JP2007052105A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device in which the number of components or the like can be reduced as compared with the case of externally mounting a color sensor module, white balance of display light of a display panel can be strictly adjusted, and the white balance and uniformity in a light emission face of brightness in a back light including a large number of light sources can be improved. <P>SOLUTION: A liquid crystal panel 800 includes an optical sensor circuit 630 integrally formed with group of optical sensors and display TFTs. The circuit 630 is provided on each light emission region 500A formed by dividing a back light 500. Each circuit 630 measures light intensity of light emitted from the back light 500 and colored by a color filter layer in a liquid crystal panel 800 at each color of the color filter layer for a corresponding light emission region 500A. A control circuit feed-back-controls light emission intensity of an LED chip 511 at each light emission region 500A and each light emission color so that the brightness of the light emission region 500A and the white balance are held in a desired state based on the measured result. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device including a display panel, a backlight, and a control circuit that controls the backlight.

  Since liquid crystal display devices are thin and light, low power consumption, high definition, and easy colorization, they are widely used as TV and monitor applications as flat panel displays that replace CRTs. The liquid crystal display device in the transmissive display mode has a structure including a backlight on the back surface of the liquid crystal panel, and displays an image by dimming light emitted from the backlight with the liquid crystal panel. As this backlight, one using a cold cathode fluorescent lamp (CCFL) is generally used.

  The cold-cathode tube achieves white light emission by mixing light emitted from phosphors of three colors of red (R), green (G), and blue (B). The emission spectrum is shown in FIG. As described above, there are some unnecessary spectra other than the three main spectra of RGB. For this reason, the color reproduction range of the display device is narrow. For example, the color reproduction range using a cold cathode tube is generally about 72% of NTSC.

  In order to widen this color reproduction range, development using a RGB three-color light-emitting diode (LED) as a backlight instead of a cold cathode tube is underway. Since the emission wavelength of the LED is defined by the band gap of the semiconductor, the LED does not emit light at an unnecessary wavelength, and the color purity can be increased. Therefore, a wider color reproduction range than that of the cold cathode tube can be realized, and for example, it is possible to achieve an NTSC ratio of 100%.

  However, since the LED is a semiconductor element, the temperature dependence of the light emission characteristics is large, and the tendency varies depending on each color. FIG. 22 is a diagram illustrating the temperature dependence of the light emission intensity of each RGB color LED. As can be seen from FIG. 22, the light emission intensity as a whole decreases as the temperature rises, and the amount of change in the light emission characteristics differs for each color. For this reason, the LED temperature rise has a problem that not only the brightness (brightness) decreases, but also the white color (white balance) synthesized by the light emission of the three RGB colors changes.

  With respect to this problem, Patent Document 1 discloses a technique in which an optical sensor corresponding to each color is arranged around an LED backlight and the emission intensity of the LED is controlled for each color based on the detection value of the optical sensor. ing. Non-Patent Document 1 discloses the specification of a color sensor module (C9303 manufactured by Hamamatsu Photonics Co., Ltd.) arranged around the LED backlight, and feedback control of the light emission intensity of the LED using the color sensor module. A configuration diagram (see FIG. 23) is disclosed.

JP 2004-29141 A JP 2000-321571 A JP 2004-350179 A Catalog of color sensor module C9303 manufactured by Hamamatsu Photonics Co., Ltd. )

  However, according to the above-described technique, it is necessary to separately attach a color sensor module, which is a discrete component, in the vicinity of the backlight, resulting in an increase in the number of components and an increase in mounting cost.

  In addition, the spectral transmittance characteristics of the color filter used in the color sensor module, which is a discrete component, and the color filter used in the liquid crystal panel do not always match. In this case, the detection obtained from the color sensor module Even if the white balance of the backlight is controlled based on the data, it is difficult to say that the white balance of the display light is strictly adjusted.

  By the way, in the case of a liquid crystal display device having a relatively large display area, it is necessary to provide a plurality (large number) of LED chips in the backlight. For example, in the case of a large liquid crystal TV, about 100 to 500 LED chips are used, depending on the screen size and the output of the LED itself. In the case where a large number of LEDs are arranged, (i) temperature dependency of light emission characteristics among RGB colors (described above), (ii) individual variations in light emission characteristics, (iii) individual variations in light emission characteristics over time, (iv ) In-plane variation of the heat dissipation characteristics of the LED, which depends on the LED arrangement position, affects the light emission of the entire backlight in a complex manner. For this reason, in-plane uniformity of white balance and luminance (brightness) may be low over the entire backlight emission surface.

  Even if the feedback control using the color sensor module shown in FIG. 23 is applied to such a case, the color sensor module can only monitor a specific range of colors near the module. On the other hand, it is considered difficult to improve the in-plane uniformity of white balance and luminance.

  In addition, a method of improving the in-plane uniformity of white balance and brightness by selecting and using LED chips with uniform light emitting characteristics in advance can be considered, but since the selection of LED chips leads to cost increase, a preferable solution It's hard to say. In addition, it is possible to improve the white balance and brightness in-plane uniformity by arranging LEDs with low emission intensity at high density and averaging the emission characteristics, but the cost increases due to the increase in the number of LED chips used. This method is also not a preferable solution. Furthermore, both of these solutions are difficult to cope with the above problem (iv), and it is considered that there are limits in performance as measures for improving the in-plane uniformity of white balance and luminance.

  Further, the entire light emitting surface of the backlight is divided into a plurality of light emitting regions, and a color sensor module is provided for each light emitting region (that is, a plurality of color sensor modules are provided in the backlight unit for the entire light emitting surface). A method of feeding back the emission intensity of each color for each region can be considered. According to this, since it is possible to cope with all the problems (i) to (iv), it can be expected as a measure for improving the in-plane uniformity of white balance and luminance. However, since a plurality of color sensor modules are required, an increase in the number of sensors to be used causes an increase in the mounting process and an increase in cost.

  The present invention has been made in view of this point, and can reduce the number of components and mounting cost compared to a configuration in which a color sensor module, which is a discrete component, is externally attached. An object of the present invention is to provide a display device that can be adjusted strictly and can improve white balance and brightness (brightness) in-plane uniformity of the backlight even when a large number of light sources are arranged in the backlight. To do.

  In order to achieve the above object, according to the present invention, in a display device, a display panel, a backlight that is arranged to be able to irradiate light to the display panel, and includes a plurality of color light sources, and the backlight is controlled. The display panel includes a display switching element having a thin film transistor structure, a first substrate having at least one photosensor group monolithically formed with the display switching element, and the first substrate. A second substrate disposed oppositely, and a color filter layer provided on any one of the first substrate and the second substrate, the color filter layer including a plurality of color filters for display. One optical sensor group is configured to determine the light intensity of the light emitted from the backlight and colored by the color filter layer for each color of the plurality of color filters. Measurably is configured, the control circuit, the at least one based on the measurement results by the optical sensors, and controls the light emission intensity of the plurality of colors of light sources for each emitting color.

  According to such a configuration, the optical sensor group is provided on the first substrate, and is monolithically formed with the display switching element having the thin film transistor structure, so that the optical sensor module, which is a discrete component, is provided on the display panel. Compared to the externally attached configuration, the number of components and mounting cost can be reduced in the display device. Furthermore, the color filter layer is composed of color filters for display, and the optical sensor group is configured to measure the light intensity of light emitted from the backlight and colored by the color filter layer for each color of the color filter. Therefore, the white balance of the display light of the display panel can be strictly adjusted. Furthermore, since the emission intensity of the light source of the backlight is controlled for each emission color based on the measurement result by the optical sensor group, even when a large number of light sources are arranged, the white balance and brightness (brightness) of the backlight can be adjusted. The uniformity in the light emitting surface can be improved.

  The at least one photosensor group is preferably arranged outside the display area of the display panel. According to such a configuration, there is no influence on display quality even if the optical sensor group is arranged (for example, a decrease in the transmittance (aperture ratio) of the pixel). Not receive. For this reason, compared with the case where an optical sensor group is arrange | positioned in the display area of a display panel, the area of an optical sensor group can be enlarged, and, thereby, high sensitivity can be achieved. In addition, since the electrodes and wiring for the optical sensor group can be designed independently from the electrodes in the display area, the driving conditions of the optical sensor group can be easily optimized (the degree of freedom in setting the driving conditions is great).

  Further, it is preferable that the at least one photosensor group is disposed in a display area of the display panel. According to such a configuration, the optical sensor group can be arranged at a position away from the outer edge of the light emitting surface of the backlight, thereby making the surrounding environment of the measurement part by the optical sensor group equal in any direction. Therefore, the light intensity can be measured as an average value. As a result, the brightness and white balance of the backlight can be adjusted more strictly.

  The at least one photosensor group is preferably a plurality of photosensor groups. According to such a configuration, measurement results from a plurality of optical sensor groups can be used for the above-described control of the light source, so that in-plane uniformity of the luminance of the backlight is improved.

  The plurality of light sensor groups are arranged so as to be able to measure the light intensity of the plurality of light emitting regions of the backlight, and the control circuit corresponds to the light emitting region for each light emitting region of the backlight. It is preferable to control the light emission intensity of the light sources of the plurality of colors for each of the light emission colors based on the measurement result by the optical sensor group. According to such a configuration, since the light emission intensity of the light source is controlled for each light emission region of the backlight, the in-plane uniformity of the luminance of the backlight is improved. Such an effect is prominent in a large-area backlight.

  In addition, the control circuit may emit the light of the light sources of the plurality of colors for each light emitting region of the backlight based on not only the measurement result by the plurality of optical sensor groups but also luminance information of an input video signal. It is preferable to control the intensity for each emission color. According to such a configuration, a screen based on an input video signal is provided by providing a group of optical sensors in each of the divided areas of so-called divided-screen active backlight driving and correcting the luminance and white balance of the backlight for each divided area. The display by the divided active backlight drive can be performed more faithfully, and the divided state (divided section) can be made inconspicuous even if the degree of temporal change of the light source is different for each divided area.

  The backlight, the second substrate, and the first substrate are arranged in this order, and the at least one photosensor group overlaps the color filter layer in a plan view of the display panel. preferable. According to such a configuration, since the photosensor group overlaps the color filter layer, the light of the backlight is colored by being incident on the display panel from the second substrate side and passing through the color filter layer. Reach the group. Thereby, the optical sensor group can receive the colored light. That is, a color sensor can be configured.

  The backlight, the first substrate, and the second substrate are arranged in this order, and the display panel directs the light colored by the color filter layer toward the at least one photosensor group. It is preferable to further include a reflecting member provided to reflect. According to such a configuration, since the reflecting member is provided so as to reflect the light emitted from the backlight and colored by the color filter layer toward the photosensor group, the photosensor group has such colored light. Can be received. That is, a color sensor can be configured.

  According to the present invention, it is possible to reduce the number of components and mounting cost of the display device as compared with a configuration in which a color sensor module, which is a discrete component, is externally attached, and to strictly adjust the white balance of display light on the display panel. Even in the case where a large number of light sources are arranged, it is possible to improve the in-plane uniformity of the white balance and luminance (brightness) of the backlight.

<Embodiment 1>
1 and 2 are a schematic view and a perspective view for explaining the display device 20 according to the first embodiment of the present invention. 3 is an enlarged perspective view of an LED (Light Emitting Diode) array 510, and FIG. 4 is an enlarged view of a portion 4 surrounded by a one-dot chain line in FIG. FIG. 5 is a block diagram for explaining the display device 20.

  First, as shown in FIG. 1, the display device 20 includes a display panel 800, a backlight (or backlight unit) 500, and a control drive device 900. Here, as the display panel 800, an active matrix type liquid crystal panel using a transmissive display mode is illustrated, and thus the display panel 800 is also referred to as a “liquid crystal panel 800”. At this time, the display device 20 can be referred to as a “liquid crystal display device 20”. The backlight 500 is arranged to be able to irradiate light from the back surface (surface opposite to the display surface) of the liquid crystal panel 800 with respect to the liquid crystal panel 800.

  The control drive device 900 is a general term for circuits, devices, and the like that are connected to the liquid crystal panel 800 and the backlight 500 to control and drive the liquid crystal panel 800 and the backlight 500, and one of such circuits. The control drive device 900 includes a backlight control circuit 910. “Backlight” is indicated as “B / L” in the drawing. As will be described in detail later, the liquid crystal panel 800 includes an optical sensor circuit 630 (see FIG. 2 and the like), and the backlight control circuit 910 is provided so as to receive the sensor signal S1 from the optical sensor circuit 630. Yes. The backlight control circuit 910 is configured to control the light emission state of the backlight 500 by the control signal S2 based on the sensor signal S1.

  Next, the display device 20 will be described more specifically with reference to FIGS. First, as shown in FIG. 2, the backlight 500 is a so-called edge light type light source, and includes two LED arrays 510 and a light guide plate 520. In FIG. 2, the LED array 510, the light guide plate 520, and the liquid crystal panel 800 are illustrated separately for the sake of explanation, and this method of illustration is also used in FIG.

  In the LED array 510, LED chips 511 as light sources are arranged in a row so as to emit light in a predetermined direction. The light guide plate 520 is a flat plate member having a main surface having the same size and shape as the liquid crystal panel 800, and is made of, for example, a transparent acrylic plate having good light transmission efficiency. The LED array 510 is disposed so that the LED chip 511 faces the side surface (end surface) of the light guide plate 520 and the light guide plate 520 is sandwiched between the two LED arrays 510. Thereby, the light of the LED chip 511 enters from the two opposite side surfaces of the light guide plate 520, and the rectangular main surface of the light guide plate 520 emits light in a planar manner.

  At this time, as shown in FIG. 3, in the LED array 510, LED chips 511R, 511B, and 511G as light sources of respective colors of red (R), blue (B), and green (G) are arranged in order. White color can be obtained by mixing color light sources.

  Returning to FIG. 2, the liquid crystal panel 800 is arranged so that the above-described planar illumination by the light guide plate 520 is applied to the entire main surface of the liquid crystal panel 800, and the illumination from the backlight 500 is displayed in the display area 810. Display is performed by dimming each pixel.

  In particular, the liquid crystal panel 800 incorporates four photosensor circuits 630 in a peripheral region 820 that surrounds the display region 810, and the photosensor circuits 630 are generally provided near the four corners of the display region 810 here. The optical sensor circuit 630 measures the light intensity of light incident on the circuit 630. As schematically shown in FIG. 4, the sub optical sensor for measuring the light intensity of each color of red, blue, and green. It consists of an assembly (or group) of circuits 630R, 630B, 630G.

  Here, the liquid crystal panel 800 is roughly divided into a display area 810 in which pixels are arranged and a peripheral area 820 surrounding the display area 810. Both the regions 810 and 820 project not only the two-dimensional region on the display surface but also the two-dimensional region in the thickness direction of the liquid crystal panel 800 (that is, the stacking direction of substrates 600 and 700 described later (see FIG. 8)). It also refers to the three-dimensional region of the liquid crystal panel 800 grasped by the above.

  Now, as shown in FIG. 2, the light emitting surface of the backlight 500 (corresponding to the main surface of the light guide plate 520) is divided into four light emitting regions 500A (this separation does not mean physical separation and division). ). Here, the light emitting region 500A is defined as a region partitioned by connecting the midpoints of two opposing sides on the rectangular main surface of the light guide plate 520, and is defined in a 2 × 2 matrix. Each light emitting area 500A is divided so as to include one of the four portions obtained by projecting the four photosensor circuits 630 onto the backlight 500, in other words, one photosensor for each light emitting area 500A. A circuit 630 is provided. Although a specific configuration / form of each photosensor circuit 630 will be described later, the plurality of photosensor circuits 630 are arranged in this manner so as to be able to measure the light intensity of the plurality of light emitting regions 500A of the backlight 500.

  As described above, the photosensor circuit 630 is an aggregate of red, blue, and green sub photosensor circuits 630R, 630B, and 630G, and therefore each photosensor circuit 630 corresponds (the photosensor circuit 630 is provided). The light intensity is measured for each of red, green, and blue colors for the light emitting region 500A. Then, the measurement result is sent to the backlight control circuit 910 as a sensor signal S1 (see FIG. 1), and the control circuit 910 emits light corresponding to the optical sensor circuit 630 based on the sensor signal S1, that is, the measurement result. The light emission intensity of the LED chip 511 (mainly the LED chip 511 adjacent to the region 500A) that contributes to the light emission of the corresponding light emitting region 500A so that the luminance (brightness) and white balance of the region 500A are maintained in a desired state. Is feedback-controlled by the control signal S2 (see FIG. 1) for each emission color, that is, for each of the LED chips 511R, 511G, and 511B.

  Specifically, as shown in FIG. 5, the backlight control circuit 910 includes a detection circuit 950, a color controller 911, a luminance / color coordinate setting data holding unit 912 made of, for example, a semiconductor memory, and red, green, and blue colors. And LED drivers 913 having drivers 913R, 913G, and 913B for LEDs of respective colors. Although simply illustrated in the drawing, drivers 913R, 913G, and 913B are provided for each light emitting region 500A, and thus each light emitting region 500A is configured to be able to control the light emitting state independently and for each light emitting color. .

  With this configuration, the color controller 911 receives the sensor signal S1 indicating the light emission intensity measured by the optical sensor circuit 630 through the detection circuit 950. The color controller 911 refers to the data in the luminance / color coordinate setting data holding unit 912 based on the received signal (sensor signal S1), and the luminance / color coordinates of the light emitting area 500A are set in advance. The LED drivers 913R, 911G, and 911B are feedback controlled so as to match the color coordinate data. A control signal S2 generated for such feedback control is output from the LED driver 913 to the LED array 510, whereby the light emission intensity of the LED chip 511 is controlled. At this time, the emission intensity is controlled for each emission region 500A and for each emission color.

  Next, FIG. 6 shows a circuit diagram for explaining an example of the optical sensor circuit 630. Since the sub photosensor circuits 630R, 630G, and 630B that constitute the photosensor circuit 630 have the same configuration, FIG. 6 shows one of the sub photosensor circuits 630R, 630G, and 630B and an associated one. A detection circuit 950 is illustrated.

  According to the configuration of FIG. 6, the sub optical sensor circuits 630B, 630G, and 630R are so-called storage-type optical sensor circuits, and include an optical sensor 631 and an optical sensor storage capacitor 632 that stores electric charges. Here, the optical sensor 631 has a thin film transistor (TFT) structure. Therefore, the optical sensor 631 is also referred to as “optical sensor TFT 631” or the like. The drain of the photosensor TFT 631 is connected to one end of the storage capacitor 632, and the source of the photosensor TFT 631 is connected to the other end of the storage capacitor 632 and the gate of the TFT 631. According to such a configuration, when light strikes strongly, the resistance value of the photosensor TFT 631 decreases, and the amount of charge in the photosensor storage capacitor 632 changes abruptly. On the other hand, when the light hits weakly, the resistance value of the photosensor TFT 631 is unlikely to decrease, and the change in the amount of charge in the photosensor storage capacitor 632 is small. In other words, the combination of the photosensor TFT 631 and the photosensor storage capacitor 632 can serve the same function as an optical photodiode.

  The detection value of the change in the amount of charge (or change in voltage) of the photosensor storage capacitor 632 is detected by the detection circuit 950, whereby the output values of the sub photosensor circuits 630R, 630G, and 630B can be obtained. In the configuration of FIG. 6, the detection circuit 950 includes a load resistor 951, a power supply 952, a switch 953, and a detection circuit capacitor 954. Specifically, one end of the load resistor 951 is connected to the one end of the photosensor storage capacitor 632 via the switch 953, and the other end of the load resistor 951 is connected to the photosensor storage capacitor 632 via the power source 952. The other end of the load resistor 951 is grounded. Then, the potential of the one end of the load resistor 951 is taken out as the output voltage Vout through the detection circuit capacitor 954. Note that the detection circuit 950 can be provided in the backlight control circuit 910 as shown in FIG. 5 described above, or the load resistor 951, the switch 953, and the like of the detection circuit 950 can be provided in the liquid crystal panel 800. It is.

  Here, the optical sensor circuit 630 is composed of an assembly of sub optical sensor circuits 630R, 630B, and 630G for red, blue, and green, and each of the sub optical sensor circuits 630R, 630B, and 630G includes an optical sensor (TFT) 631. In light of the fact that the optical sensor circuit 630 has, the optical sensor circuit 630 includes an “optical sensor (TFT) group” that is an aggregate (or group) of optical sensors (TFTs) 631 for red, blue, and green. Yes. For convenience of explanation, reference numeral 631 is also used for the “photosensor (for TFT) group”.

  Further, FIG. 7 is a circuit diagram for explaining another example of the optical sensor circuit 630. Similar to FIG. 6, FIG. 7 illustrates one of the sub optical sensor circuits 630R, 630G, and 630B, and a detection circuit 950 associated therewith. The sub photosensor circuits 630B, 630G, and 630R in FIG. 7 have a configuration in which the photosensor storage capacitor 632 is removed from the configuration in FIG. 6, and correspond to a so-called non-storage type photosensor circuit. On the other hand, the detection circuit 950 of FIG. 7 has a configuration in which the switch 953 and the detection circuit capacitor 954 are removed from the configuration of FIG. According to such a configuration, the resistance value of the photosensor TFT 631 decreases when the light hits strongly, whereas the resistance value of the photosensor TFT 631 hardly decreases when the light hits weakly. At this time, since the voltage applied to the load resistor 951 of the detection circuit 950 varies, the output value (output voltage Vout) of the sub optical sensor circuits 630R, 630G, and 630B can be obtained by detecting this voltage variation.

  Next, FIG. 8 shows a cross-sectional view for explaining the liquid crystal panel 800. As shown in FIG. 8, the liquid crystal panel 800 includes a first substrate 600 and a second substrate 700 which are arranged to face each other, and a liquid crystal (layer) 850 as a display medium sealed in a gap between the substrates 600 and 700. Is included.

  The first substrate 600 includes a base substrate (or base substrate) 610 made of glass, plastic, or the like, a photosensor TFT 631 having a so-called bottom gate thin film transistor structure, and a display TFT (display switching element). 621, an interlayer insulating film 650 made of acrylic, polyimide, benzocyclobutene (BCB), or the like, and a pixel electrode 660 made of ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or the like.

The optical sensor TFT 631 includes a gate electrode 631g, a source electrode 631s and a drain electrode 631d made of aluminum (Al) or the like, a gate insulating film 631h made of silicon nitride (SiNx), silicon oxide (SiO ₂ ), or the like, and amorphous. And a semiconductor film 631a made of silicon (a-Si) or the like. Specifically, the gate electrode 631g is disposed on the base substrate 610, and the gate insulating film 631h is disposed on the base substrate 610 so as to cover the gate electrode 631g. Note that a coating film may be provided over the base substrate 610 and the gate electrode 631g may be disposed thereon. In such a case, a configuration in which the coating film is included in the base substrate 610 can be referred to as a “base substrate”. . On the gate insulating film 631h, a semiconductor film 631a is disposed so as to face the gate electrode 631g, and further, a source electrode 631s and a drain electrode 631d are disposed so as to be on the end of the semiconductor film 631a. . In the semiconductor film 631a, a portion between both electrodes 631s and 631d forms a channel region and a light receiving region of the photosensor TFT 631.

  Similarly, the display TFT 621 includes a gate electrode 621g, a source electrode 621s and a drain electrode 621d made of the same material as the electrodes 631g, 631s and 631d of the TFT 631, and a gate insulating film made of the same material as the gate insulating film 631h of the TFT 631. 621h and a semiconductor film 621a made of the same material as the semiconductor film 631a of the TFT 631. Note that the gate insulating films 621 and 631 can be formed as a single film. The display TFT 621 has the same bottom gate type TFT structure as the photosensor TFT 631 and is monolithically formed with the photosensor TFT 631 on the base substrate 610. The same elements (for example, gate electrodes) of the TFTs 621 and 631 are used. 631g and 621g) are formed of the same layer. Therefore, a specific description of the structure of the display TFT 621 is omitted here.

  An interlayer insulating film 650 is disposed so as to cover the TFTs 621 and 631, and the pixel electrode 660 is disposed on the interlayer insulating film 650. Note that the pixel electrode 660 is electrically connected to the drain electrode 621d of the display TFT 621 in a portion not shown.

  On the other hand, the second substrate 700 includes a base substrate 710 made of glass, plastic, or the like, a colored layer or color filter layer 860 disposed on the base substrate 710, and ITO or IZO disposed on the color filter layer 860. The counter electrode 760 which consists of etc. is included.

  The color filter layer 860 is composed of three color filters for color display, red, green, and blue. In the display area 810 (see FIG. 2 and the like), each pixel P (see FIG. 9 described later) has red, green, One of the blue color filters is provided. Further, in the liquid crystal panel 800, the three color filters are provided so as to face the photosensor TFTs 631 of the sub photosensor circuits 630R, 630G, and 630B in the peripheral region 820 (see FIG. 2 and the like). More specifically, a red color filter is disposed so as to face the photosensor TFT 631 of the red sub photosensor circuit 630R, and opposes the photosensor TFT 631 of the green sub photosensor circuit 630G. Thus, the green color filter is arranged, and the blue color filter is arranged so as to face the photosensor TFT 631 of the blue sub photosensor circuit 630B. As described above, in the liquid crystal panel 800, the photosensor TFT group 631 of the photosensor circuit 630 overlaps the color filter layer 860 in a plan view of the liquid crystal panel 800. Note that a portion in the display region 810 and a portion facing the photosensor TFT group 631 in the color filter layer 860 are formed monolithically.

  Here, the color filter layer 860 composed of the above three color filters is illustrated, but the color filter layer 860 may be composed of four or more color filters, in which case the number of colors of the color filter The photosensor circuit 630 may be configured using the same number of sub photosensor circuits.

  Both the substrates 600 and 700 are arranged to face each other so that the base substrates 610 and 710 face outward, in other words, the pixel electrode 660 and the counter electrode 760 face each other. A liquid crystal 850 serving as a display medium is sealed in a gap between the two substrates 600 and 700.

  Here, FIG. 9 shows a schematic diagram for explaining the liquid crystal panel 800. As shown in FIG. 9, the liquid crystal panel 800 includes a plurality of gate lines (scanning lines) LG and a plurality of storage capacitor lines LCs that extend in a fixed direction and are aligned in a direction orthogonal to the fixed direction, and these wirings LG. , LCs, and a plurality of display signal lines (source lines) LS arranged so as to intersect (but not short-circuit) LCs. Note that the gate lines LG and the storage capacitor lines LCs are alternately arranged. These wirings LG, LS, and LCs are provided on the first substrate 600 (see FIG. 8), although not shown in FIG.

  The display area 810 is partitioned in a matrix by the gate lines LG and the display signal lines LS, and each section corresponds to a pixel (sub-pixel or cell) P. Near each intersection of the gate line LG and the display signal line LS, a display TFT 621 as an active element is provided for each pixel P, and the gate electrode 621g and the source electrode 621s (see FIG. 8) of the TFT 621 are gated. The line LG and the display signal line LS are connected to each other. The switching function of the display TFT 621 is controlled by signals to these wirings LG and LS, and the liquid crystal 850 (see FIG. 8) is driven (dimmed) for each pixel P. In FIG. 9, the storage capacitor Cs for display is formed between the storage capacitor line LS and the pixel electrode 660 (see FIG. 8), and the liquid crystal capacitor Clc is formed between the pixel electrode 660 and the counter electrode 760 (see FIG. 8). It is formed.

  Of the first substrate 600 (see FIG. 8), the base substrate 610, the display TFT 621, and the accompanying wirings LG, LS, LCs, etc. are composed of “TFT substrate”, “array substrate”, “active matrix substrate”. And so on.

  Each pixel P is provided with any one of the red, green, and blue color filters of the color filter layer 860 (see FIG. 8), and a group of three adjacent pixels P forms a unit pixel PU for color display. .

  As shown in FIG. 10 corresponding to FIG. 8 described above, in the display device 20 (see FIG. 1 and the like), the backlight 500 is disposed on the second substrate 700 side (thus, the backlight 500, the second substrate 700, and the first substrate). The substrates 600 are arranged in this order). In order to avoid complication of the drawing, the display TFT 621 is not shown in FIG. At this time, in each pixel P (see FIG. 9), the emitted light 500L from the backlight 500 passes through a color filter of a predetermined color of the color filter layer 860 and is colored (spectralized) to be observed as display light. Reach person 1.

  On the other hand, since each photosensor TFT 631 of each of the sub photosensor circuits 630R, 630G, and 630B overlaps with a color filter of a predetermined color of the color filter layer 860, the emitted light 500L from the backlight 500, like each pixel P. Passes through a color filter of a predetermined color and is colored (split) to reach the photosensor TFT 631. Thus, the colored light 500L is received by the photosensor TFT 631. When viewed as a whole of the optical sensor circuit 630, a color sensor is configured by overlapping the optical sensor TFT group 631 and the color filter layer 860, and the optical sensor TFT group 631 determines the light intensity of the colored light 510L for each color of the color filter. Can be measured.

  Then, as described above, the backlight control circuit 910 controls the emission intensity of the LED chips 511R, 511G, and 511B, which are the light sources of the backlight 500, for each emission color based on the measurement result obtained by the optical sensor group 631.

  According to such a display device 20, the photosensor TFT group 631 is provided on the first substrate 600 and is monolithically formed with the display TFT 621 having a thin film transistor structure. Compared to the configuration in which the module is externally attached to the display panel, the number of parts and the mounting cost can be reduced in the display device 20.

  Further, the light sensor group 631 measures the light intensity of the light 500L emitted from the backlight 500 and colored with the red, green, and blue color filters forming the color filter layer 860 for each color of the color filter. Compared with a configuration using color filters having different spectral transmittance characteristics (for example, a configuration in which an optical sensor module is externally attached), the white balance of the display light of the liquid crystal panel 800 can be strictly adjusted.

  Furthermore, since the emission intensity of the LED chips 511R, 511G, and 511B, which are the light sources of the backlight 500, is controlled for each emission color based on the measurement result by the optical sensor group 631, a large number of LED chips 511R, 511G, and 511B are arranged. Even so, it is possible to improve the in-plane uniformity of the white balance and luminance (brightness) of the backlight 500. In addition, since the light emission intensity of the LED chips 511R, 511G, and 511B is controlled for each light emitting region 500A of the backlight 500, the luminance in-plane uniformity improvement effect is large, and is remarkable in the large area backlight 500.

  Here, the entire light emitting surface of the backlight 500 may be configured as one light emitting area 500A, and one light sensor group 631 may be provided for the light emitting area 500A. However, each light emission is divided into a plurality of light emitting areas 500A. In the above-described configuration in which the optical sensor group 631 is provided in the region 500A, the measurement results of the plurality of optical sensor groups 631 can be used for the control of the LED chip 511. Therefore, the luminance uniformity of the backlight 500 is improved. Get higher.

  In view of these effects, the display device 20 is particularly useful when the LED chip 511 has a large change with time or individual variation with respect to the environmental temperature.

  Further, since the optical sensor group 631 is disposed in the peripheral region 820 of the liquid crystal panel 800, that is, outside the display region 810, there is no influence on display quality (for example, a reduction in pixel transmittance (aperture ratio)), The optical sensor group 631 is not limited in size in relation to the pixel P. For this reason, compared with the case where the optical sensor group 631 is arranged in the display region 810 of the liquid crystal panel 800, the area of the optical sensor group 631 can be increased, and thereby high sensitivity can be achieved. In addition, the wiring to the electrodes 631g, 631s, 631d for the optical sensor group 631 and the detection circuit 950 can be designed independently from the electrodes 621g, 621s, 621d, the wirings LG, LS, LCs, etc. in the display area 810. It is easy to optimize the driving conditions of the optical sensor group 631 (the degree of freedom in setting the driving conditions is large).

  8 and 10 illustrate a structure in which the pixel electrode 660, the liquid crystal 850, and the counter electrode 760 are present at positions facing the photosensor TFT 631, but these elements 660, 850, and 760 are illustrated as photosensors. In the above-described structure in which the TFT 631 is provided in the peripheral region 820, the TFT 631 may not be provided at a position facing the TFT 631.

  FIG. 11 is a perspective view for explaining a display device according to a modification of the first embodiment. As shown in FIG. 11, in the above-described display device 20 (see FIGS. 1 and 2), instead of the edge light type backlight 500, a direct light type backlight 501 using LEDs can be applied. The above-described effects can also be obtained by such a display device 20.

  Note that in the direct light type backlight 501, a large number of LED chips 511 are two-dimensionally arranged so as to emit light in a predetermined direction (toward the liquid crystal panel 800), thereby causing planar light emission. At this time, for example, the above-described two-dimensional array is configured by repeatedly arranging a row of red light emitting LED chips 511R, a blue light emitting LED chip 511B, and a green light emitting LED chip 511G in this order.

<Embodiment 2>
FIG. 12 is a perspective view for explaining a display device according to Embodiment 2 of the present invention. As shown in FIG. 12, the display device 20 (see FIG. 1) can be configured by applying a liquid crystal panel 801 instead of the liquid crystal panel 800 (see FIGS. 1 and 2) described above. The liquid crystal panel 801 has the same configuration as the liquid crystal panel 800 described above except that the four photosensor circuits 630 are provided in the display region 810. Also in the liquid crystal panel 801, one photosensor circuit 630 is provided for each of the four light emitting regions 500A of the backlight 500.

  Next, FIG. 13 shows a schematic diagram for explaining the liquid crystal panel 801. As shown in FIG. 13, the photosensor circuit 630 is provided for the unit pixel PU, the red pixel P is provided with a red sub photosensor circuit 630R, and the blue pixel P is provided with a blue sublight. A sensor circuit 630B is provided, and a green sub-light sensor circuit 630G is provided for the green pixel P.

  In the example of FIG. 13, the storage type photosensor (see FIG. 6) described above is used as the sub photosensor circuits 630R, 630B, and 630G, and the TFT as the switch 953 of the detection circuit 950 (see FIG. 6) is also used. It is provided in the pixel P. Signals from the sub optical sensor circuits 630R, 630B, and 630G are output to the detection line L through the TFT as the switch 953. The TFT as the switch 953 has its gate electrode connected to the gate line LG (more specifically, to the gate line LG for selecting the pixel P adjacent to the pixel P to which the sub photosensor circuits 630R, 630B, 630G belong). Connected) and is turned on / off in the same cycle as the display TFT 621 and plays a role of reading out the change in the amount of charge of the photosensor storage capacitor 632 for each frame. The TFT corresponding to the switch 953 and the detection line L are provided on the first substrate 600 (see FIG. 8), and the detection line L is a display signal line in the vicinity of the pixel P to which the sub optical sensor circuits 630R, 630B, and 630G belong. It is arranged adjacent to LS.

  As described above, in the liquid crystal panel 801, the optical sensor circuit 630 is arranged in the display region 810. However, it is necessary to keep the influence of the arrangement on the display quality as small as possible. At this time, if the occupation ratio of the sub photo sensor circuits 630R, 630B, and 630G in the pixel P is large, the sub photo sensor circuit-equipped pixel P has a lower transmittance (aperture ratio) than the other pixels P. The occupation ratio is preferably within 30%. Further, on the premise that the transmittance (aperture ratio) of the pixel P with the sub photo sensor circuit is lowered, the display signal to the pixel P is preliminarily displayed so that the pixel P with the sub photo sensor circuit can display brighter than the other pixels P in advance. It is also desirable to deal with image processing such as applying correction. As a result, even if the sub-light sensors 630R, 630B, and 630G are added to the specific pixel P, it is possible to maintain display uniformity.

  According to the display device 20 according to the second embodiment, the photosensor circuit 630 (and thus the photosensor group 631) is disposed in the display area 810 of the liquid crystal panel 801, and is located away from the outer edge of the light emitting surface of the backlight 500. Since the optical sensor group 631 can be disposed in the vicinity, the surrounding environment of the measurement part by the optical sensor group 631 can be made equal in any direction. For example, in a structure in which the optical sensor group 631 is close to the outer edge of the light emitting surface of the backlight 500 in the peripheral region 820, in the vicinity of the measurement part by the optical sensor group 631, the light emitting surface may be brighter in the center direction and dark in the opposite direction. is there. On the other hand, if the optical sensor circuit 630 is arranged near the center of the light emitting region 500A as shown in FIG. 12, the periphery of the measurement portion by the optical sensor group 631 has the same brightness in any direction. The light intensity can be measured as an average value. As a result, the brightness and white balance of the backlight 500 can be adjusted more strictly.

  The same effects as those of the display device 20 according to the first embodiment can be obtained except for the effects due to the difference in the arrangement position of the optical sensor group 631.

  Note that in the structure in which the photosensor TFT 631 is provided in the peripheral region 820 (see FIG. 2 and the like) as described above, the pixel electrode 660, the liquid crystal 850, and the counter electrode 760 at positions facing the TFT 631 are arbitrary. In the display device 20 according to the second embodiment, since the photosensor circuit 630 is provided in the pixel P, it is necessary to provide the pixel electrode 660, the liquid crystal 850, and the counter electrode 760 at a position facing the photosensor TFT 631.

  In FIG. 14, the perspective view for demonstrating the display apparatus which concerns on the modification 1 of Embodiment 2 is shown. As shown in FIG. 14, the display device 20 (see FIG. 1) may be configured by combining a liquid crystal panel 801 and a backlight 501 of a direct light type using LEDs, and the above-described effect is also achieved by such a display device 20. Can be obtained.

  FIG. 15 is a perspective view for explaining a display device according to the second modification of the second embodiment. In the above description, an example in which the entire light emission area of the backlights 500 and 501 is divided into 2 × 2 areas has been described. However, as shown in FIG. The light emitting state can be controlled for each light emitting region 501A by dividing the region into regions 501A. In the case of such division, one photosensor circuit 630 is provided for each light emitting region 501A in the liquid crystal panel 801. As the light emitting area 500A increases, the luminance and white balance of the backlight 500 can be controlled more finely.

  FIG. 16 is a block diagram of the display device 20 according to the second modification. As shown in FIG. 16, the sensor signal S1 from each optical sensor circuit 630 is input to the detection circuit 950 of the backlight control circuit 910 via a sensor readout LSI (Large Scale Integration) 890a. The sensor readout LSI 890a is provided in the peripheral region 820 of the liquid crystal panel 801 together with the gate driver LSI 890g and the source driver LSI 890s.

<Modification common to Embodiments 1 and 2>
In this common modification, a liquid crystal panel applicable to the display device 20 according to the first and second embodiments will be described. In the liquid crystal panel according to this modification, the structure of the display TFT 621 is the same as that of the above-described liquid crystal panel 800 (see FIG. 8), and thus the illustration and description of the TFT 621 are omitted.

  First, FIG. 17 shows a cross-sectional view for explaining a liquid crystal panel 802 according to the first modification. As shown in FIG. 17, the liquid crystal panel 802 has a structure in which the arrangement of the color filter layer 860 is changed to the first substrate 600 side in the liquid crystal panel 800 of FIG.

  Specifically, the first substrate 602 of the liquid crystal panel 802 includes a base substrate 610, a photosensor TFT 631 disposed on the base substrate 610, a color filter layer 860 disposed so as to cover the TFT 631, An interlayer insulating film 650 disposed on the color filter layer 860 and a pixel electrode 660 disposed on the interlayer insulating film 650 are included. At this time, the color filter layer 860 is monolithically formed not only on the pixel P (see FIG. 9) but also on the photosensor TFT 631, and more specifically, for red, green, and blue. Red, green and blue color filters of the color filter layer 860 are arranged on the photosensor TFT 631. That is, the color filter layer 860 and the optical sensor TFT group 631 overlap each other in plan view of the liquid crystal panel 802.

  On the other hand, the second substrate 702 of the liquid crystal panel 802 includes a base substrate 710 and a counter electrode 760 disposed on the base substrate 710.

  Both substrates 602 and 702 are arranged so that the base substrates 610 and 710 face each other, and a liquid crystal 850 is sealed in a gap between the substrates 602 and 702. In the display device 20 (see FIG. 1 and the like), the backlight 500 is disposed on the second substrate 702 side (the backlight 500, the second substrate 702, and the first substrate 602 are disposed in this order). .

  According to the liquid crystal panel 802, as shown in FIG. 17, in each pixel P (see FIG. 9 and the like), the emitted light 500L from the backlight 500 passes through the color filter layer 860 and is colored (split). It reaches the observer 1 as display light. On the other hand, since the color filter layer 860 is provided on the photosensor TFT 631 as described above (because it overlaps with the TFT 631), the emitted light 500L from the backlight 500 is the color filter similarly to each pixel P. The light passes through 860 and is colored (spectral), and reaches the photosensor TFT 631. In other words, the color sensor can be configured by the overlap of the photosensor TFT group 631 and the color filter layer 860 also by the structure of the liquid crystal panel 802.

  Next, FIG. 18 shows a cross-sectional view for explaining a liquid crystal panel 803 according to a common modification 2. As shown in FIG. 18, the liquid crystal panel 803 has a structure in which a light shielding film 730 and a reflective film 870 as a reflective member are added to the second substrate 700 in the liquid crystal panel 800 of FIG. Note that the liquid crystal panel 803 includes a first substrate 600 similar to the liquid crystal panel 800 of FIG.

  In the second substrate 703 of the liquid crystal panel 803, the light shielding film 730 and the reflective film 870 described above are laminated on the base substrate 710 in this order, and are arranged at and near the position where the photosensor TFT 631 is opposed. . The reflective film 870 is made of aluminum (Al), chromium (Cr), or the like. A color filter layer 860 is disposed so as to cover both the films 730 and 870, and the counter electrode 760 is disposed on the color filter layer 860. At this time, the color filter layer 860 is monolithically formed not only with respect to the pixel P (see FIG. 9) but also at a position facing the photosensor TFT 631, and more specifically, for red, green and The red, green, and blue color filters of the color filter layer 860 are disposed at positions facing the blue photosensor TFT 631. That is, the color filter layer 860 and the optical sensor TFT group 631 overlap each other in a plan view of the liquid crystal panel 803.

  Both substrates 600 and 703 are arranged so that the base substrates 610 and 710 face each other, and a liquid crystal 850 is sealed in a gap between both the substrates 600 and 703. In the display device 20 (see FIG. 1 and the like), the backlight 500 is disposed on the first substrate 600 side (the backlight 500, the first substrate 600, and the second substrate 703 are disposed in this order). .

  According to the liquid crystal panel 803, as shown in FIG. 18, in each pixel P (see FIG. 9 and the like), the emitted light 500L from the backlight 500 passes through the color filter layer 860 and is colored (split). It reaches the observer 1 as display light. On the other hand, as described above, since the reflective film 870 is disposed at and near the position facing the photosensor TFT 631, the emitted light 500L from the backlight 500 is reflected by the reflective film 870, and the photosensor TFT 631 is obtained. To reach. At this time, the light 500L travels through the color filter 860 before and after reflection, is colored (split), reaches the photosensor TFT 631, and is received by the photosensor TFT 631. That is, according to the structure of the liquid crystal panel 803, a color sensor can be configured by the photosensor TFT group 631, the color filter layer 860, and the reflective film 870. Note that the arrangement range, shape, and the like of the reflective film 870 are not limited to those illustrated in FIG. 18 as long as the light 500L from the backlight 500 can be reflected toward the photosensor TFT 631.

  Further, FIG. 19 shows a cross-sectional view for explaining a liquid crystal panel 804 according to a third modification. As shown in FIG. 19, the liquid crystal panel 804 has a structure in which a reflective film 870 is added to the first substrate 602 in the liquid crystal panel 802 of FIG. Note that the liquid crystal panel 804 includes a second substrate 702 similar to the liquid crystal panel 802 in FIG.

  In the first substrate 604 of the liquid crystal panel 804, the reflective film 870 is disposed on the interlayer insulating film 650 at a position where the TFT 631 for photosensors faces and in the vicinity thereof. In the example of FIG. 19, the pattern of the pixel electrode 660 disposed on the interlayer insulating film 650 is different from that of the first substrate 602 of FIG.

  Both substrates 604 and 702 are arranged so that the base substrates 610 and 710 face each other, and a liquid crystal 850 is sealed in a gap between the substrates 604 and 702. In the display device 20 (see FIG. 1 and the like), the backlight 500 is arranged on the first substrate 604 side (the backlight 500, the first substrate 604, and the second substrate 702 are arranged in this order). .

  According to the liquid crystal panel 804, as shown in FIG. 19, in each pixel P (see FIG. 9 and the like), the emitted light 500L from the backlight 500 passes through the color filter layer 860 and is colored (split). It reaches the observer 1 as display light. On the other hand, as described above, since the reflective film 870 is disposed at and near the position facing the photosensor TFT 631, the emitted light 500L from the backlight 500 is reflected by the reflective film 870, and the photosensor TFT 631 is obtained. To reach. That is, a color sensor can be configured by the photosensor TFT group 631, the color filter layer 860, and the reflective film 870, similarly to the liquid crystal panel 803 of FIG.

  Here, in the liquid crystal panels 802 to 804 of the above-described common modifications 1 to 3, the optical sensor circuit 630, that is, the optical sensor group 631, can be provided in either the peripheral region 820 or the display region 810. At this time, as described above, in the structure in which the photosensor TFT 631 is provided in the peripheral region 820 (see FIG. 2 and the like), the pixel electrode 660, the liquid crystal 850, and the counter electrode 760 at positions facing the TFT 631 are arbitrary. In the structure provided in the display region 810 (see FIG. 2 and the like), it is necessary to provide the pixel electrode 660, the liquid crystal 850, and the counter electrode 760 at a position facing the photosensor TFT 631.

  In the structure in which the first substrates 600 and 602 (see FIGS. 10 and 17) are arranged on the observer 1 side like the liquid crystal panels 800 to 802, the wirings LG, LS, and the like in the first substrates 600 and 602 are arranged. LCs, L (see FIGS. 9 and 13) can be seen from the observer 1. Since these wirings LG, LS, LCs, and L are usually made of a metal material such as aluminum, surface reflection of external light by the wirings LG, LS, LCs, and L is large, and as a result, display contrast and display quality are lowered. There is. In such a case, it is desirable to dispose a circularly polarizing plate (linear polarizing plate + retardation plate) on the viewer 1 side of the first substrate 600, 602, and a pair of polarizing plates provided on the front and back surfaces of the liquid crystal panel are circular. Polarized light may be used. Thereby, since the reflected light by the wirings LG, LS, LCs, and L is shielded by the circularly polarizing plate, it is possible to suppress the deterioration in display performance due to the above-described surface reflection.

  Further, in the case where the photosensor TFT 631 and the wiring associated therewith are arranged in the peripheral region 820, the substrates 600, 602, 703, and 702 on the side forming the display surface (see FIGS. 10, 17, 18, and 19). If a light-shielding film (so-called frame black matrix) is provided closer to the display surface than the photosensor TFT 631 etc. in the peripheral region 820), reflection of external light by the photosensor TFT 631 etc. can be avoided.

<Embodiment 3>
In Patent Document 2 and Patent Document 3, the backlight is divided into a plurality of N × M light emitting areas (illumination areas), and the optimum luminance is calculated based on video information for each light emitting area. A display device that performs backlight luminance control and image signal image processing (hereinafter referred to as “screen split active backlight driving” or “spatial active backlight driving”) is disclosed. At this time, the display device includes a control circuit that controls the luminance of the backlight for each of the divided light emitting regions based on the luminance information of the input video signal.

  The split screen active backlight drive enables video display with a higher dynamic range than usual by appropriately changing the light emission luminance in the light emission area of the backlight based on the input video information of the divided image. is there. In addition, when the input video information is a dark image, it is possible to display the backlight by dimming (to compensate for the display brightness by increasing the video signal accordingly), so that the power consumption of the display device can be reduced. .

  In such split screen active backlight driving, the backlight is divided into a plurality of N × M light emitting areas and driven individually, so that the backlight brightness and white balance are corrected (calibration) for each light emitting area. It is very useful if you can do that.

  Therefore, in the third embodiment, the technology according to the above-described first and second embodiments is applied to the screen split active backlight drive, and thereby the backlight brightness and white balance are reduced with respect to the display of the screen split active backlight drive. A display device that can correct each light emitting area will be described.

  FIG. 20 is a block diagram for explaining the display device 21 according to the third embodiment. The display device 21 of FIG. 20 includes a liquid crystal panel 800, a backlight 500, and a control drive device 901. Note that a liquid crystal panel 801 or the like can be applied instead of the liquid crystal panel 800, and a backlight 501 can be applied instead of the backlight 500.

  The control drive device 901 includes a backlight control circuit 920, a frame memory 991, a gradation conversion circuit 992, a backlight luminance data holding unit 993, a gradation correction circuit 994, and a gradation correction lookup table 995. Is included. In the figure, “look-up table” is expressed as “LUT”. The backlight control circuit 920 includes the detection circuit 950, the luminance / color coordinate setting data holding unit 912, the LED driver 913, the color controller 921, the image luminance calculation circuit 925, and the image luminance data holding unit 926. Is included. Under such a configuration, the display device 21 operates as follows.

  First, the input video signal (RGB input image signal) SIN is temporarily stored in the frame memory 991 and read out to the image luminance calculation circuit 925. Here, in the display device 21, the display area 810 (see FIG. 2) is grasped by dividing the four light emitting areas 500 </ b> A (see FIG. 2) divided into the four areas projected onto the display area 810. The display image is also grasped by being divided into four images displayed on the four divided areas of the display area 810. Therefore, the image luminance calculation circuit 925 reads image information for each divided image corresponding to each light emitting area 500A of the backlight 500. Then, the image luminance calculation circuit 925 calculates the luminance value (average luminance (APL)) of each divided image, and stores the calculated image luminance data (image luminance information) in the image luminance data holding unit 926 for each divided image. .

  The color controller 921 receives the image luminance data (image luminance information) stored in the image luminance data holding unit 926 and the photosensor circuit 630 (see FIG. 2) received via the detection circuit 950 in the same manner as described above. The brightness level required for each light emitting area 500A of the backlight 500 is calculated on the basis of both the sensor signal S1. Thereafter, the color controller 921 stores the calculated luminance data (luminance information) of each light emitting area 500A in the backlight luminance data holding unit 993 and transmits it to the LED driver 913.

  In the same manner as described above, the LED driver 913 determines the emission intensity of the LED chip 511 of the backlight 500 for each emission area 500A and for each emission color of the LED chip 511 based on the received luminance data of each emission area 500A. To control.

  On the other hand, the video signal (RGB input image signal) SIN stored in the frame memory 991 is sequentially read out for each unit pixel PU (see FIG. 9) of the liquid crystal panel 800 by the gradation conversion circuit 992. Then, the gradation conversion circuit 992 refers to the backlight luminance data holding unit 993, and based on the luminance data of the light emitting region 500A facing the target unit pixel PU, the gradation of the read signal (data) described above. Is converted (modulated) and transmitted to the gradation correction circuit 994.

  The gradation correction circuit 994 refers to the backlight luminance data holding unit 993 and the gradation correction lookup table 995, corrects the gradation of the signal subjected to the above-described gradation conversion, and outputs it to the source driver LSI 890s. At this time, the gradation correction is performed based on the backlight luminance data of the light emitting area 500A around the light emitting area 500A as well as the light emitting area 500A opposed to the target unit pixel PU. Is described in the gradation correction lookup table 995 in association with each backlight luminance data and correction data (for example, correction amount) of the light emitting area 500A facing each other and the peripheral light emitting area 500A.

  As described above, according to the display device 21, the luminance of the backlight 500 is controlled for each light emitting area 500A based on the input video signal SIN. Therefore, a display portion including a lot of bright image information in the entire screen. In contrast, the luminance of the backlight 500 can be increased, and the luminance of the backlight 500 can be decreased for a display portion that contains a lot of dark image information. The dynamic range can be expanded.

  When the luminance of the backlight 500 is changed for each light emitting area 500A and the input video signal SIN is supplied to the liquid crystal panel 800 with the same gradation, the luminance of the display image is shifted between the light emitting areas 500A. However, as described above, in the display device 21, the input video signal SIN is grayscaled based not only on the light emitting area 500A opposed to the target unit pixel PU but also on the backlight luminance data of the light emitting area 500A around the light emitting area 500A. Since the correction is performed, it is possible to obtain an appropriate image in which the luminance of the display image is not shifted between the light emitting regions 500A with the appropriate gradation converted according to the luminance of each light emitting region 500A. As described above, the display device 21 can display an appropriate image having a wide dynamic range, high contrast, and high quality even for an image having a large luminance gradient in the screen. .

  Furthermore, since the display device 21 combines the screen split active backlight drive and the backlight control of the first and second embodiments, the brightness (brightness) of the backlight 500 and the brightness of the backlight 500 for each of the divided regions of the display region 810. White balance can be corrected. Accordingly, display by screen divided active backlight driving based on the input video signal SIN can be performed more faithfully, and the degree of change with time of the LED chip 511 differs for each divided region, that is, for each light emitting region 500A of the backlight 500. However, the divided state (divided section) can be made inconspicuous.

  In the above description, liquid crystal display devices are exemplified as the display devices 20 and 21. However, in the case of a display panel using the backlight 500, a display panel using an electrophoretic medium or the like as a display medium instead of the liquid crystal 850 is used. It is also possible to apply to the display devices 20 and 21.

These are the schematic diagrams for demonstrating the display apparatus which concerns on Embodiment 1 of this invention. These are the perspective views for demonstrating the display apparatus which concerns on Embodiment 1 of this invention. These are the expansion perspective views for demonstrating the LED array of the display apparatus which concerns on Embodiment 1 of this invention. These are the enlarged views of the part 4 enclosed with the dashed-dotted line in FIG. These are the block diagrams for demonstrating the display apparatus which concerns on Embodiment 1 of this invention. These are circuit diagrams for demonstrating an example of the optical sensor circuit of the display apparatus which concerns on Embodiment 1 of this invention. These are the circuit diagrams for demonstrating another example of the optical sensor circuit of the display apparatus which concerns on Embodiment 1 of this invention. These are sectional drawings for demonstrating the liquid crystal panel of the display apparatus which concerns on Embodiment 1 of this invention. These are the schematic diagrams for demonstrating the liquid crystal panel of the display apparatus which concerns on Embodiment 1 of this invention. These are sectional drawings for demonstrating the display apparatus which concerns on Embodiment 1 of this invention. These are the perspective views for demonstrating the display apparatus which concerns on the modification of Embodiment 1 of this invention. These are the perspective views for demonstrating the display apparatus which concerns on Embodiment 2 of this invention. These are the schematic diagrams for demonstrating the liquid crystal panel of the display apparatus which concerns on Embodiment 2 of this invention. These are the perspective views for demonstrating the display apparatus which concerns on the modification 1 of Embodiment 2 of this invention. These are the perspective views for demonstrating the display apparatus which concerns on the modification 2 of Embodiment 2 of this invention. These are the block diagrams for demonstrating the display apparatus which concerns on the modification 2 of Embodiment 2 of this invention. These are sectional drawings for demonstrating the liquid crystal panel which concerns on the modification 1 common to Embodiment 1, 2 of this invention. These are sectional drawings for demonstrating the liquid crystal panel which concerns on the modification 2 common to Embodiment 1, 2 of this invention. These are sectional drawings for demonstrating the liquid crystal panel which concerns on the modification 3 common to Embodiment 1, 2 of this invention. These are the block diagrams for demonstrating the display apparatus which concerns on Embodiment 3 of this invention. FIG. 3 is an emission spectrum diagram of a cold cathode tube. These are figures which show the temperature dependence of the emitted light intensity of LED. These are the block diagrams of the feedback control using the color sensor module disclosed by the nonpatent literature 1. FIG.

Explanation of symbols

20, 21 Display device 500, 501 Backlight 500A, 501A Light emitting area 500L Light 511, 511R, 511G, 511B LED chip (light source)
600, 602, 604 First substrate 621 Display TFT (display switching element)
631 TFT for optical sensor (group) (photosensor (group))
700, 702, 703 Second substrate 800-804 Liquid crystal panel (display panel)
810 Display area 860 Color filter layer 870 Reflective film (reflective member)
910, 920 Backlight control circuit (control circuit)
SIN input video signal

Claims (10)

A display panel;
A backlight that is arranged to be capable of irradiating light to the display panel, and includes a light source of a plurality of colors;
A control circuit for controlling the backlight,
The display panel is
A first substrate having a display switching element having a thin film transistor structure and at least one photosensor group monolithically formed with the display switching element;
A second substrate disposed opposite the first substrate;
A color filter layer provided on either of the first substrate and the second substrate, the color filter layer including a plurality of color filters for display,
The at least one photosensor group is configured to be able to measure the light intensity of light emitted from the backlight and colored by the color filter layer for each color of the plurality of color filters,
The display device according to claim 1, wherein the control circuit controls emission intensity of the light sources of the plurality of colors for each emission color based on a measurement result by the at least one optical sensor group.   The display device according to claim 1, wherein the at least one photosensor group is disposed outside a display area of the display panel.   The display device according to claim 2, wherein the at least one photosensor group is a plurality of photosensor groups. The plurality of optical sensor groups are arranged so as to be able to measure the light intensity of the plurality of light emitting regions of the backlight,
The control circuit controls the emission intensity of the light sources of the plurality of colors for each emission color based on a measurement result by a light sensor group corresponding to the emission area for each emission area of the backlight. The display device according to claim 3.   The display device according to claim 1, wherein the at least one photosensor group is disposed in a display area of the display panel.   The display device according to claim 5, wherein the at least one photosensor group is a plurality of photosensor groups. The plurality of optical sensor groups are arranged so as to be able to measure the light intensity of the plurality of light emitting regions of the backlight,
The control circuit controls the emission intensity of the light sources of the plurality of colors for each emission color based on a measurement result by a light sensor group corresponding to the emission area for each emission area of the backlight. The display device according to claim 6.   The control circuit determines the emission intensity of the light sources of the plurality of colors for each of the light emission regions of the backlight based on not only the measurement result by the plurality of optical sensor groups but also luminance information of an input video signal. The display device according to claim 7, wherein the display device is controlled for each emission color. The backlight, the second substrate and the first substrate are arranged in this order;
The display device according to claim 1, wherein the at least one photosensor group overlaps the color filter layer in a plan view of the display panel. The backlight, the first substrate and the second substrate are arranged in this order;
The display panel is
The reflective member provided so that the said light colored with the said color filter layer may be reflected toward the said at least 1 photosensor group is further included in any one of Claim 1 thru | or 8 characterized by the above-mentioned. The display device described.

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