Display device, display device control method, and electronic instrument

Abstract

To enhance determination accuracy of a first liquid crystal panel.SOLUTION: A display device comprises: a first liquid crystal panel; a first optical detection unit that, when light of a first wavelength region is incident upon the first liquid crystal panel, detects first detection light of the first wavelength region to be emitted from the first liquid crystal panel; and a second optical detection unit that detects second detection light of a detection wavelength region serving as a longer wavelength region than the first wavelength region to be emitted from the first liquid crystal panel when the light of the first wavelength region is incident upon the first liquid crystal panel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a display device, a control method for a display device, and an electronic device. [Background technology]

[0002] A projection display device has been proposed in which light emitted from a light source unit is irradiated onto a liquid crystal panel, and the light modulated by the liquid crystal panel is projected onto a screen. In such a display device, the intensity of the light irradiated from the light source unit onto the liquid crystal panel is high, which causes the liquid crystal panel to deteriorate. When the liquid crystal panel deteriorates, the quality of the image projected onto the screen deteriorates. As a technology to suppress such deterioration in image quality, a technology has been proposed in which an optical sensor is provided to detect the chromaticity or illuminance of the light modulated by the liquid crystal panel, and a cooling fan is controlled based on the detection result of the optical sensor (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-40016 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 detects degradation of image quality by using an optical sensor to measure the chromaticity or illuminance of light modulated by a liquid crystal panel, but it is not possible to determine whether the degradation of image quality is due to degradation of the liquid crystal panel or degradation of the light source. This poses a problem in that it is not possible to accurately detect the lifespan of the liquid crystal panel. This poses a problem in that it is difficult to perform maintenance of the display device, such as replacing the liquid crystal panel, in a planned manner. [Means for solving the problem]

[0005] A display device according to one embodiment of the present invention comprises a first liquid crystal panel, a first optical detection unit that detects first detection light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel, and a second optical detection unit that detects second detection light in a detection wavelength range that is a longer wavelength range than the first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel.

[0006] One embodiment of the present invention provides a control method for a display device comprising a first liquid crystal panel, a first optical detection unit that detects first detected light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel, a second optical detection unit that detects second detected light in a detected wavelength range that is longer than the first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel, and a life determination unit, the control method comprising an acquisition step in which the life determination unit acquires a first detection value that is a detection value of the first optical detection unit and a second detection value that is a detection value of the second optical detection unit, and a determination step in which the life determination unit determines the life of the first liquid crystal panel based on the first detection value and the second detection value.

[0007] An electronic device according to one aspect of the present invention includes the display device described above and a display unit that displays an image formed by the display device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a display device according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. 10 is a diagram illustrating a change over time in the second detected light. [Figure 4] FIG. 10 is a first diagram illustrating a change over time in the intensity of the second detected light. [Figure 5] FIG. 10 is a second diagram illustrating the change over time in the intensity of the second detected light. [Figure 6] 10 is a flowchart showing a flow of determining the lifespan of a liquid crystal panel. [Figure 7] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a second embodiment. [Figure 8] FIG. 10 is a diagram schematically showing the configuration of a display device according to a modified example of the second embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a third embodiment. [Figure 10] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, each layer and each component is shown at a different scale so that they can be easily recognized. In the following description, the liquid crystal panel will be denoted by the reference numeral 35, and the corresponding colors will be denoted by the reference numerals R (red), G (green), and B (blue). However, when it is not necessary to specify the corresponding color, the panel will simply be referred to as the liquid crystal panel 35. In this embodiment, the liquid crystal panel 35 into which blue light is incident is the first liquid crystal panel 35B. The liquid crystal panel 35 into which green light is incident is the second liquid crystal panel 35G. The liquid crystal panel 35 into which red light is incident is the third liquid crystal panel 35R.

[0010] In this embodiment, the wavelength range of blue light is the first wavelength range W1. Blue light is light in the first wavelength range W1. The wavelength range of green light is the second wavelength range W2. Green light is light in the second wavelength range W2. The wavelength range of red light is the third wavelength range W3. Red light is light in the third wavelength range W3. The second wavelength range W2 has a longer wavelength than the first wavelength range W1. The third wavelength range W3 has a longer wavelength than the first wavelength range W1. The first wavelength range W1 has a shorter wavelength than both the second wavelength range W2 and the third wavelength range W3.

[0011] (First embodiment) A first embodiment of the present invention will be described below. FIG. 1 is a diagram schematically illustrating the configuration of a display device 10 according to a first embodiment. FIG. 2 is a cross-sectional view of a liquid crystal panel 35. The display device 10 of this embodiment is a projection-type display device that displays an image on a projection target 90 such as a screen. The display device 10 includes a light source unit 20, a color separation optical system 22, a liquid crystal panel 35, a combining optical system 38, a projection optical system 39, and a light detection module 60. The display device 10 includes a first liquid crystal panel 35B, a second liquid crystal panel 35G, and a third liquid crystal panel 35R. As shown in FIG. 2, the display device 10 also includes a control unit 70.

[0012] 1 is a white light source configured from an array light source having a semiconductor laser, a light source unit including a wavelength conversion member, a lamp unit having a halogen lamp, etc. The light source light emitted from the light source unit 20 is incident on a color separation optical system 22.

[0013] The color separation optical system 22 separates the light source light into three primary color lights of red (R), green (G), and blue (B). The color separation optical system 22 includes two mirrors 23 and 24 and three dichroic mirrors 26, 27, and 28. That is, the display device 10 includes the dichroic mirror 28.

[0014] Dichroic mirror 26 transmits red light and reflects light with shorter wavelengths than red light. The red light that transmits dichroic mirror 26 is guided by mirror 23 to third liquid crystal panel 35R. Red light, i.e., light in the third wavelength range W3, is incident on third liquid crystal panel 35R. The light reflected by dichroic mirror 26 is incident on dichroic mirror 27.

[0015] Dichroic mirror 27 reflects green light and transmits light with shorter wavelengths than green light. The green light reflected by dichroic mirror 27 is incident on second liquid crystal panel 35G. Green light, i.e., light in the second wavelength range W2, is incident on second liquid crystal panel 35G. Light with shorter wavelengths than green light that is transmitted through dichroic mirror 27, i.e., blue light, is reflected by mirror 24 and enters dichroic mirror 28.

[0016] The dichroic mirror 28 reflects blue light and transmits light with wavelengths longer than that of blue light. In this embodiment, the peak wavelength of blue light is 450 nm. The dichroic mirror 28 reflects 99% or more of light with a wavelength of 450 nm at a 45° incidence angle. The blue light reflected by the dichroic mirror 28 is incident on the first liquid crystal panel 35B. That is, the dichroic mirror 28 guides light in the first wavelength range W1, of the light emitted from the light source unit 20, to the first liquid crystal panel 35B.

[0017] The liquid crystal panels 35 modulate the incident light and emit the modulated light to the combining optical system 38. In this embodiment, an incident-side polarization separation element 33 is disposed on the incident side of each liquid crystal panel 35, and an exit-side polarization separation element 37 is disposed on the exit side of each liquid crystal panel 35. Light that has passed through the incident-side polarization separation element 33 enters each liquid crystal panel 35, and the light modulated by each liquid crystal panel 35 passes through the exit-side polarization separation element 37 before entering the combining optical system 38. As shown in FIG. 2, the liquid crystal panel 35 has a first substrate 41, a second substrate 45 facing the first substrate 41, a liquid crystal layer 49, and a sealant 91.

[0018] The first substrate 41 has a first substrate body 41W and a first alignment film 42. The first substrate body 41W is a light-transmitting substrate made of quartz, glass, etc. Of the outer surfaces of the first substrate body 41W, a first surface 41S facing the second substrate 45 is provided with a plurality of pixel electrodes 43, terminals 54, and a drive circuit 55.

[0019] The plurality of pixel electrodes 43 are provided in a pixel region E, which is a part of the first surface 41S surrounded by the sealing material 91. The pixel electrodes 43 are made of a light-transmitting conductive film such as ITO (Indium Tin Oxide). The plurality of pixel electrodes 43 are arranged side by side in both the X-axis direction and the Y-axis direction in the pixel region E. Each pixel electrode 43 has a liquid crystal element, a pixel switching element, and a storage capacitor, all of which are not shown.

[0020] The terminals 54 are arranged along one side of the first substrate main body 41W. The terminals 54 are connected to a drive circuit 55 by a plurality of wirings (not shown). In this embodiment, the X-axis direction is the direction in which the terminals 54 are arranged, and the Y-axis direction is the direction perpendicular to the X-axis direction. The drive circuit 55 is a circuit that drives each pixel electrode 43.

[0021] The first alignment film 42 is provided on the first surface 41S. The first alignment film 42 covers the plurality of pixel electrodes 43 and a portion of the drive circuit 55. The first alignment film 42 is formed, for example, by an inorganic alignment film containing an inorganic material such as silicon oxide formed by a vapor phase growth method such as evaporation. In this case, the first alignment film 42 aligns liquid crystal molecules having negative dielectric anisotropy approximately vertically. The first alignment film 42 may also be formed by an organic alignment film such as polyimide having a rubbed surface. In this case, the first alignment film 42 aligns liquid crystal molecules having positive dielectric anisotropy approximately horizontally.

[0022] The second substrate 45 has a second substrate main body 45W, a planarization film 46b, a common electrode 46c, and a second alignment film 47. The second substrate main body 45W is a light-transmitting substrate made of quartz, glass, or the like. Of the outer surfaces of the second substrate main body 45W, a second surface 45S facing the first substrate 41 is provided with a parting portion 46a. The parting portion 46a is provided in a portion of the second surface 45S between the sealant 91 and the pixel region E. The parting portion 46a is a light-shielding layer made of metal, metal oxide, or the like. The parting portion 46a functions as an electronic parting.

[0023] The planarization film 46b covers the parting portion 46a. The planarization film 46b is made of an inorganic material such as silicon oxide. The common electrode 46c covers the planarization film 46b. The common electrode 46c is made of ITO or the like. The common electrode 46c is electrically connected to the terminal 54 via a wiring (not shown).

[0024] The second alignment film 47 is provided on the second surface 45S. The second alignment film 47 covers the common electrode 46c. The second alignment film 47 is formed, for example, by an inorganic alignment film containing an inorganic material such as silicon oxide formed by a vapor phase growth method such as evaporation. In this case, the second alignment film 47 aligns liquid crystal molecules having negative dielectric anisotropy approximately vertically. The second alignment film 47 may also be formed by an organic alignment film such as polyimide having a rubbed surface. In this case, the second alignment film 47 aligns liquid crystal molecules having positive dielectric anisotropy approximately horizontally.

[0025] The sealant 91 bonds the first substrate 41 and the second substrate 45 together. Although not shown, the sealant 91 is in the shape of a square ring. The sealant 91 is arranged along the outer edge of the second substrate 45. The sealant 91 is, for example, an adhesive such as a thermosetting or ultraviolet-curing epoxy resin. The liquid crystal layer 49 is made of a liquid crystal material with positive or negative dielectric anisotropy. The liquid crystal layer 49 is arranged between the first substrate 41 and the second substrate 45 and inside the sealant 91.

[0026] The liquid crystal panel 35 of this embodiment is a transmissive liquid crystal panel. Therefore, depending on the optical design of the polarizing elements arranged on the light incident side and light exit side of the liquid crystal panel 35, the liquid crystal panel 35 is configured as a normally white mode liquid crystal device in which the transmittance of each pixel electrode 43 is maximized when no voltage is applied, and a normally black mode liquid crystal device in which the transmittance of each pixel electrode 43 is minimized when no voltage is applied.

[0027] As described above, the first alignment film 42 and the second alignment film 47 are inorganic alignment films. Therefore, the liquid crystal molecules contained in the liquid crystal layer 49 are aligned substantially vertically with a pretilt angle of 3° or more and 5° or less with respect to the normal direction to the first substrate 41 and the second substrate 45. When a drive signal is applied to the pixel electrode 43 and the common electrode 46c, the tilt of the liquid crystal molecules in the liquid crystal layer 49 changes due to the electric field generated between the pixel electrode 43 and the common electrode 46c.

[0028] The control unit 70 includes an image processing unit 71, a timing signal generating unit 72, and a lifespan determining unit 73. That is, the display device 10 includes the lifespan determining unit 73. The image processing unit 71, the timing signal generating unit 72, and the lifespan determining unit 73 are each an electronic circuit. The control unit 70 is a processor.

[0029] An input video signal Vin representing an image to be displayed and a control signal CLT are supplied from a higher-level device (not shown) to the image processing unit 71. The image processing unit 71 generates a gradation signal VL indicating the gradation level of the pixel electrode 43 based on the input video signal Vin and the control signal CLT, and outputs the gradation signal VL to the drive circuit 55.

[0030] The timing signal generating unit 72 generates a control signal CLT for controlling the drive circuit 55 and the image processing unit 71 based on a synchronization signal supplied from a higher-level device (not shown), and supplies the generated control signal CLT to the drive circuit 55 and the image processing unit 71.

[0031] The drive circuit 55 supplies each pixel electrode 43 with an image signal VD that specifies the gradation level to be displayed by each pixel electrode 43 based on the control signal CLT supplied from the timing signal generator 72. As a result, the liquid crystal elements included in the liquid crystal layer 49 are driven with a voltage corresponding to the image signal VD, and the light incident on the liquid crystal panel 35 is modulated in the liquid crystal layer 49. The light modulated in the liquid crystal layer 49 is emitted to the combining optical system 38 as described above.

[0032] The life determination unit 73 determines the life of the first liquid crystal panel 35B based on the first detection value H(t) detected by the first light detection unit 61 and the second detection value L(t) detected by the second light detection unit 62 of the light detection module 60. The life determination unit 73 will be described in detail later.

[0033] The combining optical system 38 shown in FIG. 1 is configured with a dichroic prism. Light of each color modulated by each liquid crystal panel 35 enters the combining optical system 38 from three directions. The red light and blue light are each reflected 90 degrees by the combining optical system 38, while the green light is transmitted. The combining optical system 38 combines the light in the first wavelength range W1 modulated by the first liquid crystal panel 35B, the light in the second wavelength range W2 modulated by the second liquid crystal panel 35G, and the light in the third wavelength range W3 modulated by the third liquid crystal panel 35R. The combining optical system 38 outputs a composite image obtained by combining the images of each primary color. The composite image formed by the combining optical system 38 enters the projection optical system 39 and is projected onto a projection target 90, such as a screen. A color image is projected onto the projection target 90.

[0034] The light detection module 60 detects light emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B. In this embodiment, a dichroic mirror 28 is disposed between the light detection module 60 and the first liquid crystal panel 35B. The light detection module 60 faces the first liquid crystal panel 35B via the dichroic mirror 28. The light detection module 60 has a first light detection unit 61 and a second light detection unit 62. That is, the display device 10 includes the first light detection unit 61 and the second light detection unit 62. In this embodiment, the light detection module 60 is a module that integrally includes the first light detection unit 61 and the second light detection unit 62.

[0035] The first optical detector 61 detects light in the first wavelength range W1 that is emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B when blue light, i.e., light in the first wavelength range W1, is incident on the first liquid crystal panel 35B. More specifically, the first optical detector 61 detects the intensity of light in the first wavelength range W1 that is diffusely reflected by the first liquid crystal panel 35B and radially emitted from the incident surface of the first liquid crystal panel 35B. In the following description, this light in the first wavelength range W1 is referred to as first detection light L1. The intensity of the first detection light L1 correlates with the intensity of light emitted from the light source unit 20. Therefore, the first detection value H(t), which is the detection value of the first optical detector 61, correlates with the intensity of light emitted from the light source unit 20. In this embodiment, the first optical detector 61 is a photodiode that has the highest light-receiving sensitivity at a wavelength of 450 nm and is capable of detecting light with a wavelength of 500 nm or shorter.

[0036] A dichroic mirror 28 is disposed between the first light detection unit 61 and the first liquid crystal panel 35B. This prevents blue light emitted from the light source unit 20 from directly entering the first light detection unit 61. Furthermore, the first detection light L1 that passes through the dichroic mirror 28 enters the first light detection unit 61. This prevents the intensity of the first detection light L1 entering the first light detection unit 61 from becoming too high. As shown in FIG. 2, the first light detection unit 61 is electrically connected to the life determination unit 73. The intensity of the first detection light L1 detected by the first light detection unit 61 is output to the life determination unit 73 as a first detection value H(t). In this embodiment, the accumulated time during which blue light, i.e., light in the first wavelength band W1, is irradiated onto the first liquid crystal panel 35B is referred to as the accumulated irradiation time t. The first detection value H(t) is the first detection value during the accumulated irradiation time t.

[0037] 1 detects second detection light L2 in a detection wavelength range Wd, which has a wavelength longer than the first wavelength range W1, emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B when blue light, i.e., light in the first wavelength range W1, is incident on the first liquid crystal panel 35B. More specifically, the second light detection unit 62 detects the intensity of the second detection light L2 emitted radially from the incident surface of the first liquid crystal panel 35B. In this embodiment, the second light detection unit 62 is a photodiode that has maximum light sensitivity at a wavelength of 650 nm and is capable of detecting light with a wavelength of 600 nm or longer.

[0038] The second detection light L2 is phosphorescence (photoluminescence), i.e., radiated light, emitted due to deterioration of the liquid crystal layer 49 of the first liquid crystal panel 35B. The second detection light L2 is red light. As described above, the detection wavelength range Wd, which is the wavelength range of the second detection light L2, has a longer wavelength than the first wavelength range W1. Because light with a high luminous flux density emitted from the light source unit 20 is incident on the liquid crystal panel 35, the liquid crystal layer 49 deteriorates over time. The deterioration of the liquid crystal layer 49 is presumably due to changes in the composition and orientation characteristics of the liquid crystal molecules that make up the liquid crystal layer 49 caused by the incidence of light with a high luminous flux density on the liquid crystal layer 49. The inventors of the present application, through a test to observe the deterioration of the liquid crystal panel 35 over time, found that the deterioration of the liquid crystal layer 49 correlates with the intensity of the second detection light L2 emitted by the liquid crystal layer 49. Specifically, the inventors discovered that the intensity of the second detection light L2 increases as the cumulative irradiation time t during which the first liquid crystal panel 35B is irradiated with blue light increases. That is, the intensity of the second detection light L2 correlates with the deterioration state of the first liquid crystal panel 35B. Furthermore, the intensity of the second detection light L2 correlates with the intensity of the light emitted from the light source unit 20. Therefore, the second detection value L(t), which is the detection value of the second light detection unit 62, correlates with both the deterioration state of the first liquid crystal panel 35B and the intensity of the light emitted from the light source unit 20. Furthermore, when the first liquid crystal panel 35B deteriorates, the quality of the blue image modulated by the first liquid crystal panel 35B deteriorates, and therefore the quality of the color image projected onto the projection target member 90 deteriorates.

[0039] A dichroic mirror 28 is disposed between the second light detection unit 62 and the first liquid crystal panel 35B. This prevents the blue light emitted from the light source unit 20 from directly entering the second light detection unit 62. The second detection light L2 that has passed through the dichroic mirror 28 enters the second light detection unit 62. As shown in FIG. 2, the second light detection unit 62 is electrically connected to the life determination unit 73. The intensity of the second detection light L2 detected by the second light detection unit 62 is output to the life determination unit 73 as a second detection value L(t).

[0040] Fig. 3 is a diagram illustrating the change over time of the second detection light L2. Fig. 4 is a first diagram illustrating the change over time of the intensity of the second detection light L2 in an accelerated aging test of the liquid crystal panel 35. Fig. 5 is a second diagram illustrating the change over time of the intensity of the second detection light L2 in an accelerated aging test of the liquid crystal panel 35. Next, the relationship between deterioration of the liquid crystal panel 35 and the intensity of the second detection light L2 will be described. The horizontal axis of Fig. 3 represents the measurement wavelength, and the vertical axis represents the intensity of light emitted from the incident surface side of the liquid crystal panel 35 irradiated with blue light. The solid line represents the light spectrum La(0) at the point when irradiation of the blue light begins, and the dashed line represents the light spectrum La(T) at the point when the integrated irradiation time t of the blue light reaches T.

[0041] When blue light is continuously irradiated onto the liquid crystal panel 35, the intensity of the light emitted from the liquid crystal panel 35 increases. In particular, the intensity of light in the detection wavelength range Wd with wavelengths of 600 nm to 650 nm, i.e., the intensity of red light, increases. This is presumably because, when electrons transition between liquid crystal molecules, a certain amount of light is emitted, but when degraded liquid crystal molecules are present, second detection light L2 containing phosphorescence with a wavelength of 600 nm to 650 nm is emitted.

[0042] Next, the change over time in the intensity of the second detection light L2 emitted from the liquid crystal panel 35 will be described. FIG. 4 is a diagram showing the spectra of the second detection light L2 at integrated irradiation times t of 0, t1, t2, t3, and t4. The horizontal axis in FIG. 4 is the measurement wavelength, and the vertical axis is the intensity of the second detection light L2 emitted from the liquid crystal panel 35 irradiated with blue light. FIG. 5 is a diagram showing the change over time in the intensity of the second detection light L2. The horizontal axis in FIG. 5 is the integrated irradiation time t, and the vertical axis is the intensity of the second detection light L2. In FIGS. 4 and 5, an integrated irradiation time t of 0 is the point when irradiation of the liquid crystal panel 35 with blue light is started. Also, the integrated irradiation time t at the time when each spectrum is measured satisfies the relationship 0 < t1 < t2 < t3 < t4. In the tests shown in FIGS. 4 and 5, the liquid crystal panel 35 was irradiated with blue light having a high light beam density, and the intensity of the second detection light L2 emitted from the incident side of the liquid crystal panel 35 was detected by the second light detection unit 62.

[0043] As shown in FIGS. 4 and 5, as the cumulative irradiation time t increases, the intensity of light in the detection wavelength range Wd, i.e., the intensity of the second detection light L2, increases. As shown in FIG. 4, the intensity of the second detection light L2 is greatest in the wavelength range from 600 nm to 650 nm. As shown in FIG. 5, the cumulative irradiation times t3 and t4 are approximately 1.15 and 1.3 times the cumulative irradiation time t2, respectively. The intensities of the second detection light L2 during cumulative irradiation times t3 and t4 are approximately 1.5 and 6.0 times the intensity of the second detection light L2 during cumulative irradiation time t2. That is, the intensity of the second detection light L2 increases rapidly as the cumulative irradiation time becomes longer than t2. Although not shown, the light emitted from the exit side of the liquid crystal panel 35 becomes darker during cumulative irradiation time t3, and the light emitted from the exit side of the liquid crystal panel 35 becomes brighter during cumulative irradiation time t4. Therefore, when the cumulative irradiation time is longer than t3, the quality of the image emitted from the liquid crystal panel 35 deteriorates. This suggests that the liquid crystal panel 35 rapidly deteriorates when the cumulative irradiation time is longer than t3. Therefore, for example, by determining that the liquid crystal panel 35 has reached the end of its life when the second light detection unit 62 detects IL, which is the intensity of the second detection light L2 between cumulative irradiation times t2 and t3, and replacing the liquid crystal panel 35, deterioration in the quality of the image modulated by the liquid crystal panel 35 can be prevented. As described above, the second detection light L2 has a peak intensity in the wavelength range from 600 nm to 650 nm. Also, as described above, the second light detection unit 62 is a photodiode that has the highest light-receiving sensitivity at a wavelength of 650 nm and is capable of receiving light with a wavelength of 600 nm or longer. Therefore, the second light detection unit 62 can detect the peak intensity of the second detection light L2, thereby accurately detecting changes in the intensity of the second detection light L2 over time.

[0044] As described above, the first wavelength range W1 is shorter than the second wavelength range W2 and the third wavelength range W3. The shorter the wavelength of the light irradiated, the more rapidly the liquid crystal panel 35 deteriorates. Therefore, the first liquid crystal panel 35B, which receives blue light, i.e., light in the first wavelength range W1, deteriorates faster than the second liquid crystal panel 35G and the third liquid crystal panel 35R. Therefore, when the intensity of the second detection light L2 emitted from the first liquid crystal panel 35B is detected and it is determined that the first liquid crystal panel 35B has reached the end of its life, the second liquid crystal panel 35G and the third liquid crystal panel 35R have not yet reached the end of their lives. Therefore, by replacing the second liquid crystal panel 35G and the third liquid crystal panel 35R at the same time as replacing the first liquid crystal panel 35B, deterioration in the quality of the image projected by the display device 10 can be suppressed.

[0045] 6 is a flowchart showing a method for controlling display device 10. The method for controlling display device 10 includes a lifespan determination flow for determining the lifespan of first liquid crystal panel 35B. The lifespan determination flow includes an acquisition step S01, a determination step S02, and a notification step S03.

[0046] In the acquisition step S01, the life determination unit 73 acquires a first detection value H(t) that is a detection value of the first light detection unit 61 and a second detection value L(t) that is a detection value of the second light detection unit 62. In this embodiment, the acquisition step S01 includes an initial acquisition step S011 and a continuous acquisition step S012. Note that the acquisition step S01 may include only the continuous acquisition step S012 and not include the initial acquisition step S011.

[0047] In the initial acquisition step S011, the life determination unit 73 acquires the first detection value H(0) and the second detection value L(0) of the first liquid crystal panel 35B at the initial time. The first detection value H(0) and the second detection value L(0) of the first liquid crystal panel 35B at the initial time are the first detection value H(t) and the second detection value L(t) when blue light is first incident on the first liquid crystal panel 35B. The first detection value H(0) and the second detection value L(0) acquired by the life determination unit 73 are stored in a storage unit (not shown) of the control unit 70. Note that, as described above, if the acquisition step S01 does not include the initial acquisition step S011, the initial acquisition step S011 is not executed.

[0048] In the continuous acquisition step S012, the life determination unit 73 acquires the first detection value H(t) and the second detection value L(t) of the first liquid crystal panel 35B during operation of the display device 10. The life determination unit 73 may acquire the first detection value H(t) and the second detection value L(t), for example, every time the accumulated irradiation time t elapses a predetermined time, or may acquire the first detection value H(t) and the second detection value L(t) continuously.

[0049] In determination step S02, the life determination unit 73 determines the life of the liquid crystal panel 35 based on the first detection value H(t) and the second detection value L(t). In this embodiment, the life determination unit 73 calculates a deterioration determination value Vj(t) at the integrated irradiation time t from the initial first detection value H(0) and second detection value L(0) stored in a storage unit (not shown) and the first detection value H(t) and second detection value L(t) at the integrated irradiation time t. The deterioration determination value Vj(t) is a value indicating the deterioration state of the first liquid crystal panel 35B. The life determination unit 73 determines that the first liquid crystal panel 35B has reached the end of its life when the deterioration determination value Vj(t) is equal to or greater than a predetermined life determination value Ve. That is, the life determination unit 73 determines the life of the first liquid crystal panel 35B based on the deterioration determination value Vj(t).

[0050] In this embodiment, the intensity of light emitted by the light source unit 20 during the cumulative irradiation time t is O(t), the loss rate of blue light in the color separation optical system 22 is Ra, the first ratio, which is the ratio of the intensity of the first detection light L1 emitted from the first liquid crystal panel 35B to the intensity of the blue light incident on the first liquid crystal panel 35B to the incident surface side, is Rb, the light receiving sensitivity of the first light detection unit 61 is Rs1, and the transmittance of the first detection light L1 through the dichroic mirror 28 is Ta1. The first detection value H(t) is correlated with the intensity O(t) of light emitted from the light source unit 20. The intensity O(t) of light emitted by the light source unit 20 gradually decreases as the cumulative irradiation time t increases due to deterioration of the light source unit 20 as the cumulative irradiation time t increases. That is, the intensity O(t) of the light emitted by the light source unit 20 changes over time. Furthermore, the light sensitivity Rs1 of the first light detection unit 61 varies for each first light detection unit 61. As a result, the first detection value H(t) changes over time and also varies for each display device 10. Note that the loss rate Ra of blue light in the color separation optical system 22, the first rate Rb, the light sensitivity Rs1 of the first light detection unit 61, and the transmittance Ta1 do not change over time.

[0051] Let Rc(t) be the second ratio, which is the ratio of the intensity of the second detection light L2 emitted from the first liquid crystal panel 35B to the intensity of the blue light incident on the first liquid crystal panel 35B, Rs2 be the light-receiving sensitivity of the second light detection unit 62, and Ta2 be the transmittance of the second detection light L2 through the dichroic mirror 28. The second detection value L(t) is O(t) × Ra × Rc(t) × Rs2 × Ta2. The second detection value L(t) correlates with Rc(t), which indicates the deterioration state of the first liquid crystal panel 35B, and the intensity O(t) of the light emitted by the light source unit 20. The light-receiving sensitivity Rs2 of the second light detection unit 62 varies for each second light detection unit 62. Therefore, the second detection value L(t) changes over time and varies for each display device 10. As described above, the first liquid crystal panel 35B deteriorates as the cumulative irradiation time t increases, and therefore the second ratio Rc(t) increases as the cumulative irradiation time t increases. The light receiving sensitivity Rs2 and transmittance Ta2 of the second light detection unit 62 do not change over time.

[0052] As described above, the acquisition step S01 does not necessarily include the initial acquisition step S011. In this case, the deterioration determination value Vj(t) is L(t) / H(t). Therefore, the deterioration determination value Vj(t) is {Rc(t)×Rs2×Ta2} / (Rb×Rs1×Ta1). As described above, the first ratio Rb, the light sensitivity Rs1 of the first light detection unit 61, the light sensitivity Rs2 of the second light detection unit 62, the transmittance Ta1 of the first detection light L1 through the dichroic mirror 28, and the transmittance Ta2 of the second detection light L2 through the dichroic mirror 28 do not change over time. Therefore, it is possible to suppress fluctuations in the deterioration determination value Vj(t) over time due to changes over time in the intensity O(t) of the light emitted by the light source unit 20. This allows the deterioration determination value Vj(t) to determine the change over time in the second rate Rc(t), i.e., the deterioration over time of the first liquid crystal panel 35B, thereby improving the accuracy of determining the deterioration state of the first liquid crystal panel 35B. Therefore, the lifespan determination unit 73 can improve the accuracy of determining the lifespan of the first liquid crystal panel 35B.

[0053] When the acquisition step S01 includes the initial acquisition step S011 as in this embodiment, the deterioration determination value Vj(t) can be set to {L(t) / H(t)} / {L(0) / H(0)}. If the initial intensity of light emitted by the light source unit 20 is O(0), the initial first detection value H(0) is O(0)×Ra×Rb×Rs1×Ta1. If the initial second ratio is Rc(0), the initial second detection value L(0) is O(0)×Ra×Rc(0)×Rs2×Ta2. Therefore, the deterioration determination value Vj(t) is Rc(t) / Rc(0). This can prevent the deterioration determination value Vj(t) from fluctuating over time due to a change over time in the intensity O(t) of light emitted by the light source unit 20. Furthermore, even if the light-receiving sensitivity Rs1 varies among the first optical detection units 61 and the light-receiving sensitivity Rs2 varies among the second optical detection units 62, the degradation determination value Vj(t) can be prevented from being affected by these variations. As a result, the degradation determination value Vj(t) can be used to more accurately determine the change in the second ratio Rc(t) over time, i.e., the degradation of the first liquid crystal panel 35B over time, thereby more accurately determining the degradation state of the first liquid crystal panel 35B. Therefore, the lifespan determination unit 73 can more accurately determine the lifespan of the first liquid crystal panel 35B. Note that, as shown in FIG. 6, if the degradation determination value Vj(t) is smaller than the lifespan determination value Ve in determination step S02, the lifespan determination unit 73 continues to acquire the first detection value (t) and the second detection value (t).

[0054] Furthermore, the life determination unit 73 may determine the life of the first liquid crystal panel 35B based on the integrated value of the first detection value H(t) and the integrated value of the second detection value (t). In this case, the degradation determination value Vj(t) is preferably, for example, ΣL(t) / ΣH(t). In this case, even if at least one of the first detection value H(t) and the second detection value L(t) fluctuates significantly instantaneously due to a detection error caused by electrical noise or a sudden fluctuation in the power supply voltage supplied to the display device 10, fluctuations in the degradation determination value Vj(t) are easily suppressed. Therefore, the transition of the degradation determination value Vj(t) during operation of the display device 10 is easily stabilized, thereby more appropriately improving the accuracy of determining the life of the first liquid crystal panel 35B.

[0055] If the deterioration determination value Vj(t) is equal to or greater than the lifespan determination value Ve, the lifespan determination unit 73 notifies the user or the like that the first liquid crystal panel 35B has reached the end of its lifespan in a notification step S03. The lifespan determination unit 73 can notify the user or the like that the first liquid crystal panel 35B has reached the end of its lifespan, for example, by projecting an image onto the projection target 90 and / or by sound or the like. By having the user or the like replace the first liquid crystal panel or the like in accordance with this notification, maintenance of the display device 10 can be performed in a planned manner. When notifying the user or the like that the first liquid crystal panel 35B has reached the end of its lifespan by projecting an image onto the projection target 90, an image in which an image indicating that the first liquid crystal panel 35B has reached the end of its lifespan may be superimposed on an image signal generated by the image processing unit 71 and projected onto the projection target 90.

[0056] Furthermore, when the deterioration determination value Vj(t) is smaller than the life determination value Ve, the life determination unit 73 may estimate the period until the end of the life of the first liquid crystal panel 35B from the deterioration determination value Vj(t), the difference between the deterioration determination value Vj(t) and the life determination value Ve, the slope of the change over time of the deterioration determination value Vj(t), and the like. In this case, the life determination unit 73 may notify the user of the period until the end of the life of the first liquid crystal panel 35B by using an image and sound projected onto the projection target member 90. This allows for more planned maintenance of the display device 10, such as replacing the first liquid crystal panel 35B.

[0057] Furthermore, when the deterioration determination value Vj(t) reaches the life determination value Ve, the control unit 70 may correct the drive conditions of the first liquid crystal panel 35B to suppress degradation of image quality. The control unit 70 can suppress degradation of image quality by, for example, correcting the gradation signal VL using the image processing unit 71.

[0058] According to this embodiment, the display device 10 includes a first liquid crystal panel 35B, a first optical detector 61 that detects first detection light L1 in a first wavelength range W1 that is emitted from the first liquid crystal panel 35B when blue light, i.e., light in a first wavelength range W1, is incident on the first liquid crystal panel 35B, and a second optical detector 62 that detects second detection light L2 in a detection wavelength range Wd that is a longer wavelength range than the first wavelength range W1 that is emitted from the first liquid crystal panel 35B when blue light is incident on the first liquid crystal panel 35B. As described above, the first detection value H(t) detected by the first optical detector 61 correlates with the intensity O(t) of light emitted by the light source unit 20. Furthermore, as described above, the second detection value L(t) detected by the second optical detector 62 correlates with both the deterioration state of the first liquid crystal panel 35B and the intensity O(t) of light emitted by the light source unit 20. As a result, as described above, by setting the degradation determination value Vj(t), which indicates the degradation state of the first liquid crystal panel 35B, to, for example, L(t) / H(t), it is possible to prevent the degradation determination value Vj(t) from fluctuating over time due to changes over time in the intensity O(t) of the light emitted by the light source unit 20. This improves the accuracy of determining the degradation state of the first liquid crystal panel 35B, thereby improving the accuracy of determining the lifespan of the first liquid crystal panel 35B. This allows for planned maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, and also prevents degradation in the quality of images projected by the display device 10.

[0059] According to this embodiment, the display device 10 includes a lifespan determination unit 73 that determines the lifespan of the first liquid crystal panel 35B. The lifespan determination unit 73 determines the lifespan of the first liquid crystal panel 35B based on the first detection value H(t) detected by the first light detection unit 61 and the second detection value L(t) detected by the second light detection unit 62. Thus, the lifespan determination unit 73 can calculate the deterioration determination value Vj(t) and determine that the first liquid crystal panel 35B has reached the end of its lifespan. This allows for planned maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, and prevents degradation in the quality of images projected by the display device 10.

[0060] According to this embodiment, when the first and second detection values of the first liquid crystal panel 35B at the initial stage are H(0) and L(0), respectively, the integrated time during which blue light is irradiated onto the first liquid crystal panel 35B is integrated irradiation time t, the first and second detection values at integrated irradiation time t are H(t) and L(t), respectively, and the deterioration determination value at integrated irradiation time t is Vj(t), the relationship Vj(t) = {L(t) / H(t)} / {L(0) / H(0)} is satisfied, and the life determination unit 73 determines the life of the first liquid crystal panel 35B based on the deterioration determination value Vj(t). Therefore, as described above, it is possible to suppress fluctuations in the deterioration determination value Vj(t) over time due to changes in the intensity O(t) of light emitted by the light source unit 20 over time. Furthermore, as described above, even if there is variation in the light-receiving sensitivity Rs1 among the first optical detection units 61 and variation in the light-receiving sensitivity Rs2 among the second optical detection units 62, the degradation determination value Vj(t) can be prevented from being affected by these variations. As a result, the accuracy of determining the degradation state of the first liquid crystal panel 35B can be more appropriately improved, and the accuracy of determining the lifespan of the first liquid crystal panel 35B can be more appropriately improved. Therefore, maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, can be performed more systematically, and degradation of the quality of images projected by the display device 10 can be more appropriately prevented.

[0061] Furthermore, in this embodiment, as described above, it is possible to more effectively suppress variations in the degradation determination value Vj(t) due to variations in the light sensitivity Rs1 among the first optical detection units 61 and variations in the light sensitivity Rs2 among the second optical detection units 62. This makes it possible to suppress variations in the degradation determination value Vj(t) for the degradation state of the first liquid crystal panel 35B among different display devices 10. This improves the accuracy of determining the lifespan of the first liquid crystal panel 35B among different display devices 10.

[0062] According to the present embodiment, the display device 10 includes a dichroic mirror 28 that reflects blue light, i.e., light in the first wavelength range W1, from the light emitted from the light source unit 20 and guides it to the first liquid crystal panel 35B. The dichroic mirror 28 is disposed between the first light detection unit 61 and the first liquid crystal panel 35B. This prevents the blue light emitted from the light source unit 20 from directly entering the first light detection unit 61. This allows the first light detection unit 61 to accurately detect the first detection value H(t), which is the intensity of the first detection light L1, which has a lower intensity than the blue light emitted from the light source unit 20. This allows the accuracy of determining the deterioration state of the first liquid crystal panel 35B to be improved, and therefore the accuracy of determining the lifespan of the first liquid crystal panel 35B to be improved.

[0063] According to the present embodiment, the dichroic mirror 28 is disposed between the second light detection unit 62 and the first liquid crystal panel 35B. This prevents the blue light emitted from the light source unit 20 from entering the second light detection unit 62. This allows the second light detection unit 62 to accurately detect the second detection value L(t), which is the intensity of the second detection light L2, which has a lower intensity than the blue light emitted from the light source unit 20. This allows the accuracy of determining the deterioration state of the first liquid crystal panel 35B to be more appropriately improved, and therefore the accuracy of determining the lifespan of the first liquid crystal panel 35B to be more appropriately improved.

[0064] According to this embodiment, the display device 10 includes a light detection module 60, and the light detection module 60 has a first light detection unit 61 and a second light detection unit 62. Therefore, by attaching the light detection module 60 to a case or the like of the display device 10, both the first light detection unit 61 and the second light detection unit 62 can be attached to the case or the like. Therefore, it is easier to prevent an increase in the number of steps required to assemble the display device 10, compared to when the first light detection unit 61 and the second light detection unit 62 are different modules.

[0065] According to this embodiment, the display device 10 includes a second liquid crystal panel 35G onto which light in a second wavelength range W2, which has a longer wavelength than the first wavelength range W1, is incident, a third liquid crystal panel 35R onto which light in a third wavelength range W3, which has a longer wavelength than the first wavelength range W1, is incident, and a combining optical system 38 that combines and outputs the light in the first wavelength range W1 modulated by the first liquid crystal panel 35B, the light in the second wavelength range W2 modulated by the second liquid crystal panel 35G, and the light in the third wavelength range W3 modulated by the third liquid crystal panel 35R. As described above, the first wavelength range W1 is shorter than both the second wavelength range W2 and the third wavelength range W3, and therefore the first liquid crystal panel 35B deteriorates faster than the second liquid crystal panel 35G and the third liquid crystal panel 35R. Therefore, when it is determined that the first liquid crystal panel 35B has reached the end of its life, by replacing the second liquid crystal panel 35G and the third liquid crystal panel 35R along with the first liquid crystal panel 35B, it is possible to prevent a deterioration in the quality of the color image formed in the combining optical system 38. Therefore, it is possible to prevent a deterioration in the quality of the image projected by the display device 10.

[0066] According to this embodiment, the control method for the display device 10 includes an acquisition step S01 in which the lifespan determination unit 73 acquires a first detection value H(t) detected by the first light detection unit 61 and a second detection value L(t) detected by the second light detection unit 62, and a determination step S02 in which the lifespan determination unit 73 determines the lifespan of the first liquid crystal panel 35B based on the first detection value H(t) and the second detection value L(t). As described above, this prevents the deterioration determination value Vj(t) from fluctuating over time due to changes over time in the intensity O(t) of light emitted by the light source unit 20. This improves the accuracy of determining the lifespan of the first liquid crystal panel 35B. This allows for planned maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, and prevents degradation in the quality of images projected by the display device 10.

[0067] (Second embodiment) The display device 110 of the second embodiment will be described below. The basic configuration of the display device 110 of this embodiment is similar to that of the display device 10 of the first embodiment, and the display device 110 of this embodiment includes a filter 165. In the following description, the same components as those of the display device 10 of the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0068] FIG. 7 is a diagram schematically showing the configuration of a display device 110 according to this embodiment. As described above, the display device 110 includes the filter 165. In this embodiment, the filter 165 has a cut-on wavelength between the first wavelength range W1 and the detection wavelength range Wd. The cut-on wavelength of the filter 165 is, for example, 550 nm. The filter 165 is a long-pass filter. The filter 165 allows the second detection light L2, which is light in the detection wavelength range Wd, to pass through while suppressing the transmission of blue light. The filter 165 is disposed between the first liquid crystal panel 35B and the second optical detection unit 62. This allows the filter 165 to reduce the intensity of the first detection light L1 entering the second optical detection unit 62. Furthermore, in this embodiment, the filter 165 is disposed between the dichroic mirror 28 and the second optical detection unit 62. This allows the filter 165 to reduce the intensity of the blue light emitted from the light source unit 20 and transmitted through the dichroic mirror 28, which enters the second optical detection unit 62.

[0069] According to this embodiment, the display device 110 includes a filter 165 having a cut-on wavelength between the first wavelength range W1 and the detection wavelength range Wd. The filter 165 is disposed between the first liquid crystal panel 35B and the second optical detection unit 62. As described above, the filter 165 reduces the intensity of the first detection light L1 incident on the second optical detection unit 62. This allows the second optical detection unit 62 to more accurately detect the intensity of the second detection light L2, which is weaker than the first detection light L1. This more accurately determines the deterioration state of the first liquid crystal panel 35B, thereby more accurately determining the lifespan of the first liquid crystal panel 35B. This allows for more planned maintenance of the display device 110, such as replacing the first liquid crystal panel 35B, and more effectively prevents degradation of the quality of images projected by the display device 110.

[0070] Furthermore, in this embodiment, as described above, the filter 165 is disposed between the dichroic mirror 28 and the second light detection unit 62. This allows the filter 165 to reduce the intensity of the blue light that is emitted from the light source unit 20 and transmitted through the dichroic mirror 28 and enters the second light detection unit 62, as described above. This allows the second light detection unit 62 to accurately detect the intensity of the second detection light L2, which has a lower intensity than the blue light that has transmitted through the dichroic mirror 28. This allows the accuracy of determining the deterioration state of the first liquid crystal panel 35B to be more appropriately improved, and therefore the accuracy of determining the lifespan of the first liquid crystal panel 35B to be more appropriately improved.

[0071] (Modification of the second embodiment) A display device 210 according to a modification of the second embodiment will be described below. The basic configuration of the display device 210 of this modified example is similar to that of the display device 110 of the second embodiment, and the display device 210 of this modified example includes a second filter 266. In the following description, the same components as those of the display device 110 of the second embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0072] FIG. 8 is a diagram schematically showing the configuration of a display device 210 in this modified example. As described above, the display device 210 includes the second filter 266. In this modification, the second filter 266 reduces the intensity of blue light, i.e., light in the first wavelength band W1. The second filter 266 is disposed between the first liquid crystal panel 35B and the first optical detection unit 61. This allows the second filter 266 to reduce the intensity of the first detection light L1 that enters the first optical detection unit 61. Also, in this modification, the second filter 266 is disposed between the dichroic mirror 28 and the first optical detection unit 61. This allows the second filter 266 to reduce the intensity of the blue light that is emitted from the light source unit 20 and transmitted through the dichroic mirror 28 and that enters the first optical detection unit 61. Note that, although the display device 210 includes the filter 165 in this modification, the display device 210 does not necessarily have to include the filter 165.

[0073] According to this modification, the display device 210 includes a second filter 266 that reduces blue light, i.e., light in the first wavelength range W1. The second filter 266 is disposed between the first liquid crystal panel 35B and the first optical detector 61. If the intensity of the first detection light L1 is greater than the intensity that the first optical detector 61 can receive, the first detection value H(t) that the first optical detector 61 outputs to the life determiner 73 becomes saturated, which may prevent the life determiner 73 from accurately obtaining the intensity of the first detection light L1. In contrast, in this modification, as described above, the second filter 266 is disposed between the first liquid crystal panel 35B and the first optical detector 61, and therefore the second filter 266 can reduce the intensity of the first detection light L1 that enters the first optical detector 61. This prevents the intensity of the first detection light L1 from becoming greater than the intensity that the first light detection unit 61 can receive, thereby preventing saturation of the first detection value H(t) that the first light detection unit 61 outputs to the life determination unit 73. Therefore, the life determination unit 73 can accurately obtain the intensity of the first detection light L1, thereby more appropriately improving the accuracy of determining the deterioration state of the first liquid crystal panel 35B. This more appropriately improves the accuracy of determining the life of the first liquid crystal panel 35B.

[0074] Furthermore, in this modification, as described above, the second filter 266 is disposed between the dichroic mirror 28 and the first light detection unit 61. This allows the second filter 266 to reduce the intensity of the blue light emitted from the light source unit 20 and transmitted through the dichroic mirror 28, which enters the first light detection unit 61. This more effectively prevents the intensity of the blue light entering the first light detection unit 61 from exceeding the intensity that the first light detection unit 61 can receive. This more effectively prevents the first detection value H(t) output by the first light detection unit 61 to the life determination unit 73 from becoming saturated. This allows the life determination unit 73 to more accurately acquire the intensity of the first detection light L1, which more effectively improves the accuracy of determining the life of the first liquid crystal panel 35B.

[0075] (Third embodiment) A display device 310 according to the third embodiment will be described below. The basic configuration of the display device 310 of this embodiment is similar to that of the display device 10 of the first embodiment, and the display device 310 of this embodiment includes a first light detection module 360a and a second light detection module 360b. In the following description, the same components as those of the display device 10 of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

[0076] FIG. 9 is a diagram schematically showing the configuration of a display device 310 according to this embodiment. As described above, the display device 310 includes the first optical detection module 360a and the second optical detection module 360b. The first optical detection module 360a includes the first optical detection unit 61. In this embodiment, the dichroic mirror 28 is disposed between the first liquid crystal panel 35B and the first optical detection module 360a. As a result, the dichroic mirror 28 is disposed between the first liquid crystal panel 35B and the first optical detection unit 61.

[0077] The second optical detection module 360b has a second optical detection unit 62. The second optical detection module 360b is disposed on the side of the first liquid crystal panel 35B. As a result, the second optical detection unit 62 is disposed on the side of the first liquid crystal panel 35B. In this embodiment, the dichroic mirror 28 is not disposed between the second optical detection unit 62 and the first liquid crystal panel 35B. The distance between the second optical detection unit 62 and the first liquid crystal panel 35B is shorter than the distance between the first optical detection unit 61 and the first liquid crystal panel 35B.

[0078] The display device 310 may include a filter 165 between the second optical detector 62 and the first liquid crystal panel 35B, similar to the display device 110 of the second embodiment described above. This reduces the intensity of the first detection light L1 incident on the second optical detector 62, allowing the second optical detector 62 to accurately detect the intensity of the second detection light L2, which has a lower intensity than the first detection light L1. The display device 310 may also include a second filter 266 between the first optical detector 61 and the first liquid crystal panel 35B, similar to the display device 210 of the modified second embodiment described above. This prevents the intensity of the first detection light L1 from becoming greater than the intensity that the first optical detector 61 can receive, thereby preventing the first detection value H(t) output by the first optical detector 61 to the life determination unit 73 from becoming saturated.

[0079] According to this embodiment, the second optical detection unit 62 is disposed on the side of the first liquid crystal panel 35B. This allows the second optical detection unit 62 to be disposed closer to the first liquid crystal panel 35B. This allows the second optical detection unit 62 to more accurately detect the intensity of the second detection light L2, which has a lower intensity. This therefore more effectively improves the accuracy of determining the deterioration state of the first liquid crystal panel 35B, and more effectively improves the accuracy of determining the lifespan of the first liquid crystal panel 35B.

[0080] According to this embodiment, the distance between the second optical detection unit 62 and the first liquid crystal panel 35B is shorter than the distance between the first optical detection unit 61 and the first liquid crystal panel 35B. Therefore, the second optical detection unit 62 can be disposed closer to the first liquid crystal panel 35B, and the second optical detection unit 62 can more accurately detect the intensity of the second detection light L2, which has a lower intensity. This can more appropriately improve the accuracy of determining the deterioration state of the first liquid crystal panel 35B, and more appropriately improve the accuracy of determining the lifespan of the first liquid crystal panel 35B.

[0081] According to this embodiment, the display device 310 includes a first optical detection module 360a and a second optical detection module 360b. The first optical detection module 360a includes a first optical detection unit 61, and the second optical detection module 360b includes a second optical detection unit 62. Therefore, the first optical detection unit 61 and the second optical detection unit 62 can be disposed at positions separated from each other, increasing the degree of freedom in the positions at which the first optical detection unit 61 and the second optical detection unit 62 are disposed. This allows the first optical detection unit 61 to be disposed at a position where the intensity of the first detection light L1 can be detected with high accuracy, and the second optical detection unit 62 to be disposed at a position where the intensity of the second detection light L2 can be detected with high accuracy. This allows the accuracy of determining the deterioration state of the first liquid crystal panel 35B to be improved, and therefore the accuracy of determining the lifespan of the first liquid crystal panel 35B to be improved.

[0082] (Fourth embodiment) A display device 410 according to the fourth embodiment will be described below. The basic configuration of the display device 410 of this embodiment is similar to that of the display device 10 of the first embodiment, and in the display device 410 of this embodiment, the light detection module 60 is disposed on the side of the first liquid crystal panel 35B. In the following description, the same components as those in the display device 10 of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

[0083] FIG. 10 is a diagram schematically showing the configuration of a display device 410 according to this embodiment. As described above, in this embodiment, the light detection module 60 is disposed on the side of the first liquid crystal panel 35B. As a result, the first light detection unit 61 and the second light detection unit 62 are each disposed on the side of the first liquid crystal panel 35B. In this embodiment, the dichroic mirror 28 is not disposed between the second light detection unit 62 and the first liquid crystal panel 35B.

[0084] The display device 410 may include a filter 165 between the second optical detection unit 62 and the first liquid crystal panel 35B, similar to the display device 110 of the second embodiment described above. This reduces the intensity of the first detection light L1 incident on the second optical detection unit 62, allowing the second optical detection unit 62 to accurately detect the intensity of the second detection light L2, which has a lower intensity than the first detection light L1. The display device 410 may also include a second filter 266 between the first optical detection unit 61 and the first liquid crystal panel 35B, similar to the display device 210 of the modified second embodiment described above. This prevents the intensity of the first detection light L1 from becoming greater than the intensity that the first optical detection unit 61 can receive, thereby preventing the first detection value H(t) output by the first optical detection unit 61 to the life determination unit 73 from becoming saturated.

[0085] According to this embodiment, the first optical detection unit 61 and the second optical detection unit 62 are each disposed on a side of the first liquid crystal panel 35B. Therefore, the first optical detection unit 61 can be disposed close to the first liquid crystal panel 35B, allowing the first optical detection unit 61 to accurately detect the intensity of the first detection light L1 emitted from the first liquid crystal panel 35B. Furthermore, the second optical detection unit 62 can be disposed close to the first liquid crystal panel 35B, allowing the second optical detection unit 62 to accurately detect the intensity of the second detection light L2, which has a lower intensity. This allows for more accurate determination of the deterioration state of the first liquid crystal panel 35B, and therefore more accurate determination of the lifespan of the first liquid crystal panel 35B.

[0086] The display device of each of the above-described embodiments can be applied to electronic devices including such a display device and a display unit that displays an image formed by the display device. For example, the display device of the present invention can be applied to electronic devices such as a projection-type head-up display, a direct-view type head-mounted display, a personal computer, a digital still camera, and a liquid crystal television.

[0087] A summary of this disclosure is provided below.

[0088] (Appendix 1) A display device comprising: a first liquid crystal panel; a first optical detection unit that detects first detection light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel; and a second optical detection unit that detects second detection light in a detection wavelength range that is a longer wavelength range than the first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel.

[0089] According to the display device having the configuration of Supplementary Note 1, it is possible to suppress fluctuations in the deterioration determination value over time due to changes in the intensity of light emitted by the light source unit over time. This increases the accuracy of determining the deterioration state of the first liquid crystal panel, thereby increasing the accuracy of determining the lifespan of the first liquid crystal panel. Therefore, it is possible to systematically perform maintenance of the display device, such as replacing the first liquid crystal panel, and suppress deterioration in the quality of images projected by the display device.

[0090] (Appendix 2) A display device as described in Appendix 1, comprising a lifespan determination unit that determines the lifespan of the first liquid crystal panel, and the lifespan determination unit determines the lifespan of the first liquid crystal panel based on a first detection value detected by the first optical detection unit and a second detection value detected by the second optical detection unit.

[0091] According to this configuration, the lifespan determination unit can calculate the deterioration determination value and determine that the first liquid crystal panel has reached the end of its lifespan.

[0092] (Appendix 3) The display device described in Appendix 2, wherein when the first detection value and the second detection value of the first liquid crystal panel at an initial stage are H(0) and L(0), respectively, the accumulated time for irradiating the first liquid crystal panel with light in the first wavelength range is accumulated irradiation time t, the first detection value and the second detection value at accumulated irradiation time t are H(t) and L(t), respectively, and the deterioration judgment value at accumulated irradiation time t is Vd(t), the relationship Vd(t) = {L(t) / H(t)} / {L(0) / H(0)} is satisfied, and the life judgment unit judges the life of the first liquid crystal panel based on the deterioration judgment value.

[0093] This configuration can prevent the deterioration determination value from fluctuating over time due to changes in the intensity of light emitted by the light source unit. Furthermore, even if there is variation in the light sensitivity of each first optical detection unit and each second optical detection unit, the deterioration determination value can be prevented from being affected by these variations. This can further improve the accuracy of determining the lifespan of the first liquid crystal panel.

[0094] (Appendix 4) 3. The display device according to claim 2, wherein the life determination unit determines the life of the first liquid crystal panel based on each of an integrated value of the first detection value and an integrated value of the second detection value.

[0095] With this configuration, even if at least one of the first and second detection values fluctuates significantly instantaneously due to a detection error caused by electrical noise or the like, a sudden change in the power supply voltage supplied to the display device, etc., the deterioration determination value can be easily prevented from fluctuating, thereby more suitably improving the accuracy of determining the lifespan of the first liquid crystal panel.

[0096] (Appendix 5) 5. The display device according to claim 1, further comprising a dichroic mirror that guides light in the first wavelength range, among light emitted from a light source unit, to the first liquid crystal panel, and the dichroic mirror is disposed between the first light detection unit and the first liquid crystal panel.

[0097] This configuration prevents blue light emitted from the light source from directly entering the first light detector, allowing the first light detector to accurately detect the first detection value, which is the intensity of the first detection light. This further improves the accuracy of determining the lifespan of the first liquid crystal panel.

[0098] (Appendix 6) 6. The display device according to claim 5, wherein the dichroic mirror is disposed between the second light detection unit and the first liquid crystal panel.

[0099] This configuration prevents blue light emitted from the light source from entering the second light detector, allowing the second light detector to accurately detect the second detection value, which is the intensity of the second detection light. This further improves the accuracy of determining the lifespan of the first liquid crystal panel.

[0100] (Appendix 7) 6. The display device according to claim 1, wherein the second light detection unit is disposed on a side of the first liquid crystal panel.

[0101] This configuration allows the second light detection unit to be located closer to the first liquid crystal panel, which allows the second light detection unit to more accurately detect the intensity of the second detection light, which has a lower intensity, and therefore more accurately determines the lifespan of the first liquid crystal panel.

[0102] (Appendix 8) 5. The display device according to claim 1, wherein the first light detection unit and the second light detection unit are disposed on sides of the first liquid crystal panel.

[0103] With this configuration, the first optical detector can be located close to the first liquid crystal panel, allowing the first optical detector to accurately detect the intensity of the first detection light. Furthermore, the second optical detector can be located close to the first liquid crystal panel, allowing the second optical detector to accurately detect the intensity of the second detection light. This further improves the accuracy of determining the lifespan of the first liquid crystal panel.

[0104] (Appendix 9) 9. The display device according to claim 1, wherein the distance between the second optical detection unit and the first liquid crystal panel is shorter than the distance between the first optical detection unit and the first liquid crystal panel.

[0105] This configuration allows the second light detection unit to be located closer to the first liquid crystal panel, which allows the second light detection unit to detect the intensity of the second detection light with higher accuracy, thereby more suitably improving the accuracy of determining the lifespan of the first liquid crystal panel.

[0106] (Appendix 10) 10. The display device of claim 1, further comprising a filter having a cut-on wavelength between the first wavelength range and the detection wavelength range, the filter being disposed between the first liquid crystal panel and the second light detection unit.

[0107] With this configuration, the filter can reduce the intensity of the first detection light incident on the second light detection unit. This allows the second light detection unit to more accurately detect the intensity of the second detection light, which is weaker than the first detection light. This can more effectively improve the accuracy of determining the lifespan of the first liquid crystal panel.

[0108] (Appendix 11) 11. The display device according to claim 1, further comprising a light detection module, the light detection module including the first light detection unit and the second light detection unit.

[0109] According to this configuration, it is easier to prevent an increase in the number of steps required to assemble the display device 10 compared to when the first light detection unit and the second light detection unit are in different modules.

[0110] (Appendix 12) 11. The display device of claim 1, further comprising a first optical detection module and a second optical detection module, wherein the first optical detection module has the first optical detection unit, and the second optical detection module has the second optical detection unit.

[0111] This configuration increases the degree of freedom in the locations where the first and second optical detection units are disposed. This allows the first optical detection unit to be disposed at a position where it can accurately detect the intensity of the first detection light, and the second optical detection unit to be disposed at a position where it can accurately detect the intensity of the second detection light. This further improves the accuracy of determining the lifespan of the first liquid crystal panel.

[0112] (Appendix 13) 13. The display device according to claim 1, comprising: a second liquid crystal panel onto which light in a second wavelength range longer than the first wavelength range is incident; a third liquid crystal panel onto which light in a third wavelength range longer than the first wavelength range is incident; and a combining optical system that combines the light in the first wavelength range modulated by the first liquid crystal panel, the light in the second wavelength range modulated by the second liquid crystal panel, and the light in the third wavelength range modulated by the third liquid crystal panel, and outputs the combined light.

[0113] With this configuration, because the first wavelength range is shorter than the second and third wavelength ranges, the first liquid crystal panel deteriorates faster than the second and third liquid crystal panels. Therefore, when it is determined that the first liquid crystal panel has reached the end of its life, replacing the first liquid crystal panel along with the second and third liquid crystal panels can prevent a deterioration in the quality of the color image formed in the composite optical system. Therefore, a deterioration in the quality of the image projected by the display device can be prevented.

[0114] (Appendix 14) A control method for a display device comprising: a first liquid crystal panel; a first optical detection unit that detects first detected light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel; a second optical detection unit that detects second detected light in a detected wavelength range that is longer than the first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel; and a life determination unit, the control method comprising: an acquisition step in which the life determination unit acquires a first detection value that is a detection value of the first optical detection unit and a second detection value that is a detection value of the second optical detection unit; and a determination step in which the life determination unit determines the life of the first liquid crystal panel based on the first detection value and the second detection value.

[0115] According to the display device control method having this configuration, it is possible to suppress fluctuations in the deterioration determination value over time due to changes in the intensity of light emitted by the light source unit over time, thereby improving the accuracy of determining the lifespan of the first liquid crystal panel.

[0116] (Appendix 15) 14. An electronic device comprising: the display device according to any one of Supplementary Note 1 to Supplementary Note 13; and a display unit that displays an image formed by the display device.

[0117] According to the electronic device having this configuration, the display device can be applied to a projection type head-up display, a direct-view type head-mounted display, a personal computer, a digital still camera, a liquid crystal television, and the like. [Explanation of symbols]

[0118] 10, 110, 210, 310, 410...display device, 28...dichroic mirror, 35B...first liquid crystal panel, 35G...second liquid crystal panel, 35R...third liquid crystal panel, 38...combining optical system, 60...photodetection module, 61...first photodetection section, 62...second photodetection section, 73...lifetime determination section, 165...filter, 360a...first photodetection module, 360b...second photodetection module, H(0)...initial first detected value, H(t)...first detected value, L(0)...initial second detected value, L(t)...second detected value, L1...first detected light, L2...second detected light, S01...acquisition step, S02...determination step, t...integrated irradiation time, Vj(t)...deterioration determination value

Claims

1. a first liquid crystal panel; a first light detection unit that detects first detected light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel; a second light detection unit that detects second detection light in a detection wavelength range that is a wavelength range longer than the first wavelength range and that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel; Equipped with Display device.

2. a lifespan determination unit that determines a lifespan of the first liquid crystal panel; the life determination unit determines the life of the first liquid crystal panel based on a first detection value detected by the first light detection unit and a second detection value detected by the second light detection unit. The display device according to claim 1 .

3. When the first detection value and the second detection value of the first liquid crystal panel at an initial stage are H(0) and L(0), respectively, the integrated time during which the first liquid crystal panel is irradiated with light in the first wavelength range is integrated irradiation time t, the first detection value and the second detection value at the integrated irradiation time t are H(t) and L(t), respectively, and the deterioration determination value at the integrated irradiation time t is Vd(t), Vd(t)={L(t) / H(t)} / {L(0) / H(0)} Fulfilling the relationship, the life determination unit determines the life of the first liquid crystal panel based on the deterioration determination value. The display device according to claim 2 .

4. the life determination unit determines the life of the first liquid crystal panel based on each of the integrated value of the first detection values and the integrated value of the second detection values. The display device according to claim 2 .

5. a dichroic mirror that guides light in the first wavelength range, out of light emitted from a light source unit, to the first liquid crystal panel; the dichroic mirror is disposed between the first light detection unit and the first liquid crystal panel. The display device according to claim 1 .

6. the dichroic mirror is disposed between the second light detection unit and the first liquid crystal panel. The display device according to claim 5 .

7. the second light detection unit is disposed on a side of the first liquid crystal panel; The display device according to claim 1 .

8. the first light detection unit and the second light detection unit are disposed on the sides of the first liquid crystal panel, The display device according to claim 1 .

9. a distance between the second light detection unit and the first liquid crystal panel is shorter than a distance between the first light detection unit and the first liquid crystal panel; The display device according to claim 1 .

10. a filter having a cut-on wavelength between the first wavelength range and the detection wavelength range; the filter is disposed between the first liquid crystal panel and the second light detection unit. The display device according to claim 1 .

11. a light detection module; the light detection module includes the first light detection unit and the second light detection unit; The display device according to claim 1 .

12. a first optical detection module and a second optical detection module; the first light detection module has the first light detection unit, the second light detection module includes the second light detection unit; The display device according to claim 1 .

13. a second liquid crystal panel onto which light in a second wavelength range longer than the first wavelength range is incident; a third liquid crystal panel onto which light in a third wavelength range, which has a wavelength longer than that of the first wavelength range, is incident; a combining optical system that combines the light in the first wavelength range modulated by the first liquid crystal panel, the light in the second wavelength range modulated by the second liquid crystal panel, and the light in the third wavelength range modulated by the third liquid crystal panel, and outputs the combined light; Equipped with The display device according to claim 1 .

14. A control method for a display device including a first liquid crystal panel, a first light detection unit that detects first detected light in a first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel, a second light detection unit that detects second detected light in a detected wavelength range that is longer than the first wavelength range that is emitted from the first liquid crystal panel when light in the first wavelength range is incident on the first liquid crystal panel, and a life determination unit, an acquisition step in which the life determination unit acquires a first detection value that is a detection value of the first light detection unit and a second detection value that is a detection value of the second light detection unit; a determination step in which the life determination unit determines a life of the first liquid crystal panel based on the first detection value and the second detection value; A method for controlling a display device, comprising:

15. The display device according to any one of claims 1 to 4; a display unit that displays an image formed by the display device; An electronic device comprising:

Images