Display unit, and method for controlling display unit

Abstract

To increase the accuracy of determining the life of a liquid crystal panel.SOLUTION: A display unit comprises: a liquid crystal panel; and a light detection unit that detects light in an infrared wavelength range emitted from a liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel. A method for controlling a display unit comprising: a liquid crystal panel; a light detection unit that detects light in an infrared wavelength range emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel; a control unit that is electrically connected to the light detection unit; and a notification unit that notifies a user of the life of the liquid crystal panel, the method including: a life determination step of determining, by the control unit, the life of the liquid crystal panel on the basis of a light detection value detected by the light detection unit; and a notification step of, when the life of the liquid crystal panel is determined, notifying, by the notification unit, the user of the life of the liquid crystal panel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a display device and a method for controlling a display 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 based on the chromaticity or illuminance of light modulated by the liquid crystal panel detected by an optical sensor, and therefore cannot determine whether the degradation of image quality is due to degradation of the liquid crystal panel or degradation of the light source unit, posing a problem of being unable to accurately detect the lifespan of the liquid crystal panel. [Means for solving the problem]

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

[0006] One embodiment of the present invention provides a control method for a display device comprising a liquid crystal panel, a photodetector that detects light in the infrared wavelength range emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel, a control unit electrically connected to the photodetector, and an alarm that notifies the lifespan of the liquid crystal panel, the control unit including a lifespan determination step in which the control unit determines the lifespan of the liquid crystal panel based on the photodetection value detected by the photodetector, and an alarm step in which the alarm unit notifies the lifespan of the liquid crystal panel when the lifespan of the liquid crystal panel has been determined. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a display device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a liquid crystal panel according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing changes over time in the intensity distribution of the first detection light in the first embodiment. [Figure 4] 4 is a flowchart showing a control method for the display device in the first embodiment. [Figure 5] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a second embodiment. [Figure 6] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a third embodiment. [Figure 7] FIG. 13 is a diagram schematically showing the configuration of a display device according to a first modified example of the third embodiment. [Figure 8] FIG. 13 is a diagram schematically showing the configuration of a display device according to a second modified example of the third embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a fourth embodiment. [Figure 10] FIG. 10 is a diagram schematically illustrating the configuration of a display device according to a fifth embodiment. [Figure 11] FIG. 13 is a first diagram schematically illustrating the configuration of a display device according to a sixth embodiment. [Figure 12] FIG. 22 is a second diagram schematically illustrating the configuration of the display device according to the sixth embodiment. [Figure 13]FIG. 13 is a diagram schematically illustrating the configuration of a display device according to a seventh embodiment. [Figure 14] FIG. 13 is a diagram schematically showing a liquid crystal panel according to a seventh embodiment. [Figure 15] 13A and 13B are diagrams showing the intensity distributions of light source light and first detection light in the seventh embodiment. [Figure 16] FIG. 13 is a first diagram schematically illustrating the configuration of a display device according to an eighth embodiment. [Figure 17] FIG. 22 is a second diagram schematically illustrating the configuration of the display device according to the eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following description will be given of an embodiment of the present invention with reference to the drawings. In the drawings referred to in the following description, the scale of each layer and each component is different so that each layer and each component is large enough to be recognizable on the drawing.

[0009] In the embodiments described below, the wavelength range of blue light LB is the first wavelength range W1. Blue light LB is light in the first wavelength range W1. That is, light in the first wavelength range W1 is light in the blue wavelength range. The wavelength range of green light LG is the second wavelength range W2. Green light LG is light in the second wavelength range W2. The wavelength range of red light LR is the third wavelength range W3. Red light LR 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 third wavelength range W3 has a longer wavelength than the second wavelength range W2. The first wavelength range W1 has a shorter wavelength than both the second wavelength range W2 and the third wavelength range W3.

[0010] In the following description, the Z-axis direction will be indicated in each figure as appropriate. In the embodiments described below, the Z-axis direction is the up-down direction. The side toward which the Z-axis arrow points (+Z side) is the upper side, and the side opposite to the side toward which the Z-axis arrow points (-Z side) is the lower side. Note that the up-down direction, upper side, and lower side are simply names used to describe the relative positional relationships of the various parts, and the actual positional relationships may be other than those indicated by these names.

[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 this embodiment. FIG. 2 is a cross-sectional view of a liquid crystal panel 35 according to this embodiment. The display device 10 according to this embodiment is a projection-type display device that displays a full-color 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 unit 60. The liquid crystal panel 35 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 and a notification unit 74.

[0012] In the following description, the liquid crystal panel will be denoted by the reference symbol 35, and the corresponding colors will be denoted by the reference symbols R (red), G (green), and B (blue). However, when it is not necessary to specify the corresponding colors, the panel will simply be referred to as the liquid crystal panel 35. In this embodiment, the liquid crystal panel 35 onto which the blue light LB is incident is the first liquid crystal panel 35B. The liquid crystal panel 35 onto which the green light LG is incident is the second liquid crystal panel 35G. The liquid crystal panel 35 onto which the red light LR is incident is the third liquid crystal panel 35R.

[0013] 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. In this embodiment, the wavelength range of the light source light is the visible light region from 400 nm to 700 nm.

[0014] 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.

[0015] The dichroic mirror 26 transmits the red light LR and reflects light with a shorter wavelength than the red light LR. The red light LR that has transmitted through the dichroic mirror 26 is guided to the third liquid crystal panel 35R by the mirror 23. The red light LR, i.e., light in the third wavelength range W3, is incident on the third liquid crystal panel 35R. The light reflected by the dichroic mirror 26 is incident on the dichroic mirror 27.

[0016] The dichroic mirror 27 reflects the green light LG and transmits light with a shorter wavelength than the green light LG. The green light LG reflected by the dichroic mirror 27 is incident on the second liquid crystal panel 35G. The green light LG, i.e., light in the second wavelength range W2, is incident on the second liquid crystal panel 35G. The light with a shorter wavelength than the green light LG that is transmitted through the dichroic mirror 27, i.e., blue light LB, is reflected by the mirror 24 and enters the dichroic mirror 28.

[0017] The dichroic mirror 28 reflects the blue light LB and transmits light with longer wavelengths than the blue light LB. In this embodiment, the peak wavelength of the blue light LB incident on the dichroic mirror 28 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 LB reflected by the dichroic mirror 28 is incident on the first liquid crystal panel 35B. That is, the blue light LB, i.e., light in the first wavelength range W1, is incident on the first liquid crystal panel 35B. The dichroic mirror 28 guides light in the first wavelength range W1, out of the light emitted from the light source unit 20, to the first liquid crystal panel 35B.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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).

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The control unit 70 includes an image processing unit 71, a timing signal generating unit 72, and a 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The lifespan determination unit 73 determines the deterioration state of the first liquid crystal panel 35B based on the light detection value D1(t) detected by the light detection unit 60. In this way, the lifespan determination unit 73 determines the lifespan of the first liquid crystal panel 35B. In other words, the lifespan determination unit 73 determines the lifespan of the liquid crystal panel 35. The lifespan determination unit 73 will be described in detail later.

[0034] The notification unit 74 notifies the user of the display device 10 of the lifespan of the liquid crystal panel 35. The notification unit 74 is capable of communicating with the lifespan determination unit 73. The notification unit 74 and the lifespan determination unit 73 may be capable of communicating via wired communication or wireless communication, for example, via wireless LAN. The notification unit 74 may, for example, notify the user that the liquid crystal panel 35 has reached the end of its lifespan by projecting an image onto the projection target 90, or may notify the user that the liquid crystal panel 35 has reached the end of its lifespan by sound or the like. When the lifespan determination unit 73 determines the lifespan of the first liquid crystal panel 35B, the control unit 70 notifies the user that the first liquid crystal panel 35B has reached the end of its lifespan by the notification unit 74. The user can replace the first liquid crystal panel 35B or the like in accordance with the notification, thereby enabling the user to perform maintenance of the display device 10 in a planned manner.

[0035] The combining optical system 38 shown in FIG. 1 is composed of 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 LR and blue light LB are each reflected 90 degrees by the combining optical system 38, while the green light LG 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.

[0036] The light detection unit 60 detects the first detection light L1 emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B. The light detection unit 60 may detect the first detection light L1 emitted from the second liquid crystal panel 35G to the incident side of the second liquid crystal panel 35G, or the first detection light L1 emitted from the third liquid crystal panel 35R to the incident side of the third liquid crystal panel 35R. In this embodiment, the dichroic mirror 28 is disposed between the light detection unit 60 and the first liquid crystal panel 35B. That is, the dichroic mirror 28 is disposed between the light detection unit 60 and the liquid crystal panel 35B. The light detection unit 60 faces the first liquid crystal panel 35B via the dichroic mirror 28.

[0037] The light detection unit 60 detects first detection light L1 in the infrared wavelength range Wi, which has a wavelength longer than the first wavelength range W1, and is emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B when blue light LB, i.e., light in the first wavelength range W1, is incident on the first liquid crystal panel 35B. More specifically, the light detection unit 60 detects the intensity of the first detection light L1 that is emitted radially from the incident surface of the first liquid crystal panel 35B. In this embodiment, the light detection unit 60 is a photodiode that can detect the intensity of light in the infrared wavelength range Wi, which has a wavelength of 700 nm or more and 800 nm or less.

[0038] The first detection light L1 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 first detection light L1 is light in the infrared wavelength range Wi. As described above, the infrared wavelength range Wi, which is the wavelength range of the first detection light L1, has a longer wavelength than the first wavelength range W1. More specifically, the infrared wavelength range Wi has a longer wavelength than each of the first wavelength range W1, the second wavelength range W2, and the third wavelength range W3. 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. It is believed that the deterioration of the liquid crystal layer 49 is caused by changes in the composition and alignment characteristics of the liquid crystal molecules that make up the liquid crystal layer 49 due to the incidence of light with a high luminous flux density on the liquid crystal layer 49. The inventors of the present application discovered through a test to observe the deterioration of the liquid crystal panel 35 over time that the deterioration of the liquid crystal layer 49 correlates with the intensity of the first detection light L1 emitted by the liquid crystal layer 49. Specifically, the inventors discovered that the intensity of the first detection light L1 increases as the cumulative irradiation time t during which the first liquid crystal panel 35B is irradiated with blue light LB increases. That is, the intensity of the first detection light L1 correlates with the deterioration state of the first liquid crystal panel 35B. More specifically, the intensity of the first detection light L1 increases as the deterioration of the liquid crystal panel 35 progresses. Therefore, the light detection value D1(t), which is the detection value of the light detection unit 60, correlates with the deterioration state of the first liquid crystal panel 35B. Furthermore, as the first liquid crystal panel 35B deteriorates, the quality of the blue image modulated by the first liquid crystal panel 35B deteriorates, thereby degrading the quality of the color image projected onto the projection target 90.

[0039] As described above, the dichroic mirror 28 is disposed between the light detection unit 60 and the first liquid crystal panel 35B. This prevents the blue light LB emitted from the light source unit 20 from directly entering the light detection unit 60. The first detection light L1 that has passed through the dichroic mirror 28 enters the light detection unit 60. As shown in FIG. 2, the light detection unit 60 is electrically connected to the life determination unit 73. That is, the control unit 70 is electrically connected to the light detection unit 60. The intensity of the first detection light L1 detected by the light detection unit 60 is output to the life determination unit 73 as a light detection value D1(t).

[0040] FIG. 3 is a diagram showing the change over time in the intensity distribution of the first detection light L1 in this embodiment. Next, the relationship between deterioration of the liquid crystal panel 35 and the intensity distribution of the first detection light L1 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 LB. The dashed line indicates the light spectrum La(0) at the time when irradiation of the blue light LB begins, and the solid line indicates the light spectrum La(T) at the time when the integrated irradiation time t of the blue light LB reaches T.

[0041] At the start of irradiation of the blue light LB, the intensity of the light emitted from the liquid crystal panel 35 is approximately constant across the visible light wavelength range and the infrared wavelength range. As the blue light LB continues to be 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 the light emitted in the wavelength range of 500 nm to 800 nm increases. This is presumably due to changes in the composition and orientation characteristics of the liquid crystal molecules constituting the liquid crystal layer 49, as described above. As described above, in this embodiment, the light detection unit 60 can detect the intensity of the first detection light L1, which is light in the infrared wavelength range Wi, having a wavelength of 700 nm or more and 800 nm or less. Therefore, in this embodiment, the deterioration state of the liquid crystal panel 35 can be detected based on the intensity of the first detection light L1 detected by the light detection unit 60, i.e., the light detection value D1(t).

[0042] Furthermore, in this embodiment, as described above, the peak wavelength of the blue light LB incident on the dichroic mirror 28 is 450 nm, which is significantly different from the detectable wavelength range of the photodetector 60, which is 700 nm or more and 800 nm or less. Therefore, even if leakage light of the blue light LB incident on the dichroic mirror 28 enters the photodetector 60, the influence on the photodetection value D1(t) detected by the photodetector 60 can be reduced. Furthermore, in this embodiment, as described above, the wavelength range of the light source light emitted by the light source unit 20 is in the range of 400 nm to 700 nm. Therefore, the infrared wavelength range Wi, which is the wavelength range of the first detection light L1, is longer than the wavelength range of the light source light. Therefore, even if leakage light of the light source light enters the photodetector 60, the influence on the photodetection value D1(t) detected by the photodetector 60 can be reduced.

[0043] 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 faster the deterioration of the liquid crystal panel 35 progresses. Therefore, the first liquid crystal panel 35B, onto which blue light LB, i.e., light in the first wavelength range W1, is incident, deteriorates faster than the second liquid crystal panel 35G and the third liquid crystal panel 35R. Therefore, when the life determination unit 73 detects the intensity of the first detection light L1 emitted from the first liquid crystal panel 35B and determines 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 life. 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, which has reached the end of its life, deterioration of the quality of the image projected by the display device 10 can be effectively prevented.

[0044] 4 is a flowchart showing a control method for the display device 10 according to this embodiment. The control method for the display device 10 includes a lifespan determination flow for determining the lifespan of the liquid crystal panel 35. The lifespan determination flow includes an acquisition step S01, a lifespan determination step S02, and a notification step S03.

[0045] In acquisition step S01, the life determination unit 73 acquires the light detection value D1(t) detected by the light detection unit 60. The life determination unit 73 may acquire the light detection value D1(t), for example, every time the integrated irradiation time t elapses a predetermined time, or may acquire the light detection value D1(t) continuously.

[0046] In the lifespan determination step S02, the lifespan determination unit 73 determines the lifespan of the first liquid crystal panel 35B based on the acquired light detection value D1(t). That is, the control unit 70 determines the lifespan of the liquid crystal panel 35B based on the light detection value D1(t) detected by the light detection unit 60. In this embodiment, the lifespan determination unit 73 determines that the first liquid crystal panel 35B has reached the end of its lifespan when the light detection value D1(t) is equal to or greater than a predetermined lifespan determination value Le stored in a storage unit (not shown). As described above, the wavelength range of the first detection light L1 detected by the light detection unit 60, i.e., the infrared wavelength range Wi, is different from both the first wavelength range W1, which is the wavelength range of the blue light LB incident on the dichroic mirror 28, and the wavelength range of the light source light. Therefore, even if the blue light LB and leakage light of the light source light enter the light detection unit 60, the influence on the light detection value D1(t) detected by the light detection unit 60 can be reduced. This improves the accuracy of determining the deterioration state of the first liquid crystal panel 35B. Therefore, the accuracy of determining the lifespan of the liquid crystal panel 35 can be improved more suitably.

[0047] The life determination unit 73 may determine that the first liquid crystal panel 35B has reached the end of its life when the difference between the light detection value D1(t) when the cumulative irradiation time t has elapsed a predetermined time and the initial light detection value D1(0) of the first liquid crystal panel 35B is equal to or greater than a life determination value different from the life determination value Le. In this case, even if the light detection value D1(t) corresponding to the deterioration state of the first liquid crystal panel 35B varies due to the influence of variations in the light receiving sensitivity of each light detection unit 60, the accuracy of determining the deterioration state of the first liquid crystal panel 35B can be more suitably improved. Therefore, the accuracy of determining the life of the liquid crystal panel 35 can be more suitably improved.

[0048] If the light detection value D1(t) is equal to or greater than the lifespan determination value Le, that is, if the lifespan of the liquid crystal panel 35 is determined, in notification step S03, the notification unit 74 notifies the user or the like that the liquid crystal panel 35 has reached the end of its lifespan. As described above, the notification unit 74 may, for example, notify the user or the like that the liquid crystal panel 35 has reached the end of its lifespan by projecting an image onto the projection target 90, or may notify the user or the like that the liquid crystal panel 35 has reached the end of its lifespan by sound or the like. When notifying the user or the like that the liquid crystal panel 35 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 liquid crystal panel 35 has reached the end of its lifespan is superimposed on an image signal generated by the image processing unit 71 may be projected onto the projection target 90.

[0049] Furthermore, when the light detection value D1(t) is smaller than the life determination value Le, the life determination unit 73 may predict the period until the first liquid crystal panel 35B reaches the end of its life from the light detection value D1(t), the difference between the light detection value D1(t) and the life determination value Le, and the slope of the change over time of the light detection value D1(t). In this case, the notification unit 74 may notify the user of the predicted 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.

[0050] Furthermore, when the light detection value D1(t) reaches the life determination value Le, 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.

[0051] According to this embodiment, the display device 10 includes a liquid crystal panel 35 and a photodetector 60 that detects first detection light L1, i.e., light in the infrared wavelength range Wi, emitted from the liquid crystal panel 35 when light LB in the first wavelength range W1 is incident on the liquid crystal panel 35. As described above, the photodetector 60 detects the intensity of the first detection light L1, which correlates with the deterioration state of the liquid crystal panel 35. Therefore, the lifespan determiner 73 can determine the deterioration state of the liquid crystal panel 35 based on the photodetector value D1(t), thereby improving the accuracy of determining the lifespan of the liquid crystal panel 35. This allows for planned maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, and prevents degradation of the quality of images projected by the display device 10.

[0052] Furthermore, in this embodiment, as described above, the deterioration state of the liquid crystal panel 35 can be determined by the first detection light L1, which has a wavelength longer than both the first wavelength range W1 of the blue light LB and the wavelength range of the light source light emitted by the light source unit 20. Therefore, as described above, even if leakage light of the blue light LB and leakage light of the light source light enters the light detection unit 60, the influence on the light detection value D1(t) detected by the light detection unit 60 can be reduced. This can more appropriately improve the accuracy of determining the deterioration state of the liquid crystal panel 35, and more appropriately improve the accuracy of determining the lifespan of the liquid crystal panel 35. Therefore, maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, can be performed more systematically, and deterioration in the quality of images projected by the display device 10 can be more appropriately prevented.

[0053] According to this embodiment, the display device 10 includes a dichroic mirror 28 that guides light in the first wavelength range W1, i.e., blue light LB, emitted from the light source unit 20, to the first liquid crystal panel 35B, i.e., the liquid crystal panel 35. The dichroic mirror 28 is disposed between the light detection unit 60 and the liquid crystal panel 35. This prevents the blue light LB emitted from the light source unit 20 from directly entering the light detection unit 60. This allows the light detection unit 60 to more accurately detect the light detection value D1(t), which is the intensity of the first detection light L1, which has a lower intensity than the blue light LB emitted from the light source unit 20. This more accurately determines the deterioration state of the liquid crystal panel 35, thereby more accurately determining the lifespan of the liquid crystal panel 35.

[0054] According to this embodiment, the light in the first wavelength range W1 is light in the blue wavelength range. Therefore, the difference between the wavelength range of the first detection light L1 in the infrared wavelength range Wi and the wavelength range of the light in the first wavelength range W1 can be increased, making it easier for the dichroic mirror 28 to separate the first detection light L1 from the light in the first wavelength range W1. This more effectively prevents the light in the first wavelength range W1 emitted from the light source unit 20 from directly entering the light detection unit 60. Therefore, the light detection unit 60 can more accurately detect the light detection value D1(t), which is the intensity of the first detection light L1. This more effectively improves the accuracy of determining the deterioration state of the liquid crystal panel 35, thereby more effectively improving the accuracy of determining the lifespan of the liquid crystal panel 35.

[0055] According to this embodiment, the display device 10 includes a combining optical system 38, and the liquid crystal panel 35 includes a first liquid crystal panel 35B onto which light in a first wavelength range W1 is incident, a second liquid crystal panel 35G onto which light in a second wavelength range W2, which has a wavelength longer than the first wavelength range W1, is incident, and a third liquid crystal panel 35R onto which light in a third wavelength range W3, which has a wavelength longer than the first wavelength range W1, is incident. The combining optical system 38 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. Because the first wavelength range W1 is shorter in wavelength than both the second wavelength range W2 and the third wavelength range W3, as described above, the first liquid crystal panel 35B deteriorates faster than the second liquid crystal panel 35G and the third liquid crystal panel 35R. Therefore, when the life determination unit 73 determines 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.

[0056] According to the present embodiment, a control method for a display device 10 includes a liquid crystal panel 35, a photodetector 60 that detects first detection light L1 (i.e., light in the infrared wavelength range Wi) emitted from the liquid crystal panel 35 when light in the first wavelength range W1 is incident on the liquid crystal panel 35, a controller 70 electrically connected to the photodetector 60, and a notifier 74 that notifies the user of a lifespan of the liquid crystal panel 35. The control method includes a lifespan determination step S02 in which the controller 70 determines the lifespan of the liquid crystal panel 35 based on a photodetection value D1(t) detected by the photodetector 60, and a notifier step S03 in which the notifier 74 notifies the user of the lifespan of the liquid crystal panel 35 upon determining the lifespan of the liquid crystal panel 35. As described above, the photodetector value D1(t) detected by the photodetector 60 is the intensity of the first detection light L1, which correlates with a deterioration state of the liquid crystal panel 35. Therefore, as described above, in the lifespan determination step S02, the lifespan determination unit 73 can accurately determine the deterioration state of the liquid crystal panel 35 based on the light detection value D1(t). This allows the lifespan determination unit 73 to accurately determine the lifespan of the liquid crystal panel 35. This allows maintenance of the display device 10, such as replacing the first liquid crystal panel 35B, to be performed in a planned manner, and also prevents deterioration in the quality of the image projected by the display device 10.

[0057] Furthermore, in this embodiment, once the lifespan determination unit 73 determines the lifespan of the liquid crystal panel 35 in the lifespan determination step S02, the notification unit 74 can notify the user, etc., that the liquid crystal panel 35 has reached the end of its lifespan in the notification step S03. Therefore, the user, etc., can systematically perform maintenance of the display device 10 by replacing the first liquid crystal panel 35B, etc., in accordance with the notification. This makes it possible to prevent a deterioration in the quality of the image projected by the display device 10.

[0058] (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.

[0059] FIG. 5 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 is a long-pass filter whose cut-on wavelength is between the first wavelength range W1 and the infrared wavelength range Wi. The cut-on wavelength of the filter 165 is, for example, 700 nm. The filter 165 allows the first detection light L1, which is light in the infrared wavelength range Wi, to pass through while suppressing the transmission of the light source light and the blue light LB. The filter 165 is disposed between the first liquid crystal panel 35B and the photodetector 60. That is, the filter 165 is disposed between the liquid crystal panel 35B and the photodetector 60. This allows the filter 165 to suppress leakage of the blue light LB and leakage of the light source light from entering the photodetector 60. Other configurations of the display device 110 of this embodiment are similar to those of the display device 10 of the first embodiment described above.

[0060] 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 infrared wavelength range Wi, and the filter 165 is disposed between the liquid crystal panel 35 and the light detection unit 60. As described above, the filter 165 can prevent leakage of the blue light LB and leakage of the light source light from entering the light detection unit 60. This allows the light detection unit 60 to more accurately detect the intensity of the first detection light L1, which is weaker than the blue light LB and the light source light. This can more accurately determine the deterioration state of the liquid crystal panel 35, thereby more accurately determining the lifespan of the liquid crystal panel 35. 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.

[0061] (Third embodiment) The display device 210 of the third embodiment will be described below. The basic configuration of the display device 210 of this embodiment is similar to that of the display device 10 of the first embodiment, and the photodetector 60 of this embodiment is disposed on the side of the first liquid crystal panel 35B. 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.

[0062] FIG. 6 is a diagram schematically showing the configuration of a display device 210 in this embodiment. As described above, the light detection unit 60 is disposed on the side of the first liquid crystal panel 35B. That is, the light detection unit 60 is disposed on the side of the liquid crystal panel 35. The light detection unit 60 detects the intensity of the first detection light L1 that is radially emitted from the incident surface of the first liquid crystal panel 35B. The distance between the light detection unit 60 and the first liquid crystal panel 35B in this embodiment is shorter than the distance between the light detection unit 60 and the first liquid crystal panel 35B in the first embodiment described above.

[0063] The display device 210 may include a filter 165 between the first liquid crystal panel 35B and the light detection unit 60, similar to the display device 110 of the second embodiment described above. In this case, it is possible to prevent leakage of blue light LB and leakage of light source light from entering the light detection unit 60. This allows the light detection unit 60 to accurately detect the intensity of the first detection light L1. Other configurations of the display device 210 of this embodiment are similar to those of the display device 10 of the first embodiment described above.

[0064] According to this embodiment, the light detection unit 60 is disposed on the side of the liquid crystal panel 35. More specifically, the light detection unit 60 is disposed on the side of the first liquid crystal panel 35B. This allows the light detection unit 60 to be disposed closer to the first liquid crystal panel 35B. This allows the light detection unit 60 to more accurately detect the intensity of the first detection light L1, which has a low intensity. This therefore makes it possible to more appropriately improve the accuracy of determining the deterioration state of the first liquid crystal panel 35B, and therefore more appropriately improve the accuracy of determining the lifespan of the first liquid crystal panel 35B.

[0065] (First modified example of the third embodiment) A display device 310 according to a first modified example of the third embodiment will be described below. The basic configuration of the display device 310 of this modified example is similar to that of the display device 10 of the first embodiment, and the photodetector 60 of this modified example is disposed on the side of the second liquid crystal panel 35G. 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 their description will be omitted.

[0066] FIG. 7 is a diagram schematically showing the configuration of a display device 310 in this modification. As described above, the light detection unit 60 is disposed on the side of the second liquid crystal panel 35G. That is, the light detection unit 60 is disposed on the side of the liquid crystal panel 35. The light detection unit 60 detects the intensity of the first detection light L1 that is radially emitted from the incident surface of the second liquid crystal panel 35G. The distance between the light detection unit 60 and the second liquid crystal panel 35G in this modification is shorter than the distance between the light detection unit 60 and the first liquid crystal panel 35B in the first embodiment described above.

[0067] The display device 310 may include a filter 165 between the second liquid crystal panel 35G and the light detection unit 60. This can prevent leakage of the green light LG and leakage of the light source light from entering the light detection unit 60, allowing the light detection unit 60 to accurately detect the intensity of the first detection light L1. Other configurations of the display device 310 of this modified example are similar to those of the display device 10 of the first embodiment described above.

[0068] According to this modification, the light detection unit 60 is disposed on the side of the liquid crystal panel 35. More specifically, the light detection unit 60 is disposed on the side of the second liquid crystal panel 35G. This allows the light detection unit 60 to be disposed closer to the second liquid crystal panel 35G. This allows the light detection unit 60 to more accurately detect the intensity of the first detection light L1, which has a low intensity. This therefore makes it possible to more appropriately improve the accuracy of determining the deterioration state of the second liquid crystal panel 35G, and therefore more appropriately improve the accuracy of determining the lifespan of the second liquid crystal panel 35G.

[0069] (Second modified example of the third embodiment) A display device 410 according to a second modification of the third embodiment will be described below. The basic configuration of the display device 410 of this modified example is similar to that of the display device 10 of the first embodiment, and the photodetector 60 of this modified example is disposed on the side of the third liquid crystal panel 35R. 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 their description will be omitted.

[0070] FIG. 8 is a diagram schematically showing the configuration of a display device 410 in this modification. As described above, the light detection unit 60 is disposed on the side of the third liquid crystal panel 35R. That is, the light detection unit 60 is disposed on the side of the liquid crystal panel 35R. The light detection unit 60 detects the intensity of the first detection light L1 radially emitted from the incident surface of the third liquid crystal panel 35R. The distance between the light detection unit 60 and the third liquid crystal panel 35R in this modification is shorter than the distance between the light detection unit 60 and the first liquid crystal panel 35B in the first embodiment described above.

[0071] The display device 410 may include a filter 165 between the third liquid crystal panel 35R and the light detection unit 60. This prevents leakage of the red light LR and leakage of the light source light from entering the light detection unit 60, allowing the light detection unit 60 to accurately detect the intensity of the first detection light L1. Other configurations of the display device 410 of this modified example are similar to those of the display device 10 of the first embodiment described above.

[0072] According to this modification, the light detection unit 60 is disposed on the side of the liquid crystal panel 35. More specifically, the light detection unit 60 is disposed on the side of the third liquid crystal panel 35R. This allows the light detection unit 60 to be disposed closer to the third liquid crystal panel 35R. This allows the light detection unit 60 to more accurately detect the intensity of the first detection light L1, which has a low intensity. This therefore makes it possible to more appropriately improve the accuracy of determining the deterioration state of the third liquid crystal panel 35R, and therefore more appropriately improve the accuracy of determining the lifespan of the third liquid crystal panel 35R.

[0073] (Fourth embodiment) A display device 510 according to the fourth embodiment will be described below. The basic configuration of the display device 510 of this embodiment is similar to that of the display device 10 of the first embodiment, and the display device 510 of this embodiment includes a light detection unit 560 and a conversion member 568. 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.

[0074] FIG. 9 is a diagram schematically showing the configuration of a display device 510 in this embodiment. Like the dichroic mirror 28 of the first embodiment described above, the dichroic mirror 28 of this embodiment guides blue light LB, i.e., light in the first wavelength range W1, out of the light emitted from the light source unit 20, to the first liquid crystal panel 35B. The dichroic mirror 28 is disposed between the first liquid crystal panel 35B and the conversion member 568 and the photodetector unit 560. That is, the dichroic mirror 28 is disposed between the liquid crystal panel 35B and the conversion member 568 and the photodetector unit 560.

[0075] The conversion member 568 is incident with the first detection light L1, that is, light in the infrared wavelength range Wi, which is emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B when light in the first wavelength range W1 is incident on the first liquid crystal panel 35B. As described above, the dichroic mirror 28 is disposed between the conversion member 568 and the first liquid crystal panel 35B. This prevents the blue light LB emitted from the light source unit 20 from directly entering the conversion member 568. The first detection light L1 that has passed through the dichroic mirror 28 is incident on the conversion member 568.

[0076] In this embodiment, the conversion member 568 is composed of a substrate made of glass, resin, or the like, a reflective film formed on the surface of the substrate, and a wavelength conversion layer provided on the reflective film. In this embodiment, the wavelength conversion layer is composed of a material in which a sensitizer is uniformly dispersed in a light-emitting body. The sensitizer may be a material obtained by synthesizing a metal complex such as porphyrin. The light-emitting body may be a polycyclic aromatic hydrocarbon with a uniform energy level. The wavelength conversion layer absorbs the first detection light L1, which is light in the infrared wavelength range Wi, and emits visible light L2, which is light with a shorter wavelength than the first detection light L1. The conversion member 568 thereby converts the first detection light L1 into visible light L2. In this embodiment, the conversion member 568 converts the first detection light L1, which is light in the infrared wavelength range Wi and has a low intensity, into visible light L2, which is reflected toward the light detection unit 560. In this embodiment, the visible light L2 is yellow light with a wavelength range from 550 nm to 600 nm. The wavelength range of the visible light L2 may be other wavelength ranges.

[0077] In this embodiment, visible light L2 is incident on the light detection unit 560. The light detection unit 560 detects the visible light L2 converted by the conversion member 568. In this embodiment, the light detection unit 560 is a photodiode that can detect the intensity of light having a wavelength of 500 nm or more and 650 nm or less. Although not shown in the figures, the light detection unit 560 is electrically connected to the life determination unit 73 (see FIG. 2). As a result, the control unit 70 is electrically connected to the light detection unit 560. The intensity of the visible light L2 detected by the light detection unit 560 is output to the life determination unit 73 as a light detection value D2(t).

[0078] As described above, the dichroic mirror 28 is disposed between the light detection unit 560 and the first liquid crystal panel 35B. This prevents the blue light LB emitted from the light source unit 20 from directly entering the light detection unit 560. Other configurations of the display device 510 of this embodiment are similar to those of the display device 10 of the first embodiment described above.

[0079] According to this embodiment, the display device 510 includes a liquid crystal panel 35, a conversion member 568 that converts the first detection light L1 emitted from the liquid crystal panel 35 when light in the first wavelength range W1 is incident on the liquid crystal panel 35, i.e., light in the infrared wavelength range Wi, into visible light L2, and a light detection unit 560 that detects the visible light L2. As described above, the conversion member 568 converts the first detection light L1, which is light in the infrared wavelength range Wi with low intensity, into visible light L2 with high intensity. This allows the light detection unit 560 to detect the visible light L2 with higher intensity than the first detection light L1. Therefore, the light detection unit 560 can sensitively detect fluctuations in the first detection light L1, the intensity of which increases as the deterioration state of the liquid crystal panel 35 progresses. Therefore, the life determination unit 73 can more accurately determine the deterioration state of the liquid crystal panel 35 based on the light detection value D2(t), thereby more appropriately improving the accuracy of determining the life of the liquid crystal panel 35. This allows maintenance of the display device 510, such as replacing the first liquid crystal panel 35B, to be performed in a more planned manner, and also makes it possible to more suitably prevent the quality of the image projected by the display device 510 from deteriorating.

[0080] According to the present embodiment, the display device 510 includes a dichroic mirror 28 that 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, i.e., the liquid crystal panel 35. The dichroic mirror 28 is disposed between the conversion member 568 and the liquid crystal panel 35. As described above, this prevents the blue light LB emitted from the light source unit 20 from directly entering the conversion member 568. This allows the light detection unit 560 to more accurately detect the light detection value D2(t), which is the intensity of visible light L2 that is lower in intensity than the blue light LB emitted from the light source unit 20. This more appropriately improves the accuracy of determining the deterioration state of the liquid crystal panel 35, and more appropriately improves the accuracy of determining the lifespan of the liquid crystal panel 35.

[0081] Furthermore, in this embodiment, as described above, the dichroic mirror 28 is disposed between the first liquid crystal panel 35B and each of the conversion member 568 and the light detection unit 560. This prevents the visible light L2 converted by the conversion member 568 from entering the liquid crystal panel 35. This prevents a decrease in the quality of the color image formed in the combining optical system 38. This prevents a decrease in the quality of the image projected by the display device 510.

[0082] (Fifth embodiment) A display device 610 according to the fifth embodiment will be described below. The basic configuration of the display device 610 of this embodiment is similar to that of the display device 510 of the fourth embodiment, and the display device 610 of this embodiment includes a filter 165. In the following description, the same components as those of the display device 510 of the fourth embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0083] FIG. 10 is a diagram schematically showing the configuration of a display device 610 according to this embodiment. As described above, the display device 610 includes the filter 165. The configuration of the filter 165 of this embodiment is similar to that of the filter 165 of the second embodiment described above. The filter 165 is a long-pass filter whose cut-on wavelength is between the first wavelength range W1 and the infrared wavelength range Wi. The filter 165 is disposed between the conversion member 568 and the first liquid crystal panel 35B. That is, the filter 165 is disposed between the conversion member 568 and the liquid crystal panel 35. This allows the filter 165 to prevent leakage of blue light LB and leakage of light from the light source from entering the conversion member 568. Other configurations of the display device 610 of this embodiment are similar to those of the display device 510 of the fourth embodiment described above.

[0084] According to this embodiment, the display device 610 includes a filter 165 having a cut-on wavelength between the first wavelength range W1 and the infrared wavelength range Wi, and the filter 165 is disposed between the conversion member 568 and the liquid crystal panel 35. As described above, the filter 165 can prevent leakage of blue light LB and leakage of light from the light source from entering the conversion member 568. This allows the light detection unit 560 to more accurately detect the light detection value D2(t), which is the intensity of visible light L2, which has a lower intensity than the blue light LB and the light source light. This can more accurately determine the deterioration state of the liquid crystal panel 35, and therefore more accurately determine the lifespan of the liquid crystal panel 35.

[0085] (Sixth embodiment) A display device 710 according to the sixth embodiment will be described below. The basic configuration of the display device 710 of this embodiment is similar to that of the display device 610 of the fifth embodiment, and in the display device 710 of this embodiment, a window 716 for emitting visible light L2 to the outside is provided in the case 715. In the following description, the same components as those in the display device 610 of the above-mentioned fifth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0086] Fig. 11 is a first diagram schematically illustrating the configuration of a display device 710 according to this embodiment. Fig. 12 is a second diagram schematically illustrating the configuration of a display device 710 according to this embodiment. 11, a display device 710 of this embodiment includes a liquid crystal panel 35, a conversion member 568, and a case 715. The configuration of the liquid crystal panel 35 of this embodiment is similar to the configuration of the liquid crystal panel 35 of the fifth embodiment described above.

[0087] As described above, the conversion member 568 shown in Fig. 12 converts the first detection light L1 emitted from the first liquid crystal panel 35B to the incident side of the first liquid crystal panel 35B when blue light LB, i.e., light in the first wavelength range W1, is incident on the first liquid crystal panel 35B, into visible light L2. As shown in Fig. 11, the conversion member 568 converts the first detection light L1 incident on the conversion member 568 into visible light L2 and reflects the visible light L2 upward (to the +Z side). Other configurations of the conversion member 568 of this embodiment are similar to those of the conversion member 568 of the fifth embodiment described above.

[0088] The case 715 is a hollow box-like structure that houses the components of the display device 710, such as the liquid crystal panel 35 and the conversion member 568. A window 716 is provided in the upper part of the case 715. In this embodiment, the window 716 is made of a translucent resin material. The window 716 transmits light in the vertical direction. Visible light L2 reflected upward by the conversion member 568 enters the window 716. The visible light L2 that enters the window 716 passes through the window 716 and is emitted to the outside of the case 715. As a result, the window 716 emits the visible light L2 to the outside. Other configurations of the display device 710 of this embodiment are similar to those of the display device 610 of the above-mentioned fifth embodiment.

[0089] According to this embodiment, the display device 710 includes a liquid crystal panel 35, a conversion member 568 that converts first detection light L1 emitted from the liquid crystal panel 35 when light in the first wavelength range W1 is incident on the liquid crystal panel 35, i.e., light in the infrared wavelength range Wi, into visible light L2, and a case 715 that houses the liquid crystal panel 35 and the conversion member 568. A window 716 that emits the visible light L2 to the outside is provided at the top of the case 715. As described above, the intensity of the first detection light L1 emitted from the liquid crystal panel 35 increases as the deterioration of the liquid crystal panel 35 progresses. Therefore, as the deterioration of the liquid crystal panel 35 progresses, the intensity of the visible light L2 emitted from the window 716 increases. Therefore, a user of the display device 710 can recognize the deterioration state of the liquid crystal panel 35 based on the intensity of the visible light L2 emitted from the window 716. Therefore, a user or the like can systematically perform maintenance of the display device 710, such as replacing the first liquid crystal panel 35B, based on the intensity of the visible light L2 emitted from the window portion 716. This makes it possible to preferably prevent a decrease in the quality of the image projected by the display device 710.

[0090] Furthermore, in this embodiment, since the window 716 is provided in the upper part of the case 715, the user can easily view the visible light L2 emitted to the outside through the window 716. Therefore, the user can more systematically perform maintenance of the display device 710, such as replacing the first liquid crystal panel 35B, based on the intensity of the visible light L2 emitted from the window 716.

[0091] In a typical display device 710, components constituting the display device 710, such as a power supply that supplies power to the light source unit 20 and the like, and a control board that controls the operation of the light source unit 20 and the liquid crystal panel 35, are arranged horizontally around the light source unit 20, the color separation optical system 22, and the liquid crystal panel 35. As described above, in this embodiment, the conversion member 568 reflects visible light L2 upward, and the window 716 is provided at the top of the case 715. Therefore, in this embodiment, it is easy to avoid arranging components such as the power supply and the control board between the conversion member 568 and the window 716. This makes it easy to avoid additional optical components such as mirrors that prevent interference between the components such as the power supply and the control board and the visible light L2. This makes it possible to avoid an increase in the number of components and manufacturing costs of the display device 710.

[0092] (Seventh embodiment) A display device 810 according to the seventh embodiment will be described below. The display device 810 of this embodiment is a projection type display device that displays a full-color image on a projection target 90 such as a screen. The display device 810 is a display device that includes only one liquid crystal panel 835. 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.

[0093] FIG. 13 is a diagram schematically illustrating the configuration of a display device 810 according to this embodiment. FIG. 14 is a diagram schematically illustrating a liquid crystal panel 835 according to this embodiment. FIG. 15 is a diagram illustrating the intensity distribution of the light source light and the first detection light L1 according to this embodiment. As shown in FIG. 13, the display device 810 includes a light source unit 820, a color separation optical system 822, a microlens array 834, a liquid crystal panel 835, a projection optical system 839, a light detection unit 60, and a filter 865. Although not shown, the display device 810 also includes a control unit 70 and an alarm unit 74. The configurations of the control unit 70 and the alarm unit 74 according to this embodiment are similar to those of the control unit 70 and the alarm unit 74 according to the first embodiment.

[0094] The light source unit 820 is a white light source configured with a light emitting diode (LED). The light source unit 820 may be a white light source configured with an array light source having a semiconductor laser, a light source unit including a wavelength conversion member, a lamp unit having a halogen lamp, or the like. The light source light emitted from the light source unit 820 is incident on the color separation optical system 822. In this embodiment, the wavelength range of the light source light is the visible light region from 400 nm to 700 nm.

[0095] The color separation optical system 822 separates the light source light into three primary color lights of red (R), green (G), and blue (B). The color separation optical system 822 includes three dichroic mirrors 826, 827, and 828. The dichroic mirrors 826, 827, and 828 are arranged so that their incident surfaces face at different angles relative to the direction in which the light source light is incident.

[0096] Dichroic mirror 826 reflects blue light LB and transmits light with longer wavelengths than blue light LB. The blue light LB reflected by dichroic mirror 826 is incident on liquid crystal panel 835. That is, light in the first wavelength range W1 is incident on liquid crystal panel 835. The light that has transmitted through dichroic mirror 826 is incident on dichroic mirror 827.

[0097] The dichroic mirror 827 reflects the red light LR and transmits light with a shorter wavelength than the red light LR, which in this embodiment is green light LG. The red light LR reflected by the dichroic mirror 827 passes through the dichroic mirror 826 and enters the liquid crystal panel 835. That is, light in a third wavelength range W3, which has a longer wavelength than the first wavelength range W1, enters the liquid crystal panel 835. The green light LG transmitted through the dichroic mirror 827 enters the dichroic mirror 828.

[0098] Dichroic mirror 828 reflects green light LG. The green light LG reflected by dichroic mirror 828 passes through dichroic mirrors 827 and 826 and enters liquid crystal panel 835. That is, light in a second wavelength range W2, which has a longer wavelength than the first wavelength range W1, enters liquid crystal panel 835.

[0099] As described above, the dichroic mirrors 826, 827, and 828 are arranged so that the incident surfaces face at different angles relative to the direction in which the light from the light source is incident. As a result, light in the first wavelength range W1, light in the second wavelength range W2 having a longer wavelength than the first wavelength range W1, and light in the third wavelength range W3 having a longer wavelength than the first wavelength range W1 are incident on the liquid crystal panel 835 at different angles.

[0100] The microlens array 834 is disposed on the incident side of the liquid crystal panel 835. Blue light LB, green light LG, and red light LR are incident on the microlens array 834 at different angles. As shown in FIG. 14 , the microlens array 834 has a plurality of microlenses 834a. Although not shown, each microlens 834a is a lens extending in the Z-axis direction. Each microlens 834a is disposed along the X-axis direction. In this embodiment, the X-axis direction is perpendicular to the Z-axis direction. The blue light LB incident on the microlens array 834 is condensed by each microlens 834a into a blue light beam extending in the Z-axis direction within the liquid crystal panel 835. The red light LR incident on the microlens array 834 is condensed by each microlens 834a into a red light beam extending in the Z-axis direction within the liquid crystal panel 835. The red light beam is condensed at a position shifted in the X-axis direction from the blue light beam. The green light LG incident on the microlens array 834 is condensed by each microlens 834a into a green light beam extending in the Z-axis direction inside the liquid crystal panel 835. The green light beam is condensed at a position shifted in the X-axis direction from each of the blue light beam and the red light beam.

[0101] 13, liquid crystal panel 835 modulates incident light and emits the modulated light to projection optical system 839. Although not shown, in this embodiment, an incident-side polarization separation element is arranged on the incident side of liquid crystal panel 835, and an exit-side polarization separation element is arranged on the exit side of liquid crystal panel 835. As shown in FIG. 14, liquid crystal panel 835 has a pair of glass substrates 835a and 835b, a scanning electrode 835c, a liquid crystal layer 835d, a signal electrode 836, and a drive circuit (not shown).

[0102] Each of the pair of glass substrates 835a, 835b is made of light-transmitting glass. The glass substrates 835a, 835b face each other with a gap in the Y-axis direction. The glass substrate 835a is disposed closer to the incident side than the glass substrate 835b. In this embodiment, the Y-axis direction is perpendicular to both the X-axis direction and the Z-axis direction. A liquid crystal layer 835d is sealed between the pair of glass substrates 835a, 835b.

[0103] The scanning electrodes 835c are provided on the surface of the glass substrate 835a facing the light-emitting side. In this embodiment, the scanning electrodes 835c are made of, for example, a transparent conductive film.

[0104] The signal electrode 836 is provided on the surface of the glass substrate 835b facing the incident side. In this embodiment, the signal electrode 836 is formed of, for example, a transparent conductive film. In this embodiment, the liquid crystal panel 835 has a plurality of signal electrodes 836. The signal electrodes 836 are arranged at intervals along each of the X-axis direction and the Z-axis direction. The plurality of signal electrodes 836 include a first signal electrode 836B, a second signal electrode 836G, and a third signal electrode 836R. One second signal electrode 836G and one third signal electrode 836R are arranged between a pair of first signal electrodes 836B in each of the X-axis direction and the Z-axis direction. One first signal electrode 836B and one third signal electrode 836R are arranged between a pair of second signal electrodes 836G in each of the X-axis direction and the Z-axis direction. In each of the X-axis direction and the Z-axis direction, one first signal electrode 836B and one second signal electrode 836G are disposed between a pair of third signal electrodes 836R.

[0105] A blue light beam is collected on each first signal electrode 836B. Blue light LB is transmitted through the first signal electrode 836B. A green light beam is collected on each second signal electrode 836G. Green light LG is transmitted through the second signal electrode 836G. A red light beam is collected on each third signal electrode 836R. Red light LR is transmitted through the third signal electrode 836R.

[0106] When a drive signal is applied to the signal electrodes 836 and the scanning electrodes 835c, the tilt of the liquid crystal molecules in the liquid crystal layer 835d changes due to the electric field generated between the signal electrodes 836 and the scanning electrodes 835c. A drive circuit (not shown) supplies each signal electrode 836 with an image signal VD that specifies the grayscale level to be displayed by each signal electrode 836 based on a control signal CLT supplied from a timing signal generator. As a result, the liquid crystal elements included in the liquid crystal layer 835d are driven with a voltage corresponding to the image signal VD, and light incident on the liquid crystal panel 835 is modulated in the liquid crystal layer 835d. More specifically, the drive circuit supplies an image signal VDB of a blue image to each first signal electrode 836B. As a result, blue light LB incident on the liquid crystal panel 835 is modulated in the liquid crystal layer 835d. The drive circuit supplies an image signal VDG of a green image to each second signal electrode 836G. As a result, green light LG incident on the liquid crystal panel 835 is modulated in the liquid crystal layer 835d. The drive circuit supplies an image signal VDR of a red image to each third signal electrode 836R. As a result, the red light LR incident on the liquid crystal panel 835 is modulated in the liquid crystal layer 835d. The blue light LB, green light LG, and red light LR modulated in the liquid crystal layer 835d are each emitted to the projection optical system 839.

[0107] 13, light of each color modulated by the liquid crystal panel 835 is incident on the projection optical system 839. The projection optical system 839 combines and outputs the light in the first wavelength range W1, i.e., blue light LB, the light in the second wavelength range W2, i.e., green light LG, and the light in the third wavelength range W3, i.e., red light LR, which have been modulated by the liquid crystal panel 835. The combined image formed by the projection optical system 839 is projected onto a projection target 90 such as a screen. As a result, a color image is projected onto the projection target 90.

[0108] The light detection unit 60 detects the first detection light L1 emitted from the liquid crystal panel 835 to the incident side of the liquid crystal panel 835. In this embodiment, the light detection unit 60 detects the first detection light L1 that has passed through the microlens array 834. The first detection light L1 is radiation light in the infrared wavelength range Wi that is emitted from the liquid crystal panel 835 when blue light LB, green light LG, and red light LR are incident on the liquid crystal panel 835. As in the first embodiment described above, the first detection light L1 in this embodiment is radiation light in the infrared wavelength range Wi, which has a longer wavelength than the first wavelength range W1. As described above, the infrared wavelength range Wi is longer than each of the first wavelength range W1, the second wavelength range W2, and the third wavelength range W3. The light detection unit 60 detects the intensity of the first detection light L1. In this embodiment, the light detection unit 60 is a photodiode that can detect the intensity of light in the infrared wavelength range Wi, which has a wavelength of 700 nm or more and 800 nm or less. Other configurations of the light detection unit 60 of this embodiment are similar to other configurations of the light detection unit 60 of the first embodiment described above. Although not shown, the light detection unit 60 is electrically connected to a life determination unit 73 (see FIG. 2). In other words, the control unit 70 is electrically connected to the light detection unit 60. The intensity of the first detection light L1 detected by the light detection unit 60 is output to the life determination unit 73 as a light detection value D1(t).

[0109] The filter 865 is a long-pass filter whose cut-on wavelength is between the third wavelength band W3 and the infrared wavelength band Wi. The cut-on wavelength of the filter 865 is, for example, 700 nm. The filter 865 allows the first detection light L1, which is light in the infrared wavelength band Wi, to pass through, while preventing the light source light, blue light LB, green light LG, and red light LR from passing through. The filter 865 is disposed between the liquid crystal panel 835 and the photodetector 60. This allows the filter 865 to prevent leakage of the light source light from entering the photodetector 60. The filter 865 also prevents leakage of the blue light LB, green light LG, and red light LR from entering the photodetector 60.

[0110] FIG. 15 is a diagram showing the intensity distribution of the source light and the first detection light L1 in this embodiment. Next, the intensity distributions of the source light and the first detection light L1 in this embodiment will be described. The horizontal axis of Fig. 15 represents the measurement wavelength, and the vertical axis represents the light intensity. The spectrum Ls of the source light is shown by a dashed line, and the spectrum La(T) of the first detection light L1 at the point when the integrated irradiation time t of the source light on the liquid crystal panel 835 reaches T is shown by a solid line.

[0111] As described above, in this embodiment, the wavelength range of the light source light is the visible light range from 400 nm to 700 nm. More specifically, the light source light has a steep peak intensity at a wavelength near 470 nm. The light source light also has a broad peak in a wavelength range centered around 570 nm. The intensity of the light source light in the wavelength range of 700 nm or more is very small. That is, the intensity of the light source light in the infrared wavelength range Wi is very small.

[0112] As described above, the first detection light L1 is light in the infrared wavelength range Wi having a wavelength of 700 nm or more and 800 nm or less. In the infrared wavelength range Wi, the intensity of the first detection light L1 is greater than the intensity of the light source light. As described above, the light detection unit 60 is a photodiode capable of detecting the intensity of light in the infrared wavelength range Wi having a wavelength of 700 nm or more and 800 nm or less. Therefore, even if leakage light of the light source light enters the light detection unit 60, the influence on the light detection value D1(t), which is the intensity of the first detection light L1 detected by the light detection unit 60, can be reduced. Other configurations of the display device 810 of this embodiment are similar to those of the display device 10 of the first embodiment described above.

[0113] According to this embodiment, the display device 810 includes a liquid crystal panel 835 and a light detection unit 60 that detects first detection light L1, i.e., light in the infrared wavelength range Wi, emitted from the liquid crystal panel 835 when light in the first wavelength range W1, light in the second wavelength range W2, and light in the third wavelength range W3 are incident on the liquid crystal panel 835. Therefore, as in the first embodiment, the life determination unit 73 can determine the deterioration state of the liquid crystal panel 835 based on the light detection value D1(t). Therefore, in a display device 810 that includes only one liquid crystal panel 835, the accuracy of determining the life of the liquid crystal panel 835 can be improved. Therefore, maintenance of the display device 810, such as replacing the liquid crystal panel 835, can be performed in a planned manner, and degradation of the quality of images projected by the display device 810 can be suppressed.

[0114] Furthermore, in this embodiment, as described above, the intensity of the first detection light L1 is greater than the intensity of the light source light in the infrared wavelength range Wi. Furthermore, as described above, the light detection unit 60 is a photodiode that can detect the intensity of light in the infrared wavelength range Wi. Therefore, as described above, even if leakage light of the light source light enters the light detection unit 60, the influence on the light detection value D1(t) can be reduced. This makes it possible to more suitably improve the accuracy of determining the deterioration state of the liquid crystal panel 835 in a display device 810 that includes only one liquid crystal panel 835, and therefore more suitably improve the accuracy of determining the lifespan of the liquid crystal panel 835.

[0115] According to this embodiment, the display device 810 includes a projection optical system 839, in which light in a first wavelength range W1, light in a second wavelength range W2 having a wavelength longer than the first wavelength range W1, and light in a third wavelength range W3 having a wavelength longer than the first wavelength range W1 are incident on the liquid crystal panel 835 at different angles, the projection optical system 839 combines the light in the first wavelength range W1, the light in the second wavelength range W2, and the light in the third wavelength range W3 modulated by the liquid crystal panel 835, and outputs the combined light, and the infrared wavelength range Wi has a wavelength longer than the first wavelength range W1, the second wavelength range W2, and the third wavelength range W3. Therefore, even if leakage light of the blue light LB, the green light LG, and the red light LR enters the photodetector 60, the influence on the photodetection value D1(t) can be reduced. This makes it possible to more suitably improve the accuracy of determining the deterioration state of the liquid crystal panel 835 in a display device 810 that includes only one liquid crystal panel 835, thereby more suitably improving the accuracy of determining the lifespan of the liquid crystal panel 835.

[0116] According to this embodiment, the display device 810 includes a filter 865 having a cut-on wavelength between the third wavelength band W3 and the infrared wavelength band Wi, and the filter 865 is disposed between the liquid crystal panel 835 and the photodetector 60. As described above, the filter 865 can prevent leakage of blue light LB, leakage of green light LG, leakage of red light LR, and leakage of light from the light source from entering the photodetector 60. This allows the photodetector 60 to more accurately detect the photodetection value D1(t), which is the intensity of the first detection light L1, which is lower than the intensity of the light source light, blue light LB, green light LG, and red light LR. Therefore, in a display device 810 including only one liquid crystal panel 835, the accuracy of determining the deterioration state of the liquid crystal panel 835 can be more appropriately improved, and the accuracy of determining the lifespan of the liquid crystal panel 835 can be more appropriately improved.

[0117] (Eighth embodiment) A display device 910 according to the eighth embodiment will be described below. The basic configuration of the display device 910 of this embodiment is similar to that of the display device 810 of the seventh embodiment, and the display device 910 of this embodiment includes a conversion member 968 and a case 915. In the following description, the same components as those of the display device 810 of the seventh embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0118] Fig. 16 is a first diagram schematically illustrating the configuration of a display device 910 according to this embodiment. Fig. 17 is a second diagram schematically illustrating the configuration of a display device 910 according to this embodiment. 16, a display device 910 of this embodiment includes a liquid crystal panel 835, a conversion member 968, and a case 915. The configuration of the liquid crystal panel 835 of this embodiment is similar to the configuration of the liquid crystal panel 835 of the seventh embodiment described above.

[0119] 17 converts first detection light L1 emitted when blue light LB, green light LG, and red light LR are incident on the liquid crystal panel 835 into visible light L2. The conversion member 968 converts the first detection light L1 incident on the conversion member 968 into visible light L2 and reflects the visible light L2 upward. In this embodiment, the visible light L2 is yellow light having a wavelength range of 550 nm to 600 nm. Other configurations of the conversion member 968 of this embodiment are similar to those of the conversion member 568 of the fifth embodiment described above.

[0120] A filter 865 is disposed between the conversion member 968 and the liquid crystal panel 835. This makes it possible to prevent leakage of blue light LB, leakage of green light LG, leakage of red light LR, and leakage of light source light from entering the conversion member 968. The first detection light L1 that has passed through the filter 865 is incident on the conversion member 968.

[0121] As shown in FIG. 16 , the case 915 is a hollow box that houses the components of the display device 910, such as the liquid crystal panel 835 and the conversion member 968. A window 916 is provided in the upper part of the case 915. In this embodiment, the window 916 is made of a translucent resin material. The window 916 transmits light in the vertical direction. Visible light L2 reflected upward by the conversion member 968 enters the window 916. The visible light L2 that enters the window 916 passes through the window 916 and is emitted to the outside of the case 915. As a result, the window 916 emits the visible light L2 to the outside. Other configurations of the display device 910 of this embodiment are similar to those of the display device 610 of the above-described fifth embodiment.

[0122] According to this embodiment, the display device 910 includes a liquid crystal panel 835, a conversion member 968 that converts first detection light L1 emitted from the liquid crystal panel 835 when light in a first wavelength range W1, a second wavelength range W2, and a third wavelength range W3 is incident on the liquid crystal panel 835, i.e., light in the infrared wavelength range Wi, into visible light L2, and a case 915 that houses the liquid crystal panel 835 and the conversion member 968. A window 916 that emits the visible light L2 to the outside is provided at the top of the case 915. This allows a user of the display device 910 to recognize the deterioration state of the liquid crystal panel 835 based on the intensity of the visible light L2 emitted from the window 916. Therefore, in a display device 910 that includes only one liquid crystal panel 835, the user can systematically perform maintenance of the display device 910, such as replacing the liquid crystal panel 835, and can effectively prevent a deterioration in the quality of images projected by the display device 910.

[0123] Furthermore, in this embodiment, the window 916 is provided in the upper part of the case 915, so that the user can easily see the visible light L2 emitted to the outside through the window 916. Therefore, the user can more systematically perform maintenance of the display device 910, such as replacing the liquid crystal panel 835, based on the intensity of the visible light L2 emitted from the window 916.

[0124] A summary of this disclosure is provided below.

[0125] (Appendix 1) A display device comprising: a liquid crystal panel; and a light detection unit that detects light in an infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel.

[0126] According to the display device having the configuration of Supplementary Note 1, the light detection value detected by the light detection unit is the intensity of the first detection light, which correlates with the deterioration state of the liquid crystal panel. Therefore, the life determination unit can determine the deterioration state of the liquid crystal panel based on the light detection value, thereby improving the accuracy of determining the life of the liquid crystal panel.

[0127] (Appendix 2) A display device comprising: a liquid crystal panel; a conversion member that converts light in the infrared wavelength range emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel into visible light; and a light detection unit that detects the visible light.

[0128] According to the display device having the configuration of Supplementary Note 2, the conversion member converts the first detection light, which is light in the infrared wavelength range with low intensity, into visible light with high intensity. This allows the light detection unit to detect visible light with a higher intensity than the first detection light. Therefore, the light detection unit can sensitively detect fluctuations in the first detection light, which increases in intensity as the deterioration state of the liquid crystal panel progresses. Therefore, the life determination unit can more accurately determine the deterioration state of the liquid crystal panel based on the light detection value, thereby more appropriately improving the accuracy of determining the life of the liquid crystal panel.

[0129] (Appendix 3) A display device comprising: a liquid crystal panel; a conversion member that converts light in the infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel into visible light; and a case that houses the liquid crystal panel and the conversion member, wherein a window portion is provided at the top of the case to emit the visible light to the outside.

[0130] According to the display device having the configuration of Supplementary Note 3, a user of the display device can recognize the deterioration state of the liquid crystal panel based on the intensity of the visible light emitted from the window. Therefore, the user can systematically perform maintenance of the display device, such as replacing the first liquid crystal panel, based on the intensity of the visible light emitted from the window, and can effectively prevent a deterioration in the quality of the image projected by the display device.

[0131] (Appendix 4) 3. 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 liquid crystal panel, and the dichroic mirror is disposed between the light detection unit and the liquid crystal panel.

[0132] This configuration can prevent the light in the first wavelength range emitted from the light source from directly entering the light detector. Therefore, the light detector can more accurately detect the light detection value, which is the intensity of the first detection light, which is lower than the intensity of the light in the first wavelength range emitted from the light source. This can more accurately improve the accuracy of determining the deterioration state of the liquid crystal panel, and therefore the accuracy of determining the lifespan of the liquid crystal panel.

[0133] (Appendix 5) 3. The display device according to claim 1, wherein the light detection unit is disposed on a side of the liquid crystal panel.

[0134] This configuration allows the light detection unit to be located closer to the liquid crystal panel. Therefore, the light detection unit can more accurately detect the intensity of the first detection light, which has a low intensity. This can more effectively improve the accuracy of determining the deterioration state of the liquid crystal panel, and therefore the accuracy of determining the lifespan of the liquid crystal panel.

[0135] (Appendix 6) 5. The display device according to claim 1, further comprising a filter having a cut-on wavelength between the first wavelength range and the infrared wavelength range, the filter being disposed between the liquid crystal panel and the light detection unit.

[0136] According to this configuration, the filter can prevent leakage light of the light in the first wavelength range and leakage light of the light source light from entering the light detection unit. Therefore, the light detection unit can more accurately detect the intensity of the first detection light, which is weaker than the light in the first wavelength range and the light source light. This can more accurately determine the deterioration state of the liquid crystal panel, thereby more accurately determining the lifespan of the liquid crystal panel.

[0137] (Appendix 7) The display device described in Appendix 3 includes a dichroic mirror that guides light in the first wavelength range, out of the light emitted from a light source unit, to the liquid crystal panel, and the dichroic mirror is arranged between the conversion member and the liquid crystal panel.

[0138] This configuration prevents the light in the first wavelength range emitted from the light source from being directly incident on the conversion member. Therefore, the light detection unit can more accurately detect the light detection value, which is the intensity of visible light that is lower than the intensity of the light in the first wavelength range emitted from the light source. This can more effectively improve the accuracy of determining the deterioration state of the liquid crystal panel, and therefore the accuracy of determining the lifespan of the liquid crystal panel.

[0139] (Appendix 8) 8. The display device according to claim 3 or 7, further comprising a filter having a cut-on wavelength between the first wavelength range and the infrared wavelength range, the filter being disposed between the conversion member and the liquid crystal panel.

[0140] According to this configuration, the filter can prevent leakage light of the first wavelength range and leakage light of the light source light from entering the conversion member. Therefore, the light detection unit can more accurately detect the light detection value, which is the intensity of visible light that is lower than the intensity of the light of the first wavelength range and the light source light. This can more accurately determine the deterioration state of the liquid crystal panel, thereby more accurately determining the lifespan of the liquid crystal panel.

[0141] (Appendix 9) 9. The display device according to claim 1, wherein the light in the first wavelength range is light in a blue wavelength range.

[0142] This configuration allows for a large difference between the wavelength range of the first detection light in the infrared wavelength range and the wavelength range of the light in the first wavelength range, making it easier to separate the first detection light from the light in the first wavelength range using the dichroic mirror. This more effectively prevents the light in the first wavelength range emitted from the light source from directly entering the light detection unit. This more effectively improves the accuracy of determining the deterioration state of the liquid crystal panel, thereby more effectively improving the accuracy of determining the lifespan of the liquid crystal panel.

[0143] (Appendix 10) 10. The display device according to claim 1, further comprising a synthesizing optical system, wherein the liquid crystal panels include a first liquid crystal panel onto which light in the first wavelength range is incident, a second liquid crystal panel onto which light in a second wavelength range having a longer wavelength than the first wavelength range is incident, and a third liquid crystal panel onto which light in a third wavelength range having a longer wavelength than the first wavelength range is incident, and the synthesizing optical system synthesizes and outputs 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.

[0144] 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 the life determination unit determines that the first liquid crystal panel has reached the end of its life, the second and third liquid crystal panels can be replaced along with the first liquid crystal panel, thereby preventing a deterioration in the quality of the color image formed in the composite optical system.

[0145] (Appendix 11) a projection optical system, wherein light in the first wavelength range, light in a second wavelength range having a wavelength longer than the first wavelength range, and light in a third wavelength range having a wavelength longer than the second wavelength range are incident on the liquid crystal panel at angles different from one another, and the projection optical system combines the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range modulated by the liquid crystal panel and emits the combined light; 10. The display device according to any one of Supplementary Note 1 to Supplementary Note 9, wherein the infrared wavelength range is longer than each of the first wavelength range, the second wavelength range, and the third wavelength range.

[0146] This configuration reduces the influence on the photodetection value even when leakage light of the first wavelength range, leakage light of the second wavelength range, and leakage light of the third wavelength range are incident on the photodetector, thereby more appropriately improving the accuracy of determining the deterioration state of the liquid crystal panel in a display device equipped with only one liquid crystal panel, and more appropriately improving the accuracy of determining the lifespan of the liquid crystal panel.

[0147] (Appendix 12) A control method for a display device comprising a liquid crystal panel, a photodetector that detects light in the infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel, a control unit electrically connected to the photodetector, and an alarm that notifies the lifespan of the liquid crystal panel, the control method including: a lifespan determination step in which the control unit determines the lifespan of the liquid crystal panel based on a photodetection value detected by the photodetector; and an alarm step in which the alarm unit notifies the lifespan of the liquid crystal panel when the lifespan of the liquid crystal panel is determined.

[0148] According to the display device control method having this configuration, in the lifespan determination step, the lifespan determination unit can accurately determine the deterioration state of the liquid crystal panel based on the light detection value, thereby enabling the lifespan determination unit to accurately determine the lifespan of the liquid crystal panel. [Explanation of symbols]

[0149] 10,110,210,310,410,510,610,710,810,910...display device, 20,820...light source unit, 28...dichroic mirror, 35,835...liquid crystal panel, 35B...first liquid crystal panel, 35G...second liquid crystal panel, 35R...third liquid crystal panel, 38...combining optical system, 60,560...light detection unit, 70...control unit, 74...alarm unit, 165,865...filter, 568,968...conversion member, 715,915...case, 716,916 window unit, 839...projection optical system, L1...first detected light (light in the infrared wavelength range), L2...visible light, S02...life determination step, S03...alarm step.

Claims

1. An LCD panel, a light detection unit that detects light in an infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel; Equipped with Display device.

2. An LCD panel, a conversion member that converts light in an infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel into visible light; a light detection unit that detects the visible light, Display device.

3. An LCD panel, a conversion member that converts light in an infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel into visible light; a case that houses the liquid crystal panel and the conversion member, A window portion for emitting the visible light to the outside is provided at the top of the case. Display device.

4. a dichroic mirror that guides light in the first wavelength range, out of light emitted from a light source unit, to the liquid crystal panel; the dichroic mirror is disposed between the light detection unit and the liquid crystal panel; 3. The display device according to claim 1 or 2.

5. The light detection unit is disposed on a side of the liquid crystal panel.

3. The display device according to claim 1 or 2.

6. a filter having a cut-on wavelength between the first wavelength range and the infrared wavelength range; the filter is disposed between the liquid crystal panel and the light detection unit.

3. The display device according to claim 1 or 2.

7. a dichroic mirror that guides light in the first wavelength range, out of light emitted from a light source unit, to the liquid crystal panel; the dichroic mirror is disposed between the conversion member and the liquid crystal panel; The display device according to claim 3 .

8. a filter having a cut-on wavelength between the first wavelength range and the infrared wavelength range; The filter is disposed between the conversion member and the liquid crystal panel. The display device according to claim 3 or 7.

9. The light in the first wavelength range is light in a blue wavelength range. The display device according to claim 1 .

10. Equipped with a synthetic optical system, The liquid crystal panel is a first liquid crystal panel onto which light in the first wavelength range is incident; 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; Including, the combining optical system 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 emits the combined light. The display device according to claim 1 .

11. A projection optical system is provided, light in the first wavelength range, light in a second wavelength range having a wavelength longer than the first wavelength range, and light in a third wavelength range having a wavelength longer than the second wavelength range are incident on the liquid crystal panel at angles different from one another; the projection optical system combines the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range modulated by the liquid crystal panel and emits the combined light; the infrared wavelength range is longer than the first wavelength range, the second wavelength range, and the third wavelength range; The display device according to claim 1 .

12. A control method for a display device including a liquid crystal panel, a light detection unit that detects light in an infrared wavelength range that is emitted from the liquid crystal panel when light in a first wavelength range is incident on the liquid crystal panel, a control unit that is electrically connected to the light detection unit, and a notification unit that notifies the user of a lifespan of the liquid crystal panel, a lifespan determination step in which the control unit determines a lifespan of the liquid crystal panel based on a light detection value detected by the light detection unit; a notification step in which, when the life of the liquid crystal panel is determined, the notification unit notifies the user of the life of the liquid crystal panel; Including, A method for controlling a display device.

Images