JP4780124B2 - Liquid crystal display device and head-up display - Google Patents

Description

  The present invention relates to a liquid crystal display device and a head-up display, and more particularly to a field sequential drive liquid crystal display device and a head-up display in which a plurality of light sources emit light sequentially.

  2. Description of the Related Art Conventionally, a field sequential drive liquid crystal display device in which a plurality of light sources emit light sequentially is known (for example, see Patent Document 1).

  Patent Document 1 discloses a liquid crystal display device (head-up display) including two types of light-emitting diode light sources that are complementary to each other and a liquid crystal display device. In Patent Document 1, color display is performed by field sequential driving in which two types of light emitting diode light sources are alternately emitted and a color image is recognized by the afterimage phenomenon of the human eye.

JP 2003-295105 A

  However, in the liquid crystal display device described in Patent Document 1, two types of light-emitting diode light sources are used when inversion driving is performed in which the application direction of the voltage applied to the liquid crystal is alternately switched each time the light emission of the light-emitting diode light source is switched. Since it is (even), when one of the two colors is displayed, the application direction of the voltage applied to the liquid crystal is always the same. For this reason, while the same image is continuously displayed, the voltage in the same application direction is continuously applied to the liquid crystal of the pixel corresponding to the image. As a result, there is a problem that the image sticking of the liquid crystal and the color reproducibility are lowered.

  The present invention has been made to solve the above-described problems, and one object of the present invention is a liquid crystal display capable of suppressing liquid crystal burn-in and color reproducibility deterioration. Is to provide a device.

Means for Solving the Problems and Effects of the Invention

A liquid crystal display device according to a first aspect of the present invention includes a pixel including a liquid crystal, a pixel electrode that applies a voltage to the liquid crystal, and a common electrode, a display unit in which a plurality of pixels are arranged in a matrix, and a light emission color. The pixels are driven in accordance with the light emission of the first even light source sequentially, and the application direction of the voltage applied to the liquid crystal is switched every vertical scanning period . The light source that emits light is switched for every second even number of vertical scanning periods that are the same as or different from the even number of 1, and when the same color light source is emitted for the same pixel, it is applied to the liquid crystal every one vertical scanning period The voltage application direction is switched between the positive side and the negative side .

In the liquid crystal display device according to the first aspect of the present invention, as described above, the application direction of the voltage applied to the liquid crystal is switched every one vertical scanning period, and the second even number of verticals which is the same as or different from the first even number. When the light source of the same color is emitted for the same pixel, the application direction of the voltage applied to the liquid crystal is switched between the positive side and the negative side every vertical scanning period. As a result, the voltage application direction is switched every vertical scanning period, and during the second even-numbered vertical scanning period in which the vertical scanning period is repeated, the light source of the same color is emitted and the light source of the same color is emitted. In the meantime, voltages in different application directions are applied. As a result, when light sources of the same color are emitted, it is possible to prevent the application direction of the voltage applied to the liquid crystal of the pixel from being always the same, so that the burn-in of the liquid crystal and the color reproducibility are reduced. Can be suppressed. In addition, when a video signal for the same image is input to the pixel, the brightness of the color displayed on the pixel varies depending on the potential difference fluctuation occurring before and after the application direction of the voltage for driving the liquid crystal is switched, but the liquid crystal is driven. Brightness can be averaged by repeatedly switching the voltage application direction.

In the liquid crystal display device according to the first aspect, preferably, the first even-numbered light source emits a first light source that emits a first color and a second light that emits a second color different from the first color. The light source includes a light source, and the application direction of a voltage applied to the liquid crystal is switched every vertical scanning period, and the first light source and the second light source alternately emit light every second even number of vertical scanning periods. Has been. With this configuration, the voltage application direction is switched every vertical scanning period, and either the first light source or the second light source is used during the second even number of vertical scanning periods in which the vertical scanning period is repeated . Since the same color light sources emit light, the voltages in the different application directions are applied while either the first light source or the second light source emits the same color light source. As a result, it is possible to prevent the application direction of the voltage applied to the liquid crystal of the pixel from being always the same when the light source of the same color of either the first light source or the second light source is sequentially emitted. In addition, it is possible to suppress deterioration of image sticking and color reproducibility.

  In the liquid crystal display device according to the first aspect, preferably, in one vertical scanning period, m is the number of vertical scanning periods in which the same light source among the even light sources emits light individually, and n is the number of even light sources. , 1/60 mn (seconds). With this configuration, since the vertical scanning period during which even-numbered light sources emit light is the same as one vertical scanning period of normal driving, even if the light source that emits light is switched every even-numbered vertical scanning period, display is possible. It is possible to prevent the image from flickering.

In the liquid crystal display device according to the first aspect, preferably, the voltage applied to the common electrode is a constant voltage, and the voltage applied to the pixel electrode is equal to the voltage applied to the common electrode for each vertical scanning period. Thus, the light source that emits light is switched every second even number of vertical scanning periods while switching between a high potential and a low potential. According to this configuration, the voltage applied to the common electrode is constant, and the DCCOM drive in which the voltage applied to the pixel electrode is switched between a high potential and a low potential is performed every second even number of vertical scanning periods. Since the light source that emits light can be switched, in the DCCOM drive, it is possible to prevent the liquid crystal burn-in and the color reproducibility from being lowered by the configuration according to the first aspect described above.

In the liquid crystal display device according to the first aspect, it is preferable that the voltage applied to the common electrode emits light every second even number of vertical scanning periods while switching between high potential and low potential every vertical scanning period. The light source to be switched is configured to be switched. With this configuration, the light source that emits light can be switched every second even number of vertical scanning periods while performing ACCOM driving in which the voltage applied to the common electrode and the pixel electrode is switched between a high potential and a low potential. Therefore, in the ACCOM driving, it is possible to suppress the liquid crystal burn-in and the color reproducibility from being lowered by the configuration according to the first aspect described above.

In the liquid crystal display device according to the first aspect, the second even-numbered vertical scanning period is preferably performed while switching the application direction of the voltage applied to the liquid crystal for each horizontal line of a plurality of pixels arranged in a matrix. The light source that emits light is switched every time. With this configuration, it is possible to switch the light source that emits light every second even number of vertical scanning periods while performing line inversion driving in which the voltage applied to the liquid crystal is different for each horizontal line. The configuration according to the first aspect described above can prevent liquid crystal burn-in and color reproducibility from decreasing.

  In the liquid crystal display device including the first light source and the second light source, the colors emitted from the first light source and the second light source are preferably different colors selected from red, green, and blue. If comprised in this way, a color image can be easily displayed by additive color mixing.

  A head-up display according to a second aspect of the present invention includes the liquid crystal display device according to any one of claims 1 to 7. With such a configuration, it is possible to obtain a head-up display capable of suppressing liquid crystal burn-in and color reproducibility.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an overall configuration of a field sequential liquid crystal display device according to a first embodiment of the present invention. 2 and 3 are diagrams showing a detailed configuration of the liquid crystal display device according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining a video output signal of the liquid crystal display device according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating a configuration of a pixel according to the first embodiment of the present invention. First, the structure of the field sequential liquid crystal display device 100 according to the first embodiment will be described with reference to FIGS. In the first embodiment, a case where the present invention is applied to a field sequential liquid crystal display device 100 which is an example of a liquid crystal display device will be described.

  As shown in FIG. 1, the field sequential liquid crystal display device 100 according to the first embodiment includes a drive unit 1 and a display unit 2. Details will be described below.

  As shown in FIG. 1, the drive unit 1 includes a microcomputer unit 11, an A / D converter 12, a PLL (phase synchronization) circuit 13, a memory 14, an analog driver 15, a SYNC processor 16, and a level conversion circuit. 17, a common electrode driver 18, and an LED control circuit 19.

  The microcomputer unit 11 is connected to all the circuits included in the driving unit 1 and has a function of controlling the operation of the entire driving unit 1. The A / D converter 12 is connected to the memory 14. The A / D converter 12 has a function of converting an analog VIDEO signal (video signal) into a digital signal. The memory 14 has a function of storing RG digital signals. As shown in FIG. 2, the memory 14 includes a memory 14a, a memory 14b, a memory 14c, and a memory 14d. The memories 14a and 14b are configured to receive an R (red) digital VIDEO signal. The memories 14c and 14d are configured to receive a G (green) digital VIDEO signal.

  The PLL circuit 13 is connected to the SYNC processor 16. The PLL circuit 13 has a function of generating a clock necessary for field sequential driving. The SYNC processor 16 has a function of generating a signal for driving a pixel 22 described later. As shown in FIG. 2, the SYNC processor 16 includes a memory timing circuit 16a and an inverting circuit 16b. In addition, the memory timing circuit 16a has a function of generating a timing signal for storing the VIDEO signal converted into an RG digital signal in the memory 14 for each RG and generating a timing signal for calling necessary for field sequential driving. .

  Further, as shown in FIG. 3, the inverting circuit 16b includes a DFF circuit (D flip-flop circuit) 16c and a switching circuit 16d. The DFF circuit 16c is connected to the switching circuit 16d. The DFF circuit 16c is configured such that an internal HD signal (horizontal synchronization signal) is input to the input unit 161c. The DFF circuit 16c is configured to receive a RESET signal or a SET signal from the switching circuit 16d. The output unit 162c is configured to output a switching signal to the analog driver 15 (see FIG. 1). The output unit 163c is configured to output an inverted signal of the signal output from the output unit 162c. The input unit 164c is configured to receive this inverted signal.

  The switching circuit 16d is configured such that an internal VD signal (vertical synchronization signal) is input from the input unit 161d. The output unit 162d is configured to output a SET signal to the DFF circuit 16c. The output unit 163d is configured to output a RESET signal to the DFF circuit 16c.

  As shown in FIG. 1, the memory 14 is connected to an analog driver 15. The analog driver 15 has a function of converting an RG digital signal into an RG analog signal and supplying the RG analog signal to the display unit 2. As shown in FIG. 2, the analog driver 15 includes a D / A conversion circuit 15a, a D / A conversion circuit 15b, an inverting circuit 15c, and a changeover switch 15d. The D / A conversion circuit 15a is connected to the changeover switch 15d. The D / A conversion circuit 15a has a function of converting an input digital signal into an analog signal and outputting the analog signal as a high-side signal of the VIDEO signal. The inversion circuit 15c is connected to the D / A conversion circuit 15b. The inverting circuit 15c has a function of inverting and outputting the input digital signal. The D / A conversion circuit 15b is connected to the changeover switch 15d. The D / A conversion circuit 15b has a function of converting an input digital signal into an analog signal and outputting it as a Low-side signal. The changeover switch 15d is configured to switch the connection of the D / A conversion circuits 15a and 15b based on a changeover signal output from the inverting circuit 16b of the SYNC processor 16.

  Also, pixel data (VIDEO signal) is output as shown in FIG. 4 in conjunction with the changeover of the changeover switch 15d. Specifically, in the first embodiment, a voltage applied to a common electrode 223 (see FIG. 5) described later is a constant voltage (DCCOM). A voltage (VIDEO signal) applied to the pixel electrode 222 (see FIG. 5) is a voltage that switches between a high potential and a low potential with respect to a voltage applied to the common electrode 223 every vertical scanning period. In addition, the application direction of the voltage applied to the pixel electrode 222 is configured to be switched by the switch 15d based on a switching signal output from the inverting circuit 16b of the SYNC processor 16 every vertical scanning period. . Further, the LEDs 26 (26a and 26b) to be described later are configured so that the LEDs 26 (LEDs 26a and 26b) that emit light every two vertical scanning periods are switched. The VIDEO signal is configured to output a High side and a Low side of the VIDEO signal so that positive (+) and negative (-) voltages are applied to the liquid crystal 224 described later. In the first embodiment, the voltage applied to the common electrode 223 is such that the LEDs 26 (LEDs 26a and 26b) that emit light every two vertical periods are switched while switching between a high potential and a low potential every vertical scanning period. A large voltage (ACCOM).

  As shown in FIG. 1, the SYNC processor 16 is connected to a memory 14, an analog driver 15, a level conversion circuit 17, and an LED control circuit 19. The level conversion circuit 17 has a function of generating pulses (horizontal / vertical control signals, field sequential drive control signals) for driving the pixels 22. Further, the LED control circuit 19 has a function of controlling the light emission of the LED 26 and the stop of the light emission in accordance with the field sequential drive timing. The LED control circuit 19 is configured to control to switch the LED 26 (LEDs 26a and 26b) that emits light every two vertical scanning periods. At the same time, the application direction of the voltage applied to the liquid crystal 224, which will be described later, is switched between positive (+) and negative (−) every vertical scanning period. The common electrode driver 18 has a function of determining a voltage to be applied to the common electrode 223 described later and supplying the voltage to the pixel 22.

  As shown in FIG. 1, the display unit 2 drives the substrate 21, the plurality of pixels 22, the H driver 23 and the V driver 24 connected to the plurality of pixels 22, and the H driver 23 and the V driver 24. And an LED 26 (LEDs 26a and 26b) that emits red (R) and green (G) light as a backlight (light source) of the pixel 22. The LED 26 is an example of the “light source” in the present invention. In the first embodiment, the LED 26a that emits red (R) is an example of the “first light source” of the present invention, and the LED 26b that emits green (G) of the “second light source” of the present invention. It is an example.

  In the first embodiment, the plurality of pixels 22 are configured to be driven in accordance with light emission in which the LEDs 26 (LEDs 26a and 26b) emit light sequentially. Further, as shown in FIG. 5, a plurality of signal lines 31 and a plurality of scanning lines 32 are arranged on the substrate 21 so as to be orthogonal to each other. The signal line 31 is connected to the H driver 23, and the scanning line 32 is connected to the V driver 24. Pixels 22 are arranged at positions where the signal lines 31 and the scanning lines 32 intersect. FIG. 5 shows only the configuration for four pixels for the sake of simplicity. Each pixel 22 includes an n-channel transistor 221, a pixel electrode 222, a common electrode 223 disposed opposite to the pixel electrode 222, and a liquid crystal disposed so as to be sandwiched between the pixel electrode 222 and the common electrode 223. 224 and an auxiliary capacitor 225. The drain region D of the n-channel transistor 221 is connected to the signal line 31, and the source region S is connected to the pixel electrode 222 and one electrode of the auxiliary capacitor 225. The gate G of the n-channel transistor 221 is connected to the scanning line 32.

  6 and 7 are diagrams for explaining the operation of the field sequential liquid crystal display device according to the first embodiment. Next, the operation of the field sequential liquid crystal display device 100 according to the first embodiment will be described with reference to FIG. 1, FIG. 2, FIG. 6, and FIG.

  First, as shown in FIG. 1, an analog VIDEO signal is input to the A / D converter 12, and the analog VIDEO signal is converted into a digital signal. A horizontal / vertical synchronization signal is input to the PLL circuit 13. Further, the RG digital signal is stored in the memory 14 in accordance with the timing signal generated by the memory timing circuit 16a (see FIG. 2) of the SYNC processor 16 and stored in the memory 14 for each of the red and green signals. Further, VD (vertical synchronizing signal) is counted once by the inverting circuit 16 b (see FIG. 2) of the SYNC processor 16, and a switching signal is output to the analog driver 15. Thereby, the application direction of the voltage for driving the liquid crystal 224 is switched between positive (+) and negative (−) every vertical scanning period.

  The SYNC processor 16 generates RG image data write timing and LED 26 light emission timing signals. Based on the timing signal generated by the SYNC processor 16, a horizontal / vertical control signal and a field sequential drive control signal are supplied to the display unit 2 via the level conversion circuit 17. The voltage applied to the common electrode 223 (see FIG. 5) is determined by the common electrode driver 18 and supplied to the display unit 2.

  In the first embodiment, as shown in FIG. 6, the application direction of the voltage applied to the liquid crystal 224 is switched for each horizontal line of the plurality of pixels 22 arranged in a matrix. Specifically, a voltage that switches between a high potential and a low potential is applied to the pixel electrode 222 (see FIG. 4) (VIDEO signal), and the voltage applied to each horizontal line is positive (with respect to the common electrode 223). Different line inversion driving is performed for the (+) side voltage and the negative (−) side voltage. Note that a constant voltage is applied to the common electrode 223 of the pixel 22.

  Next, the operation of the field sequential liquid crystal display device 100 when an image is displayed on the display unit 2 will be described.

  First, as shown in FIG. 6, the pixel electrodes 222 of the pixels 22 in the odd-numbered rows (first line, third line,...) Of the pixels 22 arranged in a matrix in the vertical scanning period A and the vertical scanning period C. A positive (+) voltage is applied to. Further, a negative (−) voltage is applied to the pixel electrodes 222 of the pixels 22 in the even-numbered rows (second line, fourth line...) Of the pixels 22 arranged in a matrix. On the other hand, the pixel electrodes 222 of the pixels 22 in the odd-numbered rows (first line, third line,...) Of the pixels 22 arranged in a matrix in the vertical scanning period B and the vertical scanning period D are negative. (−) A voltage is applied. Further, a positive (+) voltage is applied to the pixel electrodes 222 of the pixels 22 in the even-numbered rows (second line, fourth line,...) Of the pixels 22 arranged in a matrix.

  Further, as shown in FIG. 4, even when the same video signal is input to the pixel 22, the potential difference between the voltage applied to the pixel electrode 222 (VIDEO signal) and the voltage applied to the common electrode 223 (DCCOM). Is different before and after the application direction of the voltage for driving the liquid crystal 224 is switched due to variations in the COM voltage (DCCOM voltage) or the like. Specifically, the potential difference V1 between the DCCOM voltage and the high-side VIDEO signal voltage and the potential difference V2 between the DCCOM voltage and the low-side VIDEO signal voltage are caused by variations in the COM voltage (DCCOM voltage). Different. Further, the potential differences V1 and V2 vary due to the variation of the VIDEO signal or DCCOM. Thus, before and after the voltage for driving the liquid crystal 224 is switched, the brightness of the color displayed on the pixel 22 is different even when a video signal for the same image is input to the pixel 22. In FIG. 7, in order to explain such a phenomenon, the brightness of red and green displayed on the display unit 2 (FIG. 6) is illustrated by the thickness of the line, and the thick line is compared with the thin line. It shows bright emission. In the vertical scanning period A (red light emission period), red light and green light emission displayed on the display unit 2 are displayed in red on the pixels 22 of the display unit 2, and the odd-numbered rows (first line, third line) of the pixels 22 are displayed. The red color displayed on the line (...) is bright (potential difference V1 shown in FIG. 4), and the red color displayed on the even-numbered lines (second line, fourth line ...) of the pixel 22 is dark (FIG. 4). Potential difference V2) is displayed.

  Next, in the vertical scanning period B (red light emission period), red is displayed on the pixels 22 of the display unit 2 in the same manner as the light emission in the vertical scanning period A (red light emission period). The red color displayed on the line 3, the third line,..., Is dark, and the red color displayed on the even-numbered lines (second line, fourth line,...) Of the pixels 22 is displayed brightly.

  In the vertical scanning period C (green light emitting period), unlike the light emission in the vertical scanning period B (red light emitting period), green is displayed on the pixels 22 of the display unit 2, and the odd rows (first line, 3) of the pixels 22 are displayed. The green color displayed on the line (...) is bright, and the green color displayed on the even-numbered lines (second line, fourth line ...) of the pixels 22 is dark.

  Next, in the vertical scanning period D (green light emission period), green is displayed on the pixels 22 of the display unit 2 in the same manner as the light emission in the vertical scanning period C (green light emission period). The green displayed on the line 3, the third line,... Is dark, and the green displayed on the even-numbered lines (second line, fourth line,...) Of the pixel 22 is displayed bright. Thereafter, in the vertical scanning period E (not shown), light emission similar to that in the vertical scanning period A is performed. Also, as shown in FIG. 7, the brightness of yellow before and after switching the voltage application direction is averaged by switching the application direction of the voltage for driving the liquid crystal 224 to display red and green.

  The liquid crystal display device 100 according to the first embodiment can be used for a head-up display 400 as shown in FIG. The liquid crystal display device 100 is attached to a predetermined device so that the display light L1 can be projected onto a display target body 401 (for example, a windshield of an automobile) 401. Specifically, the liquid crystal display device 100 includes a display unit 2 and an LED 26, and the display unit 2 is disposed between the LED 26 and the concave mirror 402. The display light L <b> 1 emitted from the liquid crystal display device 100 is generated when the light L <b> 2 from the LED 26 is incident on the display unit 2.

  Further, the display light L <b> 1 emitted from the liquid crystal display device 100 is reflected by the concave mirror 402 toward the display target 401 and is projected onto the display target 401. The liquid crystal display device 100 and the concave mirror 402 described above are housed in a case 403 having a window portion 403a for transmitting the display light L1. Such an in-vehicle head-up display 400, as shown in FIG. 9, displays information necessary for driving a car (for example, direction indication, inter-vehicle distance, travel distance, various warning information, road information and road guidance information, Such information display is different from natural images and the like, and the number of colors used for display may be small. Since the liquid crystal display device 100 of the present invention is a display device that displays red, green, and additive color mixture of red and green, it can be a liquid crystal display device suitable for such a head-up display 400. .

  In the first embodiment, as described above, by configuring the LEDs 26 (LEDs 26a and 26b) to emit light alternately every two vertical scanning periods, the voltage application direction is switched every vertical scanning period. During the two vertical scanning periods in which the scanning period is repeated, the LED 26 (LEDs 26a and 26b) of any one of the LEDs 26 (LEDs 26a and 26b) emits light, so that one of the LEDs 26 (LEDs 26a and 26b) While LEDs 26 of the same color (LEDs 26a and 26b) emit light, voltages in different application directions are applied. Thereby, when the LED 26 (LEDs 26a and 26b) of any one of the LEDs 26 (LEDs 26a and 26b) emits light sequentially, the application direction of the voltage applied to the liquid crystal 224 of the pixel 22 is always the same. Therefore, the burn-in of the liquid crystal 224 and the decrease in color reproducibility can be suppressed.

  In the first embodiment, as described above, the voltage applied to the common electrode 223 is a constant voltage, and the voltage applied to the pixel electrode 222 is the voltage applied to the common electrode 223 every vertical scanning period. By switching the LED 26 (LEDs 26a and 26b) that emits light every two vertical scanning periods while switching between a high potential and a low potential, the voltage applied to the common electrode 223 is constant, and the pixel electrode The LED 26 (LEDs 26a and 26b) that emits light every two vertical scanning periods can be switched while performing DCCOM driving in which the voltage applied to 222 is switched between a high potential and a low potential. With the configuration according to the embodiment, the burn-in of the liquid crystal 224 and the color reproducibility can be suppressed from decreasing.

  In the first embodiment, as described above, the voltage applied to the common electrode 223 is the LED 26 (LEDs 26a and 26b) that emits light every two vertical scanning periods while switching between a high potential and a low potential every vertical scanning period. ) Are switched so that the LED 26 (LED 26a and LED 26a and LED 26a) emits light every two vertical scanning periods while performing ACCOM driving in which the voltage applied to the common electrode 223 and the pixel electrode 222 is switched between a high potential and a low potential. 26b) can be switched, and in the ACCOM drive, the burn-in of the liquid crystal 224 and the color reproducibility can be suppressed from being lowered by the configuration according to the first embodiment.

  In the first embodiment, as described above, light emission is performed every two vertical scanning periods while switching the application direction of the voltage applied to the liquid crystal 224 for each horizontal line of the plurality of pixels 22 arranged in a matrix. By switching the LEDs 26 (LEDs 26a and 26b) to be switched, the LEDs 26 (LEDs 26a and 26b) that emit light every two vertical scanning periods while performing line inversion driving in which the voltage applied to the liquid crystal 224 is different for each line. Since the switching can be performed, in the line inversion driving, it is possible to suppress the burn-in of the liquid crystal 224 and the color reproducibility from being lowered by the configuration according to the first embodiment.

(Second Embodiment)
FIG. 10 is a diagram showing a detailed configuration of the liquid crystal display device according to the second embodiment of the present invention. FIG. 11 is a diagram for explaining the operation of the field sequential liquid crystal display device according to the second embodiment of the present invention. With reference to FIGS. 10 and 11, in the second embodiment, unlike the first embodiment described above, a case will be described in which the frequency of a pulse input to the SYNC processor 16 is doubled (double speed).

  In the configuration of the liquid crystal display device 100 according to the second embodiment, the SYNC processor 16 has twice the HD (horizontal synchronization signal) and VD (vertical synchronization signal) input to the SYNC processor 16 of the first embodiment. (Double speed) pulse frequency is set to be input.

  Further, as shown in FIG. 10, the SYNC processor 16 is configured to generate the timing of writing the RG image data and the timing signal of the light emission of the LED 26, and based on this timing signal, the LED control circuit 19 The light emission of the LED 26 is controlled according to the timing of field sequential driving.

  Next, the operation of the field sequential liquid crystal display device 100 when an image is displayed on the display unit 2 according to the second embodiment will be described.

  In the liquid crystal display device 100 according to the second embodiment, as shown in FIG. 10, the SYNC processor 16 has double (double speed) HD (horizontal synchronization signal) and VD (vertical synchronization signal) of the first embodiment described above. ) Is entered. Based on this signal, the SYNC processor 16 generates an RG image data write timing and an LED 26 light emission timing signal. Based on this timing signal, the LED control circuit 19 controls the light emission of the LED 26 in accordance with the field sequential drive timing.

  In the second embodiment, one vertical scanning period is substantially equal to 1/60 mn (seconds), where m is the number of vertical scanning periods in which the same LED 26 is individually emitting light among the LEDs 26 and n is the number of LEDs 26. It is set to be. As shown in FIG. 11, specifically, when the number (m) of vertical scanning periods in which the same LED 26 of the LEDs 26 individually emits light is 1 and the number (n) of LEDs 26 is 2, One vertical scanning period is a period of 1 / (60 × 1 × 2) = 1/120 (seconds). The light emission period of the LED 26 is set to be one half (1/2) the number of LEDs 26 that emit light in one vertical scanning period shown in the first embodiment.

  Further, during one vertical scanning period of the vertical scanning period A shown in the first embodiment, the LEDs 26 for two vertical scanning periods of the vertical scanning periods A1 and A2 emit light. At the same time, in the second embodiment, the voltage applied to the liquid crystal 224 for two vertical scanning periods of the vertical scanning periods A1 and A2 during one vertical scanning period of the vertical scanning period A shown in the first embodiment. The direction of application is switched. Thereafter, similarly to the vertical scanning periods A1 and A2, the vertical scanning periods B1 and B2, the vertical scanning periods C1 and C2, and the vertical scanning periods D1 and D2 are the same as the one vertical scanning period shown in the first embodiment. During the period, the LEDs 26 for two vertical scanning periods emit light.

  The other configuration of the liquid crystal display device 100 is the same as that of the first embodiment.

  In the second embodiment, as described above, m is the number of vertical scanning periods in which one LED 26 (LEDs 26a and 26b) individually emits light in one vertical scanning period. The vertical scanning period during which the LEDs 26 (LEDs 26a and 26b) emit light is set to be the same as one vertical scanning period of normal driving by setting n to be 1/60 mn (seconds). Therefore, even if the LEDs 26 (LEDs 26a and 26b) that emit light every two vertical scanning periods are switched, it is possible to prevent the display image from flickering.

  The remaining effects of the second embodiment are similar to those of the first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which two colors of red (R) and green (G) are applied as an even number of light sources is shown as an example of the present invention. However, the present invention is not limited thereto, and the number of light sources is not limited. If it is an even number, four colors other than the two colors can be applied.

  In the above embodiment, as an example of the present invention, an example in which two vertical scanning periods are used as even vertical scanning periods has been described. However, the present invention is not limited to this, and the number of vertical scanning periods is 2 if the number is even. The present invention can also be applied to four vertical scanning periods other than the vertical scanning period.

  Moreover, in the said embodiment, although the example which uses LED which light-emits red (R) and green (G) light was shown as an example of the light source of this invention, this invention is not limited to this, Red (R) And blue (B), or a combination of green (G) and blue (B).

  Moreover, in the said embodiment, although the example which uses LED which light-emits red (R) and green (G) light as an example of the light source of this invention was shown, this invention is not limited to this, cyan, magenta, and You may use LED which light-emits the light of yellow color. Thereby, a color image can be easily displayed by subtractive color mixing.

  In the above embodiment, an example in which the voltage applied to the pixel electrode of the pixel performs line inversion driving is shown. However, the present invention is not limited to this, and frame inversion driving, source inversion driving, and dot are not limited thereto. Other inversion driving such as inversion driving may be performed.

  Moreover, in the said embodiment, although the example using LED was shown as an example of the light source of this invention, this invention is not limited to this, For example, you may use the light source which consists of light-emitting bodies like organic EL.

1 is a block diagram showing an overall configuration of a field sequential liquid crystal display device according to a first embodiment of the present invention. It is a figure which shows the detailed structure of the liquid crystal display device by 1st Embodiment of this invention. It is a figure which shows the detailed structure of the liquid crystal display device by 1st Embodiment of this invention. It is a figure for demonstrating the video output signal of the liquid crystal display device by 1st Embodiment of this invention. It is a figure which shows the structure of the pixel by 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the field sequential liquid crystal display device by 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the field sequential liquid crystal display device by 1st Embodiment of this invention. It is a figure for demonstrating the head-up display using the liquid crystal display device by 1st Embodiment of this invention. It is a figure for demonstrating the head-up display using the liquid crystal display device by 1st Embodiment of this invention. It is a figure which shows the detailed structure of the liquid crystal display device by 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the field sequential liquid crystal display device by 2nd Embodiment of this invention.

Explanation of symbols

2 Display unit 22 pixels 26 LED (light source)
26a LED (first light source)
26b LED (second light source)
DESCRIPTION OF SYMBOLS 100 Liquid crystal display device 222 Pixel electrode 223 Common electrode 224 Liquid crystal 400 Head-up display

Claims (7)

A pixel including a liquid crystal, a pixel electrode for applying a voltage to the liquid crystal, and a common electrode;
A display unit in which a plurality of the pixels are arranged in a matrix;
A first even number of light sources each having a different emission color,
The pixels are driven in response to light emission of the first even number of light sources sequentially,
The application direction of the voltage to be applied to the liquid crystal is switched every vertical scanning period, and the light source that emits light is switched every second even vertical scanning period that is the same as or different from the first even number. When the light source of the same color is emitted, the liquid crystal display device switches the application direction of the voltage applied to the liquid crystal between the positive side and the negative side every vertical scanning period . The first even-numbered light source includes a first light source that emits a first color and a second light source that emits a second color different from the first color;
The application direction of the voltage applied to the liquid crystal is switched every vertical scanning period, and the first light source and the second light source alternately emit light every second even number of vertical scanning periods. The liquid crystal display device according to claim 1. The voltage applied to the common electrode is a constant voltage,
The voltage applied to the pixel electrode is a light source that emits light every second even number of vertical scanning periods while switching between a high potential and a low potential with respect to the voltage applied to the common electrode every vertical scanning period. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to be switched. The voltage applied to the common electrode is configured such that a light source that emits light is switched every second even number of vertical scanning periods while switching between a high potential and a low potential every vertical scanning period. Item 3. A liquid crystal display device according to item 1 or 2. For each horizontal line of the plurality of pixels arranged in the matrix, the light source that emits light is switched every second even number of vertical scanning periods while switching the application direction of the voltage applied to the liquid crystal. The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 2, wherein colors emitted from the first light source and the second light source are different colors selected from red, green, and blue.   A head-up display comprising the liquid crystal display device according to claim 1.

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