JP2006106294A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control emission luminance without increasing the number of components, also without damaging flexibility of design, and according to brightness of the surroundings. <P>SOLUTION: In lighting a liquid crystal display panel 11 comprising a plurality of pixels from the rear side with an organic EL backlight 12 comprising at least a light emitting portion including an organic electroluminescence element, external light is detected by utilizing light receiving characteristics of the organic El element, and display luminance is adjusted according to the brightness of the surroundings with a luminance controlling portion 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device using an organic electroluminescence element as a backlight of a liquid crystal display panel.

  As a backlight of a liquid crystal display panel, a backlight using an organic electroluminescence element (hereinafter referred to as an organic EL element) has been actively developed. The organic EL element is characterized by low voltage driving, good color reproducibility, and thinness. Although the organic EL light emitting device has been improved, there are problems that the power consumption is large, the life characteristics are not sufficient, and the luminance is deteriorated when it is lit for a long time. On the other hand, particularly when used as a mobile device such as a mobile terminal device or a video camera, the ambient brightness differs depending on the environment used, and depending on the environment, it may be difficult for the user to recognize the display content on the display. For this reason, it is conceivable that the display brightness should be set to be large so that it can be easily recognized in as many environments as possible. However, in a dark environment, the power consumption is unnecessarily large, and it may be too bright and difficult to see. .

  In addition, when the liquid crystal panel is a transflective liquid crystal panel, it can be fully recognized without using a backlight by using reflection of external light as a reflection type in very bright places such as under sunlight. It becomes. For this reason, it is conceivable to provide a mechanism that adjusts the brightness appropriately according to the ambient brightness, or lowers the brightness of the backlight when unnecessary. This function does not unnecessarily increase the brightness of the backlight, and can greatly contribute to the improvement of power consumption and life characteristics for the organic EL element. Conventionally, various techniques for performing brightness setting according to ambient brightness have been proposed (see, for example, Patent Documents 1 to 7).

JP 2002-23658 A JP 2002-62856 A JP 2002-158757 A Japanese Patent Laid-Open No. 2002-174806 JP 2002-196705 A JP 2003-98984 A JP 2003-209855 A

  However, since all of the conventional techniques are provided with a dedicated light receiving device such as a phototransistor for detecting ambient brightness, the cost increases due to an increase in the number of parts, for example, a phototransistor. When one light is received, the brightness is detected by one point, and the position where the brightness can be detected is biased with respect to the surface area of the surface. Therefore, it is difficult to accurately detect the surrounding brightness. However, there are problems such as placing restrictions on the design by placing dedicated devices. In addition, since many of the light receiving elements have a light receiving wavelength sensitivity characteristic that is different from human visual sensitivity characteristics, there arises a problem that a deviation in light emission luminance due to recognition of human brightness and ambient brightness occurs.

  The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to emit light in accordance with ambient brightness when an organic EL element is used as a backlight in a liquid crystal display panel. An object of the present invention is to provide a liquid crystal display device capable of controlling the above.

  Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of embodiments described below.

  In order to achieve the above object, the present invention solves the above problems by detecting external light with an organic EL element used for a backlight, utilizing the light receiving characteristics of the organic EL element.

  That is, the liquid crystal display device according to the present invention is a liquid crystal display composed of a plurality of pixels, a driving means for driving the liquid crystal display, and at least one light emitting portion including an organic electroluminescence element. A backlight that illuminates the display from the back side; luminance control means that controls the backlight; and an optical sensor that includes at least one light receiving portion including an organic electroluminescence element, the luminance control means comprising: The brightness of the backlight is controlled based on the detection result of the external light by the optical sensor.

  The liquid crystal display device according to the present invention includes a liquid crystal display composed of a plurality of pixels, a driving means for driving the liquid crystal display, and the liquid crystal display composed of a light emitting and receiving part including an organic electroluminescence element. A backlight that illuminates from the back side; and a luminance control unit that controls the backlight, wherein the luminance control unit adjusts the luminance of the backlight based on a detection result of outside light by a light emitting and receiving part of the backlight. It is characterized by controlling.

  Furthermore, the liquid crystal display device according to the present invention is a liquid crystal display comprising a plurality of pixels, a liquid crystal display comprising a plurality of pixels, a driving means for driving the liquid crystal display, and a plurality of light receiving and emitting portions including an organic electroluminescence element. A backlight for illuminating the device from the back side, and a brightness control means for controlling the backlight, wherein the brightness control means is based on the detection result of the external light by the light emitting and receiving part of the backlight. The brightness is controlled.

  According to the present invention, since the organic EL backlight has a function as a light receiving element and a function as a light emitting element, the brightness of the surroundings can be improved without increasing the number of parts and without sacrificing the degree of freedom of design. Accordingly, the display luminance can be adjusted by changing the light emission time, and low power consumption and improved visibility can be achieved in a wide environment from a dark environment to a very bright environment. In addition, by adjusting the liquid crystal transmittance during light reception of the organic EL backlight, it is possible to easily absorb variations in light reception.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Needless to say, the present invention is not limited to the following examples, and can be arbitrarily changed without departing from the gist of the present invention.

  Before specifically describing the embodiment of the liquid crystal display device according to the present invention, characteristics of the organic EL elements used in the liquid crystal display device according to the present invention will be briefly described.

  FIG. 1 shows the configuration of a measurement circuit 5A that measures the light emission characteristics of an organic EL element. The measurement circuit 5A shown in FIG. 1 includes an organic EL element 1, a variable voltage source 2, and an ammeter 3. The positive electrode of the variable voltage source 2 is connected to the anode of the organic EL element 1, the cathode of the organic EL element 1, and the variable voltage. An ammeter 3 is connected between the negative electrodes of the source 2. In this measurement circuit 5A, the anode voltage with respect to the cathode of the organic EL element 1 is V, the current density flowing through the organic EL element 1 based on the current value observed by the ammeter 3 is J, and the emission luminance at that time is L. The relationship between the current density J and the light emission luminance L is shown in FIG.

  As shown in FIG. 2, the light emission luminance L is proportional to the current density J. Therefore, when the organic EL element is used as a liquid crystal backlight, the light emission luminance can be adjusted by controlling the current flowing through the organic EL element.

  FIG. 3 shows the relationship between the anode-cathode voltage V and the light emission luminance L observed in the measurement circuit 5A.

  As shown in FIG. 3, when the voltage V is increased, the light emission luminance L monotonously increases to the voltage V with the point A as a threshold value. Therefore, when the organic EL element is used as a liquid crystal backlight, the light emission luminance can be adjusted by controlling the voltage applied to the organic EL element.

  Next, an organic EL element used as a light receiving element will be described.

  FIG. 4 shows the configuration of a measurement circuit 5B that measures the light receiving characteristics of the organic EL element.

  A measurement circuit 5B shown in FIG. 4 includes an organic EL element 1, a variable voltage source 2, and an ammeter 3. The negative electrode of the variable voltage source 2 is connected to the anode of the organic EL element 1, the cathode of the organic EL element 1, and the variable voltage. An ammeter 3 is connected between the positive electrodes of the source 2. FIG. 5 shows the relationship between the received light amount L and the electromotive current J when the organic EL element 1 is irradiated with light in the measurement circuit 5B shown in FIG.

  As shown in FIG. 5, an organic EL element used as a light receiving element generates an electromotive current substantially proportional to the amount of light received. Further, as the voltage is increased, the electromotive current for a certain amount of received light is increased.

  A liquid crystal display device 10 according to the present invention includes, for example, a liquid crystal panel 11, an organic EL backlight 12, a data control drive unit 13, a luminance control unit 14, a calculation unit 15, and a resistor 16, as shown in FIG. .

  The data control drive unit 13 is a circuit that drives the liquid crystal panel 11. The luminance control unit 14 is a circuit that performs luminance control of the organic EL backlight 12. When the organic EL backlight 12 functions as a light receiving element, a current proportional to the ambient brightness flows through the resistor 16 as shown in FIG. Current-voltage conversion is performed by the resistor 16 and is taken into the calculation unit 15. The arithmetic unit 15 includes, for example, an AD converter in the first stage, and the AD converter converts the terminal voltage between the resistor 16 and the organic EL backlight 12 into a numerical value. In addition, the calculation unit 15 includes a calculation mechanism that calculates the luminance according to the numerical value converted into a numerical value by the AD converter, and transfers the luminance setting value calculated by the calculation mechanism to the luminance control unit 14. The luminance control unit 14 adjusts the luminance of the organic EL backlight 12 by a control signal corresponding to the luminance setting value transferred from the calculation unit 15. The luminance adjustment of the organic EL backlight 12 by the luminance control unit 14 may be current control, voltage control, or light emission time control.

  In the liquid crystal display device 10 having such a configuration, the organic EL backlight 12 can be switched between a function as a light emitting element and a function as a light receiving element. The configuration of the peripheral circuit 20 of the organic EL backlight 12 is shown in FIG.

  As shown in FIG. 7, the peripheral circuit 20 of the organic EL backlight 12 includes an organic EL backlight 12, an analog switch 21, a positive power source 22, a negative power source 23, an amplifier 24, a resistor 25, an AD converter 26, and a luminance setting circuit 27. It is composed of

  The operation of the peripheral circuit 20 of the organic EL backlight 12 shown in FIG. 7 will be described.

  First, when the organic EL backlight 12 functions as a light receiving element, the analog switch 21 is connected to the B side. At this time, if the two input terminal voltages of the amplifier 24 are equal, the organic EL backlight 12 is connected to the organic EL backlight 12 by the negative power source 23 as in FIG. Therefore, when the organic EL backlight 12 is irradiated with external light, an electromotive current is generated from the anode of the organic EL backlight 12, and if the input impedance of the amplifier 24 is infinite, the electromotive current is converted into a current / voltage by the resistor 25. Is done. This voltage is received by the AD converter 26, and the result is transferred to the luminance setting circuit 27. That is, the luminance setting according to the ambient brightness is performed by the function as the light receiving element of the organic EL backlight. In the case of light emission, the analog switch 21 is connected to the A side. Since the anode of the organic EL backlight 12 is connected to the positive power source 22, the connection state is the same as that in FIG. The positive power supply 22 is controlled by the luminance setting circuit 27, and the organic EL backlight 12 is turned on so that the luminance is in accordance with the ambient brightness.

  Here, in the peripheral circuit 20 of the organic EL backlight 12 shown in FIG. 7, the set luminance of the backlight 12 is controlled by a variable voltage, but the current may be controlled. Further, the lighting time may be controlled for a certain luminance.

  In the liquid crystal display device 10, as the liquid crystal panel 11, for example, a transflective liquid crystal panel 30 having a structure as shown in the cross-sectional view of FIG. 8 is used.

  As shown in FIG. 8, the transflective liquid crystal panel 30 includes a polarizing plate 31, a wave plate 32, a color filter 33, electrodes 34 and 36, a liquid crystal layer 35, a substrate 37, the organic EL backlight 12, and a reflecting plate 38. Composed. The region of the reflecting plate 38 is the reflecting portion 39A, and the region of the electrode 39 is the transmitting portion 39B. In a bright environment, the transflective liquid crystal panel 30 functions as a reflective type because light is irradiated from the front side, reflected by the reflecting plate 38, and light travels upward again. On the other hand, in a dark environment, it is difficult to recognize the reflected light from the reflecting plate 38, and the light from the organic EL backlight 12 provided on the back side of the liquid crystal panel 30 passes through the electrode 36 and travels to the front side. , Function as a transmission type. Here, the brightness setting can be lowered to such an extent that the display is not easily recognized in a dark environment. Further, in a bright environment, the liquid crystal panel 30 functions as a reflection type, and the brighter the light, the stronger the reflected light, so the luminance setting can be lowered.

Here, FIG. 9 shows an example of the luminance setting of the organic EL backlight 12 that illuminates the transflective liquid crystal panel 30 from the back side. In FIG. 9, the horizontal axis represents the external light intensity, and the vertical axis represents the luminance setting value when the display white is 100%. The external light is 0 lux and the initial value is 100 Cd / m ^2, and 1000 lux is 300 Cd / m ² . Further, it is assumed that the setting is made so that the luminance is gradually lowered when it exceeds 3000 lux.

As described above, when the luminance setting is performed in both a dark environment and a bright environment using the transflective liquid crystal panel 30, the illuminance range becomes very wide. For example, in FIG. 9, if the set luminance is set to be 0 Cd / m ² at 10000 lux, the light receiving range needs to correspond to 10000 lux, and the S / N ratio becomes low in a dark environment of about several tens of lux. It becomes difficult to adjust the brightness accurately. This can be dealt with by changing the transmittance of the liquid crystal layer 35 by controlling the signal voltage applied to the electrodes 34 and 36 shown in FIG.

  Here, one pixel of a general liquid crystal panel includes a liquid crystal 51, a data write transistor 52, a storage capacitor 53, a data line 54, a data scanning line 55, and a storage capacitor line 56, as shown in a pixel circuit in FIG. And a reference voltage line 57. When the voltage corresponding to the video signal is written to the pixel, the data scanning line 55 becomes High, the data writing transistor 52 is turned ON, and the data line 54 and one terminal of the liquid crystal 51 are connected. At this time, by applying a voltage corresponding to the video signal to the data line 54, a voltage is applied between the data line 54 side terminal of the liquid crystal 51 and the reference voltage line 57, and the voltage is held by the holding capacitor 53. When the data scanning line 55 becomes Low, the data writing transistor 52 is turned OFF, and one terminal of the data line 54 and the liquid crystal 51 is insulated. Since the voltage is held by the holding capacitor 53, the liquid crystal state is held until the data scanning line 55 becomes High again.

  A configuration of a liquid crystal panel including such a pixel circuit is shown in FIG.

  That is, the liquid crystal panel 11 includes a data line 54, a data scanning line 55, a pixel 61, a V scan driving circuit 62, an external data line 63, an external light receiving data line 64, and an H switch 65. Pixels 61 are arranged at the intersections of the data lines 54 and the data scanning lines 55. VCK and VSP are supplied to the V scanning drive circuit 62, and the data scanning line 55 repeats High and Low sequentially. When the video signal is written to the pixel, the H switch 65 is connected to the external data line 63 side. When a certain data scanning line 55 becomes High, the horizontal row of pixels is in a data writing state, and a voltage corresponding to a video signal applied to the external data line 63 passes through the data line 54 and the liquid crystal in the pixel. Given to. Further, when the H switch is connected to the external light receiving data line 64 side, for example, if the voltage of the external light receiving data line 64 is constant for one field period, the voltages applied to the liquid crystals in all the pixels are equal. A certain raster can be displayed.

  One pixel of the liquid crystal panel 11 constituting the liquid crystal display device 10 according to the embodiment of the present invention includes, for example, a liquid crystal 51, a data write transistor 52, a storage capacitor 53, and a data line as shown in FIG. 54, a data scanning line 55, a storage capacitor line 56, a reference voltage line 57, a light receiving data write transistor 67, an external light receiving data line 64, and a light receiving data scanning line 68. In this liquid crystal panel 11, in the pixel circuit of the liquid crystal panel shown in FIG. 10, an external light receiving data line 64 is connected to one terminal of the liquid crystal 51 via a light receiving data write transistor 67, and light receiving data writing is performed. A light receiving data scanning line 68 is connected to the gate of the transistor 67. When the light reception data scanning line 68 is in the Low state, when the voltage corresponding to the video signal is written to the pixel, the data scanning line 55 becomes High, the data writing transistor 52 is turned on, and the data line 54 and the liquid crystal 51 are turned on. One terminal is connected. At this time, by applying a voltage corresponding to the video signal to the data line 54, a voltage is applied between the data line 54 side terminal of the liquid crystal 51 and the reference voltage line 57, and the voltage is held by the holding capacitor 53. When the data scanning line 55 becomes Low, the data writing transistor 52 is turned OFF, and one terminal of the data line 54 and the liquid crystal 51 is insulated. Since the voltage is held by the holding capacitor 53, the liquid crystal state is held until the data scanning line 55 becomes High again or the light reception data scanning line 68 becomes High. When the data scanning line 55 is Low, the light reception data scanning line 68 is High, the light reception data writing transistor 67 is turned on, and the external light reception data line 64 and one terminal of the liquid crystal 51 are connected. The At this time, by applying a voltage corresponding to the external light reception data line to the external light reception data line 64, a voltage is applied between the external light reception data line 64 side terminal of the liquid crystal 51 and the reference voltage line 57, and the voltage is held by the holding capacitor 53. The When the light reception data scanning line 68 becomes Low, the light reception data write transistor 67 is turned off, and the external light reception data line 64 and one terminal of the liquid crystal 51 are insulated. Since the voltage is held by the holding capacitor 53, the liquid crystal state is held until the light receiving data scanning line 68 becomes High or the data scanning line 55 becomes High again.

  FIG. 13 shows a configuration of the liquid crystal panel 11 including the pixel circuit shown in FIG.

  The liquid crystal panel 11 includes a data line 54, a data scanning line 55, a pixel 61, a V scanning drive circuit 62, an external light receiving data line 64, and a light receiving data line scanning line 68. Pixels 61 are arranged at the intersections of the data lines 54 and the data scanning lines 55. VCK and VSP are supplied to the V scanning drive circuit 62, and the data scanning line 55 repeats High and Low sequentially. The writing of the video signal to the pixel is performed by the data scanning line 55. When a certain data scanning line 55 becomes High, the horizontal row of pixels is in a data writing state, and a voltage corresponding to a video signal applied to the data line 54 is applied to the liquid crystal in the pixel. Further, when the light receiving data scanning line 68 is set High when all the data scanning lines 55 are LOW, the voltage of the external light receiving data line 64 is applied to the liquid crystals in all the pixels, and as a result Since the voltages related to the liquid crystals in the pixels are equal, a certain raster can be displayed.

  Here, the operation of the liquid crystal display panel shown in FIG. 10 is shown in the time chart of FIG.

  When the refresh rate is 60 Hz, when VSP is given to the V scan drive circuit 62 for one field 16.67 ms, the V scan line output from the V scan drive circuit 62 is synchronized with VCK as shown in FIG. Then, High and Low are repeated sequentially. A period until the bottom V scan is completed is defined as a data writing period. At this time, if the external light receiving control line 66 in FIG. 11 is Low, the V scanning line is reflected in the OR gate output in FIG. 11, that is, the scanning line 55 to the pixel. Further, it is assumed that the H switch 65 in FIG. 11 is High and connected to the external data line 63 side in FIG. All the V scanning lines become Low, and the backlight emission is performed at the timing when the liquid crystal inversion in the lowermost stage is settled. At this time, the analog switch 21 in FIG. 7 is set to the low light emission function side as shown in FIG. The light emission period is from the start of backlight emission to the end of light emission. When the H switch 65 in FIG. 11 is Low and connected to the external light reception data line 64 after the backlight emission ends, when the external light reception control line 66 in FIG. 11 becomes High as shown in FIG. The OR gate outputs are all high, and the same signal can be written to all the pixels by the external light receiving data line 64. This period is set as a light reception data writing period. The analog switch is set to High at the timing when the liquid crystal inversion operation is settled, and light is received within the period when the backlight is on the light receiving function side, and the received light data is taken into the AD converter 26 in FIG. When the light reception ends, the analog switch becomes Low again and the H switch becomes High, and the data writing period starts. By alternately writing, for example, two types of data for every 1V period as light reception data of the external light reception data line 64 given within the light reception data writing period, light reception in a bright environment and light reception in a dark environment are separated in a 1V period. Therefore, the S / N ratio can be improved in a wide illuminance range, and accurate external light detection can be performed.

  The operation of the liquid crystal display panel shown in FIG. 12 is shown in the time chart of FIG.

  When the refresh rate is 60 Hz, when VSP is given to the V scan drive circuit 62 for one field 16.67 ms, the V scan line output from the V scan drive circuit 62 is synchronized with VCK as shown in FIG. Then, High and Low are repeated sequentially. A period until the bottom V scan is completed is defined as a data writing period. In the meantime, it is assumed that the light reception data scanning line 68 in FIG. 13 is Low. All the V scanning lines become Low, and the backlight emission is performed at the timing when the liquid crystal inversion in the lowermost stage is settled. At this time, the analog switch 21 in FIG. 7 is set to the low light emission function side as shown in FIG. The light emission period is from the start of backlight emission to the end of light emission. When the light reception data scanning line 68 in FIG. 13 becomes high after the backlight emission ends, as shown in FIG. 15, all the light reception data write transistors 67 of each pixel in FIG. 12 become high, and the external light reception data line in FIG. 64 makes it possible to write the same signal to all pixels. This period is set as a light reception data writing period. The analog switch is set to High at the timing when the liquid crystal inversion operation is settled, and light is received within the period when the backlight is on the light receiving function side, and the received light data is taken into the AD converter 26 in FIG. When the light reception ends, the analog switch becomes Low again, and the data writing period starts. By alternately writing, for example, two types of data for every 1V period as light reception data of the external light reception data line 64 given within the light reception data writing period, light reception in a bright environment and light reception in a dark environment are separated in a 1V period. Therefore, the S / N ratio can be improved in a wide illuminance range, and accurate external light detection can be performed. Also, as shown in FIG. 16, it is possible to increase the sampling frequency by repeating the light reception data writing and light reception twice or more within a 1V period.

  Here, the organic EL backlight 12 in the liquid crystal display device 10 shown in FIG. 6 can employ a structure divided into a plurality of regions.

  For example, like the liquid crystal display device 10A shown in FIG. 17, the organic EL backlight 12 in the liquid crystal display device 10 of FIG. 6 described above can be divided into two regions 71 and 72.

  The liquid crystal display device 10A includes a liquid crystal panel 11, an organic EL backlight 12, a data control drive unit 13, a luminance control unit 14, a calculation unit 15, and resistors 16A and 16B. A control signal from the luminance control unit 14 is given to the first backlight region 71 and the second backlight region 72. One resistor 16 is provided in each region, and each bias terminal is input from the calculation unit 15.

  The configuration of the liquid crystal panel in the liquid crystal display device 10A is shown in the block diagram of FIG.

  The liquid crystal panel 11 includes a data line 54, a data scanning line 55, a pixel 61, a V scanning drive circuit 62, an external data line 63, two external light receiving data lines 64A and 64B, and an H switch 65. The light receiving data lines 64 are divided into two as shown in FIG. 18, the external light receiving data lines 64A are connected to the pixels of the first backlight region 71, and the external light receiving data lines 64B are connected to the second backlight region. It is connected to 72 pixels.

  In this case, since there are two external light receiving data lines 64A and 64B, by changing the voltage applied to the two external light receiving data lines 64A and 64B, external light of two types of brightness can be obtained in one light receiving period. Detection is possible. Therefore, sampling can be performed twice as fast.

  Furthermore, another example of the liquid crystal display device according to the embodiment of the present invention is shown in FIG.

  A liquid crystal display device 10B shown in FIG. 19 is a case where the organic EL backlight 12 is divided into two regions in the liquid crystal display device 10 shown in FIG. The first area 73 corresponds to the effective display area of the liquid crystal panel 11, and the second area 74 corresponds to the dummy pixel area (or non-display area) 75 disposed outside the effective display area of the liquid crystal panel 11. is doing. The first area 73 functions as a light emitting area, and the second area 74 functions as a light receiving area. In the liquid crystal display device 10 </ b> B, the control signal output from the luminance control unit 14 is given only to the first region 73. In addition, the resistor 16 is connected only to the second region 74, and data received by the second region 74 is input to the calculation unit 15. In the liquid crystal display device 10B having such a configuration, since light reception and light emission are divided in areas, it is not necessary to switch between light reception and light emission in a time division manner as shown in FIG. Also, by providing data to the dummy pixels, it is possible to adjust the transmittance of the dummy pixel liquid crystal according to the surrounding brightness and improve the S / N ratio.

  The above description is not limited to a transflective liquid crystal panel, and external light can be detected by a similar method in a transmissive liquid crystal panel.

  In other words, the liquid crystal display devices 10, 10 </ b> A, and 10 </ b> B may be configured using a transmissive liquid crystal panel as the liquid crystal panel 11.

It is a circuit diagram which shows the structure of the measurement circuit which measures the light emission characteristic of an organic EL element. It is a characteristic view which shows the relationship between the current density of an organic EL element, and light emission luminance. It is a characteristic view which shows the relationship between the anode-cathode voltage of the organic EL element observed in the said measurement circuit, and light emission luminance. It is a circuit diagram which shows the structure of the measurement circuit which measures the light reception characteristic of an organic EL element. It is a characteristic view which shows the relationship between the light reception amount at the time of irradiating light with respect to the organic EL element 1 in the said measurement circuit, and an electromotive current. It is a block diagram which shows the structural example of the liquid crystal display device which concerns on this invention. It is a block diagram which shows the structure of the peripheral circuit of the organic electroluminescent backlight with which the said liquid crystal display device was equipped. It is sectional drawing which shows the structure of the transflective liquid crystal panel used as a liquid crystal panel in the said liquid crystal display device. It is a characteristic view which shows an example of the brightness | luminance setting of the organic electroluminescent backlight which illuminates the said transflective liquid crystal panel from the back side. It is a pixel circuit diagram which shows the structure of 1 pixel of a general liquid crystal panel. It is a block diagram which shows the structure of the liquid crystal panel provided with the pixel circuit shown in FIG. It is a pixel circuit diagram which shows the structure of 1 pixel of the liquid crystal panel which comprises the said liquid crystal display device. It is a block diagram which shows the structure of the liquid crystal panel provided with the pixel circuit shown in the said FIG. 11 is a time chart illustrating an operation of the liquid crystal display panel illustrated in FIG. 10. 13 is a time chart showing the operation of the liquid crystal display panel shown in FIG. 13 is another example of a time chart showing the operation of the liquid crystal display panel shown in FIG. It is a block diagram which shows the structural example of the liquid crystal display device which divided | segmented the organic electroluminescent backlight into two area | regions. It is a block diagram which shows the structure of the liquid crystal panel in the liquid crystal display device shown in FIG. It is a block diagram which shows another structural example of the liquid crystal display device which concerns on this invention.

Explanation of symbols

  10, 10A, 10B liquid crystal display device, 11 liquid crystal panel, 12 organic EL backlight, 13 data control drive unit, 14 brightness control unit, 15 arithmetic unit, 16, 16A, 16B resistor, 20 peripheral circuit, 21 analog switch, 22 Positive power source, 23 Negative power source, 24 Amplifier, 25 Resistance, 26 AD converter, 27 Brightness setting circuit, 30 Transflective liquid crystal panel, 31 Polarizing plate, 32 Wavelength plate, 33 Color filter, 34, 36 Electrode, 35 Liquid crystal layer, 37 Substrate, 38 Reflector, 39A Reflector, 39B Transmitter, 51 Liquid Crystal, 52 Data Write Transistor, 53 Storage Capacitor, 54 Data Line, 55 Data Scan Line, 56 Storage Capacitance Line, 57 Reference Voltage Line, 61 Pixels 62 V scanning drive circuit, 63 external data line, 64, 64A, 64B external light receiving data , 65 H switch, 66 external light reception control line, 67 light reception data write transistor, 68 light reception data scanning line, 71 first backlight region, 72 second backlight region, 73 first region, 74 second Area, 75 dummy pixel area

Claims (30)

A liquid crystal display comprising a plurality of pixels;
Driving means for driving the liquid crystal display;
A backlight for illuminating the liquid crystal display composed of at least one light-emitting portion including an organic electroluminescence element from the back side;
Brightness control means for controlling the backlight;
An optical sensor composed of at least one light receiving portion including an organic electroluminescence element,
The liquid crystal display device, wherein the luminance control means controls the luminance of the backlight based on a detection result of outside light by the optical sensor.   2. The liquid crystal display device according to claim 1, wherein at least a part of the light emitting part constituting the backlight and the light receiving part constituting the photosensor are manufactured by the same process.   2. The liquid crystal display device according to claim 1, further comprising a transmittance control means capable of controlling the transmittance on the optical sensor.   5. The liquid crystal display device according to claim 4, wherein the transmittance control means comprises a liquid crystal manufactured by the same process as the liquid crystal display.   2. The liquid crystal display device according to claim 1, wherein the brightness control means adjusts the brightness by controlling a voltage applied to the organic electroluminescence element.   2. The liquid crystal display device according to claim 1, wherein the luminance control means adjusts the luminance by controlling an amount of current flowing through the organic electroluminescence element.   The liquid crystal display device according to claim 1, wherein the luminance control unit adjusts luminance by controlling a light emission time of the organic electroluminescence element.   2. The liquid crystal display device according to claim 1, wherein the liquid crystal display is a transmissive liquid crystal display composed of a plurality of pixels.   2. The liquid crystal display device according to claim 1, wherein the liquid crystal display is a transflective liquid crystal display composed of a plurality of pixels. A liquid crystal display comprising a plurality of pixels;
Driving means for driving the liquid crystal display;
A backlight for illuminating the liquid crystal display composed of a light receiving and emitting part including an organic electroluminescence element from the back side;
Brightness control means for controlling the backlight,
The liquid crystal display device, wherein the luminance control means controls the luminance of the backlight based on a detection result of outside light by a light emitting / receiving portion of the backlight.   11. The liquid crystal display device according to claim 10, wherein the organic electroluminescence element of the backlight includes switching means for functioning as a light emitting element or a light receiving element.   The display device according to claim 10, wherein the luminance control unit performs luminance adjustment by controlling a voltage applied to the organic electroluminescence element.   11. The liquid crystal display device according to claim 10, wherein the luminance control means adjusts luminance by controlling an amount of current flowing through the organic electroluminescence element.   11. The liquid crystal display device according to claim 10, wherein the luminance control means adjusts the luminance by controlling a light emission time of the organic electroluminescence element.   The driving means of the liquid crystal display writes one type or several types of fixed patterns as data in the liquid crystal display every one field period or several field periods, and during this period, the organic electroluminescence element is received by the switching means by the switching means. The liquid crystal display device according to claim 10, wherein the liquid crystal display device is made to function as:   16. The liquid crystal display device according to claim 15, wherein the fixed pattern is a raster. The driving means of the liquid crystal display writes a fixed pattern as data in the liquid crystal display every 1 field period or every several field periods, and during this period, the switching means causes the organic electroluminescence element to function as a light receiving element, When functioning as a light receiving element, apply a plurality of voltages to the organic electroluminescence element,
11. The liquid crystal display device according to claim 10, wherein the luminance control means sets the light emission luminance based on a detection result of external light according to a light reception result at each voltage applied to the organic electroluminescence element. .   The liquid crystal display device according to claim 17, wherein the fixed pattern is a raster.   11. The liquid crystal display device according to claim 10, wherein the liquid crystal display is a transmissive liquid crystal display composed of a plurality of pixels.   11. The liquid crystal display device according to claim 10, wherein the liquid crystal display is a transflective liquid crystal display composed of a plurality of pixels. A liquid crystal display comprising a plurality of pixels;
Driving means for driving the liquid crystal display;
A backlight for illuminating the liquid crystal display composed of a plurality of light receiving and emitting portions including the organic electroluminescence element from the back side;
Brightness control means for controlling the backlight,
The liquid crystal display device, wherein the luminance control means controls the luminance of the backlight based on a detection result of outside light by a light emitting / receiving portion of the backlight.   The liquid crystal display device according to claim 21, further comprising switching means for causing the organic electroluminescence element of the backlight to function as a light emitting element or a light receiving element.   The driving means of the liquid crystal display writes a fixed pattern as data in the liquid crystal display every one field period or every several field periods, and the organic electroluminescence element functions as a light receiving element by the switching means during this period. The liquid crystal display device according to claim 21.   The liquid crystal display device according to claim 21, wherein the fixed pattern is a fixed pattern in which average data of pixels corresponding to the plurality of light receiving and emitting portions is different.   25. The liquid crystal display device according to claim 24, wherein the setting brightness of the brightness control means is performed by processing the results detected by the plurality of light emitting / receiving portions simultaneously or in a time-sharing manner.   The liquid crystal display device according to claim 21, wherein the luminance control means adjusts the luminance by controlling a voltage applied to the organic electroluminescence element.   The liquid crystal display device according to claim 21, wherein the brightness control means adjusts the brightness by controlling an amount of current flowing through the organic electroluminescence element.   The liquid crystal display device according to claim 21, wherein the brightness control means adjusts the brightness by controlling a light emission time of the organic electroluminescence element.   The liquid crystal display device according to claim 21, wherein the liquid crystal display is a transmissive liquid crystal display composed of a plurality of pixels. The liquid crystal display device according to claim 21, wherein the liquid crystal display is a transflective liquid crystal display composed of a plurality of pixels.

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