JP3368245B2 - Liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display for displaying an image or the like. 2. Description of the Related Art In recent years, research on liquid crystals has progressed, and development as a video display medium such as a television using the characteristics of liquid crystals has been advanced. In particular, a display device using a liquid crystal is expected to be used as a portable television or a large-screen television because the thickness of a screen can be reduced, and a part thereof has been generally sold. [0003] However, the liquid crystal display device also has a unique problem derived from the properties of the liquid crystal.
One of them is non-uniform orientation at the edge of the screen. This is because there is no adjacent pixel electrode at the end, so that a step occurs on the pixel electrode substrate, which affects the orientation of the liquid crystal. Further, even if the step is reduced, the orientation can be arbitrarily set, so that it is affected by the drive voltage of the pixel electrode at the end, which is a factor that hinders the sharpness of the display at the end. [0004] In addition, as teletext broadcasting is being carried out in television broadcasting, there is a demand for an apparatus that displays text and non-text display under optimum conditions. An object of the present invention is to solve the above-mentioned problems and to provide a liquid crystal display device capable of displaying a higher quality image. That is, the present invention provides a TFT substrate having an active matrix circuit in which a plurality of pixel electrodes and thin film transistors are arranged in a matrix,
A horizontal shift register for driving the pixel electrode;
A direct shift register, a counter electrode substrate provided with a color filter and a counter electrode arranged at an interval with respect to the TFT substrate and opposed to the pixel electrode, and a liquid crystal arranged at the interval. A liquid crystal display device,
A sub-display is provided at least partially around the main display in which the pixel electrode and the thin film transistor are arranged. In the sub-display, a TFT substrate has a pixel electrode, and a counter electrode substrate is provided on the pixel electrode. A laminate of a color filter and a counter electrode facing each other, wherein the horizontal shift register and the vertical
The shift register is multi-staged by the number of pixels of the sub display unit,
A voltage applying unit for applying a voltage to the pixel electrode and the counter electrode in the sub-display unit, and applying either a luminance signal for displaying the main display unit or a black level signal for displaying the sub-display unit. A liquid crystal display device having a switch for selection, wherein the switch is controlled in accordance with the logical sum of a horizontal blanking signal and a vertical blanking signal. [0007] The features of the liquid crystal display device of the present invention are as follows:
The display unit comprises a main display unit and a sub display unit. In the present invention, the main display section is a display section for conventional image display, and the sub-display section is for displaying characters in addition to the main display section, and for displaying black for improving image quality.
In the present invention, black display is performed. In particular, to perform a black display in the sub-display section is an effective means for enhancing the sharpness tightening screen, at least a portion of the upper, lower, left and right main display unit, preferably provided around. The black display according to the present invention is desirably driven by an alternating current in order to prevent burn-in. Further, the main display section may be surrounded by a sub-display section for displaying black, and a second sub-display section for displaying characters may be provided on the periphery separately from these. [0008] In the present invention, the main display section and sub-display section is synchronous drive Suruga, asynchronously driven by the separate drive circuit
You can also . The black display area according to the present invention is preferably as wide as possible in view of preventing the deterioration of the display characteristics of the screen. However, it is preferable that the width of the scanning line and the display line be about 5 to 6 lines. Therefore, a sufficient effect is recognized, and the precision of alignment with a light shielding layer described later does not cause a decrease in yield. With ten or more wires, the above deterioration can be almost completely prevented. In the liquid crystal display device of the present invention, three color filters of green (G), red (R) and blue (B) are provided on the counter electrode substrate so as to correspond in order to each pixel, and these color arrangements are provided. Is used for multi-color display. In the present invention,
A color filter is also provided on the sub display unit. In the present invention, when black display is performed in the sub-display section, by providing a light-shielding layer on the counter electrode substrate corresponding to the black display area, the screen can be more securely tightened. This light-shielding layer may extend outside the black display region, and the main display portion may be defined by the opening of the light-shielding layer. In this case, the alignment between the black display region and the light shielding layer is facilitated, and the production yield is improved. The present invention will be described below in more detail with reference to Examples, but it should not be construed that the present invention is limited thereto. Embodiment 1 FIG. 1 shows a first embodiment of the present invention. This embodiment is an embodiment showing a basic structure of the present invention, and a TFT is provided for each pixel.
This is a liquid crystal display device of an active matrix drive type provided with a switching element composed of a (thin film transistor). In the figure, 1 is a display (signal) line, 2 is a scanning (signal) line,
Reference numeral 3 denotes a TFT element, 4 denotes a pixel electrode, 5 denotes a horizontal shift register, and 6 denotes a vertical shift register. FIG. 2 shows a drive circuit diagram of the present liquid crystal display device. In the figure, 7 is a video signal input terminal, 8 is a black level signal terminal, 9 is a Y / C signal processing circuit, 10 is a pulse generator, 1
1 is a chroma signal line, 12 is a luminance signal, 13 is a switching line, 14 is an analog switch, 15 is an RGB decoder (primary color signal converter), 16 is a drive signal processing circuit, 17 is a shift register built-in LCD (liquid crystal panel) 18 Denotes a vertical blanking pulse signal line, and 19 denotes a horizontal blanking pulse signal line. FIGS. 3 and 4 are waveform diagrams passing through the circuit of FIG. In FIG. 3, 31 is a luminance signal waveform, 32 is a black level signal waveform, 33 is a horizontal blanking pulse, 3
4 is an analog switch output waveform, 35 is a reference potential, 36
And 37 are black level potentials. Normal potential difference 36, 37
Are the same value. FIG. 4 shows a signal state near the vertical blanking period. In FIG. 4, reference numeral 41 denotes a luminance signal of the first field, reference numeral 42 denotes a luminance signal of the second field, reference numeral 43 denotes a vertical blanking pulse, and reference numeral 44 denotes a luminance signal of the first field. , 45 is a horizontal blanking pulse in the second field, 46 is an output waveform of the analog switch in the first field, and 47 is an output waveform of the analog switch in the second field. One of the video signals input from the video signal input terminal 7 is input to the Y / C signal processing circuit 9 and the other is input to the pulse signal generator 10. The video signal is separated into a luminance signal and a chroma signal by the Y / C signal processing circuit 9 and output to the signal lines 11 and 12, respectively. Luminance signal 31,
41 and 42 are input to the analog switch 14. The analog switch 14 is controlled by a signal on the switching line 13. When the signal is at "H" level, the analog switch 14 receives the black level signal 32 input from the black level signal input terminal 8; Select 42.
The signal on the switching line 13 is the logical sum of the horizontal blanking signals 33, 44, 45 generated by the pulse generator 10 and the vertical blanking signal 43. Therefore, the waveform output from the analog switch 14 is a black level signal during the vertical and horizontal blanking periods, and a luminance signal during the other periods, resulting in waveform diagrams 34, 46 and 47. This signal and a chroma signal from the chroma signal line 11 are input to an RGB decoder 15 and converted into an RGB signal. Each of the primary color signals is input to a drive signal processing circuit 16, which performs signal processing for driving the LCD to perform LCD 1 processing.
It is sent to 7. The shift register of the LCD 17 outputs a portion driven by a black level signal around the image display unit to output a display line side shift register (horizontal shift register 5 in FIG. 1) and a scanning line side shift register (FIG. 1). One vertical shift register 6) is multi-staged for each of the black level driving pixels. In addition, the start pulse of the shift register has a timing 52 corresponding to the black level driving pixel as shown in a waveform 51 in FIG.
Is sampled. Therefore, black display can be performed on the left and right sub-display portions of the screen. Conventionally, the start pulse of the shift register is located at 53 and the sampling range is 54, so that the target area cannot be displayed in black. Similarly, by setting the scanning line shift register start pulse at a timing corresponding to the scanning line for scanning at the black level as shown by the waveform 61 in FIG. 6, the sub-display portions at the top and bottom of the screen can be displayed in black. Embodiment 2 FIG. 7 shows a second embodiment of the present invention. In the figure, 71 is a TFT substrate, 72 to 72 ″ are insulating layers, 73 is a pixel electrode, 74 and 74 ′ are alignment control films, 75 is a sealing material, 76 is a liquid crystal, 77
Denotes a counter electrode, 78 denotes a color filter, 79 denotes a parting plate, 80 denotes a polarizing plate, 81 denotes a main display portion, and 82 denotes a sub-display portion to perform black display. In the present invention, by providing a dummy color filter corresponding to the sub-display unit 82 on the counter electrode substrate, the orientation of the liquid crystal is kept uniform, and the sharpness of the image at the end of the main display unit 81 is improved. . FIG. 8 shows a circuit in the case where the switching of the video signal and the black level signal is performed not by the luminance signal but by the RGB signal in the present embodiment. In the figure, 83 is a video signal input terminal, 84 is a black level signal input terminal, 85 is an RGB decoder, 86 is a pulse generator, 87 is an analog switch, 8
8 is a drive circuit, 89 is an LCD panel. FIG. 9 shows the main display area and the sub-display area when a light-shielding layer is further provided in this embodiment. In the figure, reference numeral 91 denotes a main display section, 92 denotes a light shielding layer, and 93 denotes a black display area. In the figure, the light-shielding layer 92 extends its area further toward the main display portion than the black display area 93, and
, The sub-display section is limited. In the present invention, the color filter RG
Although there are various types of pixel arrangements for B, it is only necessary to adopt an arrangement suitable for each of the main display unit and the sub-display unit, and it is not necessary to match the arrangement of both. FIG. 19A shows an example of an apparatus in which the pixel arrangement is changed between the main display unit and the sub display unit. In the figure, reference numeral 191 denotes a main display unit, 1
Reference numeral 92 denotes a sub display unit. As described above, the image quality can be further improved by optimizing the pixel arrangement according to the use of each display unit. In the present embodiment, the main display may display images other than characters in color, and the sub-display may display character information in black and white two colors. This device example is shown in FIG.
Shown in In the figure, reference numeral 191 denotes a main display, and 192 denotes a sub-display. When the sub display unit is displayed in black and white, the resolution is improved as compared with the case of color display, and character display that is easier to read can be performed. [0024] showing a reference example 1 of the present invention in reference example 1 Fig. The present embodiment is a dot matrix type liquid crystal display device. In FIG. 10, 101
Is a black level signal input terminal, 102 is a video signal input terminal,
103 is a pulse generator, 104 is a drive signal generator, 10
5 is a logic conversion unit, 106 is a level shifter, 107 is a scanning-side multiplexer, 108 is an LCD panel, 109
Is a scanning level generator, 110 is a signal side multiplexer,
111 is a level shift, and 112 is a signal level generator. Reference Example 2 FIG. 11 shows a second reference example of the present invention. This reference example is an apparatus that displays character information on a sub display unit and displays images other than characters on a main display unit. 11, 113 is a video signal input terminal, 114 is a Y / C signal processing circuit, 115 is a pulse signal generator, 116 is a control circuit, 117 is a ROM (read only memory), 118 is an external control signal input terminal,
119 is an RGB decoder, 120 is a drive circuit, and 121 is an LCD panel. In this reference example, it is controlled type of characters to be output to the screen by an external control signal, and outputs the corresponding data from the ROM. With this circuit, a state in which no character is output, for example, black display can also be performed. Book
In the reference example, since the character information and the image are independent, both can be clearly displayed. [0026] shows a circuit of a third reference example the present invention in Reference Example 3 FIG. In this reference example, character information is displayed on the sub-display unit, and an image other than the character information is displayed on the main display unit. The main display unit and the sub-display unit are asynchronously driven, that is, the display is driven independently of each other. Device. 12, reference numeral 122 denotes a video signal input terminal; 123, an external control signal input terminal; 124, a video signal detector;
6 is a signal processing circuit, 127 is a ROM, 128 is a signal processing circuit, 129 and 130 are clock pulse generators, 13
1 is a drive circuit of the main display unit, 132 is a main display unit LCD, 1
33 is a sub display LCD. [0027] in this reference example in FIG. 13 to 15 shows a combination example of the main display section and sub-display section. In the figure, reference numeral 134 denotes a horizontal shift register for the sub-display unit, which has a start pulse input terminal φ _DX and transfer clock input terminals φ _CLDX1 and φ _CLDX2 . 135 is a sub-display unit display signal input terminal, 136 is a sub-display unit sample holder, 137 is a sub-display vertical shift register, and has a start pulse φ _DY and transfer clock input terminals φ _CLDY1 and φ _CLDY2 . 138 main display in the vertical shift register for unit a start pulse input terminal phi _Y transfer clock input terminals φ _CLY1, and a φ _CLY2. Thirteen
_{Reference numeral} 9 denotes a sample holder for the main display unit, and 140 denotes a shift register for the main display unit, which has a start pulse input terminal φ _X and transfer clock input terminals φ _CLX1 and φ _CLX2 . 141 is a video signal (main display section display signal) input terminal. FIG. 13 shows an example in which a sub-display section is provided above the main display section, FIG. 14 shows an example in which sub-display sections are provided above and below the main display section,
FIG. 15 shows an example in which a sub display unit is provided around a main display unit.
In addition to these, similarly, the sub-display units can be arranged on the left and / or right of the main display unit, or on the lower side, or on the upper and left sides, and on the lower and right sides. In the present invention, for example, when a black display and a character display are simultaneously performed by combining a sub-display unit that is driven synchronously with the main display unit and a sub-display unit that is driven asynchronously, the main display unit and the black display are displayed. The sub-display unit for performing the character display may be driven synchronously, and the sub-display unit for performing the character display may be driven asynchronously. FIG. 20 shows an example of the apparatus. In the figure, reference numeral 201 denotes a main display unit;
Reference numeral 2 denotes a sub-display unit a, and reference numeral 203 denotes a sub-display unit b. The sub-display unit a201 performs black display by synchronous driving with the main display unit 201, and displays character information on the sub-display unit b202 that is asynchronously driven. In this apparatus, the resolution is further improved by asynchronously performing the character display on the sub-display unit and the image display on the main display unit, and the image quality is improved by performing black display on the main display unit. Image quality can be improved. Reference Example 4 FIG. 16 shows a fourth reference example of the present invention. This reference example is
In Reference Example 3 , there is provided a circuit for driving each pixel with the same signal by short-circuiting the display signal line and / or the scanning signal line of the sub display unit to one or a plurality of transmission lines without using a shift register. I have. In FIG. 16, 161 is a video signal input terminal, 162 is a video signal detector, 163 is a sub-display unit drive signal generator, 164 is a signal processing circuit, 165 is a clock pulse generator, 165 is a drive circuit, 166 is a clock circuit, etc. The control signal generator 168 is a main display LCD, and 169 is a sub display LCD. In the reference example in FIG. 18 shows a device example in which a short circuit to the scanning line side and the display line side both. The present embodiment is a sub-display section which was focused on a point is not to display an image, such as the well also the main display unit in the main display unit and the asynchronous when black display, shift register and sample Input directly to the signal line without providing a circuit such as a hold. Therefore, black display on the sub display unit can be realized without increasing the scale of the circuit. Reference Example 5 FIG. 17 shows a circuit according to a fifth reference example of the present invention. This Example is an apparatus for displaying an image of the still image or the like by dividing the sub-display unit in the plurality. In the figure, reference numeral 171 denotes a video signal input terminal;
Is an external control signal input terminal, 173 is a video signal detector, 1
74 is a control circuit, 175 is a signal processing circuit, 176 is a frame memory, 177 and 178 are clock pulse generators, 179 is a driving circuit, 180 is a signal processing circuit, 181
Denotes a main display LCD, and 182 denotes a sub display LCD. According to the liquid crystal display device of the present invention, by providing the sub-display portion, a uniform and clear image can be displayed up to the end portion, and a high quality display can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a first embodiment of the present invention. FIG. 2 is a drive circuit diagram according to the first embodiment of the present invention. FIG. 3 is a waveform chart of the first embodiment of the present invention. FIG. 4 is a waveform chart of the first embodiment of the present invention. FIG. 5 is a waveform chart of the first embodiment of the present invention. FIG. 6 is a waveform chart of the first embodiment of the present invention. FIG. 7 is a diagram showing a second embodiment of the present invention. FIG. 8 is a circuit diagram of a second embodiment of the present invention. FIG. 9 is a diagram showing an application example of the second embodiment of the present invention. FIG. 10 is a diagram showing a reference example 1 of the present invention. FIG. 11 is a diagram showing a second reference example of the present invention. FIG. 12 is a diagram showing a third reference example of the present invention. FIG. 13 is a diagram showing a combination example of the third reference example of the present invention. FIG. 14 is a diagram showing a combination example of the third reference example of the present invention. FIG. 15 is a diagram showing a combination example of the third reference example of the present invention. FIG. 16 is a diagram showing a fourth reference example of the present invention. FIG. 17 is a diagram showing a fifth reference example of the present invention. FIG. 18 is a diagram showing a fourth reference example of the present invention. FIG. 19 is a diagram showing a second embodiment of the present invention. FIG. 20 is a diagram showing a third reference example of the present invention. [Description of Signs] 1 display line 2 scanning line 3 TFT element 4 pixel electrode 5 horizontal shift register 6 vertical shift register 7 video signal input terminal 8 black level signal terminal 9 Y / C signal processing circuit 10 pulse generator 11 chroma signal line 12 Luminance signal 13 Switching line 14 Analog switch 15 RGB decoder 16 Drive signal processing circuit 17 LCD with built-in shift register 31 Luminance signal waveform 32 Black level signal waveform 33 Horizontal blanking pulse 34 Analog switch output waveform 35 Reference potential 36, 37 Black level potential 41 First field luminance signal 42 Second field luminance signal 43 Vertical blanking pulse 44 Horizontal blanking pulse 45 in the first field 45 Horizontal blanking pulse 46 in the second field 46 Output waveform of analog switch in the first field 47th Output waveforms 51, 53 of the analog switch in the field display line side shift register start pulse 52, 54 sample range 61 scan line side shift register start pulse 71 TFT substrate 72 to 72 ″ insulating layer 73 pixel electrode 74, 74 ′ alignment control film 75 sealing material 76 liquid crystal 77 counter electrode 78 color filter 79 parting plate 80, 80 'polarizing plate 81 main display section 82 sub-display section 83 video signal input terminal 84 black level signal input terminal 85 RGB decoder 86 pulse generator 87 analog switch Reference numeral 88 Drive circuit 89 LCD panel 91 Main display unit 92 Light shielding layer 93 Black display area 101 Black level signal input terminal 102 Video signal input terminal 103 Pulse generator 104 Drive signal generation unit 105 Logic conversion unit 106 Level shift 107 Scanning multiplexer 108 LCD Panel 109 Switch scanning level signal generator 110 Signal side multiplexer 111 Level shift 112 Signal level generator 113 Video signal input terminal 114 Y / C signal processing circuit 115 Pulse generator 116 Control circuit 117 ROM 118 External control signal input terminal 119 RGB decoder 120 Drive circuit 121 LCD panel 122 Video signal input terminal 123 External control signal input terminal 124 Video signal detector 125 Control circuit 126 Signal processing circuit 127 ROM 128 Signal processing circuit 129, 130 Clock pulse generator 131 Drive circuit 132 Main display LCD 133 Sub display LCD 134 Sub display horizontal shift register 135 Sub display signal input terminal 136 Sub display sample holder 137 Sub display vertical shift register 138 Main display vertical shift register Star 139 Sample holder 140 for main display unit Horizontal shift register 141 for main display unit 141 Video signal (main display unit display signal) input terminal 161 Video signal input terminal 162 Video signal detector 163 Sub-display unit drive signal generator 164 Signal processing circuit 165 Clock pulse generator 166 Driving circuit 167 Clock etc. control signal generator 168 Main display LCD 169 Sub display LCD 171 Video signal input terminal 172 External control signal input terminal 173 Video signal detector 174 Control circuit 175 Signal processing circuit 176 Frame Memory 177, 178 Clock pulse generator 179 Drive circuit 180 Signal processing circuit 181 Main display section LCD 182 Sub display section LCD 191 Main display section 192 Sub display section 201 Main display section 202 Sub display section a 203 Sub display section b

Continuation of the front page (72) Inventor Akira Ishizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Mamoru Miyawaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-9095 (JP, A) JP-A-4-13988 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/133 550 G02F 1 / 1368

Claims (1)

(57) Claims 1. A TFT substrate provided with an active matrix circuit in which a plurality of pixel electrodes and thin film transistors are arranged in a matrix, and a water for driving the pixel electrodes.
Flat shift register and vertical shift register, and the TFT
A liquid crystal display device, comprising: a counter electrode substrate including a color filter and a counter electrode disposed to face the pixel electrode and spaced apart from the substrate, and a liquid crystal disposed at the distance, A sub-display is provided at least partially around the main display in which the pixel electrode and the thin film transistor are arranged. In the sub-display, a TFT substrate has a pixel electrode, and a counter electrode substrate is provided on the pixel electrode. It has a laminated body of the opposing color filter and the counter electrode, the horizontal
The shift register and the vertical shift register
In addition to having voltage applying means for applying a voltage to the pixel electrode and the counter electrode in the sub-display unit , which is multistaged by the number of pixels,
A switch for selecting one of a luminance signal for displaying the main display portion and a black level signal for displaying the sub display portion, wherein the switch has a horizontal blanking signal, a vertical blanking signal, A liquid crystal display device controlled according to the logical sum of