Display device

Abstract

To provide a display device capable of reproducing optical characteristics of a print display medium, in particular a display device capable of generating a sense as if the display device is a printing medium such as paper.SOLUTION: In a display device, with respect to a light flux of external light incident into a specific area in a display panel, a light flux emitted from a pixel in the specific area is controlled in a predetermined diffuse reflection factor, thereby an emission light flux is acquired from a product of the incident light flux and the diffuse reflection factor. Thus, display on the display device can give a sense as if it is a printing medium such as paper.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a display device, and more particularly to a display device that reproduces the diffuse reflected light of a printed display medium.

[0002] 2. Description of the Related Art Display devices such as liquid crystal display devices and organic electroluminescence display devices have been known for some time. For these display devices, a method of controlling the display brightness in response to the illuminance of external light is also known. In conventional display devices such as liquid crystal displays using backlights, the brightness is generally increased to improve visibility when the surroundings are bright, but reduced to eliminate glare when the surroundings are dark. Furthermore, in dark places, it is necessary to suppress the brightness from the viewpoint of power saving.

[0003] On the other hand, reflective displays, such as electrophoretic displays and reflective liquid crystal displays, that reflect ambient light such as external light and display images with optical characteristics similar to those of paper print media such as copy paper, photographs, and calendars, are also being developed.

[0004] Patent Document 1 discloses a technology for adjusting the brightness and color tone of a display device according to the brightness of external light, changing the brightness of the display device for each part, and lowering the brightness of the relevant part when the illuminance of external light is reduced due to a shadow of an object. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-48196 A Summary of the Invention [Problem to be solved by the invention]

[0006] Although the conventional technology and the technology disclosed in Patent Document 1 describe changing the brightness of the display device by adjusting the brightness and color tone according to the brightness of the external light, they only describe adjusting the brightness from the viewpoint of visibility and power saving. Patent Document 1 describes that it is possible to provide an atmosphere of writing characters on real paper, but this also only describes that the shadow of the pen is made to look like it is being reflected by lowering the brightness of the picture elements included in the area of ​​the shadow of the pen, and it does not change the fact that when the illuminance of the external light is reduced due to the shadow of an object, the luminance of the relevant area is lowered to match the reduced illuminance of the external light.

[0007] Furthermore, even in reflective displays that reflect ambient light such as external light, when color is displayed, the reflected light is significantly reduced due to light absorption by the color filters of the three primary colors, and visibility may be significantly reduced compared to print media.

[0008] Therefore, the present invention aims to provide a display device that reproduces the optical characteristics of a printed display medium, giving the viewer the sensation that the display device is a printed medium such as paper, and displaying information to the viewer as if it were a familiar printed medium, thereby conveying information without any sense of incongruity. [Means for solving the problem]

[0009] The display device of the present invention comprises a display panel and at least one optical sensor, and is characterized in that in order to reproduce the diffuse reflection of light from a printed display medium in response to external light, the light flux emitted from a pixel in a specific region within the display panel is controlled at a predetermined rate of diffuse reflectance. According to the above configuration, the light flux emitted from the pixel is controlled at a predetermined rate of diffuse reflectance, making it possible for the display device to reproduce the diffuse reflected light of a printed display medium, giving the impression that the display device is a printed medium such as paper.

[0010] The diffuse reflectance can also be set to a value equal to or less than 1. Since the amount of light emitted from a print medium such as paper is generally smaller than the amount of light emitted from a display device, setting the diffuse reflectance value to 1 or less makes it possible to better control the diffuse reflected light.

[0011] Furthermore, the optical sensor may be made capable of detecting the three primary colors of light individually, the diffuse reflectance may be determined for each of the three primary colors of light, and the light flux emitted from the pixel may be controlled based on the diffuse reflectance. This allows the diffuse reflectance of each color to be determined taking into account the light diffusion and spectral absorption of various types of printing media such as paper for each of the three primary colors, and the light flux to be controlled based on the diffuse reflectance, making it possible to perform more precise control of the diffuse reflected light.

[0012] The optical sensors may also be arranged as a two-dimensional array, which allows the distribution of the light beam incident on the display panel for each region to be properly reflected. The optical sensors may be arranged at various locations, such as the surface of the rear substrate, the surface of the front substrate, or the surface of another transparent substrate.

[0013] A black absorbing portion may be formed on the surface of the pixel on which the optical sensor is provided, thereby blocking display light that interferes with the optical sensor that detects external light.

[0014] Furthermore, a color filter for the three primary colors may be provided on the light receiving surface of the optical sensor. In this case, it is preferable to use a color filter equivalent to the color filter for the three primary colors of the pixel. This makes it possible to make the sensitivity of the light receiving surface of the optical sensor the same as the sensitivity of the pixel.

[0015] In addition, a reflection suppressing layer or an anti-glare layer may be laminated on the display panel, which makes it possible to suppress specular reflection that occurs in normal display devices but does not occur in print display media such as paper.

[0016] Furthermore, the angular dependency of the emitted light intensity of the pixel may be the uniform diffusion distribution of a perfect diffuser based on Lambert's cosine law, i.e., the luminance has no angular dependency (luminance is isotropic), or the half-value angle of the luminance (the angle at which the luminance is half the value of the front luminance) is as wide as 120° or more, and the light distribution gradually decreases from the direction perpendicular to the substrate surface. This makes it possible to reproduce the optical characteristics of a print display medium such as paper. In addition, when a liquid crystal element is used, the backlight serving as the light source may have a similar light distribution. Effect of the Invention

[0017] The present invention provides a display device that reproduces the optical characteristics of a print display medium, and can provide a sensation as if the display device were a print medium such as paper. [Brief description of the drawings]

[0018] [Figure 1] 1 is a block diagram showing a configuration of a liquid crystal display device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a detailed configuration of a liquid crystal panel. [Diagram 3] FIG. 2 is a diagram showing a cross section of a liquid crystal panel and a backlight. [Figure 4] FIG. 2 is a diagram showing the relationship between pixels and optical sensors. [Diagram 5] 11A and 11B are diagrams showing the relationship between the intensity of incident light in a liquid crystal panel, the output signal of an optical sensor, and the intensity of reflected light from a print display medium. [Figure 6] 13 is a modified example of the structure of the liquid crystal panel. [Figure 7] This is an image from a display experiment using a backlight and liquid crystal element that approximates a Lambertian light distribution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a liquid crystal display device according to an embodiment of the present invention. A liquid crystal display device 10 includes a liquid crystal panel 11, an image processing unit 12, an A / D converter 13, a backlight power supply circuit 14, and a backlight 15. The liquid crystal panel 11 includes a panel driving circuit 17 and a display area 18, and the display area 18 includes a plurality of pixel circuits and a plurality of optical sensors arranged two-dimensionally, as described later.

[0020] Display data D1 and an output control signal OC are input from the outside to the image processing unit 12 of the liquid crystal display device 10, display data processing is performed within the image processing unit 12, and display data D2 is output to the liquid crystal panel 11. The display data D2 is input to a panel driving circuit 17 of the liquid crystal panel 11, and the panel driving circuit 17 writes data to pixel circuits of a display area 18 based on the display data D2. As a result, an image is displayed in the display area 18.

[0021] The backlight 15 is composed of LEDs, and emits light as backlight from behind the liquid crystal panel 11. The backlight power supply circuit 14 supplies or cuts off power to the backlight 15 based on a control signal output from the image processing unit 12. In addition, as will be described later, it also controls the drive of the liquid crystal panel 11 and the backlight 15 based on a signal from a light sensor. The backlight 15 is composed of white LEDs, but it can also be configured by combining red, green, and blue LEDs.

[0022] The panel drive circuit 17 writes a voltage to the pixel circuits of the liquid crystal panel 11. At the same time, the panel drive circuit 17 also reads out a voltage corresponding to the amount of received light from the optical sensor 2 (not shown in FIG. 1) of the liquid crystal panel 11. A signal SS output from the optical sensor is output to the outside of the liquid crystal panel 11 and input to the A / D converter 13. The A / D converter 13 converts the analog signal output from the optical sensor 2 into a digital signal. Based on the digital signal output from the A / D converter 13, the image processing unit 12 drives and controls the liquid crystal panel 11 and the backlight 15 by the control described below.

[0023] 2 is a diagram showing a detailed configuration of the liquid crystal panel 11. The pixel array in the display region 18 includes m scanning signal lines G1-Gm and 3n data signal lines Sr1-Srn, Sg1-Sgn, and Sb1-Sbn, and m×3n pixel circuits are formed at the intersections of the scanning signal lines and the data signal lines. Furthermore, the pixel array in the display region 18 includes optical sensors 2, sensor readout lines Rw1-Rwm, and sensor lines Srw1-Srwn, Sgw1-Sgwn, and Sbw1-Sbwn corresponding to each pixel circuit.

[0024] The scanning signal lines G1 to Gm are arranged in parallel to each other. The data signal lines Sr1 to Srn, Sg1 to Sgn, and Sb1 to Sbn are arranged in parallel to each other so as to be perpendicular to the scanning signal lines G1 to Gm, and pixel circuits 1 are provided at the intersections of the scanning signal lines G1 to Gm and the data signal lines Sr1 to Srn, Sg1 to Sgn, and Sb1 to Sbn. The pixel circuits 1 are arranged two-dimensionally, with m in number in the direction parallel to the scanning signal lines and 3n in number in the direction parallel to the data signal lines. Red, green, and blue color filters are provided in this order in the direction parallel to the data signal lines to form an R (red) pixel circuit 1r, a G (green) pixel circuit 1g, and a B (blue) pixel circuit 1b in this order, and the three types of pixel circuits form one pixel.

[0025] The pixel circuit 1 includes a TFT 3 and a liquid crystal capacitor 4. The gate terminal of the TFT 3 is connected to a scanning signal line, and the source terminal is connected to one of the data signal lines. The drain terminal is connected to an electrode of the liquid crystal capacitor. A common voltage is applied to an electrode other than the electrode to which the drain terminal is connected.

[0026] A scanning signal line driving circuit 31, a data signal line driving circuit 32, a sensor row driving circuit 33, a sensor column driving circuit 34, switches (35, 36), etc. are provided around the display area 18. The scanning signal line driving circuit 31, the data signal line driving circuit 32, the sensor row driving circuit 33, and the sensor column driving circuit 34 correspond to the panel driving circuit 17 in FIG. The data signal line driving circuit 32 has 3n output terminals corresponding to the 3n data signal lines. A switch is provided between the data signal line driving circuit 32 and each data line.

[0027] The luminance of the pixel circuit 1 is determined by the voltage written to the pixel circuit 1. To write a voltage to the pixel circuit 1, a high-level voltage for turning on the TFT 3 is applied to the scanning signal line Gi (i is an integer from 1 to m), and a voltage to be written is applied to the data signal line Sxj (x is any of r, g, or b, and j is an integer from 1 to n). By writing a voltage according to the display data D2 to the pixel circuit 1, it is possible to set the luminance of each pixel to a desired level.

[0028] FIG. 3 is a diagram showing a cross section of the liquid crystal panel 11 and a backlight 15. The liquid crystal panel 11 has a structure in which a liquid crystal layer 42 is sandwiched between two glass substrates 41a and 41b. The glass substrate 41a is provided with three color filters 43r, 43g, and 43b, a black absorbing portion 44, and a counter electrode 45. The glass substrate 41b is provided with a pixel electrode 46 and a data signal line 47. In this example, the optical sensor 2 is also provided on the glass substrate 41b. The photodiode 6 in the optical sensor 2 is provided in the vicinity of the pixel electrode 46. An alignment film 48 is provided on the surfaces of the glass substrates (41a, 41b) facing each other, and a polarizing plate 49 is provided on the surface opposite to the surface on which the alignment film 48 is provided. In FIG. 3, the surface on the glass substrate 41a side is the front surface, and the surface on the glass substrate 41b side is the back surface. The backlight 15 is provided on the back side, that is, on the glass substrate 41b side. In FIG. 3, the optical sensor 2 is provided near the pixel electrode 46 on the glass substrate 41b side, but it may also be provided on the surface facing the glass substrate 41a side, or on the side portion of the glass substrate 41a or the glass substrate 41b.

[0029] In the example shown in FIG. 2, one optical sensor 2 is provided for one pixel circuit, and includes a photodiode 6. A sensor readout line Rwi is connected to an anode electrode of the photodiode 6, and sensor lines (Srwj, Sgwj, Sbwj (j is an integer from 1 to n)) are connected to a cathode electrode of the photodiode 6. When a reverse bias voltage is applied from the sensor column drive circuit 14 to the sensor lines (Srwj, Sgwj, Sbwj (j is an integer from 1 to n)) of the photodiode 6, a current corresponding to the amount of incident light flows through the photodiode 6, and the voltage of the cathode terminal of the photodiode 6 drops accordingly. This makes it possible to determine the amount of light detected by the optical sensor 2.

[0030] In the example shown in Fig. 2, a simple configuration is used in which a photodiode is connected to the wiring intersection in the matrix circuit section, but a configuration in which a field effect transistor for line selection, an amplification transistor, a reset transistor, and a transfer transistor are provided at the intersection and the photodiode is connected to the output of the transistor may also be used. By using such a connection configuration, it is possible to obtain clear light detection signals such as current and voltage with little electrical noise from each photodiode. As a semiconductor used in a field effect transistor, it is possible to use semiconductors such as amorphous or polycrystalline Si, metal oxides, etc., which are used in existing thin film transistors.

[0031] In the liquid crystal panel 11, the backlight 15 disposed on the rear side directly emits outgoing light, and the brightness is controlled by the pixel circuit 1. On the other hand, a print display medium such as paper does not have a light emitting source like the backlight in a liquid crystal panel, so the light incident from the outside is reflected on the surface of the paper and enters the observer's eyes as diffuse reflected light. Therefore, the amount of light emitted is generally less than the light directly emitted by the backlight in a liquid crystal panel, and the amount of light is also lower than the amount of light incident from the outside.

[0032] This invention focuses on the difference in the emitted light between liquid crystal panels and print display media such as paper, and controls the direct emitted light from a backlight or the like in the liquid crystal panel so that it becomes equivalent to the diffuse reflected light on paper, thereby making the display look like it is printed on paper, even though it is displayed on a liquid crystal panel.

[0033] 5(a) is a graph showing the relationship between the light intensity, which indicates the intensity of light incident on a unit area of ​​the liquid crystal panel 11, and the voltage signal output from the optical sensor 2. As shown in this graph, the light intensity and the voltage signal are roughly proportional to each other, although there is an offset voltage (Vs). Based on this relationship, it is possible to obtain parameters by actual measurement, and to calculate the light intensity relative to the voltage signal based on the obtained parameters.

[0034] Fig. 5(b) is a graph showing the relationship between light intensity, which indicates the intensity of light incident on a unit area, and the intensity of a print display medium such as paper at that time. As shown in this graph, the relationship between light intensity and reflected light intensity is approximately proportional. Based on this relationship, it is possible to obtain parameters by actual measurement, and calculate the reflected light intensity relative to the light intensity based on the obtained parameters. As explained above, this proportionality constant is approximately a value equal to or less than 1.

[0035] To detect the amount of incident external light, the output of the optical sensor provided for each pixel is averaged when driving the pixels in the liquid crystal panel, but it is also possible to use the output from each optical sensor and multiply it by the diffuse reflectance for each pixel to determine the amount of incident external light.

[0036] In addition, as shown in FIG. 4, the optical sensor 2 is provided for each pixel circuit. However, one optical sensor may be provided for each pixel, or one for each of more pixels. It is also possible to provide one optical sensor for the entire liquid crystal panel, or to provide multiple optical sensors in the periphery of the liquid crystal panel. As shown in FIG. 4, when an optical sensor is provided for each sub-pixel of red, green, and blue, it is also possible to use the same color filter as that provided for the pixel for each optical sensor so that the three primary colors of red, green, and blue can be detected individually with the same sensitivity as that of the pixel. In such a configuration, for each of the three primary colors, the diffuse reflectance according to the type of print display medium such as paper is obtained in advance based on the value of the diffuse reflected light by actually irradiating the print display medium with light.

[0037] In addition, it is generally known that the diffuse reflectance (total light reflectance) of white paper used for copy paper is 85 to 91%, and that of newspaper is 40 to 50%, and by using these diffuse reflectance values, differences in paper quality can be easily expressed. It is also useful to store a plurality of these diffuse reflectance values ​​and switch between them as appropriate. Furthermore, even though they are both white, the diffuse reflectance of white cloth is 60 to 70%, and that of white tile is 70 to 80%, so by using these diffuse reflectance values, surfaces other than paper can be reproduced. In addition, if the present invention is configured with a color sensor and display pixels of three primary colors, it is necessary to obtain and use the diffuse reflectance of each of the three primary colors on the paper. This makes it easy to reproduce not only the brightness of the paper but also its color tone.

[0038] Also, on the liquid crystal panel side, the relationship between the amount of incident external light and the output of the optical sensor, and the relationship between the driving state of the pixel and the amount of light emitted from the pixel are obtained in advance for each of the three primary colors. Then, the pixels in the liquid crystal panel are driven so that the amount of light emitted from the pixel in the liquid crystal panel for each of the three primary colors is the amount of light emitted with a diffuse reflectance obtained by multiplying the amount of incident external light detected by the optical sensor by the diffuse reflectance of a specific print display medium.

[0039] The following describes an example of the pre-adjustment, calibration, and drive method for a specific LCD panel. The standard white light assumed to be used is irradiated at maximum illuminance, and the maximum input and output values ​​of the optical sensor at that time are set. The output value of the optical sensor is made proportional to the light intensity of the optical sensor. As the standard white light, it is recommended to use the D50 light source or D65 light source, which are standard white light sources defined by the International Commission on Illumination. Under the illuminance of these light sources, the diffuse reflectance of a commercially available standard diffuse white board is set to an ideal 100%, and the luminance is calculated as luminance = illuminance / π, or the luminance of the standard diffuse white board is measured with a luminance meter. Then, the three primary color drive signals are adjusted so that the luminance value obtained in this way matches the luminance of the display. The drive signals of the three primary colors at this time correspond to the maximum values ​​of each color.

[0040] Also, the display drive signal is set to change in proportion to the output signal of the light sensor. With these adjustments, the balance of the three primary colors, i.e., chromaticity, color temperature, and hue, is maintained on the display even if the intensity of the illumination light changes. When adjusting the brightness of the display, the drive signal can be adjusted while keeping the balance of the three primary colors constant, but the backlight light source (LED, etc.) can also be adjusted to save power.

[0041] Meanwhile, measure the three primary color reflectances of the paper you want to simulate. The reflectance of the paper can be roughly considered as the ratio of decrease in luminance when paper is used instead of the standard diffuse white plate. If the reflectance of each of the three primary colors of the paper is known, the display drive signal can be calculated by multiplying the reflectance ratio (1 or less) by the maximum drive signal when the standard diffuse white plate is used. For example, when reproducing the reflected light of white copy paper, which has the same reflectance of 80% for all three primary colors, the actual drive signal can be calculated by multiplying the drive signals of the three primary colors by 80%. If the reflected light of white copy paper is assumed to have a Lambertian distribution, the luminance of the white copy paper can be roughly approximated by the formula: luminance = reflectance x illuminance / π.

[0042] This allows the display's three primary color luminance to be automatically determined and controlled even if the lighting environment of the usage environment changes. For example, if the light is switched from standard white light to lighting light with a different brightness or color temperature, the display's three primary color display will be linked to the change in the three primary color output of the optical sensor, so the luminance and color of white paper can be reproduced simultaneously on the display. Furthermore, when reproducing the reflected light of paper other than white copy paper (such as dull white paper or colored paper) on the display, the reflectance of the three primary colors of each paper can be obtained by a predetermined value or a luminance measurement, and the drive level for each of the three primary colors can be obtained by multiplying the diffuse reflectance by the maximum drive level for the three primary color display. This allows the reflected light of paper with various diffuse reflectances to be reproduced as display light on the display.

[0043] Fig. 6 shows a modified example of the structure of the liquid crystal panel in Fig. 3. In the example of Fig. 6, an anti-glare layer is provided on the outer surface of the polarizing plate 49 to suppress specular reflection light. Unlike liquid crystal panels, print display media such as paper do not have specular reflection light on the surface. Therefore, by providing an anti-glare layer on the surface of the liquid crystal panel to suppress specular reflection light, it is possible to make the display closer to a print display medium such as paper. Also, in the example of Fig. 6, an anti-glare layer is provided on the outer surface of the polarizing plate 49, but it is also possible to provide a reflection suppressing layer instead of the anti-glare layer.

[0044] Some papers and cloths have patterns or the like on their surfaces. In such cases, the diffuse reflectance of the surface may differ depending on the presence or absence of a pattern, the shape of the pattern, etc. In such cases, the diffuse reflectance of each area of ​​the paper or cloth is calculated in detail in advance in accordance with the pattern, and when displaying on a liquid crystal panel, each area is multiplied by a different diffuse reflectance in accordance with the pattern, making it possible to reproduce the texture of the paper or cloth while also displaying the pattern by changing the brightness.

[0045] In the description of these embodiments, a display device using liquid crystal has been used, but the present invention is not limited to liquid crystal display devices, and can also be applied to self-luminous display devices such as organic electroluminescence (EL) display devices. In the case of a self-luminous display device, the emitted light flux can be calculated as the product of the incident light flux of external light and the diffuse reflectance, and the display device can be driven in the same manner as in the case of a liquid crystal display device.

[0046] The ideal light distribution for a display device is a Lambertian distribution, but when the half-value angle of the luminance of white copy paper was measured, it was found to be approximately 160°, with a light distribution that gradually decreased from the vertical direction of the display surface. Therefore, a backlight box (half-value angle of luminance is 160°) was prototyped in which the LED light was diffused so that the luminance was close to an isotropic Lambertian distribution, and a display experiment was carried out by layering it with a commercially available liquid crystal element. As a result, it was confirmed that a high-quality display image could be obtained that was indistinguishable from color printed paper, whether viewed from the front or at an angle. Figure 7 shows the results of comparing the prototype device with a printed image under indoor lighting.

[0047] It has also been confirmed that a light distribution close to the Lambertian distribution (half-value angle of brightness is 160°) can be obtained even if a strong diffusion plate is laminated on an existing light guide plate backlight. In this case, the stronger the diffusion effect of the diffusion plate, the closer the light distribution becomes to the Lambertian distribution, but there is a risk of a decrease in brightness. Furthermore, in the lamination relationship with the polarizing plate, liquid crystal panel, light diffusion film, etc., if there is an air layer between them, Fresnel reflection occurs, and light with a large inclined angle of incidence is totally reflected and not emitted to the outside, so it does not contribute to the light for display, and in this case too, the brightness may decrease and the display may become dark. In order to prevent this, it is preferable to configure the lamination of various optical components with a tight contact structure such as lamination or injection of matching oil. This makes it possible to prevent a decrease in the intensity of the obliquely emitted light, and significantly suppress the decrease in the half-value angle of brightness caused by Fresnel reflection.

[0048] On the other hand, the more the light distribution is expanded by increasing the light diffusion effect in order to bring the backlight closer to the Lambertian distribution, the lower the front brightness becomes. Therefore, from a practical point of view, it is desirable for the half-value angle of the brightness of the display device or backlight to be 120° or more. For the liquid crystal element to be stacked on the backlight, it is desirable to use a display operation method that provides wide viewing angle characteristics, such as the in-plane switching liquid crystal method (IPS) or the vertical alignment liquid crystal method (VA).

[0049] <1> a display panel having pixels arranged two-dimensionally to emit display light; At least one light sensor that detects external light; In order to reproduce the diffuse reflection of the print display medium against the external light, In a specific region of the display panel, a light flux emitted from a pixel in the specific region is controlled by a product of a predetermined rate of diffuse reflectance and the light flux of the external light incident on the specific region, the light flux being detected by the optical sensor and being incident on the specific region from the outside. A display device comprising: <2> The diffuse reflectance is equal to or less than 1. Characterized by <1> The display device according to claim 1 . <3> The optical sensor is capable of detecting three primary colors of light individually; The diffuse reflectance is determined for each of the three primary colors of light, The light flux emitted from the pixels in the specific region is controlled based on the diffuse reflectance determined for each of the three primary colors of light. Characterized by <1> or <2> The display device according to claim 1 . <4> The optical sensors are arranged in a two-dimensional array. Characterized by <1> ~ <3> 13. The display device according to claim 12, <5> The optical sensor is provided on the surface of the rear substrate on which the thin film transistor for driving the pixel is formed, on the inner surface or outer surface of the front substrate, or on the surface of another transparent substrate to be laminated. Characterized by <1> ~ <4> 13. The display device according to claim 12, <6> A black absorbing portion is formed on the surface of the pixel on which the optical sensor is provided. Characterized by <5> The display device according to claim 1 . <7> A color filter for the three primary colors is provided on the light receiving surface of the optical sensor. Characterized by <3> ~ <6> 13. The display device according to claim 12, <8> The pixel is composed of a liquid crystal element or an organic EL element that is voltage-driven by a thin film transistor. Characterized by <1> ~ <7> 13. The display device according to claim 12, <9> A reflection suppressing layer and an anti-glare layer are laminated on the display panel. Characterized by <1> ~ <8> 13. The display device according to claim 12, <10> The angular dependence of the radiated light intensity of the pixel is equal to the uniform diffusion distribution of a perfect diffuser based on Lambert's cosine law, or has a light distribution with a half-value angle of luminance of 120° or more and gradually decreasing from the direction perpendicular to the substrate surface. Characterized by <1> ~ <9> 13. The display device according to claim 12, <11> The orientation characteristics of the backlight used in the liquid crystal element are uniform diffusion distribution of a perfect diffuser, or the half-value of the luminance is 40° or more and gradually decreases from the direction perpendicular to the substrate surface. Characterized by <1> ~ <10> 13. The display device according to claim 12, [Explanation of symbols]

[0050] 1 Pixel circuit 2. Light Sensor 6 Photodiode 10 LCD display device 11 Liquid crystal panel 12 Image processing section 13 A / D Converter 14 Backlight power circuit 15 Backlight 17 Panel drive circuit 18 Display area 31 Scanning signal line driver circuit 32 Data signal line driver circuit 33 Sensor row driver circuit 34 Sensor row driver circuit 41 Glass Substrate 42 Liquid crystal layer 43 Color Filter 44 Black absorbing part 45 Counter Electrode 46 Pixel electrode 48 Alignment Film 49 Polarizing Plate

Claims

[Claim 1] a liquid crystal display panel having pixels arranged two-dimensionally to emit display light; A light sensor for detecting external light; A backlight is provided. A diffusion plate is laminated on the backlight, The liquid crystal display panel has a structure in which a liquid crystal layer is sandwiched between two glass substrates, A polarizing plate is provided in a contact structure on each of the surfaces of the two glass substrates opposite to the surfaces facing each other, and an anti-glare layer is provided in a contact structure on each of the outer surfaces of the pair of polarizing plates, The pixel is composed of a liquid crystal element that is voltage-driven by a thin film transistor, In order to reproduce the diffuse reflection of the print display medium against the external light, a light flux emitted from a pixel in a specific region of the liquid crystal display panel is controlled by a product of a predetermined rate of diffuse reflectance and the light flux of the external light detected by the light sensor disposed corresponding to the specific region, a driving signal for three primary colors for setting the luminance of a pixel when reproducing the diffuse reflection light of the print display medium with respect to the external light is adjusted based on a formula of diffuse reflectance×illuminance / π using an illuminance based on a luminous flux of the external light detected by the optical sensor arranged corresponding to a specific region of the liquid crystal display panel; A liquid crystal display device, wherein the diffuse reflectance used in a calculation formula for adjusting drive signals for three primary colors that set the luminance of the pixel has a value of 1 or less.

Images