuit output signal; The negative voltage transition circuit connects voltage follower, converts positive voltage to required negative voltage, the work of driving liquid crystal device.
Described ripple circuit comprises resistance R 120, resistance R 78, resistance R 79, capacitor C 40; Resistance R 78, resistance R 79 form series connection, are connected between single-chip microcomputer and the voltage follower, and the single-chip microcomputer output terminal is through resistance R 120 ground connection, and the voltage follower input end is through capacitor C 40 ground connection.
Described voltage follower comprises amplifier chip AR1A, resistance R 82, capacitor C 42, capacitor C 44; The 3rd pin of transport and placing device AR1A is an input end, spread groove wave circuit 21; The 1st pin of amplifier chip AR1A is an output terminal; Connect the negative voltage transition circuit; The 1st pin of chip AR1A is connected with the 2nd pin of chip AR1A, and the 1st pin of chip AR1A is connected on the series connection point of resistance R 78 and resistance R 79 through capacitor C 44 feedbacks simultaneously; The 8th pin of chip AR1A connects PING+ through resistance R 82, simultaneously through capacitor C 42 ground connection.
Described negative voltage transition circuit comprises voltage transitions chip IC 2, resistance R 83, R147, capacitor C 43, C46, C47, C48, C49, diode D16, D17; The voltage input pin of voltage transitions chip IC 2 is connected to the output terminal of amplifier chip AR1A through resistance R 83; Voltage input simultaneously is preceding through capacitor C 43 ground connection filtering; The voltage output pin of voltage transitions chip IC 2 connects reverse diode D16, the D17 of placing; Be connected to LCD through resistance R 147 then, the rear and front end after diode D16, the D17 series connection is respectively through capacitor C 47, the filtering of C49 ground connection; The capacitance cathode pin of voltage transitions chip IC 2 is connected through capacitor C 46 with electric capacity negative pole pin, and the electric capacity negative pole pin of voltage transitions chip IC 2 is connected on diode D16, the D17 series connection point through capacitor C 49 simultaneously.
After adopting such scheme, the present invention has many beneficial effects:
The present invention comes the environment temperature of the current liquid crystal work of perception through thermistor, passes through temperature sampling circuit again, is sampled by single-chip microcomputer.Single-chip microcomputer goes out the offset that Current Temperatures need be exported through computation of table lookup, and this offset is the duty cycle signals of a fixed-frequency.This signal outputs to the compensation output circuit, can export a negative voltage, and this negative voltage is supplied with liquid crystal work, and so just can regulate liquid crystal can both operate as normal in full temperature section.
Because thermistor; Components and parts such as single-chip microcomputer can both be in surpassing the voltage range of operate as normal operate as normal, so instrument can the current environment temperature of real-time sampling; Ability real-Time Compensation liquid crystal required voltage so just can make liquid crystal carry out operate as normal at-30 ℃～80 ℃ total temperatures.And greatly reduce the cost of instrument.
Description of drawings
Fig. 1 is the module diagram of preferred embodiment of the present invention;
Fig. 2 is the circuit diagram of preferred embodiment of the present invention;
Fig. 3 is an A point waveform synoptic diagram among Fig. 2;
Fig. 4 is a B point waveform synoptic diagram among Fig. 2;
Fig. 5 is a C point waveform synoptic diagram among Fig. 2.
Fig. 6 is the temperature compensation parameter table of preferred embodiment of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described further.
Like Fig. 1, shown in Figure 2, preferred embodiment of the present invention comprises: temperature sampling branch road 1, single-chip microcomputer 2, compensation output circuit 3, LCD 4.Temperature sampling branch road 1 collecting temperature signal connects the input end of single-chip microcomputer 2; Single-chip microcomputer 2 goes out the offset that Current Temperatures need be exported through computation of table lookup; This offset is the duty cycle signals of a fixed-frequency, from output terminal, exports in the compensation output circuit 3, obtains a negative voltage from compensation output circuit 3; This negative voltage is supplied with LCD 4 work, regulates liquid crystal in full temperature section operate as normal.
Temperature sampling branch road 1 comprises power supply 5V, pull-up resistor R115, thermistor R116, current-limiting resistance R9, and power supply 5V and pull-up resistor R115 and thermistor R116 are connected serially to earth terminal; Current-limiting resistance R9 one end connects pull-up resistor R115 and thermistor R116, and the other end is connected to single-chip microcomputer 2.Thermistor R116 sense ambient temperature with the different resistances of the different formation of temperature, obtains different magnitudes of voltage with pull-up resistor R115 dividing potential drop thus, delivers in the single-chip microcomputer 2 through current-limiting resistance R9 formation temperature signal.
Single-chip microcomputer 2 inner burning temperature polling routines, resulting temperature signal in the input end tabled look-up draws corresponding offset, thereby at the duty cycle signals of a fixed frequency of output terminal output, the waveform that this signal is as shown in Figure 3.
Compensation output circuit 3 comprises ripple circuit 31, voltage follower 32, negative voltage transition circuit 33.
Ripple circuit 31 comprises resistance R 120, resistance R 78, resistance R 79, capacitor C 40; Resistance R 78, resistance R 79 form series connection, are connected between single-chip microcomputer 2 and the voltage follower 32, and single-chip microcomputer 2 output terminals are through resistance R 120 ground connection, and voltage follower 32 input ends are through capacitor C 40 ground connection.Ripple circuit 31 converts the duty cycle signals of output in the single-chip microcomputer 2 to a signal near direct current, and is as shown in Figure 4.
Voltage follower 32 comprises transport and placing device AR1A, resistance R 82, capacitor C 42, capacitor C 44.The 3rd pin of transport and placing device AR1A is an input end, spread groove wave circuit 31.The 1st pin of transport and placing device AR1A is an output terminal; Connect the negative voltage transition circuit; The 1st pin of transport and placing device AR1A is connected with the 2nd pin of transport and placing device AR1A, and the 1st pin of transport and placing device AR1A is connected on the series connection point of resistance R 78 and resistance R 79 through capacitor C 44 feedbacks simultaneously; The 8th pin of transport and placing device AR1A connects PING+ (power supply signal, the voltage signal of direct current 12V is to amplifier work power supply) through resistance R 82, simultaneously through capacitor C 42 ground connection.Because the amplifier chip is selected NVC2904 for use in the present embodiment, has two transport and placing devices in this chip, so, strengthen antijamming capability for the working stability of amplifier.Another transport and placing device AR1B the 6th pin in this chip links to each other the 5th pin ground connection with the 7th pin.The direct current signal of output in the ripple circuit 21, stable through voltage follower 32 amplifiers, be sent to and carry out positive and negative conversion in the negative voltage transition circuit 33.
Voltage conversion circuit 33 comprises voltage transitions chip IC 2, resistance R 83, R147, capacitor C 43, C46, C47, C48, C49, diode D16, D17.Voltage transitions chip IC 2 is selected TPS60400 for use in the present embodiment; The voltage input pin of voltage transitions chip IC 2 is connected to the output terminal of amplifier chip AR1A through resistance R 83; Voltage input simultaneously is preceding through capacitor C 43 ground connection filtering; The voltage output pin of voltage transitions chip IC 2 connects reverse diode D16, the D17 of placing, and is connected to LCD through resistance R 147 then, and the rear and front end after diode D16, the D17 series connection is respectively through capacitor C 47, the filtering of C49 ground connection; The capacitance cathode pin of voltage transitions chip IC 2 is connected through capacitor C 46 with electric capacity negative pole pin, and the electric capacity negative pole pin of voltage transitions chip IC 2 is connected on diode D16, the D17 series connection point through capacitor C 49 simultaneously.Voltage conversion circuit 33 converts positive voltage to a negative voltage at last, 4 work of driving liquid crystal device.
In the present embodiment, also a driving voltage that needs under each temperature of liquid crystal is carried out strict test and experimental verification.The worker's driving voltage that guarantees each point is the optimum working temperature of lattice lcd.As shown in Figure 6, be the temperature compensation parameter table of each temperature spot.
Principle of work of the present invention is following:
Through thermistor R116, sample the environment temperature of current lattice lcd work.Through temperature sampling branch road 1, temperature transition is become magnitude of voltage, and, convert the AD value to and discerned by single-chip microcomputer 2 through single-chip microcomputer 2A/D thief hatch.Single-chip microcomputer 2 programs are confirmed the current needed dutyfactor value of output through tabling look-up, and through delivery outlet output.Compensation output circuit 3 receives this duty cycle signals.Through using the RC ripple circuit of forming by resistance and electric capacity 31, make duty cycle signals convert direct current signal to, and the voltage follower 32 through forming by amplifier, this marking current is amplified.Convert the voltage conversion circuit 33 that the integrated package of negative voltage forms to through a positive voltage again and convert a negative voltage to.This negative voltage is lattice lcd display needed driving voltage under current this temperature, has so just accomplished the temperature compensation work of lattice lcd screen.
For example: Current Temperatures is 20 ℃, and the driving voltage that lattice lcd needs is-7.05V.Be placed on instrument in 70 ℃ the high temperature this moment.It is 70 ℃ that thermistor R116 in the instrument samples current temperature, and single-chip microcomputer 2 receives current environment temperature, and through tabling look-up, a frequency exporting needs output under this temperature is a signal of 70% for the 2KHz dutycycle.This signal is compensated output circuit 3 and is received, through the conversion and the calculating of circuit, and the negative voltage of one-6V of output, and offer lattice lcd display 4 work.This moment, this voltage just can be lattice lcd operate as normal in 70 ℃ high temperature.
The foregoing description only is used to the inventive concept of the present invention of explaining, but not to the qualification of rights protection of the present invention, allly utilizes this design that the present invention is carried out the change of unsubstantiality, all should fall into protection scope of the present invention.
Claims (6)
1. full temperature section liquid crystal temperature compensating circuit is characterized in that: comprise temperature sampling branch road, single-chip microcomputer, compensation output circuit, LCD; Temperature sampling branch road acquisition instrument ambient temperature signal, and this signal inputed in the single-chip microcomputer, the single-chip microcomputer internal processes is exported compensating signal according to temperature signal, and compensating signal forms drive signal through the over-compensation output circuit, the work of driving liquid crystal device.
2. full temperature section liquid crystal temperature compensating circuit as claimed in claim 1; It is characterized in that: described temperature sampling branch road comprises power supply, pull-up resistor R115, thermistor R116, current-limiting resistance R9, and power supply and pull-up resistor R115 and thermistor R116 are connected serially to earth terminal; Current-limiting resistance R9 one end connects pull-up resistor R115 and thermistor R116, and the other end is connected to single-chip microcomputer.
3. full temperature section liquid crystal temperature compensating circuit as claimed in claim 1, it is characterized in that: described compensation output circuit comprises ripple circuit, voltage follower, negative voltage transition circuit; The ripple circuit connects the pulse signal of single-chip microcomputer output, converts this pulse signal near direct current signal; Voltage follower is a discharge circuit, increases the driving force of the signal of ripple circuit output; The negative voltage transition circuit connects voltage follower, converts positive voltage to required negative voltage, the work of driving liquid crystal device.
4. full temperature section liquid crystal temperature compensating circuit as claimed in claim 2, it is characterized in that: described ripple circuit comprises resistance R 120, resistance R 78, resistance R 79, capacitor C 40; Resistance R 78, resistance R 79 form series connection, are connected between single-chip microcomputer and the voltage follower, and the single-chip microcomputer output terminal is through resistance R 120 ground connection, and the voltage follower input end is through capacitor C 40 ground connection.
5. full temperature section liquid crystal temperature compensating circuit as claimed in claim 2, it is characterized in that: described voltage follower comprises amplifier chip AR1A, resistance R 82, capacitor C 42, capacitor C 44; The 3rd pin of transport and placing device AR1A is an input end, spread groove wave circuit 21; The 1st pin of amplifier chip AR1A is an output terminal; Connect the negative voltage transition circuit; The 1st pin of chip AR1A is connected with the 2nd pin of chip AR1A, and the 1st pin of chip AR1A is connected on the series connection point of resistance R 78 and resistance R 79 through capacitor C 44 feedbacks simultaneously; The 8th pin of chip AR1A connects PING+ through resistance R 82, simultaneously through capacitor C 42 ground connection.
6. full temperature section liquid crystal temperature compensating circuit as claimed in claim 2, it is characterized in that: described negative voltage transition circuit comprises voltage transitions chip IC 2, resistance R 83, R147, capacitor C 43, C46, C47, C48, C49, diode D16, D17; The voltage input pin of voltage transitions chip IC 2 is connected to the output terminal of amplifier chip AR1A through resistance R 83; Voltage input simultaneously is preceding through capacitor C 43 ground connection filtering; The voltage output pin of voltage transitions chip IC 2 connects reverse diode D16, the D17 of placing; Be connected to LCD through resistance R 147 then, the rear and front end after diode D16, the D17 series connection is respectively through capacitor C 47, the filtering of C49 ground connection; The capacitance cathode pin of voltage transitions chip IC 2 is connected through capacitor C 46 with electric capacity negative pole pin, and the electric capacity negative pole pin of voltage transitions chip IC 2 is connected on diode D16, the D17 series connection point through capacitor C 49 simultaneously.
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| CN2011104531434A CN102543021A (en) | 2011-12-30 | 2011-12-30 | Full-temperature-section liquid crystal temperature compensating circuit |
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| CN2011104531434A CN102543021A (en) | 2011-12-30 | 2011-12-30 | Full-temperature-section liquid crystal temperature compensating circuit |
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Cited By (2)
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| CN103684276A (en) * | 2012-09-04 | 2014-03-26 | 纬创资通股份有限公司 | Temperature compensation circuit and electronic device with temperature compensation |
| WO2015109801A1 (en) * | 2014-01-27 | 2015-07-30 | 京东方科技集团股份有限公司 | Gamma reference voltage generation device, and display |
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| CN103684276A (en) * | 2012-09-04 | 2014-03-26 | 纬创资通股份有限公司 | Temperature compensation circuit and electronic device with temperature compensation |
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| US9997097B2 (en) | 2014-01-27 | 2018-06-12 | Boe Technology Group Co., Ltd. | Gamma reference voltage generating device and display with temperature compensation |
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Application publication date: 20120704 |