WO2016143236A1

WO2016143236A1 - Display device

Info

Publication number: WO2016143236A1
Application number: PCT/JP2016/000076
Authority: WO
Inventors: 亮佑中越
Original assignee: 株式会社Ｊｖｃケンウッド
Priority date: 2015-03-10
Filing date: 2016-01-08
Publication date: 2016-09-15

Abstract

A display device (1) that has: a projection unit (20) that emits light that corresponds to a first video signal that comprises a three-primary-color signal; a display unit (30) that is provided with a transmission-type liquid crystal panel (301) that, in accordance with a second video signal that comprises a three-primary-color signal, modifies the polarization direction of each of the three primary colors of light from the projection unit, with a polarizing plate (302), and with a screen (303); and a display control unit (50) that generates the first video signal and the second video signal from an input video signal that comprises a three-primary-color signal, that controls the projection unit (20) on the basis of the first video signal, and that outputs a video signal that is for controlling the transmission-type liquid crystal panel (301) on the basis of the second video signal. The display unit (30) is configured such that the transmission-type liquid crystal panel (301), the polarizing plate (302), and the screen (303) are arranged in that order in the advancement direction of the light emitted from the projection unit (20).

Description

Display device

The present invention relates to a display device.

In recent years, there has been a demand for a display device that displays a high dynamic range (HDR) image. The dynamic range is the ratio between the brightest part and the darkest part. In relation to such a display device, for example, Patent Document 1 discloses a video display device that displays a high-contrast video.

The video display device described in Patent Literature 1 includes an RGB projection display device that outputs light based on three primary color signals, and a Y projection display device that modulates light from an RGB projection display device based on a luminance signal. High contrast is realized using a display device.

JP 2007-310045 A

In the technique described in Patent Document 1, as described above, the projection display device for Y modulates the luminance of light including RGB components. For this reason, in the projection display apparatus for RGB, since it is affected by the leakage light of the R modulation element, the G modulation element, or the B modulation element, the dynamic range is reduced. In order to facilitate understanding of this point, a case where only the R color is displayed will be described as an example. For example, when displaying only the R color, leakage light from the G modulation element and the B modulation element enters the Y projection display device in addition to the R light from the R modulation element. As a result, the dynamic range is narrowed.

The present invention has been made in view of the above points, and an object thereof is to provide a display device capable of realizing display with a high dynamic range.

The display device according to the present embodiment modulates and emits incident light according to a projection unit that emits light modulated according to a first video signal composed of three primary color signals and a second video signal composed of three primary color signals. For driving the projection unit from an input video signal composed of three primary color signals, a display unit comprising a transmissive liquid crystal panel, a polarizing plate that emits light of a predetermined polarization direction among incident light, and a first screen Generating the first video signal and the second video signal for driving the transmissive liquid crystal panel, and synchronizing the first video signal and the second video signal The display control unit is arranged in the order of the traveling direction of the light emitted from the projection unit, in the order of the transmissive liquid crystal panel, the polarizing plate, and the first screen. It is configured.

According to the present embodiment, it is possible to provide a display device capable of realizing display with a high dynamic range.

1 is a perspective view illustrating an appearance of a display device according to a first embodiment. 1 is a configuration diagram illustrating an example of an internal configuration of a display device according to a first exemplary embodiment; FIG. 6 is a diagram schematically illustrating a polarization state in the display device according to the first exemplary embodiment, and illustrates a polarization state of light incident on the phase difference plate. FIG. 6 is a diagram schematically illustrating a polarization state in the display device according to the first exemplary embodiment, and illustrates a polarization state of light emitted from the phase difference plate. It is a figure which shows typically the polarization state in the display apparatus concerning Embodiment 1, and shows the polarization state of the light inject | emitted from the display part. It is a figure which shows typically the polarization state in the structure of a comparative example, and shows the polarization state of the light which injects into a phase difference plate. It is a figure which shows typically the polarization state in the structure of a comparative example, and shows the polarization state of the light inject | emitted from the phase difference plate. It is a figure which shows typically the polarization state in the structure of a comparative example, and shows the polarization state of the light inject | emitted from the display part. 1 is a block diagram showing a configuration of a display device according to a first exemplary embodiment. FIG. 2 is a block diagram showing a configuration of a signal processing unit according to the first exemplary embodiment; 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of an input video signal. 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a transmissive liquid crystal panel. 6 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a projection unit. 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of an input video signal. 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a transmissive liquid crystal panel. 6 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a projection unit. 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of an input video signal. 4 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a transmissive liquid crystal panel. 6 is a graph showing an example of gamma characteristics in the display device according to the first exemplary embodiment, and shows gamma characteristics of a projection unit. FIG. 6 is a configuration diagram illustrating an example of an internal configuration of a display device according to a second exemplary embodiment; It is the table | surface which put together the characteristic of each liquid crystal panel of TN system, VA system, and IPS system. It is the table | surface summarized about the structural example in the case of comprising a display apparatus with the projection part which inject | emits a linearly polarized light. It is the table | surface summarized about the structural example in the case of comprising a display apparatus with the projection part which inject | emits circularly polarized light. It is the table | surface summarized about the structural example in the case of comprising a display apparatus with the projection part which inject | emits non-polarized light.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an appearance of the display device 1. The display device 1 is a rear projection type projector (rear projector), and a display unit 30 is provided on the front surface of the housing 10. More specifically, the display device 1 is a rear projector configured using LCOS (Liquid Crystal Crystal on Silicon) which is a reflective liquid crystal display element. FIG. 2 is a configuration diagram illustrating an example of the internal configuration of the housing 10 of the display device 1.

2, the display device 1 includes a projection unit 20, a display unit 30, a mirror 40, and a display control unit 50. The mirror 40 reflects the light emitted from the projection unit 20 toward the display unit 30.

Projection unit 20 generates projection light based on the video signal in order to project an image on display unit 30. More specifically, the projection unit 20 emits linearly polarized light corresponding to a first video signal, which will be described later, composed of three primary color signals. Hereinafter, the configuration of the projection unit 20 will be described.

The projection unit 20 has a light source 201. The light source 201 is, for example, a lamp. The light emitted from the light source 201 is incident on the dichroic mirror 203 via an integrator 202 that emits the light emitted from the light source 201 with a uniform illuminance distribution in a plane perpendicular to the optical axis. The dichroic mirror 203 separates the incident light into R light having a red band component, G light having a green band component, and B light having a blue band component. The R light and G light separated by the dichroic mirror 203 enter the mirror 204. Further, the B light separated by the dichroic mirror 203 is incident on the mirror 205.

The R light and G light separated by the dichroic mirror 203 are reflected by the mirror 204 and enter the dichroic mirror 206. The dichroic mirror 206 separates the incident R light and G light. The R light separated by the dichroic mirror 206 passes through the R field lens 207R and enters the R polarization control element 208R inclined at 45 °.

The R polarization control element 208R is, for example, a wire grid type polarization beam splitter, and transmits P-polarized light and reflects S-polarized light. The P-polarized R light transmitted through the R polarization control element 208R is incident on the R display element 209R. The R display element 209 </ b> R is configured by LCOS, and modulates R light based on a video signal output from the display control unit 50 described later. The R light incident on the R display element 209R is reflected by the R display element 209R and returns to the R polarization control element 208R. At this time, the component modulated into S-polarized light by the R display element 209R is reflected toward the dichroic prism 210 by the R polarization control element 208R. The R light reflected in the direction of the dichroic prism 210 is incident on the first surface of the dichroic prism 210. On the other hand, the component not modulated by the R display element 209R is transmitted through the R polarization control element 208R and returns to the R field lens 207R.

G light separated by the dichroic mirror 206 passes through the G field lens 207G and enters the G polarization control element 208G inclined by 45 °. The G polarization control element 208G is, for example, a wire grid type polarization beam splitter, and transmits P-polarized light and reflects S-polarized light. The P-polarized G light transmitted through the G polarization control element 208G enters the G display element 209G. The G display element 209 </ b> G is configured by LCOS, and modulates the G light based on the video signal output from the display control unit 50. The G light incident on the G display element 209G is reflected by the G display element 209G and returns to the G polarization control element 208G. At this time, the component modulated into S-polarized light by the G display element 209G is reflected in the direction of the dichroic prism 210 by the G polarization control element 208G. The G light reflected in the direction of the dichroic prism 210 is incident on the second surface of the dichroic prism 210. On the other hand, the component not modulated by the G display element 209G is transmitted through the G polarization control element 208G and returns to the direction of the G field lens 207G.

The B light separated by the dichroic mirror 203 is reflected by the mirror 205, passes through the B field lens 207B, and enters the B polarization control element 208B inclined at 45 °. The B polarization control element 208B is, for example, a wire grid type polarization beam splitter, and transmits P-polarized light and reflects S-polarized light. The P-polarized B light transmitted through the B polarization control element 208B is incident on the B display element 209B. The B display element 209 </ b> B is configured by LCOS, and modulates the B light based on the video signal output from the display control unit 50. The B light incident on the B display element 209B is reflected by the B display element 209B and returns to the B polarization control element 208B. At this time, the component modulated to S-polarized light by the B display element 209B is reflected by the B polarization control element 208B in the direction of the dichroic prism 210. The B light reflected toward the dichroic prism 210 is incident on the third surface of the dichroic prism 210. On the other hand, the component not modulated by the B display element 209B is transmitted through the B polarization control element 208B and returns to the B field lens 207B. In the following description, the R display element 209R, the G display element 209G, and the B display element 209B may be collectively referred to as a display element 209.

The dichroic prism 210 emits S-polarized components of R light, G light, and B light incident from three directions toward the projection lens 212. Therefore, linearly polarized light is emitted to the projection lens 212. The light emitted from the dichroic prism 210 enters the projection lens 212 via the phase difference plate 211. The phase difference plate 211 adjusts the polarization direction of the light emitted from the projection unit 20 to the polarization direction required as the incident light of the display unit 30. Note that the polarization direction required as the incident light of the display unit 30 is, for example, a direction obtained by rotating the polarization direction that transmits a polarizing plate 302 (to be described later) of the display unit 30 by 90 °. The projection lens 212 projects the incident light onto the display unit 30 via the mirror 40 to form an image. Thus, the light emitted from the projection unit 20 is linearly polarized light. As described above, in the present embodiment, the linearly polarized light emitted from the projection unit 20 enters the transmissive liquid crystal panel 301 via the phase difference plate 211. However, even if the retardation plate 211 is not used, if the polarization direction of the light emitted from the projection unit 20 is already the polarization direction required as the incident light of the display unit 30, the retardation plate 211 is provided. It does not have to be. For example, the phase difference plate 211 is omitted, and the light emitted from the projection unit 20 is arbitrarily adjusted by rotating the projection unit 20 around the traveling direction of the light emitted from the projection unit 20 as an axis. The polarization direction may be the polarization direction required as the incident light of the display unit 30.

Next, the display unit 30 will be described. As shown in FIG. 2, the display unit 30 includes a transmissive liquid crystal panel 301 having a predetermined resolution, a polarizing plate 302 having a size corresponding to the size of the display surface of the transmissive liquid crystal panel 301, and a transmissive liquid crystal panel. A screen 303 having a size corresponding to the size of the liquid crystal panel 301 is provided.

Here, in the display unit 30, the transmissive liquid crystal panel 301, the polarizing plate 302, and the screen 303 are arranged in the order of the traveling direction of the light emitted from the projection unit 20 in the order. They are arranged in a row in order. Here, as shown in FIG. 2, the polarizing plate is not necessarily provided on the light incident side from the projection unit 20 in the transmissive liquid crystal panel 301. This is because, as described above, since the light emitted from the projection unit 20 is linearly polarized light, it is not necessary to align the plane of polarization on one plane before the light enters the transmissive liquid crystal panel 301. .

The transmissive liquid crystal panel 301 has a liquid crystal layer and a glass substrate (not shown), and modulates each primary color light from the projection unit 20 and changes the polarization direction in accordance with a later-described second video signal including the three primary color signals. Light that has passed through the transmissive liquid crystal panel 301 enters the polarizing plate 302. The polarizing plate 302 transmits light polarized in a predetermined direction. With such a configuration, the display unit 30 controls the transmission amount of each of R light, G light, and B light incident from the projection unit 20 for each pixel based on the second video signal, and displays the image. Do. The resolution of the display unit 30 corresponds to the resolution of the projection unit 20, and each pixel in the projection unit 20 has a one-to-one correspondence with each pixel of the transmissive liquid crystal panel 301. Accordingly, each of R light modulated by the R display element 209R, G light modulated by the G display element 209G, and B light modulated by the B display element 209B, which corresponds to one pixel of the projection unit 20, Are modulated in the display unit 30 in accordance with the second video signal. Note that the light dots projected by the projection unit 20 and the pixels of the transmissive liquid crystal panel 301 need to be aligned with each other.

Here, the polarization state in the display device 1 will be described. 3A to 3C are diagrams schematically illustrating the polarization state in the display device 1. FIG. 4A to 4C are diagrams schematically showing a polarization state in the configuration of the comparative example. Here, as a comparative example, a configuration in which the configuration of the projection unit 20 is replaced with DLP (Digital Light Processing) is assumed. That is, in the configuration according to the comparative example, it is assumed that the configuration upstream of the phase difference plate 211 in the projection unit 20 is realized by DLP. 3A and 4A show the polarization state of the light incident on the phase difference plate 211, FIGS. 3B and 4B show the polarization state of the light emitted from the phase difference plate 211, and FIGS. 3C and 4C show the display. The polarization state of the light emitted from the unit 30 is shown. More specifically, FIG. 4B shows a polarization state after the light emitted from the phase difference plate 211 is transmitted through the added polarizing plate.

As described above, in the present embodiment, the light incident on the phase difference plate 211 is linearly polarized light (see FIG. 3A). In this embodiment, the polarization direction is adjusted by the phase difference plate 211 (see FIG. 3B). On the other hand, in the configuration according to the comparative example, the light incident on the phase difference plate 211 is in a non-polarized state (see FIG. 4A). For this reason, in the case of the configuration according to the comparative example, it is necessary to provide a polarizing plate in front of the transmissive liquid crystal panel 301. By providing the polarizing plate in the previous stage of the transmissive liquid crystal panel 301 in this manner, polarization required for incident light of the transmissive liquid crystal panel 301 is realized (see FIG. 4B). However, when the polarizing plate is provided in the front stage of the transmissive liquid crystal panel 301 in this way, the light amount is lost due to the polarizing plate. In addition, an increase in cost is caused by providing a polarizing plate corresponding to the size of the transmissive liquid crystal panel 301. Note that the polarization state of the light emitted from the display unit 30 varies depending on the characteristics of the screen 303. That is, when the screen 303 has the characteristic of maintaining the polarization of the incident light, the polarization of the light incident on the screen 303 is maintained, but when the screen 303 does not have the characteristic of maintaining the polarization, the screen 303 Will disappear. In the configuration shown in the comparative example, the phase difference plate 211 may be omitted.

FIG. 5 is a block diagram showing the configuration of the display device 1. As illustrated in FIG. 5, the display control unit 50 includes a signal processing unit 500, a first synchronization unit 511, and a second synchronization unit 512. Each configuration of the display control unit 50 may be realized by software based on a program, or may be realized by any combination of hardware, firmware, and software. When realized by a program, for example, it is realized by executing a program stored in a memory (not shown) of the display control unit 50 by a CPU (Central Processing Unit) (not shown) of the display control unit 50.

The input video signal and the synchronization signal are input to the signal processing unit 500. The input video signal input to the signal processing unit 500 may be transmitted to the display device 1 from another device, for example, or may be stored in a storage device (not shown) of the display device 1. Good. As the synchronization signal, for example, a synchronization signal generated by a synchronization signal generation circuit (not shown) is input to the signal processing unit 500.

The input video signal is a video signal composed of RGB three primary color signals. The input video signal is, for example, a video signal having a higher bit than an 8-bit video signal that is generally used as a video signal. That is, for example, the input video signal is composed of an R-color 16-bit input video signal, a G-color 16-bit input video signal, and a B-color 16-bit input video signal. The input video signal is a video signal that has been subjected to gamma correction of a predetermined gamma value. As an example, the gamma value of the gamma characteristic of the input video signal is 2.2.

The signal processing unit 500 generates a first video signal for performing display control by the projection unit 20 and a second video signal for performing display control by the display unit 30 from the input video signal. That is, the signal processing unit 500 generates a first video signal and a second video signal from the input video signal, controls the projection unit 20 based on the first video signal, and based on the second video signal. Thus, the transmissive liquid crystal panel 301 is controlled. The generation of the first video signal and the second video signal by the signal processing unit 500 will be described later. The signal processing unit 500 performs processing in synchronization with the input synchronization signal.

The signal processing unit 500 outputs the generated first video signal to the first synchronization unit 511. Further, the signal processing unit 500 outputs the generated second video signal to the second synchronization unit 512. A synchronization signal is also output to the first synchronization unit 511 and the second synchronization unit 512.

The first video signal is supplied to the device driving unit 250 of the projection unit 20 via the first synchronization unit 511. Further, the second video signal is supplied to the panel driving unit 350 of the display unit 30 via the second synchronization unit 512.

In the projection unit 20 and the transmissive liquid crystal panel 301, various signal processing (driving, etc.) is performed from when a video signal is input until it is output. For this reason, a certain amount of time is required until the image is output. Here, since the time required for image output in the projection unit 20 and the time required for image output in the transmissive liquid crystal panel 301 are different, it is necessary to synchronize in order to align the image output timing of both. For this reason, the first synchronization unit 511 and the second synchronization unit 512 perform delay processing for adding optimal delays to the first video signal and the second video signal, respectively. Note that delay processing may be performed in either the first synchronization unit 511 or the second synchronization unit 512. The first synchronization unit 511 and the second synchronization unit 512 perform delay processing based on the synchronization signal. Then, the first synchronization unit 511 outputs the first video signal to the device driving unit 250 of the projection unit 20. Further, the second synchronization unit 512 outputs the second video signal to the panel drive unit 350 of the display unit 30.

The device driving unit 250 generates a driving signal for driving the display element 209 according to the first video signal, and drives the display element 209 by the driving signal. In addition, the panel driving unit 350 generates a drive signal for driving the transmissive liquid crystal panel 301 according to the second video signal, and drives the transmissive liquid crystal panel 301 by the drive signal.

FIG. 6 is a block diagram illustrating a configuration of the signal processing unit 500. As shown in FIG. 6, the signal processing unit 500 includes a first LUT (Lookup table) unit 501 and a second LUT unit 502. The first LUT unit 501 and the second LUT unit 502 are realized by a storage device such as a memory (not shown) of the display control unit 50, for example.

The first LUT unit 501 is a lookup table that adjusts the projection unit 20 to the first output characteristic. The second LUT unit 502 is a lookup table that adjusts the transmissive liquid crystal panel 301 to the second output characteristic. However, the sum of the gamma value in the first output characteristic and the gamma value in the second output characteristic is equal to the gamma value of the input video signal. Here, a description will be given assuming that the gamma value of the input video signal is 2.2. In this case, the input video signal is correctly displayed when the gamma value of the output characteristic is 2.2. Therefore, it is necessary to realize a display device having a gamma value of 2.2 as an output characteristic for the output from the projection unit 20 and the output from the display unit 30 as a whole. Therefore, for example, the first LUT unit 501 is configured as a table adjusted so that the output characteristic of the projection unit 20 is gamma 1.1. The second LUT unit 502 is configured as a table adjusted so that the output characteristic of the display unit 30 is gamma 1.1. Such a table can be created, for example, by actually outputting in the projection unit 20 or the display unit 30 and measuring the illuminance at that time with an illuminometer. As a result, the display device 1 can have output characteristics with a gamma value of 2.2 (= 1.1 + 1.1).

The signal processing unit 500 provides an input video signal as an input to the first LUT unit 501 and the second LUT unit 502. Then, the signal processing unit 500 sets the output of the first LUT unit 501 for the input video signal as the first video signal, and sets the output of the second LUT unit 502 for the input video signal as the second video signal. At this time, a first video signal or a second video signal is generated for each RGB signal in the input video signal. That is, an R first video signal and an R second video signal are generated from the R input video signal. A G first video signal and a G second video signal are generated from the G input video signal. Further, a B first video signal and a B second video signal are generated from the B input video signal. Here, in the generation of the first video signal and the second video signal, as described above, RGB may be processed independently by the LUT, and the bits of the first video signal and the second video signal may be processed. The number can be any number of bits. For example, when the input video signal is 16 bits, the first video signal and the second video signal may be 16-bit video signals, or the upper 8-bit signal on the MSB (most significant bit) side is used. It may be supplied as a first video signal, and a lower 8-bit signal on the LSB (least significant bit) side may be supplied as a second video signal.

Here, the gamma value realized by the LUT will be further described. In the present embodiment, as described above, since the gamma characteristic of the input video signal is divided into two, the first output characteristic and the second output characteristic are close to linear. For this reason, the reproducibility of dark part gradation is improved. For example, when the gamma value of the gamma characteristic of the input video signal is defined by 2.2, the first output characteristic and the second output characteristic are 1.1 when simply divided as described above. When the gamma value is 2.2, the value of 1 in 8-bit input is about 0.000005 for white (value of 255 in 8-bit input) in terms of brightness. Therefore, unless the contrast on the display surface can be displayed at 2,000,000: 1, the brightness indicated by the value of 1 (8 bits) in the theoretical gamma curve cannot be reproduced. On the other hand, when the gamma value is 1.1, the value of 1 in 8-bit input is about 0.0023 with respect to white (255 value in 8-bit input), and the contrast on the display surface is 440. : 1 can be displayed. Therefore, the contrast performance required for the transmissive liquid crystal panel 301 can be suppressed. That is, an ideal gamma characteristic can be obtained by combining the transmissive liquid crystal panel 301 and the projection unit 20 that are relatively easily available.

Also, as described above, when the first video signal and the second video signal are generated from the input video signal, since RGB is independent, it is easy to realize gamma adjustment. For example, as described in Japanese Patent Application Laid-Open No. 2007-310045, when luminance is modulated, a Y (luminance) signal is generated from RGB of an input video signal. Not easy to keep. This is because one dimension is added to generate the Y signal, and conversion from the three-dimensional RGB to the four-dimensional RGBY is required. In contrast, in the present embodiment, the RGB signal of the input video signal is divided into the RGB signal of the first video signal and the RGB signal of the second video signal, so that each color is processed independently. It is easy to maintain gradation. Further, since the conversion is from RGB three-dimensional to RGB three-dimensional, the generation of the first video signal and the second video signal can be realized relatively easily.

Furthermore, according to the display device 1 according to the present embodiment, it is possible to display an input video signal having a large gamma value of 2.2 or more as the gamma characteristic. This is due to the following reason. For example, when the gamma characteristic is 2.2, a value obtained by raising the input video signal to the power of 2.2 has a specified luminance (brightness). For example, the value of 1 of the 8-bit signal is 1/255 = 0.39221... But the luminance (brightness) is (1/255) ^ 2.2 = 0.00000000077. Therefore, when the gamma characteristic is set to a value larger than 2.2, the luminance is smaller (that is, darker) than that when the input video signal is the same as that of the second power. For this reason, as the gamma characteristic of the input video signal becomes larger than the power of 2.2, it becomes a region where it is difficult to display the specified luminance on the conventional display. On the other hand, in the present embodiment, since the multiplication of the output values of the projection unit 20 and the transmissive liquid crystal panel 301 is the final output value, it can be realized relatively easily. Thus, according to the display device 1, it is possible to display an input video signal having a large gamma value of 2.2 or more as the gamma characteristic. As the gamma value of the gamma characteristic of the input video signal is larger, the dark portion gradation is maintained, so according to the display device 1 according to the present embodiment, the error when quantizing the image data is expressed in the floating-point format. By making it image data, it also contributes to reducing the quantization error of dark part gradation.

In the above description, as an example, the gamma value of the first output characteristic (that is, the gamma value of the output characteristic of the projection unit 20) is 1.1, and the gamma value of the second output characteristic (that is, the output of the display unit 30). The characteristic gamma value) is 1.1, but is not limited thereto. That is, the sum of the gamma value in the first output characteristic and the gamma value in the second output characteristic may be equal to the gamma value of the input video signal. 7A to 7C, FIG. 8A to FIG. 8C, and FIG. 9A to FIG. 9C show the relationship (gamma characteristic) between the input value that is the input video signal or the video signal and the light output in the display device 1 of the present embodiment. It is a graph which shows an example. 7A, 8A, and 9A show the gamma characteristics of the input video signal, FIGS. 7B, 8B, and 9B show the gamma characteristics of the transmissive liquid crystal panel 301, and FIGS. 7C, 8C, and 9C show the projections. The gamma characteristic of the part 20 is shown. 7A to 7C, 8A to 8C, and 9A to 9C, the horizontal axis represents an input video signal or an input value that is a video signal, and the vertical axis represents an optical output value. That is, in FIG. 7B, FIG. 8B, and FIG. 9B, the horizontal axis indicates the input value that is the second video signal output from the second LUT unit 502, and the vertical axis indicates the light output value of the transmissive liquid crystal panel 301. Show. 7C, FIG. 8C, and FIG. 9C, the horizontal axis represents the input value that is the first video signal output from the first LUT unit 501, and the vertical axis represents the light output value of the projection unit 20.

FIGS. 7A to 7C show the first output characteristic (output characteristic of the projection unit 20) and the second output when the gamma value of the gamma characteristic of the input video signal specified in the above description is 2.2. This is an example in which the gamma value of the output characteristics (output characteristics of the transmissive liquid crystal panel 301) is 1.1.

8A to 8C, when the gamma value of the gamma characteristic of the input video signal is defined by 3.2, the gamma value of the first output characteristic (output characteristic of the projection unit 20) is 2.2. This is an example in which the gamma value of the second output characteristic (output characteristic of the transmissive liquid crystal panel 301) is 1. Here, it is assumed that the projection unit 20 has a higher contrast than the transmissive liquid crystal panel 301. Thus, the gamma value in the higher contrast output characteristics of the projection unit 20 and the transmissive liquid crystal panel 301 is the gamma value in the lower contrast output characteristics of the projection unit 20 and the transmissive liquid crystal panel 301. Larger adjustments may be made. Thereby, the contrast of the entire display device 1 can be improved.

9A to 9C show an example in which the modulation of the transmissive liquid crystal panel 301 is limited to a predetermined range on the dark side. In the example shown in FIGS. 9A to 9C, when the gamma value of the gamma characteristic of the input video signal is defined by 2.2, the gamma value of the first output characteristic (output characteristic of the projection unit 20) is 2 .2 (where the gamma value is 1.2 when the input is 0.25 or less) and the gamma value of the second output characteristic (the output characteristic of the transmissive liquid crystal panel 301) is 1. In the second output characteristic, when the input value is 0.25 or more, the light output amount is uniformly maximized. As described above, the output characteristics of the transmissive liquid crystal panel 301 may be fixed to the maximum value when the input value is equal to or greater than a predetermined value. As a result, all the gradations of the transmissive liquid crystal panel 301 can be assigned to a gamma region having an input value of 0.25 or less, and there is an advantage that gradations on the dark side can be expressed with finer gradations. .

The display device 1 according to the present embodiment has been described above. In the display device 1, as described above, light that is modulated for each of RGB by the projection unit 20 is output, and each of the RGB light that is emitted from the projection unit 20 is further modulated by the transmissive liquid crystal panel 301. Thereby, the influence of leaking light can be suppressed and the contrast can be improved. Here, a case where only the R color is displayed will be described as an example with a comparative example. For example, as a comparative example, assuming a liquid crystal display in which the first modulation is performed by control of the backlight and the second modulation is performed on the light of the backlight, G in the second modulation device is assumed. The leakage of light and B light causes a decrease in contrast. Further, due to the influence of leakage light of G light and B light, a color shifted from the original color, that is, a color shifted to a point in the white direction in the chromaticity diagram is displayed. Further, for example, as described in Japanese Patent Application Laid-Open No. 2007-310045 as a comparative example, even when the luminance is modulated by the second modulation device, it is improved as compared with the comparative example of the liquid crystal display. A similar situation occurs. On the other hand, in the display device 1 according to the present embodiment, the R light, the G light, and the B light are each modulated in a double manner, so that leakage light can be suppressed. For this reason, it is possible to suppress a decrease in contrast and color misregistration, and in particular, it is possible to expand the dynamic range even for chromatic colors.

Embodiment 2
Next, a second embodiment of the present invention will be described. In the display device 1 according to the first embodiment and the display device 2 according to the present embodiment, as described above, both the dot of light projected by the projection unit 20 and the pixel of the transmissive liquid crystal panel 301 correspond to each other. Must be aligned. Here, when the projection light from the projection unit 20 is accurately focused on the transmissive liquid crystal panel 301, moire may appear due to the projection light dots from the projection unit 20 and the pixel structure of the transmissive liquid crystal panel 301. Therefore, in the present embodiment, generation of moire is suppressed by diffusing the projection light from the projection unit 20 incident on the transmissive liquid crystal panel 301 immediately before the incident.

FIG. 10 is a configuration diagram illustrating an example of an internal configuration of the display device 2 according to the second embodiment. In the following description, the same elements as those described above are denoted by the same reference numerals, and redundant description is omitted. As shown in FIG. 10, the display device 2 is different from the display device 1 in that the display unit 30 is replaced with a display unit 31.

The display unit 31 includes a screen 304 having a size corresponding to the size of the transmissive liquid crystal panel 301, a transmissive liquid crystal panel 301, a polarizing plate 302, and a screen 303. Here, in the display unit 31, the screen 304, the transmissive liquid crystal panel 301, the polarizing plate 302, and the screen 303 are arranged in the order of the traveling direction of the light emitted from the projection unit 20, the screen 304, the transmissive liquid crystal panel 301, The polarizing plate 302 and the screen 303 are arranged side by side in this order. The screen 304 is a screen having a characteristic of maintaining the polarization of incident light. As a screen having the property of maintaining polarized light, for example, a blue ocean screen manufactured by Nitto Resin Co., Ltd. can be used.

With this configuration, in the present embodiment, the light emitted from the projection unit 20 is diffused by the screen 304 and then enters the transmissive liquid crystal panel 301. For this reason, since the projection light is not directly focused on the transmissive liquid crystal panel 301, the occurrence of moire can be reduced. Therefore, since it is not necessary to adjust the position for reducing moire, the projection unit 20 and the transmissive liquid crystal panel 301 can be easily aligned. Further, for example, since the transmissive liquid crystal panel 301 has a thickness, when the viewpoint position deviates from the front of the display unit 30, two images of an image projected on the screen 303 and an image displayed on the transmissive liquid crystal panel 301 are parallax. However, there is an advantage that the two images can be visually recognized by being shifted because the screen 304 is arranged.

Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, in the above embodiment, the input video signal, the first video signal, and the second video signal have been described as RGB signals, but may be signals expressed in other color spaces. For example, a signal represented by a luminance signal and two color difference signals such as a YPbPr signal may be used.

In the above embodiment, the projection unit 20 emits linearly polarized light. However, the projection unit 20 emits light other than the linearly polarized light that is modulated according to the first video signal. It may be replaced with a part. That is, for example, a projection unit that emits circularly polarized light modulated according to the first video signal described above, or a projection unit that emits non-polarized light modulated according to the first video signal described above is used. May be. Further, the driving method of the transmissive liquid crystal panel 301 can be any method. For example, the transmissive liquid crystal panel 301 may be a TN (Twisted Nematic) liquid crystal panel, a VA (Vertical Alignment) liquid crystal panel, or an IPS (In-Place-Switching) method. It may be a liquid crystal panel.

Here, TN, VA, and IPS liquid crystal panels that control the polarization direction of incident light by the voltage applied to the liquid crystal will be described. FIG. 11 is a table summarizing the characteristics of each of the TN, VA, and IPS liquid crystal panels. Here, as an example of the TN method, when the voltage applied to the liquid crystal panel is maximum, the light is blocked and the screen is displayed in black, and when the voltage is not applied to the liquid crystal panel, the screen is displayed in white. Show. On the other hand, in the VA method and the IPS method, when no voltage is applied to the liquid crystal panel, the light is blocked and the screen is displayed in black, and when the voltage applied to the liquid crystal panel is maximum, the screen is displayed in white. The type is shown as an example.

Also, comparing the contrast of each method, the VA method has the largest contrast, and the TN method has the next highest contrast. For this reason, the IPS system is the most inferior in contrast performance among these three systems. Further, when comparing the viewing angle of each method, the IPS method has the largest viewing angle, and the VA method has the next largest viewing angle. For this reason, the TN system is the most inferior in viewing angle performance among these three systems. In FIG. 11, the numbers in the columns for contrast and viewing angle indicate that the smaller the value, the better.

Hereinafter, a configuration example of the display device when the above-described transmission type liquid crystal panel is used as the transmission type liquid crystal panel 301 will be described in detail.

Here, the polarization direction of the polarizing plate 302 on the light emission side of the liquid crystal panel, that is, the transmission axis of the polarizing plate 302 is used as a reference. Here, when a TN type liquid crystal panel in which the phase of light changes by 1 / 2λ without using a voltage is applied to the liquid crystal panel, the polarization direction of light transmitted through the liquid crystal panel is incident on the liquid crystal panel. It is orthogonal to the polarization direction of the light. Therefore, when this type of TN liquid crystal panel is used, the polarization direction of light incident on the liquid crystal panel is required to be rotated by 90 ° with respect to the reference.

In the case of the VA method and IPS method in which the phase of light changes by 1 / 2λ with the maximum voltage applied to the liquid crystal panel, the polarization direction of the light incident on the liquid crystal panel is rotated by 90 ° with respect to the reference. It is required to do. On the other hand, there is no change in the polarization state when no voltage is applied to the liquid crystal panel.

Therefore, even if a liquid crystal panel of any type of TN, VA, and IPS as described above is used, the polarization direction of the light emitted from the projection unit 20 may be a direction orthogonal to the reference.

FIG. 12 is a table summarizing configuration examples when the display device is configured by the projection unit 20 that emits linearly polarized light as shown in the above embodiment. As described above, the polarization direction of light incident on the liquid crystal panel is required to be rotated by 90 ° with respect to the reference. For this reason, as shown in configuration examples 1 and 4 in FIG. 12, when the polarization direction of the light emitted from the projection unit 20 is the same as the reference, the slow axis or the fast axis is relative to the polarization plane of the incident light. A 1 / 2λ plate, which is a retardation plate arranged at an azimuth angle of 90 °, is inserted between the projection unit 20 and the transmissive liquid crystal panel 301 so that the polarization direction is orthogonal to the reference. The retardation plate 211 corresponds to such a retardation plate. As shown in configuration examples 2 and 3 in FIG. 12, when the polarization direction of the emitted light from the projection unit 20 is orthogonal to the reference, it is necessary to change the polarization direction of the emitted light from the projection unit 20. Therefore, it is not necessary to insert a retardation plate.

FIG. 13 is a table summarizing configuration examples in the case where the display device is configured by a projection unit that emits circularly polarized light. In the case where the above-described display device is configured using a projection unit in which the emitted light is circularly polarized light instead of the projection unit 20 that emits linearly polarized light, as shown in the configuration examples 5 and 6 in FIG. A quarter-wave plate, which is a retardation plate whose slow axis or fast axis is arranged at an azimuth angle of 45 degrees, is inserted between the projection unit 20 and the transmissive liquid crystal panel 301, and based on the polarization direction. Make them orthogonal. In FIG. 13, Configuration Example 5 illustrates a configuration example when the projection unit emits counterclockwise or clockwise circularly polarized light when the transmission axis of the polarizing plate is in the vertical direction. Configuration example 6 shows a configuration example when the projection unit emits counterclockwise or clockwise circularly polarized light when the transmission axis of the polarizing plate is in the horizontal direction. In any configuration example, the polarization direction of the light incident on the liquid crystal panel can be made orthogonal to the reference by rotating and adjusting the optical axis of the phase difference plate according to the rotation direction of the circularly polarized light.

FIG. 14 is a table summarizing configuration examples in the case where the display device is configured by a projection unit that emits non-polarized light. When the above-described display device is configured using a projection unit that emits non-polarized light instead of the projection unit 20 that emits linearly polarized light, as shown in Configuration Examples 7 and 8 in FIG. A display device is configured. That is, in this display device, a polarizing plate having a transmission axis perpendicular to the transmission axis of the polarizing plate 302 on the light emission side of the liquid crystal panel is inserted between the projection unit 20 and the transmissive liquid crystal panel 301, and The polarization direction of light incident on the transmissive liquid crystal panel 301 is orthogonal to the reference. In this display device, the retardation plate is not always necessary.

As described above, various types of projection units can be used. In FIGS. 12 to 14, as an example, only the case where the polarization direction of the polarizing plate 302 on the light emission side of the liquid crystal panel is the horizontal direction or the vertical direction is shown. However, it goes without saying that the display device can be appropriately configured.

As described above, various types of panels including the TN mode, the VA mode, and the IPS mode can be adopted as the mode of the transmissive liquid crystal panel. In addition, when a person who views an image on a display device, that is, a user is a liquid crystal panel, it is preferable to use an IPS method in which a viewing angle is superior to that of the TN method and the VA method. However, in the above-described embodiment, since the object to be viewed by the user is the screen 303, the contrast performance is more important than the viewing angle performance by the liquid crystal panel method. Therefore, a VA liquid crystal panel is preferably used as the transmissive liquid crystal panel 301.

In addition, the liquid crystal panel having a configuration that transmits light when the polarization direction is rotated by 90 ° by the liquid crystal has been described as an example. However, for example, a configuration that blocks light when the polarization direction is rotated by 90 ° by the liquid crystal is provided. When a liquid crystal panel is used, the polarization direction of the light emitted from the projection unit may coincide with the reference. Thus, the display device may be configured so that light having a polarization direction required as incident light of the liquid crystal panel is incident on the liquid crystal panel.

This application claims priority based on Japanese Patent Application No. 2015-047096 filed on Mar. 10, 2015 and Japanese Application No. 2015-235420 filed on Dec. 2, 2015. The entire disclosure is incorporated herein.

The present invention is applicable to display devices and has industrial applicability.

DESCRIPTION OF

SYMBOLS

1, 2 Display apparatus 10 Case 20

Projection part

30, 31

Display part

40, 204, 205 Mirror 50 Display control part 201 Light source 202

Integrator

203, 206 Dichroic mirror 207B B field lens 207GG G field lens 207RR R field lens 208B B polarization control element 208G G polarization control element 208R R polarization control element 209B B display element 209G G display element 209R R display element 210 Dichroic prism 211 Phase difference plate 212 Projection lens 250 Device driver 301 Transmission type Liquid crystal panel 302

Polarizing plate

303, 304 Screen 350 Panel drive unit 500 Signal processing unit 501 First LUT unit 502 Second LUT unit 511 First synchronization unit 512 Second synchronization unit

Claims

A projection unit for emitting light modulated in accordance with a first video signal composed of three primary color signals;
A transmissive liquid crystal panel that modulates and emits light of each of the three primary colors emitted from the projection unit according to a second video signal composed of three primary color signals; and a polarizing plate that emits light of a predetermined polarization direction among incident light. A display unit comprising a first screen;
The first video signal for driving the projection unit and the second video signal for driving the transmissive liquid crystal panel are generated from an input video signal consisting of three primary color signals, and the first video A display control unit for generating a synchronization signal for synchronizing the signal and the second video signal,
The display unit is configured by arranging the transmissive liquid crystal panel, the polarizing plate, and the first screen in the order of the traveling direction of light emitted from the projection unit.
The display unit further includes a second screen, and the second screen, the transmissive liquid crystal panel, the polarizing plate, and the first screen are arranged in order of the traveling direction of the light emitted from the projection unit. The display device according to claim 1, wherein the display device is arranged in order.
The display device according to claim 1, wherein light emitted from the projection unit is linearly polarized light.
A retardation plate;
The light emitted from the projection unit is linearly polarized light or circularly polarized light, and the light emitted from the projection unit is incident on the transmissive liquid crystal panel via the retardation plate. The display device described.
On the incident side of the transmissive liquid crystal panel, there is an incident side polarizing plate that is a polarizing plate different from the polarizing plate,
The light emitted from the projection unit is non-polarized light, and the light emitted from the projection unit is incident on the transmissive liquid crystal panel via the incident-side polarizing plate. The display device described.
The display control unit includes a first look-up table unit that adjusts an output characteristic of the projection unit to a first output characteristic, and a second that adjusts an output characteristic of the transmissive liquid crystal panel to a second output characteristic. A lookup table unit that adjusts the input video signal to the first video signal by the first lookup table unit, and the input video signal by the second lookup table unit. 2 to adjust the video signal,
6. The display device according to claim 1, wherein a sum of a gamma value in the first output characteristic and a gamma value in the second output characteristic is equal to the gamma value of the input video signal.
When comparing the output characteristics of the projection unit and the transmissive liquid crystal panel, the gamma value in one output characteristic showing a higher contrast is compared when comparing the output characteristics of the projection unit and the transmissive liquid crystal panel. The display device according to claim 6, wherein the display device is adjusted to be larger than a gamma value in the other output characteristic exhibiting a lower contrast.
7. The display device according to claim 6, wherein the output characteristics of the transmissive liquid crystal panel are such that when the input value of the second video signal is greater than or equal to a predetermined value, the light output is a maximum value.