CN111243537B - Common voltage generating circuit, method and display device - Google Patents
Common voltage generating circuit, method and display device Download PDFInfo
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- CN111243537B CN111243537B CN202010047348.1A CN202010047348A CN111243537B CN 111243537 B CN111243537 B CN 111243537B CN 202010047348 A CN202010047348 A CN 202010047348A CN 111243537 B CN111243537 B CN 111243537B
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- 239000004973 liquid crystal related substance Substances 0.000 description 5
- RVCKCEDKBVEEHL-UHFFFAOYSA-N 2,3,4,5,6-pentachlorobenzyl alcohol Chemical compound OCC1=C(Cl)C(Cl)=C(Cl)C(Cl)=C1Cl RVCKCEDKBVEEHL-UHFFFAOYSA-N 0.000 description 2
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3696—Generation of voltages supplied to electrode drivers
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Abstract
The invention discloses a public voltage generating circuit, a method and a display device, wherein the public voltage generating circuit comprises: a first signal generator providing a viewing angle control signal; a second signal generator providing a reference square wave signal; the first switching module outputs one of a first pull-up signal and a second pull-up signal according to the visual angle control signal; the second switching module outputs one of the first power supply signal and the second power supply signal according to the visual angle control signal; and the comparator receives the reference voltage signal and outputs a first common voltage according to the reference voltage signal, the reference square wave signal, the first pull-up signal and the first power supply signal or outputs a second common voltage according to the reference voltage signal, the reference square wave signal, the second pull-up signal and the second power supply signal. The invention can provide the first public voltage and the second public voltage with different amplitudes for the display device, and has the advantages of small circuit volume, simple structure and low cost.
Description
Technical Field
The invention relates to the technical field of display, in particular to a common voltage generating circuit, a common voltage generating method and a display device.
Background
Liquid Crystal Displays (LCDs) have many advantages such as being light and thin, saving energy, and having no radiation, and thus have gradually replaced conventional Cathode Ray Tube (CRT) displays. Liquid crystal displays are widely used in high definition digital televisions, desktop computers, Personal Digital Assistants (PDAs), notebook computers, mobile phones, digital cameras, and other electronic devices.
At present, the wide viewing angle belongs to the mainstream development direction of the liquid crystal display. For example, wide viewing angle technology is used in portable electronic devices with wide viewing angles, such as notebook computers, personal digital assistants, tablet computers, and mobile phones, so that people can see complete and undistorted pictures when watching wide viewing angle displays from different directions. However, when the privacy and important information are concerned, the wide viewing angle display is inconvenient for people in some situations, for example, when a vehicle is at a station, people beside and behind the user are likely to see the contents on the screen of the wide viewing angle portable electronic device.
Therefore, in addition to the demand for a wide viewing angle, displays capable of switching or adjusting the display to a narrow viewing angle mode have been developed in the case where peep prevention is required. The display has mixed visual angles, and can realize switching between Wide visual Angle (Wide Viewing Angle) and Narrow visual Angle (Narrow Viewing Angle).
As shown in fig. 1, fig. 1 shows a block diagram of a conventional common voltage generating circuit, which includes a signal generator 110, a microcontroller 120, a digital-to-analog converter 130, a first voltage follower 140, a second voltage follower 150 and an adder 160, wherein the signal generator 110 provides an HVA signal (Viewing Angle control signal) to the microcontroller 120, the microcontroller 120 transmits data to the digital-to-analog converter 130 through an I2C bus according to the HVA signal, the digital-to-analog converter 130 generates square waves of different amplitudes according to the transmitted data and outputs the first voltage follower 140 to generate a first analog signal FB1 of different amplitudes, the second voltage follower 150 receives a negative voltage signal-VS to generate a second analog signal FB2, and the adder 160 generates first and second common voltages of different amplitudes required for the liquid crystal display device according to the first and second analog signals FB1 and FB 2.
However, the existing common voltage generating circuit occupies a serial interface, and meanwhile, the cost of the digital-to-analog converter in the existing common voltage generating circuit is slightly higher than that of common elements, the size of the existing common voltage generating circuit is large, a large part of PCBA board space can be occupied, and high design cost is caused.
Therefore, there is a need to provide an improved technical solution to overcome the above technical problems in the prior art.
Disclosure of Invention
In order to solve the technical problems, the invention provides a common voltage generating circuit, a method and a display device, which can provide a first common voltage and a second common voltage with different amplitudes for the display device, and have the advantages of small circuit size, simple structure and low cost.
According to the present invention, there is provided a common voltage generating circuit comprising: a first signal generator for providing a viewing angle control signal; a second signal generator for providing a reference square wave signal; the first switching module is connected with the first signal generator and used for receiving the visual angle control signal and outputting one of a first pull-up signal and a second pull-up signal according to the visual angle control signal; the second switching module is connected with the first signal generator and used for receiving the visual angle control signal and outputting one of a first power supply signal and a second power supply signal according to the visual angle control signal; and the comparator is respectively connected with the second signal generator, the first switching module and the second switching module, receives a reference voltage signal, and is used for outputting a first common voltage according to the reference voltage signal, the reference square wave signal, the first pull-up signal and the first power supply signal or outputting a second common voltage according to the reference voltage signal, the reference square wave signal, the second pull-up signal and the second power supply signal.
Preferably, the common voltage generation circuit further includes: a pull-up resistor connected in series between the output terminal of the first switching module and the output terminal of the comparator.
Preferably, the common voltage generation circuit further includes: and the output control module is positioned between the output end of the first switching module and the output end of the comparator and is used for controlling the first switching module to only pull up the first common voltage and the second common voltage with high level.
Preferably, the first switching module includes: the first switch tube is connected with the positive power supply end through a first resistor and a second resistor which are connected in series in sequence, the second switch tube is grounded, and the control end receives the visual angle control signal; and the non-inverting input end of the voltage follower is connected with the connecting node of the first resistor and the second resistor, the inverting input end of the voltage follower is connected with the output end, the first power supply end of the voltage follower is connected with the positive voltage source, the second power supply end of the voltage follower is connected with the negative voltage source, and the first switching tube is an NMOS transistor.
Preferably, the second switching module includes: the first path end of the second switching tube receives the visual angle control signal, the second path end of the second switching tube is connected with the negative power supply end sequentially through a fourth resistor and a fifth resistor, and the control end of the second switching tube is grounded; and the connection node of the fourth resistor and the fifth resistor is connected with the negative power supply end of the comparator, wherein the second switching tube is a PMOS transistor.
Preferably, the output control module includes: the first path end of the third switching tube is connected with the positive power supply end through a third resistor, the second path end of the third switching tube is grounded, and the control end of the third switching tube receives the reference square wave signal; and the first path end of the fourth switching tube is connected with the output end of the voltage follower, the second path end of the fourth switching tube is connected with the output end of the comparator through the pull-up resistor, the control end of the fourth switching tube is connected with the positive power supply end through the third resistor, the third switching tube is an NMOS transistor, and the fourth switching tube is a PMOS transistor.
Preferably, the output control module includes: and a first path end of the fifth switching tube is connected with the output end of the voltage follower, a second path end of the fifth switching tube is connected with the output end of the comparator through the pull-up resistor, and a control end of the fifth switching tube receives the reference square wave signal, wherein the fifth switching tube is an NMOS transistor.
Preferably, the voltage value of the first pull-up signal is smaller than that of the second pull-up signal, and the voltage value of the first power supply signal is larger than that of the second power supply signal.
Preferably, the second signal generating means is one of a microprocessor and a timing controller.
The invention provides a common voltage generation method, which comprises the following steps: receiving the positive power supply voltage and the negative power supply voltage by a comparator, and outputting a first common voltage according to a reference square wave signal and a reference voltage signal; and/or changing the voltage value of the negative power supply voltage received by the comparator according to the viewing angle control signal when the reference square wave signal is at a low level to generate a second common voltage, wherein the level state of the viewing angle control signal is changed to control the generation of pull-up signals with different voltage values and the generation of the negative power supply voltage with different voltage values.
According to the present invention, there is provided a display device comprising: the display panel is provided with a common electrode wire; the common voltage generating circuit is used for outputting a first common voltage and a second common voltage with different amplitudes to the common electrode line for connection so as to control the display panel to switch between a wide viewing angle and a narrow viewing angle.
The invention has the beneficial effects that: the invention discloses a common voltage generating circuit, a method and a display device.
The pull-up resistor is arranged, so that the circuit can be kept stable, false triggering is avoided, and meanwhile, the impedance matching of the circuit can be enhanced to keep the integrity of signals.
The output control module is arranged, the first switching module can be controlled to only pull up the first public voltage and the second public voltage of the high level, the signal confusion caused by invalid pull-up when the comparator outputs the low level is avoided, the output quality of the first/second public voltage is improved, and the energy loss is saved.
By setting the magnitude relation of the voltage values of the signals output by the comparator, the maximum amplitude difference output of the first common voltage and the second common voltage can be realized, and the easiness of identifying the first common voltage and the second common voltage by the display device is improved.
The timing controller can provide a reference square wave signal, and the circuit size is further reduced.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 is a block diagram showing a structure of a common voltage generating circuit;
FIG. 2 is a block diagram of an improved common voltage generation circuit according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a common voltage generating circuit according to an embodiment of the present invention;
FIG. 4 is a graph showing simulation results of the common voltage generation circuit of FIG. 3;
fig. 5 is a flowchart illustrating a common voltage generation method according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The present invention will be described in detail below with reference to the accompanying drawings.
Fig. 2 is a block diagram showing a configuration of a common voltage generating circuit according to an embodiment of the present invention.
As shown in fig. 2, in the present embodiment, the common voltage generation circuit includes: a first signal generator 210, a second signal generator 220, a comparator 230, a first switching module 240, and a second switching module 250.
Wherein the first signal generator 210 is used to provide the viewing angle control signal HVA.
The second signal generator 220 is used to provide a reference square wave signal.
In this embodiment, in an embodiment of the present invention, the second signal generator 220 may be a Micro Controller Unit (MCU) including a clock terminal SCL and a data terminal SDA. The clock terminal SCL is used for sending a clock signal, and the data terminal SDA is used for sending a voltage signal. In another possible embodiment, the second signal generator 220 may be a Timing Controller (TCON), which may eliminate the design of a microprocessor and its peripheral circuits, and further save the PCBA board space.
The first switching module 240 is connected to the first signal generator 210 and the comparator 230, respectively, and is configured to receive the viewing angle control signal HVA and output one of a first pull-up signal and a second pull-up signal to the comparator 230 according to the viewing angle control signal HVA.
The second switching module 250 is respectively connected to the first signal generator 210 and the comparator 230, and is configured to receive the viewing angle control signal HVA and output one of the first power supply signal and the second power supply signal to the comparator 230 according to the viewing angle control signal HVA.
The comparator 230 is connected to the second signal generator 220, the first switching module 240, and the second switching module 250, respectively, and receives a reference voltage signal, and is configured to output a first common voltage according to the reference square wave signal, the reference voltage signal, the first pull-up signal, and the first power supply signal; or for outputting a second common voltage in dependence on the reference square wave signal, the reference voltage signal, the second pull-up signal and the second supply signal.
Further, the voltage value of the first pull-up signal is smaller than that of the second pull-up signal, and the voltage value of the first power supply signal is larger than that of the second power supply signal. And then the output of the first common voltage and the second common voltage with the largest difference value can be realized.
It should be noted that, in other embodiments of the present invention, the magnitude relationship between the voltage values corresponding to the first pull-up signal, the second pull-up signal, the first power supply signal, and the second power supply signal may also be in other forms, as long as the final amplitudes of the output first common voltage and the output second common voltage are different, and the wide viewing angle switching and the narrow viewing angle switching of the display device can be controlled and realized.
In this embodiment, the first common voltage and the second common voltage are respectively used to realize the wide viewing angle/narrow viewing angle switching of the liquid crystal display device.
In this embodiment, the output terminal of the first switching module 240 is connected to the output terminal OUT of the comparator 230, and the output signal of the comparator 230 is pulled up to change the voltage values corresponding to the high levels of the first common voltage and the second common voltage output by the comparator 230. When the comparator 230 outputs the first common voltage, the first switching module 240 outputs a first pull-up signal (e.g., 2.5V) to pull up the first common voltage to a first voltage value; when the comparator 230 outputs the second common voltage, the first switching module 240 outputs a second pull-up signal (e.g., 5V) to pull up the second common voltage to the second voltage value.
Optionally, the output of the first switching module 240 may also be connected to the positive voltage supply of the comparator 230.
Further, a pull-up resistor Rp is also connected in series between the output terminal of the first switching module 240 and the output terminal OUT of the comparator 230, so as to keep the circuit stable, avoid false triggering, and enhance the impedance matching of the circuit to keep the signal integrity.
In this embodiment, the output terminal of the second switching module 250 is connected to the negative power supply terminal of the comparator 230, and provides negative power supply signals with different voltage values, such as-2.5V/-5V, to the comparator 230, so as to change the voltage values corresponding to the low levels of the first common voltage and the second common voltage output by the comparator 230. Further, when the comparator 230 outputs the first common voltage, the second switching module 250 outputs a first power supply signal (e.g., -2.5V); when the comparator 230 outputs the second common voltage, the second switching module 250 outputs a second power supply signal (e.g., -5V). The second switching module 250 changes the voltage value of the negative voltage supply terminal of the comparator 230, and thus changes the voltage value of the low level of the common voltage output by the comparator 230.
In another preferred embodiment, an output control module 260 is further disposed between the output end of the first switching module 240 and the output end OUT of the comparator 230, and the output control module 260 is configured to control the first switching module 240 to pull up only when the comparator 230 outputs a high level, so as to avoid signal confusion caused by invalid pull-up when the comparator 230 outputs a low level, improve the output quality of the first/second common voltages, and save energy loss.
In this embodiment, the first switching module 240 and the second switching module 250 are configured to simultaneously adjust the amplitudes of the high level and the low level of the reference voltage output by the comparator 230, and the first switching module 240 outputs the first pull-up signal and the second switching module 250 outputs the first power supply signal (or the first switching module 240 outputs the second pull-up signal and the second switching module 250 outputs the second power supply signal) as in-phase outputs, so that the maximum amplitude adjustment between the first common voltage and the second common voltage can be realized.
Fig. 3 is a schematic circuit diagram of a common voltage generating circuit according to an embodiment of the present invention.
As shown in fig. 3, in the present embodiment, the non-inverting input terminal of the comparator U2 receives the reference square wave signal, the inverting input terminal receives the reference voltage signal Vref, and the output terminal outputs one of the first common voltage and the second common voltage.
Further, the voltage value of the reference voltage signal Vref is smaller than the voltage value corresponding to the high level of the reference square wave signal and larger than the voltage value corresponding to the low level of the reference square wave signal.
The first switching module 240 includes a first switching tube Q1, a first resistor R1, a second resistor R2, and a voltage follower U1. The first path end of the first switch tube Q1 is connected to the positive power terminal VCC through the first resistor R1 and the second resistor R2 connected in series in sequence, the second path end of the first switch tube Q1 is grounded, and the control end of the first switch tube Q1 receives the view angle control signal HVA. The non-inverting input end of the voltage follower U1 is connected with the connection node of the first resistor R1 and the second resistor R2, the inverting input end is connected with the output end, the first power supply end is connected with the positive voltage source VCC, and the second power supply end is connected with the negative voltage source VEE.
Further, the first switch Q1 is an NMOS transistor.
The second switching module 250 includes a second switching tube Q2, a fourth resistor R4, and a fifth resistor R5. The first path end of the second switch tube Q2 is connected to the viewing angle control signal HVA, the second path end is connected to the negative power supply VEE through the fourth resistor R4 and the fifth resistor R5 in sequence, and the control end of the second switch tube Q2 is grounded. The connection node of the fourth resistor R4 and the fifth resistor R5 is connected with the negative voltage supply end of the comparator U2.
Further, the second switch Q2 is a PMOS transistor.
In one possible implementation, the output control module 260 includes a third switching tube Q3, a fourth switching tube Q4, and a third resistor R3. The first path of the third switch Q3 is connected to the positive power terminal VCC through the third resistor R3, the second path of the third switch Q3 is grounded, and the control terminal of the third switch Q3 receives the reference square wave signal. A first pass end of the fourth switching tube Q4 is connected with an output end of the voltage follower U1, a second pass end of the fourth switching tube Q4 is connected with an output end OUT of the comparator U2 through a pull-up resistor Rp, and a control end of the fourth switching tube Q4 is connected with a positive power supply end VCC through a third resistor R3.
Furthermore, the third switch Q3 is an NMOS transistor, and the fourth switch Q4 is a PMOS transistor.
In another possible implementation, the output control module 260 includes a fifth switch tube. The fifth switching tube is an NMOS transistor, a first path end of the fifth switching tube is connected with the output end of the voltage follower U1, a second path end of the fifth switching tube is connected with the output end OUT of the comparator U2 through a pull-up resistor Rp, and a control end of the fifth switching tube receives the reference square wave signal.
The operation principle of the common voltage generating circuit in the present embodiment will be further described with reference to fig. 4.
Fig. 4 is a graph showing simulation results of the common voltage generation circuit of fig. 3.
As shown in fig. 4, in the common voltage generating circuit disclosed in the present invention, on the one hand, when the viewing angle control signal HVA is at a high level, the first switch Q1 is controlled to be turned on, and at this time, due to the voltage division function of the first resistor R1 and the second resistor R2, the voltage at the forward input end (i.e., the node a) of the voltage follower U1 is less than the voltage at the positive power source terminal VCC, e.g., VCC is 5V, the voltage at the point a is 2.5V, and the output end of the voltage follower U1 outputs the first pull-up signal at the first voltage value (e.g., 2.5V). Meanwhile, when the view angle control signal HVA is at a high level, the gate-source voltage of the second switch transistor Q2 is less than the turn-on voltage thereof, and the second switch transistor Q2 is turned on, at this time, due to the voltage division effect of the fourth resistor R4 and the fifth resistor R5, the negative voltage supply terminal (i.e., node B) of the comparator U2 receives the first power supply signal at the third voltage value (e.g., -2.5V).
In the above case (i.e., when the view angle control signal HVA is at the high level), the output terminal OUT of the comparator U2 outputs a high level signal when the reference square wave signal is at the high level. Meanwhile, the third switching tube Q3 is turned on, the control terminal (node C) of the fourth switching tube Q4 is grounded through the third switching tube Q3, the fourth switching tube Q4 is turned on, and then the first pull-up signal output by the voltage follower U1 pulls up the high-level signal output by the comparator U2 to the first voltage value.
When the reference square wave signal is at a low level, the output terminal OUT of the comparator U2 outputs a low level signal corresponding to the third voltage value. Meanwhile, the third switching tube Q3 is turned off, the control terminal (node C) of the fourth switching tube Q4 is connected with the positive voltage source VCC through the third resistor R3, the fourth switching tube Q4 is turned off, and the first pull-up signal output by the voltage follower U1 does not pull up the signal output by the comparator U2.
In summary, when the view angle control signal HVA is at the high level, the comparator U2 outputs the first common voltage with the high level being the first voltage value and the low level being the third voltage value.
On the other hand, when the view angle control signal HVA is at a low level, the first switch Q1 is controlled to turn off, and at this time, since the current paths of the first resistor R1 and the second resistor R2 are disconnected, the voltage at the positive input terminal (i.e., the node a) of the voltage follower U1 is pulled up to the voltage at the positive power terminal VCC (e.g., VCC is 5V), and the output terminal of the voltage follower U1 outputs a second pull-up signal at a second voltage value (e.g., 5V). Meanwhile, when the view angle control signal HVA is at a low level, the gate-source voltage of the second switch transistor Q2 is greater than its turn-on voltage, and the second switch transistor Q2 is turned off, and at this time, the negative voltage supply terminal (i.e., node B) of the comparator U2 receives the second power supply signal having a fourth voltage value (e.g., -5V).
In the above case (i.e., when the view angle control signal HVA is at the low level), the output terminal OUT of the comparator U2 outputs a high level signal when the reference square wave signal is at the high level. Meanwhile, the third switching tube Q3 is turned on, the control terminal (node C) of the fourth switching tube Q4 is grounded through the third switching tube Q3, the fourth switching tube Q4 is turned on, and then the second pull-up signal output by the voltage follower U1 pulls up the high-level signal output by the comparator U2 to the second voltage value.
When the reference square wave signal is at a low level, the output terminal OUT of the comparator U2 outputs a low level signal corresponding to the third voltage value. Meanwhile, the third switching tube Q3 is turned off, the control terminal (node C) of the fourth switching tube Q4 is connected with the positive voltage source VCC through the third resistor R3, the fourth switching tube Q4 is turned off, and the first pull-up signal output by the voltage follower U1 does not pull up the signal output by the comparator U2.
In summary, when the view angle control signal HVA is at the low level, the comparator U2 outputs the second common voltage with the high level being the second voltage value and the low level being the fourth voltage value.
Further, the first voltage value is smaller than the second voltage value, and the third voltage value is larger than the fourth voltage value.
Fig. 5 is a flowchart illustrating a common voltage generation method according to an embodiment of the present invention.
As shown in fig. 5, in this embodiment, the common voltage generation method includes the following steps:
in step S01, the positive polarity power supply voltage and the negative polarity power supply voltage are received by the comparator, and the first common voltage is output according to the reference square wave signal and the reference voltage signal.
Referring to fig. 3 and 4, the comparator U2 has a first power supply terminal receiving the positive power supply voltage, a second power supply terminal receiving the negative power supply voltage, a non-inverting input terminal receiving the reference square wave signal, an inverting input terminal receiving the reference voltage signal Vref, and an output terminal outputting the first reference voltage. The high level voltage of the reference square wave signal is greater than the voltage value corresponding to the reference voltage signal Vref, and the low level voltage of the reference square wave signal is less than the voltage value corresponding to the reference voltage signal Vref. That is, the comparator U2 outputs the first reference voltage as a square wave according to the reference square wave signal.
In step S02, the first common voltage is pulled up according to the viewing angle control signal when the reference square wave signal is at a high level, and/or the voltage value of the negative polarity supply voltage received by the comparator is changed according to the viewing angle control signal when the reference square wave signal is at a low level to generate the second common voltage.
In this embodiment, the first switching module 240 is controlled to generate the first pull-up signal and the second pull-up signal with different voltage values, and the second switching module 250 is controlled to generate the first negative power voltage and the second negative power voltage with different voltage values by changing the level state of the HVA. For the specific principle, reference may be made to fig. 3 and 4, which are not described herein again.
Further, in the first embodiment of the present invention, the voltage value of the negative polarity power supply voltage of the comparator U2 is controlled to be constant (for example, the second switch transistor Q2 in fig. 3 is removed, and one end of the fourth resistor R4 is directly connected to the power input terminal outputting the same voltage as the high level of the view angle control signal HVA) during the low level phase of the reference square wave signal, the voltage value of the pull-up signal generated by the first switching module 240 is changed according to the view angle control signal HVA only during the high level phase of the reference square wave signal, and the output signal of the comparator U2 is pulled up, thereby generating the second common voltage having a different magnitude from the first common voltage.
In the second embodiment of the present invention, the voltage value of the pull-up signal generated by the first switching module 240 is controlled to be unchanged in the high level stage of the reference square wave signal (for example, the first switching transistor Q1 in fig. 3 is removed, and one end of the second resistor R2 is directly grounded), and the voltage value of the negative polarity power supply voltage generated by the second switching module 250 is changed according to the view angle control signal HVA only in the low level stage of the reference square wave signal, so as to change the voltage value corresponding to the low level state of the output signal of the comparator U2, and generate the second common voltage with the amplitude different from the first common voltage.
In the third embodiment of the present invention, the voltage value of the pull-up signal generated by the first switching module 240 is changed according to the viewing angle control signal HVA at the high level stage of the reference square wave signal, and the voltage value of the negative polarity supply voltage generated by the second switching module 250 is changed according to the viewing angle control signal HVA at the low level stage of the reference square wave signal, thereby simultaneously changing the high level state corresponding voltage value and the low level state corresponding voltage value of the output signal of the comparator U2, and generating the second common voltage having a different amplitude from the first common voltage.
The public voltage generating method disclosed by the invention can realize the adjustment of the public voltage amplitude in different degrees while reducing the circuit volume.
Based on the same inventive concept, the invention also discloses a display device, which comprises a display panel, wherein a common electrode wire is arranged on the display panel; the common voltage generating circuit shown in fig. 2 to 3 is configured to output a first common voltage and a second common voltage with different amplitudes to a common electrode line of the display panel to control the display panel to switch between a wide viewing angle and a narrow viewing angle.
In summary, the common voltage generating circuit disclosed in the embodiment of the present invention is configured with a structure in which two switching modules and a comparator are provided to provide a first common voltage and a second common voltage with different amplitudes for a display device, so as to switch a wide viewing angle and a narrow viewing angle of the display device.
It should be noted that, in this document, the contained terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (10)
1. A common voltage generation circuit, comprising:
a first signal generator for providing a viewing angle control signal;
a second signal generator for providing a reference square wave signal;
the first switching module is connected with the first signal generator and used for receiving the visual angle control signal and outputting one of a first pull-up signal and a second pull-up signal according to the visual angle control signal;
the second switching module is connected with the first signal generator and used for receiving the visual angle control signal and outputting one of a first power supply signal and a second power supply signal according to the visual angle control signal; and
and the comparator is respectively connected with the second signal generator, the first switching module and the second switching module, receives a reference voltage signal, and is used for outputting a first common voltage according to the reference voltage signal, the reference square wave signal, the first pull-up signal and the first power supply signal or outputting a second common voltage according to the reference voltage signal, the reference square wave signal, the second pull-up signal and the second power supply signal.
2. The common voltage generating circuit according to claim 1, wherein the common voltage generating circuit further comprises:
and the output control module is positioned between the output end of the first switching module and the output end of the comparator and is used for controlling the first switching module to only pull up the first common voltage and the second common voltage with high level.
3. The common voltage generating circuit according to claim 2, wherein the common voltage generating circuit further comprises:
a pull-up resistor connected in series between the output terminal of the first switching module and the output terminal of the comparator.
4. The common voltage generating circuit according to claim 1, wherein the first switching module comprises:
the first switch tube is connected with the positive power supply end through a first resistor and a second resistor which are connected in series in sequence, the second switch tube is grounded, and the control end receives the visual angle control signal;
a voltage follower, the non-inverting input terminal of which is connected with the connection node of the first resistor and the second resistor, the inverting input terminal of which is connected with the output terminal, the first power supply terminal of which is connected with a positive voltage source, the second power supply terminal of which is connected with a negative voltage source,
the first switch tube is an NMOS transistor.
5. The common voltage generating circuit according to claim 1, wherein the second switching module comprises:
the first path end of the second switching tube receives the visual angle control signal, the second path end of the second switching tube is connected with the negative power supply end sequentially through a fourth resistor and a fifth resistor, and the control end of the second switching tube is grounded;
the connection node of the fourth resistor and the fifth resistor is connected with the negative power supply end of the comparator,
the second switch tube is a PMOS transistor.
6. The common voltage generating circuit according to claim 3, wherein the output control module comprises:
the first path end of the third switching tube is connected with the positive power supply end through a third resistor, the second path end of the third switching tube is grounded, and the control end of the third switching tube receives the reference square wave signal;
a fourth switch tube, the first path end is connected with the output end of the voltage follower, the second path end is connected with the output end of the comparator through the pull-up resistor, the control end is connected with the positive power supply end through the third resistor,
the third switching tube is an NMOS transistor, and the fourth switching tube is a PMOS transistor.
7. The common voltage generating circuit according to claim 3, wherein the output control module comprises:
a fifth switch tube, the first path end is connected with the output end of the voltage follower, the second path end is connected with the output end of the comparator through the pull-up resistor, the control end receives the reference square wave signal,
wherein the fifth switch tube is an NMOS transistor.
8. The common voltage generating circuit according to claim 1, wherein a voltage value of the first pull-up signal is smaller than a voltage value of the second pull-up signal, and a voltage value of the first power supply signal is larger than a voltage value of the second power supply signal.
9. A common voltage generating method applied to the common voltage generating circuit according to any one of claims 1 to 8, the method comprising:
receiving the positive power supply voltage and the negative power supply voltage by a comparator, and outputting a first common voltage according to a reference square wave signal and a reference voltage signal;
the first common voltage is pulled up according to a viewing angle control signal when the reference square wave signal is at a high level, and/or the voltage value of the negative polarity supply voltage received by the comparator is changed according to the viewing angle control signal when the reference square wave signal is at a low level to generate a second common voltage,
wherein, the level state of the visual angle control signal is changed to control and generate the pull-up signal with different voltage values and the negative power supply voltage with different voltage values.
10. A display device, comprising:
the display panel is provided with a common electrode wire;
the common voltage generating circuit as claimed in any one of claims 1 to 8, for outputting a first common voltage and a second common voltage different in magnitude to the common electrode line connection to control the display panel to perform switching of a wide viewing angle and a narrow viewing angle.
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| CN111640404B (en) * | 2020-06-10 | 2022-06-14 | 昆山龙腾光电股份有限公司 | Wide-narrow viewing angle switching circuit and display device thereof |
| TWI738417B (en) * | 2020-07-10 | 2021-09-01 | 友達光電股份有限公司 | Display device and driving method thereof |
| CN112382248B (en) * | 2020-11-06 | 2022-02-15 | 昆山龙腾光电股份有限公司 | Drive circuit and display device |
| CN113611252A (en) * | 2021-05-31 | 2021-11-05 | 北海惠科光电技术有限公司 | Display panel driving method and display device |
| CN113380206A (en) * | 2021-05-31 | 2021-09-10 | 北海惠科光电技术有限公司 | Display panel driving method and display device |
| CN113707071B (en) * | 2021-08-31 | 2024-01-12 | Tcl华星光电技术有限公司 | Reference voltage generating circuit and display device |
| CN114785335B (en) * | 2022-04-25 | 2024-03-22 | 荣湃半导体（上海）有限公司 | Pull-up resistor circuit, I2C isolation circuit and pull-up resistor setting method |
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