JP2020187199A - Liquid crystal display device - Google Patents

Abstract

To provide a liquid crystal display device that can correct a characteristic of a liquid crystal panel with high accuracy when a conversion characteristic of a wavelength conversion member is changed.SOLUTION: In a liquid crystal display device 100 comprising a liquid crystal panel 101 using a wavelength conversion member in a plurality of colors, a light source device having a blue light source, a luminance detection element, acquisition means for acquiring a detection value detected by the luminance detection element when the blue light source is lit with a predefined intensity, and liquid crystal control means for controlling the transmittance for each pixel of the liquid crystal panel 101, the acquisition means detects the amount of light when the liquid crystal pixel using the wavelength conversion member is closed and the amount of light when the liquid crystal pixel not using the wavelength conversion member is closed, and the transmittance of the liquid crystal panel 101 is changed based on the amount of change in the ratio of these detection values from a certain point.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquid crystal display device.

Conventionally, a liquid crystal display device displays an image of a desired color by transmitting white light emitted from a backlight from the back surface of a liquid crystal panel provided with a color filter and controlling the transmittance of the liquid crystal. Here, the color filter is generally composed of, for example, a red, green, and blue filter. However, such a liquid crystal panel has a problem that high-luminance display is difficult due to a large loss of light because the filters of each color constituting the color filter pass only the light of a predetermined color. Also, in terms of the display color gamut, it is common to use a white LED in which a blue LED (light emitting diode) is excited by a yellow, red, or green phosphor as the light source of the backlight, and it is excited by the phosphor. Since the spectrum of colors is often a broad characteristic, BT. It was difficult to realize a wide color gamut like the 2020 standard.

As a method for solving such a problem, a technique of a liquid crystal panel in which a wavelength conversion member such as a phosphor or a quantum dot is mixed in the liquid crystal instead of the color filter of the liquid crystal panel is disclosed (Patent Document 1).

The liquid crystal panel of Patent Document 1 uses a blue light source as a backlight light source, provides a wavelength conversion unit that generates red instead of a red color filter for red subpixels, and uses green instead of a green color filter for green subpixels. It has a wavelength conversion unit to generate, and the blue subpixel does not have a wavelength conversion unit. By using quantum dots in this wavelength conversion unit, high-purity colors can be obtained, so that a liquid crystal display device having a wide color gamut can be obtained.

On the other hand, the wavelength conversion member having such a phosphor or a quantum dot changes its wavelength conversion characteristics due to aged deterioration, temperature rise, etc., and therefore needs to be corrected according to the characteristic change. For example, when the wavelength conversion member has a wavelength conversion element that excites blue light to red light and a wavelength conversion element that excites blue light to green light, the spectral characteristics of red and green after the wavelength conversion member is transmitted are affected by the temperature rise. It shifts to the long wavelength side. In particular, in a light source device having quantum dots as a wavelength conversion member, this tendency is remarkable because the change in spectral characteristics is large with the temperature rise of the quantum dots.

Here, as a technique for correcting a change in the characteristics of a liquid crystal panel in a liquid crystal display device, light transmitted through a dummy liquid crystal panel in which a part of light from a light source is incident is detected, and the emission brightness of the backlight light source is based on the detected value. (Patent Document 2). According to this technique, the display quality of the liquid crystal display device can be stabilized by correcting the emission brightness of the backlight light source according to the characteristic change of the liquid crystal panel.

Further, in Patent Document 3, in a liquid crystal display device, the amount of reflected light emitted from a light source and reflected by the liquid crystal panel is detected by a CMOS image sensor having the same number of pixels as the number of pixels of the liquid crystal panel, and the light source is determined according to the detected amount of light. A technique for correcting at least one of the amount of emitted light and the opening degree of the liquid crystal display panel is disclosed.

Japanese Unexamined Patent Publication No. 2016-0585886 JP-A-2010-152375 Japanese Unexamined Patent Publication No. 2008-292892

In the correction technique disclosed in Patent Document 2 above, it is necessary to provide another liquid crystal panel in addition to the display panel. Further, the correction technique of Patent Document 3 cannot detect the brightness or color of the light transmitted through the wavelength conversion member. Therefore, it is difficult to correct the characteristics of the liquid crystal panel with high accuracy when the conversion characteristics of the wavelength conversion member change.

Therefore, an object of the present invention is to provide a liquid crystal display device capable of correcting the characteristics of a liquid crystal panel with high accuracy even when the conversion characteristics of the wavelength conversion member change.

In order to achieve the above object, the liquid crystal display device according to the present invention
A liquid crystal panel using a wavelength conversion member of a plurality of colors, a light source device provided with a blue light source, a brightness detection element, and a detection value detected by the brightness detection element when the blue light source is lit with a predetermined intensity. In a liquid crystal display device including an acquisition means for acquiring the light source and a liquid crystal control means for controlling the transmittance of each pixel of the liquid crystal panel, the acquisition means determines the amount of light in a closed state of the liquid crystal pixel using the wavelength conversion member. It is characterized in that the amount of light in a closed state of a liquid crystal pixel that does not use a wavelength conversion member is detected, and the transmittance of the liquid crystal panel is changed based on the amount of change in the ratio of both detected values from a certain point in time. ..

According to the liquid crystal display device according to the present invention, even when the conversion characteristics of the wavelength conversion member change, the characteristics of the liquid crystal panel can be corrected with high accuracy.

The figure which shows an example of the structure of the liquid crystal display device which concerns on Example 1 of this invention. Functional block diagram showing an example of the liquid crystal display device according to the first embodiment of the present invention. The figure which shows an example of the liquid crystal panel structure which concerns on this invention. The figure which shows an example of the wavelength conversion layer of the liquid crystal panel which concerns on this invention. The figure which shows an example of the spectroscopic property by the light source and the wavelength conversion member which concerns on this invention. A flowchart for explaining the manufacturing image quality adjustment of the liquid crystal display device according to the first embodiment of the present invention. A flowchart for explaining deterioration correction of the liquid crystal display device according to the first embodiment of the present invention. Functional block diagram showing an example of a liquid crystal display device according to a third embodiment of the present invention. A flowchart for explaining deterioration correction of the liquid crystal display device according to the third embodiment of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

<Example 1>
Hereinafter, Example 1 of the present invention will be described.

The liquid crystal display device according to the present embodiment is a liquid crystal display device that uses a blue LED as a light source, converts the wavelength of blue light emitted from the light source by a liquid crystal panel to produce red and green components, and displays an image.

(overall structure)
FIG. 1 is a diagram showing an example of the structure of the liquid crystal display device according to the present embodiment. Further, FIG. 2 is a functional block diagram showing an example of the liquid crystal display device according to the present embodiment.

As shown in FIG. 1, the liquid crystal display device 100 includes a liquid crystal panel 101, a liquid crystal panel holding structure 102, a light source unit 103, a diffusion member 104, a light source holding structure 105, an optical sensor 106, a panel bezel 107, and the like.

Further, as shown in FIG. 2, the liquid crystal display device 100 has a video signal input unit 121, a video signal processing unit 122, a liquid crystal panel drive circuit unit 123, a backlight light source drive circuit unit 124, and a storage unit as interface and control related units. It has 125, a control unit 126, and the like.

The liquid crystal panel 101 has a panel structure having a wavelength conversion member. An example of the panel structure is shown in FIGS. 3 and 4. The liquid crystal panel 101 includes an array substrate 130 and a counter substrate 136, and a liquid crystal layer 135 is provided between the array substrate 130 and the counter substrate 136. The array substrate 130 includes a glass substrate 131 on which a TFT or the like is formed, a wavelength conversion layer 132, an in-cell polarizing plate 133, and a pixel electrode 134. The facing substrate 136 includes a glass substrate and the like, and a polarizing plate 137 is provided on the opposite side of the facing substrate 136. The light from the light source unit 103 is incident from the glass substrate 131 side, and the user of the liquid crystal display device observes the image from the polarizing plate 137 side.

The wavelength conversion layer 132 is composed of a red layer 132_R that converts the excitation light from the light source unit 103 to red, a green layer 132_G that converts the excitation light to green, and a blue layer 132_B that transmits the blue color of the excitation light. Here, a partition wall (not shown) may be provided between the respective color layers to prevent color mixing of light.

The red layer 132_R has a wavelength conversion element (R phosphor). Here, the R phosphor is a phosphor that generates red light (red light) when excitation is caused by blue light. The spectrum of red light generated in the red layer 132_R has a peak in the wavelength range of 580 nm or more and 700 nm or less, for example.

Further, the green layer 132_G has a wavelength conversion element (G phosphor). The G phosphor is a phosphor that generates green light (green light) when excitation is caused by blue light. The spectrum of green light generated in the green layer 132_G has a peak in the wavelength range of, for example, 500 nm or more and 550 nm or less.

In this embodiment, the phosphor emits light on the longer wavelength side than the excitation light. Therefore, the phosphor can also be called an "optical conversion element" or a "wavelength conversion element". The spectrum of light transmitted through the wavelength conversion layer 132 has three spectral peaks of blue, red and green, and the light obtained by synthesizing these is, for example, white light. In this embodiment, it is assumed that the number (ratio) of the R phosphor and the G phosphor is adjusted so that the desired white light can be obtained when the transmittance of the liquid crystal panel 101 is set to a desired value.

Further, in this embodiment, as shown in FIG. 4, it has a red quantum dot 141 as an R phosphor and a green quantum dot 142 as a G phosphor. Here, the quantum dot is a phosphor that emits light of a color corresponding to the particle size in response to ultraviolet light or blue light. By using quantum dots, it is possible to obtain red light or green light with a half-value width of about 40 nm from blue light, so it is possible to express colors in a wide color gamut as a whole liquid crystal display device rather than using a phosphor. it can.

The liquid crystal panel unit 101 has a plurality of liquid crystal elements in the liquid crystal layer 135, and the transmission rate of each liquid crystal element is determined by the video signal output from the video signal processing unit 122 described later or the control unit 126. An image is displayed on the liquid crystal panel according to the liquid crystal drive signal that is controlled according to the tuning amplification amount and supplied based on the transmission rate. The light from the light source unit 103 passes through the liquid crystal panel unit 101 (each liquid crystal element) at a transmittance corresponding to the image data, so that the image is displayed on the liquid crystal screen. The characteristics of the liquid crystal element in the liquid crystal panel section 101 and the method of controlling the transmittance of the liquid crystal element are not particularly limited. As an example of a specific control method, for example, by inputting a liquid crystal drive signal having a value of 8 bits (value of 0 to 255) to the liquid crystal element, the transmittance of the liquid crystal element follows a predetermined gamma curve and the liquid crystal is liquid crystal. The transmittance is controlled to X% corresponding to the drive signal.

The gamma curve is a curve (function) representing the correspondence between the value of the liquid crystal drive signal and the transmittance, and the predetermined gamma curve is, for example, a gamma curve having a gamma value = 2.2. When the transmittance of the liquid crystal element is controlled to X%, X% of the light irradiated to the liquid crystal element is transmitted through the liquid crystal element. When the transmittance of the liquid crystal element is controlled to 0%, the light irradiated to the liquid crystal element is blocked by the liquid crystal element. When the transmittance of the liquid crystal element is controlled to 100%, the light applied to the liquid crystal element passes through the liquid crystal element.

The liquid crystal panel holding structure 102 is a structure that holds the liquid crystal panel 101 and the optical sensor 106 described later.

The light source unit 103 is composed of one or more light emitting elements (light sources) or a light source block composed of a plurality of light emitting elements (light sources), and lights the light source with the power supplied from the backlight drive circuit unit 124 described later. This is a light source that irradiates light from the back surface of the liquid crystal panel unit 101. In this embodiment, a blue LED is used as the light emitting element of the light source unit 103. Further, the light emitted from the light source unit 103 is used as excitation light for the wavelength conversion layer 132 inside the liquid crystal panel 101, and is converted into light on the long wavelength side. Therefore, as the light emitted from the light source unit 103, light having a shorter wavelength at the peak (maximum value) of the spectrum than the red / green generated in the wavelength conversion layer 132 is used.

In this embodiment, blue light having a spectral peak in the wavelength range of 440 nm or more and 480 nm or less is used as the light emitted from the light source unit 103. FIG. 5A shows an example of the spectrum (spectral characteristics) of blue light emitted from the light source unit 103. Further, FIG. 5B shows an example of green light and red light generated by exciting the wavelength conversion layer 132 with blue light. Here, the horizontal axis of FIG. 5 indicates the wavelength, and the vertical axis indicates the intensity.

The light emitting element (light source) included in the light source unit 103 is not limited to the LED. For example, a laser element, an organic EL element, a cold cathode tube element, a plasma element, or the like may be used as the light emitting element. Further, the light source unit 103 may have one light emitting element or may have a plurality of light emitting elements.

Further, the structure of the light source unit 103 may be any structure as long as the brightness can be controlled. For example, an edge-type backlight device using a light guide plate may be used as the light source unit 103, or a direct-type backlight device in which a light source is arranged directly under the liquid crystal panel unit 101 may be used. The shape is not particularly limited. Further, the number of arrangements of the light sources arranged in the light source unit 103 and the arrangement interval are determined according to the required specifications of the liquid crystal display device 100.

The diffusion member 104 is a member that diffuses the light emitted from the light source unit 103. Since the LED used in this embodiment is a point light source, uneven brightness and uneven color are likely to occur. Therefore, by diffusing the light emitted from the light source unit 103 by the diffusing member 104, it is possible to reduce the brightness unevenness and the color unevenness of the light. As the diffusion member 104, a diffusion plate, a diffusion sheet, a light condensing sheet, a polarizing sheet, or the like can be used. The diffusion member 104 may be composed of one member, or may have a structure in which a plurality of members are superposed. In this embodiment, the transmittance of the diffusion member 104 is about 50% to 70%, but is not limited to this.

The light source holding structure 105 is a structure that holds a substrate on which the light source unit 103 is mounted, a heat dissipation structure of the light source unit 103, a diffusion member 104, a reflection member (not shown), and the like.

The optical sensor 106 (sensor unit) has at least one of the brightness and color of the light emitted by the light source unit 103 and the light that passes through the wavelength conversion layer inside the liquid crystal panel 101 and is reflected by the in-cell polarizing plate 133 and the pixel electrode 134. Is one or more sensors that detect. As the optical sensor 106, a luminance sensor (photodiode, phototransistor, etc.) that detects the luminance of the incident light can be used. Further, as the optical sensor 106, a color sensor that detects the color of light or an optical sensor that detects both the brightness and color of light can also be used. In the case of analog values, the brightness and color of the received light are digitally converted by an A / D converter (not shown) and then output to the control unit 126.

The optical sensor 106 in this embodiment uses a color sensor having a sensitivity peak at 400 nm to 500 nm and a low sensitivity at 500 nm to 700 nm in order to detect the brightness of the blue LED of the light source unit 103 with high accuracy. I will do it.

The panel bezel 107 is a member for fixing the liquid crystal panel 101 in combination with the liquid crystal panel holding structure 102.

The video signal input unit 121 receives a video signal output from an imaging device (not shown) or a video signal reproducing device (not shown).

The video signal processing unit 122 decodes the video signal received by the video signal input unit 121, and transmits a control signal for controlling the liquid crystal panel drive circuit unit 123 based on the data for each pixel of the video signal. Further, the video signal processing unit 122 calculates the brightness of the video signal by converting each pixel data of the input video signal into a brightness value. For example, when an RGB signal is input as a video signal, it is converted into a luminance value Y using the following formula.

Y = αR + βG + γB ... (Equation 1)
Here, α, β, and γ are luminance conversion coefficients when converting each signal value of RGB into luminance, and the calculation formula is as follows, for example.

Y = 0.2126R + 0.7152G + 0.0722B ... (Equation 2)
The liquid crystal panel drive circuit unit 123 transmits a liquid crystal drive signal (liquid crystal drive signal) so that the transmission rate of the liquid crystal panel unit 101 is controlled by the video signal of the video signal processing unit 122 or the transmission rate determined by the control unit 126. It is supplied to the liquid crystal panel unit 101. Here, the liquid crystal drive signal is a voltage applied to the liquid crystal panel (liquid crystal element), a current supplied to the liquid crystal panel, and the like.

The backlight light source drive circuit unit 124 adjusts the brightness of the light source of the light source unit 103 according to the brightness set by the control unit 126 such as the video signal and the brightness setting of the liquid crystal panel unit 101 specified by the user, and the light source. It is a drive circuit that supplies the power required to light the LCD with the set brightness. Specifically, the backlight light source drive circuit unit 124 supplies the light source drive signal to the light source of the light source unit 103 so that the light emission brightness of the light source unit 103 is controlled by the emission brightness determined by the control unit 126. The emission brightness of the light source unit 103 can be changed by changing at least one of the magnitude of the light source drive signal and the supply time for supplying the light source drive signal to the light source unit 103. Here, the light source drive signal is a voltage applied to the light source unit 103, a current supplied to the light source unit 103, and the like. The larger the voltage applied to the light source unit 103, the higher the emission brightness of the light source unit 103 is controlled. Further, the longer the total application time for applying the voltage to the light source unit 103, the higher the emission brightness of the light source unit 103 is controlled. Further, the light source drive signal may be intermittently supplied (for example, PWM drive) to the light source unit 103 so that the light source unit 103 is repeatedly turned on and off.

Here, a case where the brightness control of the LED is specifically performed by PWM (Pulse Width Modulation) control will be described as an example.

The duty ratio of PWM control is represented by a value of 4096 levels (referred to as PWM value). The duty ratio is the ratio of the LED lighting period to a certain period (for example, PWM cycle). The PWM value 0 corresponds to the case where the brightness of the LED is the minimum (turns off), and here, the case where the duty ratio is 0% is defined as the PWM value 0. The PWM value 4095 corresponds to the case where the brightness of the LED is maximum, and here, the case where the duty ratio is 100% is defined as the PWM value 4095. In this embodiment,% is used as the unit of emission brightness for the sake of clarity. Specifically, the emission brightness is related to the duty ratio, the maximum brightness is 100% when the duty is 100%, and the minimum value of the emission brightness (value corresponding to the extinguished state) is 0%.

The light source block constituting the light source unit 103 is turned on during the period of the PWM cycle corresponding to the PWM value, and turned off during the other periods. When the PWM value is 0, the light source block is turned off over the entire PWM cycle, and when the PWM value is 4095, the light source block is turned on over the entire PWM cycle. When the PWM value is any other value, a part of the PWM cycle is the lighting period and the remaining part is the extinguishing period.

Further, in the input video signal, assuming that the Vsync signal, which is a vertical synchronization signal of the liquid crystal panel unit 101, is the timing at which one frame starts, the start timing of one cycle of the PWM signal is determined with reference to the Vsync signal. .. One cycle of the PWM signal may start from the lighting period or the extinguishing period. When one cycle of the PWM signal starts from the lighting period, the period of the length corresponding to the duty ratio from the start timing of one cycle of the PWM signal is set as the lighting period, and the other period is set as the extinguishing period. When one cycle of the PWM signal starts from the extinguishing period, the period of the length corresponding to the duty ratio is defined as the extinguishing period by going back in time from the end timing of one cycle of the PWM signal. For example, the frequency of the PWM signal of the backlight light source drive circuit unit 124 is set to 60 Hz. Therefore, when the frame frequency of the input video signal is 60 Hz, the length of one cycle (referred to as PWM cycle) of the PWM control of the backlight light source drive circuit unit 124 is equal to the length of one frame period.

The backlight light source drive circuit unit 124 adjusts the brightness of the light source unit 103 by counting the lighting period of the light source according to the PWM value based on the time obtained by dividing 1/60 second into 4095.

Further, the backlight light source drive circuit unit 124 may be provided for each light source or light source block constituting the light source unit 103, and the PWM value may be set independently for each light source block. As a result, the brightness can be controlled independently for each light source or light source block. In this case, the backlight light source drive circuit unit 124 is composed of a plurality of constant current circuits and a PWM drive circuit.

The characteristics of the light source unit 103 and the method of controlling the emission brightness of the light source unit 103 are not particularly limited.

The storage unit 125 is a memory that stores the luminance value and the like detected by the optical sensor unit 106 at the time of manufacturing inspection of the liquid crystal display device, characteristic correction, and the like. In addition, the storage unit 125 also stores programs for performing various controls described later.

The control unit 126 is composed of a CPU and an FPGA (Field Programmable Gate Array), and various controls described later are realized by executing a program read from the storage unit 125.

The control unit 126 has input / output gradation characteristics of the video signal of the video signal processing unit 122 based on the light intensity information detected by the optical sensor unit 106 when the transmittance of each liquid crystal pixel of the liquid crystal panel 101 is changed. , The transmittance of the liquid crystal panel unit 101, the emission brightness of the light source unit 103, and the like are controlled.

Next, a series of operations performed by the control unit 126 will be described with reference to FIGS. 6 to 7. In the series of operations, the control of the present invention is started by receiving the power ON operation in the image quality adjustment step at the time of manufacturing inspection.

First, in step S151 of FIG. 6, the luminance control of the light source unit 103 by the backlight light source drive circuit unit 124 and the signal of the video signal processing unit 122 are performed so that the display state of the liquid crystal display device 100 has a predetermined color and brightness. Perform processing control.

The process proceeds to step S152 in a state where the brightness of the light source unit 103 and the video signal processing are completed and the colors and brightness are specified.

In step S152, in order to measure the brightness of the light source unit 103, the transmittance of the liquid crystal element of the blue pixel of the liquid crystal panel 101 is 0% (fully closed), and the transmittance of the other pixels is 100% (fully open). The control of the liquid crystal panel drive circuit unit 123 is changed as described above. In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the intensity of light at the time of displaying the specified luminance in the manufacturing stage of the light source unit 103. The intensity of light at this time is set to the reference luminance L_bl, and is stored in the storage unit 125.

Next, in step S153, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the red pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the intensity of transmitted light whose wavelength has not changed even after being subjected to wavelength conversion by the red layer 132_R of the wavelength conversion layer 132 used for the red pixel. The intensity of light at this time is set to the reference luminance L_r of the red layer 132_R at the time of displaying the defined luminance in the manufacturing stage, and is stored in the storage unit 125.

Next, in step S154, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the green pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the intensity of transmitted light whose wavelength has not changed even after the wavelength conversion by the green layer 132_G of the wavelength conversion layer 132 used for the green pixel. The light intensity at this time is set as the reference brightness L_g of the green layer 132_G at the time of the specified brightness display in the manufacturing stage, and is stored in the storage unit 125.

Next, in step S155, the wavelength conversion ratio is calculated from each reference luminance measured in steps S152 to S154.

The wavelength conversion ratio Tr of the red layer 132_R is
Tr = L_r / L_bl ... (Equation 3)
Is required by.

Similarly, the wavelength conversion ratio Tg of the green layer 132_G is
Tg = L_g / L_bl ... (Equation 4)
Is required by.

After calculating the wavelength conversion ratio of each color layer, these values are stored in the storage unit 125 as correction target values. After that, the power is turned off to end the image quality adjustment process at the time of manufacturing inspection.

Next, FIG. 7 will explain the operation after the user has used it.

After the power of the liquid crystal display device 100 is turned on, in step S161, the elapsed use time from the time when the color / luminance correction was performed immediately before to the present is compared with the predetermined correction sampling time. If the elapsed use time is equal to or longer than the sampling time, the process proceeds to step S162, and the process proceeds to correction control.

In step S162, the set values having the specified color and brightness performed in step S151 of FIG. 6 are transmitted to the backlight light source drive circuit unit 124 and the video signal processing unit 122 under the same conditions as the image quality adjustment step at the time of manufacturing inspection. Display it.

Next, in step S163, in order to measure the brightness of the light source unit 103 after the lapse of the sampling time, the transmittance of the blue pixel of the liquid crystal panel 101 is 0% (fully closed), and the transmittance of the other pixels is 100%. The control of the liquid crystal panel drive circuit unit 123 is changed so as to be (fully open). In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the light intensity at the time of displaying the specified luminance after the lapse of the sampling time. The intensity of light at this time is set to the reference luminance Ln_bl, and is stored in the storage unit 125.

Next, in step S164, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the red pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the intensity of transmitted light whose wavelength has not changed even after the wavelength conversion by the red layer 132_R of the wavelength conversion layer 132 used for the red pixel after the lapse of the sampling time. It becomes. The intensity of the light at this time is set to the brightness Ln_r of the red layer 132_R at the time of displaying the specified brightness after the lapse of the sampling time, and is stored in the storage unit 125.

Next, in step S165, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the green pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, the light intensity is measured using the optical sensor 106. By performing this operation, it is possible to measure the intensity of transmitted light whose wavelength has not changed even after the wavelength conversion by the green layer 132_G of the wavelength conversion layer 132 used for the green pixel. The intensity of the light at this time is set to the brightness Ln_g of the green layer 132_G at the time of displaying the specified brightness after the lapse of the sampling time, and is stored in the storage unit 125.

Next, in step S166, the wavelength conversion ratio after the lapse of the sampling time is calculated from the brightness measured in steps S163 to S165.

The wavelength conversion ratio Tn_r of the red layer 132_R is
Tn_r = Ln_r / Ln_bl ... (Equation 5)
Is required by.

Similarly, the wavelength conversion ratio Tn_g of the green layer 132_G is
Tn_g = Ln_g / Ln_bl ... (Equation 6)
Is required by.

Next, in step S167, the correction target value of the wavelength conversion ratio calculated in the image quality adjustment step at the time of manufacturing inspection is compared with the wavelength conversion ratio after the lapse of the sampling time. As a result of comparing the conversion ratios, if the conversion ratio changes within a predetermined value, the process proceeds to step S170 to maintain the current correction process. If the conversion ratio changes by or more than the specified value in step S167, the process proceeds to step S168, and the signal correction process of the liquid crystal panel 101 is performed.

In step S168, the adjustment coefficient Cb of the blue pixel is calculated using each conversion ratio stored in the storage unit 125. Specifically, the adjustment coefficient is calculated from the following colors.

Cb = (Tn_r / T_r) x (R gradation / R maximum gradation of input video signal)
+ (Tn_g / T_g) x (G gradation / G maximum gradation of input video signal) ... (Equation 7)
Here, R indicates red and G indicates green.

Wavelength conversion by driving the liquid crystal panel drive circuit unit 123 with the adjustment coefficient of the blue pixel calculated by the above equation 7 as the corrected blue gradation by multiplying the blue (B) gradation of the input video signal by Cb. The effect of the change in the conversion efficiency of the layer can be canceled by adjusting the transmittance of the blue pixel. Since the R gradation and the G gradation of the input video signal change at any time depending on the video signal input from the outside of the apparatus, Cb is updated in real time in step S170 or later.

Next, the color / brightness set by the user in step S169 is set.

Next, in step S170, a video signal is output from an external image pickup device or a video signal reproduction device, and the liquid crystal display device 100 multiplies the input video signal by the blue pixel adjustment coefficient Cb to obtain a blue pixel video signal. The video data adjusted so as to be output to the liquid crystal panel 101 and displayed as a video.

The above series of operations will be repeated until the user gives an instruction to turn off the power (S171).

In the first embodiment, when Cb <1, the display brightness of the liquid crystal display device 100 decreases, so that the brightness of the light source unit 103 may be adjusted. Specifically, the brightness value Yn of the video signal is calculated by the following formula 8, and the ratio Cbl to the brightness value Y of the input video signal calculated by the formula 9 is multiplied by the brightness of the light source unit 103. ..

Yn = αR + βG + CbγB ... (Equation 8)
Cbl = Y / Yn ... (Equation 9)
The above is the control of the first embodiment.

<Example 2>
Hereinafter, Example 2 of the present invention will be described.

In the first embodiment, an example in which a color sensor capable of detecting a blue component with high accuracy is used for the optical sensor 106 has been described. However, in the present embodiment, the optical sensor 106 is a color sensor capable of detecting red, green, and blue components. An example of using is described. The members having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The optical sensor 106 (sensor unit) in this embodiment includes a sensor having a sensitivity peak in blue, which is the light source color of the light source unit 103, a sensor having a sensitivity peak in the green component converted by the wavelength conversion layer, and red. A sensor with a peak of sensitivity will be used.

Next, the difference between the actual control of the second embodiment and the first embodiment will be described.

In step S153 of FIG. 6, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the red pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, both the intensity of blue light and the intensity of red light are measured using the optical sensor 106. By performing this operation, the intensity of the transmitted light whose wavelength is not changed even after the wavelength conversion by the red layer 132_R of the wavelength conversion layer 132 used for the red pixel and the red layer 132_R of the wavelength conversion layer 132 turn red. It is possible to measure both the intensity of transmitted light whose wavelength has changed. The intensity of the blue light at this time is set to the reference brightness L_r of the red layer 132_R at the time of the specified luminance display in the image quality adjusting step at the time of manufacturing inspection, and the intensity of the red light is set to Lc_r and stored in the storage unit 125.

Next, in step S154, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the green pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, both the intensity of blue light and the intensity of green light are measured using the optical sensor 106. By performing this operation, the intensity of the transmitted light whose wavelength has not changed even after the wavelength conversion by the green layer 132_G of the wavelength conversion layer 132 used for the green pixel and the green layer 132_G of the wavelength conversion layer 132 turn green. It is possible to measure both the intensity of transmitted light whose wavelength has changed. The intensity of the blue light at this time is set to the reference brightness L_g of the green layer 132_G at the time of the specified luminance display in the image quality adjusting step at the time of manufacturing inspection, and the intensity of the green light is set to Lc_g and stored in the storage unit 125.

Next, the difference between the operation after the user is used in the second embodiment and the first embodiment will be described.

In step S164 of FIG. 7, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the red pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, both the intensity of blue light and the intensity of red light are measured using the optical sensor 106. By performing this operation, after the lapse of the sampling time, the intensity of the transmitted light whose wavelength has not changed even after the wavelength conversion by the red layer 132_R of the wavelength conversion layer 132 used for the red pixel and the intensity of the transmitted light of the wavelength conversion layer 132. The red layer 132_R makes it possible to measure both the intensities of transmitted light whose wavelength has changed to red. The intensity of the blue light at this time is defined as the brightness Ln_r of the red layer 132_R at the time of displaying the specified luminance after the lapse of the sampling time, and the intensity of the red light is defined as Lcn_r, which is stored in the storage unit 125.

Next, in step S165, the control of the liquid crystal panel drive circuit unit 123 is changed so that the transmittance of the green pixel of the liquid crystal panel 101 is 0% (fully closed) and the transmittance of the other pixels is 100% (fully open). To do. In this state, both the intensity of blue light and the intensity of green light are measured using the optical sensor 106. By performing this operation, the intensity of the transmitted light whose wavelength is not changed even after the wavelength conversion by the green layer 132_G of the wavelength conversion layer 132 used for the green pixel and the green layer 132_G of the wavelength conversion layer 132 turn green. It is possible to measure both the intensity of transmitted light whose wavelength has changed. The intensity of the blue light at this time is defined as the brightness Ln_g of the green layer 132_G at the time of displaying the specified luminance after the lapse of the sampling time, and the intensity of the green light is defined as Lcn_g, which is stored in the storage unit 125.

In step S168, in addition to calculating the adjustment coefficient Cb of the blue pixel using each conversion ratio stored in the storage unit 125, the adjustment coefficient Cr of the red pixel and the adjustment coefficient Cg of the green pixel are also calculated. Specifically, the adjustment coefficient is calculated from the following colors.

Cr = Lc_r / Lcn_r ... (Equation 10)
Cg = Lc_g / Lcn_g ... (Equation 11)
In step S169, by driving the liquid crystal panel drive circuit unit 123 with the value obtained by multiplying each gradation of the input video signal by each coefficient calculated by the equations 7, 10, and 11, as the correction gradation, the wavelength conversion layer is formed. The effect of the change in conversion efficiency can be canceled by adjusting the transmittance of each pixel.

Finally, in step S170, the video signal is output from an external imaging device or video signal reproduction device, and the liquid crystal display device 100 multiplies the input video signal by the adjustment coefficient of each color pixel to obtain the video signal of each color pixel. The video data adjusted so as to be output to the liquid crystal panel 101 and displayed as a video.

The above series of operations will be repeated until the user gives an instruction to turn off the power.

In the second embodiment, by using a color sensor capable of detecting red, green, and blue components as the optical sensor 106, it is possible to correct the characteristic change of the wavelength conversion layer 132 by adjusting the transmittance of each color pixel. Since it is not necessary to adjust the brightness of the light source unit 103 by such control, it is possible to suppress the temperature rise of the liquid crystal display device 100, and there is an effect of gradual deterioration of the wavelength conversion layer.

<Example 3>
Hereinafter, Example 3 of the present invention will be described.

As shown in FIG. 8, the liquid crystal display device 300 according to the third embodiment is newly provided with a temperature sensor 327 for detecting the temperature of the liquid crystal panel unit 101 and the temperature of a portion having a temperature correlation with the liquid crystal panel unit 101. It is characterized in that both the characteristic change due to the temperature change of the wavelength conversion layer 132 and the characteristic change due to aged use are corrected. The members having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Next, the difference between the actual control of the third embodiment and the first embodiment will be described with reference to FIG.

In step S170 of FIG. 9, a video signal is output from an external image pickup device or a video signal reproduction device, and the liquid crystal display device 100 multiplies the input video signal by the blue pixel adjustment coefficient Cb to obtain a blue pixel video signal. The video data adjusted so as to be output to the liquid crystal panel 101 and displayed as a video.

Next, in step S372, the temperature of the liquid crystal panel section 101 or the temperature of a portion having a high temperature correlation with the liquid crystal panel section 101 is measured using the temperature sensor 327, and this temperature measurement value is defined as Tp.

Next, in step S373, the temperature correction coefficient Ct of each pixel is calculated by the following equation 12 and multiplied by the video signal of each pixel of the input video signal. At this time, the correction coefficient is multiplied by both the correction coefficient Cb due to the fluctuation of the wavelength conversion ratio of the wavelength conversion layer and the correction coefficient Ct due to the temperature change.

t = η (Tp-reference temperature) ... (Equation 12)
Here, η is the amount of fluctuation in wavelength conversion efficiency per unit temperature, and may be determined from the spec characteristics of the wavelength conversion layer 132 used in the liquid crystal panel section 101, or in a state where the liquid crystal display device 101 is configured. It may be determined from the experimental data of. Further, the reference temperature may be the temperature when the specifications of the wavelength conversion layer 132 are defined or the temperature when the experimental data is calculated.

The above series of operations will be repeated until the user gives an instruction to turn off the power (S171).

The third embodiment has the effect of correcting both the characteristic change due to aged use of the wavelength conversion layer 132 and the characteristic change due to the temperature rise by calculating the correction coefficient from the optical sensor 106 and the temperature sensor 327.

(Modification example)
The liquid crystal display device according to the present invention is not limited to the above-mentioned Examples 1 to 3, and various modifications may be made without departing from the gist of the present invention.

For example, after arranging a plurality of optical sensors 106, the adjustment coefficient Cb may be calculated from the average value of the detection results. Alternatively, the plurality of optical sensors 106 and the liquid crystal panel unit 101 are virtually divided into display areas, and the adjustment coefficient Cb of the liquid crystal panel unit 101 is calculated for each display area according to the detection results of the plurality of optical sensors 106. May be corrected.

Further, although the optical sensor 106 is held in the liquid crystal panel holding structure 102, it may be arranged in another place as long as the reflected light from the liquid crystal panel unit 101 can be observed, and is the same as the light source unit 103. It may be arranged on a surface or a different surface, such as a side surface.

Further, the operations after step S161 in FIGS. 7 and 9 may be performed at each power ON or OFF, or at any time according to a user's instruction. Further, since steps S163 to S165 are affected by external light, the external light intensity is determined in advance by controlling the transmittance of the blue pixel to be 100% and detecting the external light intensity before entering step S161. The operation after S161 may be performed when the value is equal to or less than the threshold value. Here, when the external light intensity is equal to or higher than the threshold value, the control may be such that the adjustment coefficient of each pixel is set to 1 and the characteristic correction is turned off, giving priority to displaying in high brightness.

Further, as long as the internal structure of the liquid crystal panel portion 101 is a panel structure having a wavelength conversion member, other structures may be changed according to the display image quality performance and the like.

Further, the present invention has described an example in which the control unit 126 is configured by a CPU, and various controls executed by the control unit 126 are realized by the CPU reading a program from the storage unit 125 and executing the program. The method of executing the control method of is not limited to this. For example, a process of supplying a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device read and execute the program. But it is feasible. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 liquid crystal display device, 101 liquid crystal panel, 102 liquid crystal panel holding structure,
103 light source unit, 104 diffusion member, 105 light source holding structure,
106 optical sensor, 107 panel bezel, 121 video signal input unit,
122 Video signal processing unit, 123 Liquid crystal panel drive circuit unit,
124 Backlit light source drive circuit unit, 125 storage unit, 126 control unit,
327 temperature sensor unit, 130 array substrate, 131 glass substrate,
132 wavelength conversion layer, 133 in-cell polarizing plate, 134 pixel electrode,
135 liquid crystal layer, 136 opposed substrate, 137 polarizing plate

Claims (12)

A liquid crystal panel that uses multiple color wavelength conversion members,
A light source device equipped with a blue light source and
Luminance detection element and
An acquisition means for acquiring a detection value detected by a luminance detection element when a blue light source is lit with a predetermined intensity, and
A liquid crystal control means that controls the transmittance of each pixel of the liquid crystal panel,
In a liquid crystal display device equipped with
The acquisition means includes the amount of light in a closed state of the liquid crystal pixel using the wavelength conversion member and
Detects the amount of light when the liquid crystal pixels that do not use the wavelength conversion member are closed,
A liquid crystal display device characterized in that the transmittance of a liquid crystal panel is corrected and controlled based on an amount of change in the ratio of both detected values from a certain point in time. The liquid crystal display device includes a temperature detecting element for detecting the temperature of the liquid crystal panel or a temperature corresponding to the temperature of the liquid crystal panel, and changes the transmission rate of the liquid crystal panel based on an amount of change from a certain point in time. The liquid crystal display device according to claim 1. The liquid crystal display device according to claim 1 or 2, wherein the liquid crystal control means controls the transmittance of the liquid crystal pixels corresponding to the light source color of the light source device. The acquisition means according to any one of claims 1 to 3, wherein the acquisition control is performed when the liquid crystal display device is started, when the liquid crystal display device is terminated, or every time a predetermined usage time elapses. Liquid crystal display device. The acquisition means is characterized in that it detects the brightness when a liquid crystal pixel corresponding to the light source color of the light source device is opened, and performs acquisition control when the brightness detection value is equal to or less than a predetermined threshold value. The liquid crystal display device according to any one of 1 to 4. The liquid crystal display device according to any one of claims 1 to 5, wherein the liquid crystal display device has a plurality of the luminance detecting elements and each has a different spectral sensitivity. The liquid crystal control means is characterized in that it detects the brightness when a liquid crystal pixel corresponding to the light source color of the light source device is opened, and stops the transmittance correction control when the brightness detection value is equal to or higher than a predetermined threshold value. The liquid crystal display device according to any one of claims 1 to 6. The liquid crystal display device according to any one of claims 1 to 7, wherein the liquid crystal panel using the wavelength conversion member of a plurality of colors is provided with a color filter between the glass and the in-cell polarizing plate. .. The liquid crystal display device according to any one of claims 1 to 8, wherein the wavelength conversion member has a phosphor. The liquid crystal display device according to any one of claims 1 to 9, wherein the conversion member has quantum dots. The invention according to any one of claims 1 to 10, wherein the wavelength conversion member includes a wavelength conversion element that converts blue light into green light and a wavelength conversion element that converts blue light into red light. LCD display device. The blue light spectrum has a peak in the wavelength range of 440 nm or more and 480 nm or less, the green light spectrum has a peak in the wavelength range of 500 nm or more and 550 nm or less, and the red light spectrum has a peak in the wavelength range of 580 nm or more and 700 nm. The liquid crystal display device according to claim 9 or 10, wherein the liquid crystal display device has a peak in the following wavelength range.