Projector

Abstract

To suppress the occurrence of illuminance unevenness in a projection image in a projector.SOLUTION: A projector according to an aspect of the invention includes a light source apparatus that periodically outputs first light, a light scanning apparatus that periodically scans the first light outputted from the light source apparatus, a light modulator that modulates the first light outputted from the light scanning apparatus in accordance with image information, and a projection system that projects image light outputted from the light modulator. The light modulator includes a liquid crystal element that converts the first light into image light in accordance with inputted image information. A modulation period in which the first light is modulated in the liquid crystal layer of the liquid crystal element includes a first period from a time when the electric signal is input to a time when a modulation amount changes to a predetermined value, and a second period in which the refractive index is held at the predetermined value. The first light outputted from the light source apparatus is incident on the light modulator in the second period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a projector. [Background technology]

[0002] As a projector, which is an image display device, a device has been proposed in which illumination light emitted from a light source device is scanned temporally on the modulation surface of an optical modulation device such as a liquid crystal panel, thereby illuminating the optical modulation device with colored light, and the image light emitted from the optical modulation device is projected onto a projection surface such as a screen using a projection optical system.

[0003] For example, Patent Document 1 discloses a projector including a light source lamp that emits illumination light, a liquid crystal display element, a fly's eye lens that irradiates the illumination light onto some pixels of the liquid crystal display element, a superimposing lens, a collimating lens, and a rotating prism that scans the illumination light to illuminate the liquid crystal display element. Patent Document 1 discloses that the rotating prism scans the illumination light in synchronization with the period in which information for modulating the illumination light is input to the pixels of the liquid crystal display element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-325576 Summary of the Invention [Problem to be solved by the invention]

[0005] In the projector disclosed in the aforementioned Patent Document 1, the illuminance of one or more colored lights may increase or decrease more than expected during the period from when the liquid crystal on the modulation surface of the liquid crystal display element starts to rise until it finishes rising, and during the period from when the liquid crystal starts to fall until it finishes falling, which may cause uneven illuminance in the image projected onto a projection surface such as a screen. Therefore, measures to suppress uneven illuminance in the projected image are desired. [Means for solving the problem]

[0006] A projector according to one aspect of the present invention includes a light source device that periodically emits a first light, an optical scanning device that periodically scans the first light emitted from the light source device, an optical modulation device that modulates the first light emitted from the optical scanning device in accordance with image information, and a projection optical system that projects the image light emitted from the optical modulation device. The light source device includes a first light-emitting element that emits the first light. The optical scanning device includes a transmissive optical element having an incident surface onto which the first light emitted from the light source device is incident and an exit surface from which the first light incident from the incident surface exits. The optical modulation device includes a liquid crystal element that forms an image by converting the first light, which is irradiated along a first direction in accordance with input image information, into image light. The direction in which the optical scanning device scans the first light is the first direction. The optical scanning device scans the first light in synchronization with the drive cycle of the light source device and the image formation cycle of the optical modulation device. The liquid crystal element includes a liquid crystal layer whose modulation amount for the first light changes in accordance with an input electrical signal. The modulation period during which the first light is modulated in the liquid crystal layer includes a first period from the time when the electrical signal is input to the time when the modulation amount changes to a predetermined value, and a second period during which the refractive index is maintained at a predetermined value. The first light emitted from the light source device is incident on the light modulation device during the second period. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a projector according to a first embodiment. [Figure 2] 2 is a schematic diagram for explaining the behavior of the optical scanning device of the projector in FIG. 1. FIG. [Figure 3] 2 is a schematic diagram for explaining the behavior of the optical scanning device of the projector in FIG. 1. FIG. [Figure 4] 2 is a schematic diagram for explaining the behavior of the optical scanning device of the projector in FIG. 1. FIG. [Figure 5] 2 is a time chart relating to the operation of a light source of the light source device and a liquid crystal panel of the light modulation device of the projector of FIG. [Figure 6]5 is a schematic diagram showing the timing of colored light emitted from each part of the projector in FIG. 4. [Figure 7] 2 is a schematic diagram showing an example of the distribution of color regions on a modulation surface of a light modulation device and in a projected image in the projector of FIG. 1. FIG. [Figure 8] 5 is another schematic diagram showing the timing of colored light emitted from each part of the projector in FIG. 4. [Figure 9] 1. FIG. 4 is another schematic diagram showing an example of the distribution of color regions on the modulation surface of the light modulation device and in the projected image in the projector of FIG. [Figure 10] 2 is a flowchart relating to control performed by a control unit of the projector in FIG. [Figure 11] FIG. 10 is another schematic diagram showing the timing of colored light emitted from each part of a conventional projector. [Figure 12] 10A and 10B are other schematic diagrams showing an example of the distribution of color regions on the modulation surface of a light modulation device and in a projected image in a conventional projector. [Figure 13] FIG. 10 is a schematic diagram of a projector according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the drawings referred to below, the scale of the dimensions of some components may be changed to make them easier to see.

[0009] [First embodiment] First, a first embodiment of the present invention will be described with reference to FIGS.

[0010] First, the basic configuration of a projector 201 according to a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram of the projector 201. The projector 201 is a single-panel image display device that includes one liquid crystal panel as a light modulation device. As shown in FIG. 1, the projector 201 includes a light source device 20, an optical scanning device 40, a light modulation device 60, a projection optical system 80, a light source output control device 110, a rotation control device 120, a drive control device 130, a central processing unit 140, a user interface 150, a video processing circuit 160, and a video interface 170.

[0011] The light source device 20 includes a light-emitting element 21 that emits white light WL and a collimating lens 26. The light-emitting element 21 corresponds to a first light-emitting element described in the claims below. The white light WL corresponds to a first light described below and includes red light, green light, and blue light. In the following description, the axis parallel to the optical axis AX and the principal ray of the white light WL emitted from the light-emitting element 21 is defined as the Z axis, one side parallel to the Z axis is defined as the -Z side, and the other side parallel to the Z axis is defined as the +Z side. An axis perpendicular to the Z axis is defined as the X axis, one side parallel to the X axis is defined as the -X side, and the other side parallel to the X axis is defined as the +X side. An axis perpendicular to the Z axis and the X axis is defined as the Y axis, one side parallel to the Y axis is defined as the -Y side, and the other side parallel to the X axis is defined as the +Y side.

[0012] The light emitting element 21 emits white light WL from the emission surface 21e toward the +Z side along the Z axis. The light emitting element 21 is, for example, a white laser diode (LD) or a white light emitting diode (LED).

[0013] The collimating lens 26 is disposed on the optical path of the white light WL emitted from the light-emitting element 21, and is disposed on the +Z side of the emission surface 21e of the light-emitting element 21. The central axis of the collimating lens 26 overlaps with the optical axis AX.

[0014] The collimating lens 26 converts the white light WL emitted from the light-emitting element 21 into parallel light parallel to the Z axis and emits it along the optical axis AX. The collimating lens 26 is, for example, a biconvex lens. The collimating lens 26 may also be a plano-convex lens having a flat entrance surface parallel to the XY plane including the X and Y axes and an exit surface that is convex on the +Z side. In FIG. 1, the collimating lens 26 is disposed away from the exit surface 21e of the light-emitting element 21, but if the collimating lens 26 is a plano-convex lens, the collimating lens 26 may be in contact with the exit surface 21e of the light-emitting element 21.

[0015] The optical scanning device 40 is disposed on the optical path of the white light WL emitted from the collimating lens 26 of the light source device 20, and is disposed on the +Z side of the collimating lens 26. The optical scanning device 40 scans the white light WL emitted from the light source device 20 within the XY plane.

[0016] The optical scanning device 40 has a light-transmitting member 42 and a rotating device such as a motor (not shown). The light-transmitting member 42 corresponds to a transmissive optical element (described later). The light-transmitting member 42 is disposed on the optical path of the white light WL emitted from the collimating lens 26 of the light source device 20, and is disposed on the +Z side of the collimating lens 26. The light-transmitting member 42 is formed in a cylindrical shape. The central axis JX of the light-transmitting member 42 is parallel to the X-axis and intersects with the optical axis AX or passes near the optical axis AX. The light-transmitting member 42 is a polygonal prism having the central axis JX.

[0017] The light-transmitting member 42 has two end faces 51, 52 that intersect the central axis JX and are parallel to a YZ plane that includes the Y and Z axes, and a plurality of side faces 54. The end faces 51, 52 correspond to the first faces described below and are relatively located on the +X side. The plurality of side faces 54 correspond to the incident face, exit face, and second face described below and are located on the -X side of the end face 51 and overlap with the end face 51 when viewed along the X axis. The end faces 51, 52 have a polygonal shape centered on the central axis JX.

[0018] The number of side surfaces 54 is the same as the number of corners and sides of end surfaces 51 and 52. Side surfaces 54 connect each of the multiple outer peripheral edge edges of end surface 51 to the outer peripheral edge edges of end surface 52 that overlap with the aforementioned outer peripheral edge edges when viewed along the X-axis.

[0019] The end faces 51 and 52 are, for example, regular quadrilaterals and have the same shape, size, and area. The light-transmitting member 42 has two end faces 51 and 52 and four side faces 54A, 54B, 54C, and 54D. The side faces 54A, 54B, 54C, and 54D have the same size and area. The size and area of ​​the side faces 54A, 54B, 54C, and 54D are appropriately larger than the irradiation area centered on the optical axis AX of the white light WL emitted from the collimating lens 26 of the light source device 20, depending on the scanning area of ​​the white light WL, as described below.

[0020] When viewed along the X-axis, the side surfaces 54A and 54C face each other across the central axis JX and are parallel to each other. The side surfaces 54B and 54D face each other across the central axis JX and are parallel to each other. In this specification, the two side surfaces 54 being parallel to each other means that the angle between the two side surfaces is within a range of 0° to 5°, taking into consideration the processing accuracy of the material of the light-transmitting member 42, the allowable range of parallelism of the white light WL, and the like.

[0021] The light-transmitting member 42 is disposed so as to be rotatable about a central axis JX. The central axis JX corresponds to the rotation axis CX of the light-transmitting member 42. While rotating about the rotation axis CX, the light-transmitting member 42 transmits white light WL that is incident from the -Z side along the Z axis and the optical axis AX and emits it to the +Z side.

[0022] In this specification, a state in which the light-transmitting member 42 rotates around the rotation axis CX may be referred to as a rotating state. In the rotating state of the light-transmitting member 42, the side surface 54 through which the white light WL emitted from the collimating lens 26 of the light source device 20 enters the light-transmitting member 42 is not fixed to one of the four side surfaces 54A, 54B, 54C, and 54D, but is one or two of the four side surfaces 54A, 54B, 54C, and 54D, and changes over time.

[0023] The number of side surfaces 54 in the light-transmitting member 42 is not limited to four, and is preferably 2×m, where m is a natural number greater than or equal to 2. If the number of side surfaces 54 is an even number greater than or equal to 4, all of the side surfaces 54 are parallel to the opposing side surfaces 54, which reduces the generation of stray light of the white light WL that passes through the light-transmitting member 42 and improves the light utilization efficiency of the projector 201.

[0024] The material of the light-transmitting member 42 is a material that is translucent to white light WL, and is, for example, any one of optical glass such as borosilicate crown glass BK7 or high-transparency crown glass B270, quartz, transparent resin, and the like.

[0025] The optical modulation device 60 is disposed on the optical path of the white light WL emitted from the light-transmitting member 42 of the optical scanning device 40 and in the area scanned by the white light WL, and is disposed on the +Z side of the light-transmitting member 42. The optical modulation device 60 has a modulation surface 64 parallel to the XY plane. The position, size, area, and shape of the modulation surface 64 on the XY plane are equivalent to the area that can be irradiated with the white light WL as the white light WL is scanned by the light-transmitting member 42, and are equivalent to the range in which an appropriate margin area is secured outside the irradiation area of ​​the white light WL on the XY plane.

[0026] The light modulation device 60 modulates white light WL incident from the -Z side by the optical scanning device 40 using an electrical signal input from the drive control device 130 as described below in accordance with image information of the projection target, and converts the light into image light IL. The light modulation device 60 is, for example, a transmissive liquid crystal panel 62. The liquid crystal panel 62 corresponds to a liquid crystal element as described below. The liquid crystal panel 62 constituting the light modulation device 60 has a plurality of pixels arranged two-dimensionally along the X-axis and Y-axis on the XY plane. The plurality of pixels of the liquid crystal panel 62 constitute a modulation surface 64.

[0027] The plurality of pixels of the liquid crystal panel 62 are equipped with switching elements. The switching elements are, for example, polysilicon thin film transistors (TFTs). White light WL incident on the plurality of pixels of the liquid crystal panel 62 includes red light, green light, and blue light, which constitute the three primary colors of light. The switching elements of each pixel are supplied with electrical signals from the drive control device 130 according to the brightness and light amount of the red light, green light, and blue light at the relative position of each pixel on the modulation surface 64 of the light modulation device 60 in the image to be projected by the projector 201.

[0028] Each pixel of the liquid crystal panel 62 modulates the vibration direction of each of the red light, green light, and blue light contained in the white light WL by the operation of a switching element in response to the above-mentioned electrical signal, generates red image light, green image light, and blue image light, and emits image light IL according to the light intensity ratio of the three colors. The light modulation device 60 emits the image light IL generated by the liquid crystal panel 62 to the +Z side along the optical axis AX and the Z axis.

[0029] Each pixel of the liquid crystal panel 62 has red, green, and blue color filters (not shown). Therefore, the light modulation device 60 emits full-color image light IL that can be generated by red image light, green image light, and blue image light. The projector 201 is capable of full-color display.

[0030] Note that each pixel of the liquid crystal panel 62 does not need to have a color filter. In that case, when any color light of red light, green light, or blue light is emitted from the light emitting element 21 of the light source device 20, the light modulation device 60 emits monochromatic image light IL corresponding to any of the aforementioned color lights. When each pixel of the liquid crystal panel 62 does not have a color filter, the projector 201 can display a monochromatic image.

[0031] The driving method of the liquid crystal panel 62 is not particularly limited, but may be, for example, a twisted nematic (TN) method, a vertical alignment (VA) method, or an in plane switching (IPS) method.

[0032] The projection optical system 80 is disposed on the optical path of the image light IL emitted from the liquid crystal panel 62 of the light modulation device 60, and is disposed on the +Z side of the liquid crystal panel 62. The projection optical system 80 enlarges and projects the image light IL generated by the light modulation device 60 onto a projection surface such as a screen. The projection optical system 80 is composed of multiple optical lenses disposed along the Z axis. The optical lenses include, for example, plano-convex lenses, plano-concave lenses, biconvex lenses, biconcave lenses, meniscus lenses, aspherical lenses, and free-form surface lenses.

[0033] An exit-side polarizing plate (not shown) may be disposed on the optical path of the image light IL between the light modulation device 60 and the projection optical system 80. The exit-side polarizing plate transmits specific linearly polarized light of the image light IL exiting from the light modulation device 60, and absorbs or reflects polarized light components other than the specific linearly polarized light. If an absorptive polarizing plate is used as the exit-side polarizing plate, the return light from the exit-side polarizing plate to the -Z side is reduced, the generation of stray light in the projector 201 is suppressed, and light utilization efficiency is improved.

[0034] The light source device 20 , the optical scanning device 40 , the optical modulation device 60 and the projection optical system 80 described above constitute the optical section 10 of the projector 201 .

[0035] The light source output control device 110 is electrically connected to the light emitting element 21 of the light source device 20 by wire or wirelessly, and controls the light intensity of the white light WL emitted from the light emitting element 21. Specifically, the light source output control device 110 outputs an electrical signal related to a drive voltage or drive current to the light emitting element 21 for controlling the light intensity of the white light WL emitted from the light emitting element 21, causing the light emitting element 21 to periodically emit the white light WL. The light source output control device 110 is, for example, an LD driver or an LED driver. A program of periodic drive voltage values ​​or drive current values ​​to the light emitting element 21 corresponding to elapsed time and time t is stored and saved in the driver, which is the light source output control device 110. The drive voltage values ​​or drive current values ​​to the light emitting element 21 corresponding to elapsed time and time t will be described later.

[0036] The rotation control device 120 is electrically connected to the light-transmitting member 42 of the optical scanning device 40 via a motor, either wired or wirelessly, and controls the rotation speed of the light-transmitting member 42 about the rotation axis CX. The rotation control device 120 is configured by, for example, a motor driver.

[0037] The drive control device 130 is electrically connected to the light source output control device 110 and the rotation control device 120, and is also electrically connected by wire or wirelessly to the liquid crystal panel 62 of the light modulation device 60. The drive control device 130 outputs electrical signals to each of the light source output control device 110 and the rotation control device 120, and controls the position, area, and timing on the XY plane at which the white light WL emitted from the light emitting element 21 of the light source device 20 is scanned by the light-transmitting member 42 of the optical scanning device 40 and irradiated on the modulation surface 64 of the liquid crystal panel 62 of the light modulation device 60. The drive control device 130 supplies electrical signals to each pixel of the liquid crystal panel 62 on the modulation surface 64 in accordance with the irradiation position, irradiation area, and timing of the white light WL.

[0038] The drive control device 130 drives the light emitting elements 21 of the light source device 20, the light-transmitting members 42 of the optical scanning device 40, and the pixels corresponding to the three primary colors of the liquid crystal panel 62 of the light modulation device 60 in synchronization with one another, based on the refresh rate of the liquid crystal panel 62. If a synchronization error occurs between the above-mentioned components, the error may be corrected by feedback, for example, by detecting the amount of light of the image light IL at regular intervals. Image information output to the liquid crystal panel 62 may be subjected to appropriate processing, such as image processing and frame interpolation. Area dimming may be performed on the white light WL emitted from the light emitting elements 21, based on the scanning position of the light-transmitting members 42 and the image information output to the video panel 62.

[0039] The drive control device 130 is, for example, a processor. The timing for supplying a drive voltage value or a drive current value to the light-emitting element 21, the timing for increasing or decreasing the rotation speed of the light-transmitting member 42, and the timing for supplying a drive voltage with a modulation amount of color light suitable for each pixel of the liquid crystal panel 62 are stored and saved in the processor that is the drive control device 130.

[0040] The central processing unit (CPU) 140 is electrically connected to the drive control device 130 via a wired or wireless connection. The central processing unit 140 transmits video information and drive information to the drive control device 130. The central processing unit 140 receives frame information from the video processing circuit 160 and receives information such as the refresh rate of the liquid crystal panel 62 from a user interface (UI) 150. The refresh rate of the liquid crystal panel 62 is arbitrarily set by the user of the projector 201 from pre-set options, and is, for example, 60 Hz or 90 Hz.

[0041] The user interface 150 is electrically connected to the central processing unit 140 via a wired or wireless connection. The user interface 150 transmits information such as the refresh rate to the central processing unit 140. The user interface 150 is, for example, an input device or a tablet terminal device installed in the projector 201.

[0042] The video processing circuit 160 is electrically connected to the central processing unit 140 via a wired or wireless connection. The video processing circuit 160 receives video information from the video interface 170, breaks down the received video information into frame information for each color, and transmits the frame information for each color of the video or image to the central processing unit 140. The video processing circuit 160 includes, for example, a VRAM (Video Random Access Memory), which is a memory dedicated to video processing.

[0043] The video interface 170 is electrically connected to the video processing circuit 160 via a wired or wireless connection. The video interface 170 transmits image information and video information of the object to be projected by the projector 201 to the video processing circuit 160.

[0044] The light source output control device 110 , rotation control device 120 , drive control device 130 , central processing unit 140 , user interface 150 , video processing circuit 160 and video interface 170 described above constitute the control unit 100 of the projector 201 .

[0045] Next, we will explain the scanning of the white light WL by the optical scanning device 40 of the projector 201. When viewed from the +X side, i.e., the front side of the paper surface of Fig. 1, toward the -X side, i.e., the back side of the paper surface of Fig. 1, the light-transmitting member 42 of the optical scanning device 40 rotates clockwise, for example, as indicated by the arrow, around the rotation axis CX.

[0046] FIG. 1 shows a first, or initial, state of rotation of the light-transmitting member 42 of the optical scanning device 40. In the first state, the side surface 54A of the light-transmitting member 42 is located furthest from the -Z side of the four side surfaces 54 and is parallel to the XY plane. The rotation angle ω is the counterclockwise angle from an imaginary line TX that passes through the central axis JX and the rotation axis CX and is perpendicular to the side surface 54A to an axis PX that starts at the central axis JX and the rotation axis CX and extends parallel to the Z axis and toward the -Z side. The actual white light WL has a predetermined beam width on the X axis, Y axis, and XY plane. In describing the scanning and behavior of the white light WL, we will focus on the light ray WBM on the optical axis AX of the white light WL.

[0047] As shown in FIG. 1 , in the first state, the rotation angle ω is 0°, and the white light WL incident on the light-transmitting member 42 from the -Z side is not refracted at the side surface 54A because it is perpendicular to the side surface 54A. The white light WL travels parallel to the Z axis, is perpendicular to the side surface 54C, is not refracted at the side surface 54C, and is emitted from the side surface 54C to the +Z side along the Z axis. A ray WBM of the white light WL passes through the center of the side surface 54A in the XY plane, the central axis JX, the rotation axis CX, and the center of the side surface 54C in the XY plane. The distance d along the Z axis between the light ray WBM emitted from the side surface 54C of the light-transmitting member 42 and an axis QX that starts at the central axis JX and the rotation axis CX and extends parallel to the Z axis and toward the +Z side is approximately zero.

[0048] 2 is a schematic diagram of a second state in which the light-transmitting member 42 has rotated from the first state. As shown in FIG. 2, in the second state, the rotation angle ω is greater than 0° and less than 45°. In the second state, white light WL incident on the light-transmitting member 42 from the -Z side is incident on the side surface 54A at an angle of incidence equivalent to the narrow angle formed by the normal to the side surface 54A and the light ray WBM. Therefore, in accordance with the angle of incidence on the side surface 54A, the refractive index n of the material of the light-transmitting member 42, and Snell's law, the white light WL is refracted at the side surface 54A toward the -Y side of the central axis JX.

[0049] In the second state, as described above, the white light WL entering the light-transmitting member 42 is refracted at the side surface 54A, enters the side surface 54C at an angle determined by the angle of incidence of the white light WL on the side surface 54A, the refractive index n, and Snell's law, is refracted at the side surface 54C, and is emitted from the side surface 54C to the +Z side along the Z axis. The separation distance d in the second state is greater than the separation distance d in the first state.

[0050] Regardless of the rotation state of the light-transmitting member 42, the rotation angle ω determines one or two of the four side surfaces 54A, 54B, 54C, and 54D of the light-transmitting member 42 onto which the white light WL is incident and the angle of incidence at which the white light WL is incident on one or two side surfaces 54. The separation distance d is determined by the angle of incidence of the white light WL onto one or two side surfaces 54 according to the rotation angle ω, the refractive index n, and the distance on the Z axis between the side surfaces 54A and 54C and between the side surfaces 54B and 54D, i.e., the length of one side of the polygon of the end surfaces 51 and 52.

[0051] 3 is a schematic diagram of a third state in which the rotation of the light-transmitting member 42 has progressed further from the second state. As shown in FIG. 3, the rotation angle ω is 45°, and a ray WBM of white light WL incident on the light-transmitting member 42 from the -Z side is incident on the angle between side surfaces 54A and 54B. In the third state, the white light WL incident on the light-transmitting member 42 from the -Z side, which is on the +Y side of the angle between side surfaces 54A and 54B, is refracted by side surface 54A, as in the second state, and is incident on side surface 54C at an angle determined by the angle of incidence of the white light WL on side surface 54A, the refractive index n, and Snell's law. Then, the white light WL is refracted by side surface 54C and emitted from side surface 54C to the +Z side along the Z axis.

[0052] In the third state, of the white light WL incident on the light-transmitting member 42 from the -Z side, the white light WL on the -Y side of the angle between side surfaces 54A and 54B is refracted at side surface 54B, enters side surface 54D at an angle determined by the angle of incidence of the white light WL on side surface 54B, the refractive index n, and Snell's law, is refracted at side surface 54D, and is emitted from side surface 54D to the +Z side along the Z axis. The separation distance d in the third state is greater than the separation distance d in the second state.

[0053] 4 is a schematic diagram of a fourth state in which the rotation of the light-transmitting member 42 has progressed further from the third state. As shown in FIG. 4, in the fourth state, the rotation angle ω is greater than 45° and less than 90°. In the fourth state, the white light WL incident on the light-transmitting member 42 from the -Z side is incident at an angle of incidence equal to the narrow angle formed between the normal to the side surface 54B and the light ray WBM. Therefore, in accordance with the angle of incidence on the side surface 54B, the refractive index n, and Snell's law, the white light WL is refracted toward the +Y side of the central axis JX at the side surface 54B.

[0054] In the fourth state, as described above, white light WL entering the light-transmitting member 42 is refracted at side surface 54B, enters side surface 54D at an angle of incidence determined by the angle of incidence of white light WL on side surface 54B, the refractive index n, and Snell's law, is refracted at side surface 54D, and is emitted from side surface 54D to the +Z side along the Z axis. The separation distance d in the fourth state is smaller than the separation distance d in the third state.

[0055] Although not shown, as the rotation state of the light-transmitting member 42 progresses, in the behavior from the first state to the fourth state described above, the side surface 54A of the light-transmitting member 42 is replaced with the side surface 54B, and the side surface 54B is replaced with the side surface 54C. Thereafter, in the behavior from the first state to the fourth state described above, the side surface 54A of the light-transmitting member 42 is replaced with the side surface 54C, and the side surface 54B is replaced with the side surface 54D. Further thereafter, in the behavior from the first state to the fourth state described above, the side surface 54A of the light-transmitting member 42 is replaced with the side surface 54D, and the side surface 54B is replaced with the side surface 54A.

[0056] These behaviors are cyclical, causing the white light WL emitted from the light-transmitting member 42 of the optical scanning device 40 to scan along the Y axis. The beam width of the white light WL incident on the light-transmitting member 42 in the X axis is larger than the beam width in the Y axis and is equivalent to the size of the modulation surface 64 of the optical modulation device 60 in the X axis, causing the white light WL emitted from the light-transmitting member 42 to scan in the XY plane. In the behaviors from the first state to the fourth state described above, the maximum value of the separation distance d is set to be equivalent to half the size of the modulation surface 64 in the Y axis. Based on this, the length and size of one side of the end faces 51, 52 of the light-transmitting member 42 and the refractive index n are appropriately set so that the maximum value of the separation distance d is equivalent to half the size of the modulation surface 64 in the Y axis.

[0057] Next, a description will be given of the control by the control unit 100 over the optical unit 10 of the projector 201. Fig. 5 is a time chart relating to the operation of the light emitting element 21 of the light source device 20 and the liquid crystal panel 62 of the light modulation device 60.

[0058] In the following description, an input image to the liquid crystal panel 62 of the light modulation device 60 is divided into eight regions along the X axis, which is perpendicular to the scanning direction of the white light WL. When viewed along the Z axis from the -Z side, the input image to the liquid crystal panel 62 is divided along the X axis from the -X side to the +X side into a first region X1, a second region X2, a third region X3, a fourth region X4, a fifth region X5, a sixth region X6, a seventh region X7, and an eighth region X8.

[0059] In the input image to the liquid crystal panel 62, the first region X1 is assigned white and is displayed by combining red, green, and blue light. The second region X2 is assigned red and is displayed by monochromatic red light only. The third region X3 is assigned yellow and is displayed by combining red and green light. The fourth region X4 is assigned green and is displayed by monochromatic green light only. The fifth region X5 is assigned cyan and is displayed by combining green and blue light. The sixth region X6 is assigned blue and is displayed by monochromatic blue light only. The seventh region X7 is assigned magenta and is displayed by combining red and blue light. The eighth region X8 is assigned black and does not include any of the red, green, or blue light colors.

[0060] As shown in FIG. 5, in each pixel of the liquid crystal panel 62, for each of the red region R, green region G, and blue region B, there is a rise period T1 from the rise start time to the rise completion time, a fixed period T2 from the rise completion time to the fall start time, and a fall period T3 from the fall start time to the fall completion time.

[0061] The rise period T1 corresponds to a first period, which will be described later. The fixed period T2 corresponds to a second period, which will be described later. In the liquid crystal panel 62, the rise period T1 is, for example, about 1.5 ms, and the fall period T3 is, for example, about 3.0 ms.

[0062] The time chart shown in Figure 5 assumes that the colors red, green, and blue are displayed one frame at a time at a driving speed of 360 Hz. In this case, the frame rate is 180 fps, which corresponds to 60 fps for color display. One cycle is approximately 2.78 ms.

[0063] Figure 6 is a time chart in which, as in Figure 5, the horizontal axis represents time t, and the vertical axis represents the liquid crystal response rate and colored light intensity in each region when the modulation surface 64 of the liquid crystal panel 62 of the projector 201 of the first embodiment is divided along the scanning direction, i.e., the Y axis, from the +Y side to the -Y side into five regions, from the first region Y1 to the second region Y2, the third region Y3, the fourth region Y4, and the fifth region Y5.

[0064] 5 and 6, the red light of the white light WL emitted from the light emitting element 21 of the light source device 20 is irradiated onto the modulation surface 64 through a color filter during a red irradiation period TR that does not overlap with the fall period T3 of the blue region B or the rise period T1 of the green region G within a certain period T2 of the red region R. The fall start time of the red region R and the rise start time of the green region G coincide with each other.

[0065] The green light of the white light WL emitted from the light-emitting element 21 is irradiated through a color filter onto the modulation surface 64 during a green irradiation period TG in a fixed period T2 of the green region G that does not overlap with the fall period T3 of the red region R or the rise period T1 of the blue region B. The blue light of the white light WL emitted from the light-emitting element 21 is irradiated through a color filter onto the modulation surface 64 during a blue irradiation period TB in a fixed period T2 of the blue region B that does not overlap with the fall period T3 of the green region G or the rise period T1 of the red region R.

[0066] That is, in the projector 201, each color light is emitted only during the period in which the liquid crystal response of each pixel of the liquid crystal panel 62 is complete. Therefore, the color of the input image input from the control unit 100 is accurately reproduced over the entire area of ​​the image projected onto a projection surface such as a screen (not shown). In each of the red area R, green area G, and blue area B, the color light from the light emitting element 21 is emitted over the entire period in which the liquid crystal response is complete and does not overlap with the rise period or fall period of the other color areas.

[0067] A positive drive voltage PR1 and a negative drive voltage PR2 corresponding to red light, a positive drive voltage PG3 and a negative drive voltage PG4 corresponding to green light, and a positive drive voltage PB5 and a negative drive voltage PB6 corresponding to blue light are sequentially supplied to each pixel of the liquid crystal panel 62 of the optical modulation device 60 in accordance with the frame rate.

[0068] Fig. 7 is a schematic diagram showing the distribution of each color region on the five-divided modulation surface 64. As shown in Fig. 7, in the scanning illumination projector 201 controlled as shown in Fig. 5 and Fig. 6, the brightness of the image light IL is improved compared to a conventional projector with in-plane collective illumination. By the above-described control, in any region of the modulation surface 64 and at time t, unevenness and loss of illuminance of the projected image on the projection surface are suppressed, and color mixing does not occur.

[0069] In the scanning illumination projector 201, the white light WL scanned by the optical scanning device 40 and emitted from the optical scanning device 40 has a large relative beam width in the Y axis, and the red irradiation period TR, green irradiation period TG, and blue irradiation period TB are each ensured to be relatively long, as shown in FIGS. 5 to 7. When a certain brightness of the image light IL is obtained, the light density is suppressed, and the reliability of the projector 201 is high. The large relative beam width of the white light WL in the Y axis increases the irradiation efficiency of the white light WL. Note that, when the red irradiation period TR, green irradiation period TG, and blue irradiation period TB are each ensured to be relatively long, as shown in FIGS. 5 to 7, measures are required to prevent additional colored light from appearing from the beginning as the white light WL scans toward the end.

[0070] In the scanning illumination projector 201, when the relative beam width on the Y axis of the white light WL scanned by the optical scanning device 40 and emitted from the optical scanning device 40 is shortened, the red irradiation period TR, the green irradiation period TG, and the blue irradiation period TB are each shortened relatively. When a constant brightness of the image light IL is obtained, the light density increases and the reliability of the projector 201 is low. Because the relative beam width on the Y axis of the white light WL is small, the irradiation efficiency of the white light WL is low. Increasing the driving frequency of the liquid crystal of the liquid crystal panel 62 approaches the above-mentioned tendency.

[0071] FIG. 8 is a different time chart from FIG. 6, in which the vertical axis represents the liquid crystal response rate and the light intensity of the colored light in each region when the modulation surface 64 of the liquid crystal panel 62 is divided into five parts along the scanning direction, i.e., the Y axis, at time t.

[0072] 8, the red irradiation period TR may be extended to the period between the intersection time of the falling edge of the blue region B and the rising edge of the red region R and the intersection time of the falling edge of the red region R and the rising edge of the green region G. Similarly, the green irradiation period TG may be extended to the period between the intersection time of the falling edge of the red region R and the rising edge of the green region G and the intersection time of the falling edge of the green region G and the rising edge of the blue region B. The blue irradiation period TB may be extended to the period between the intersection time of the falling edge of the green region G and the rising edge of the blue region B and the intersection time of the falling edge of the blue region B and the rising edge of the red region R.

[0073] Fig. 9 is a schematic diagram different from Fig. 7 showing the distribution of each color region on the modulation surface 64 divided into five. As shown in Fig. 9, in the red irradiation period TR when controlled as shown in Fig. 8, the red region R becomes more white than when controlled as shown in Figs. 5 and 6. In the green region G and the blue region B, the red becomes more faintly red than when controlled as shown in Figs. 5 and 6.

[0074] In the green irradiation period TG when controlled as shown in Fig. 8, the green region G becomes whiter than when controlled as shown in Figs. 5 and 6. In the blue region B and the red region R, the green becomes slightly more green than when controlled as shown in Figs. 5 and 6. In the blue irradiation period TB when controlled as shown in Fig. 8, the blue region B becomes whiter than when controlled as shown in Figs. 5 and 6. In the red region R and the green region G, the blue becomes slightly more blue than when controlled as shown in Figs. 5 and 6.

[0075] 8, the scanning illumination projector 201 improves the brightness of the image light IL compared to a conventional in-plane illumination projector. The above-described control reduces unevenness and loss of illuminance of the projected image on the projection surface in any region of the modulation surface 64 and at any time t.

[0076] However, unlike the projector 201 with scanning illumination controlled as shown in Fig. 6, color mixing occurs uniformly in any area of ​​the modulation surface 64 and at any time t. Therefore, the triangular area of ​​the chromaticity diagram that can be represented by a full-color image projected onto the projection surface of the projector 201 with scanning illumination controlled as shown in Fig. 8 has each vertex closer to the center and is narrower than that of the projector 201 with scanning illumination controlled as shown in Fig. 6.

[0077] Fig. 10 is a flowchart relating to the control performed by the control unit 100 as exemplified in Fig. 5 to Fig. 9. As shown in Fig. 10, in step S301, the central processing unit 140 transmits various initial values ​​to the drive control device 130 based on the video information received from the video processing circuit 160 and the refresh rate of the liquid crystal of the liquid crystal panel 62 set by the user interface 150 or the like. The various initial values ​​include the video information of the projection target, the drive frequency of the light-emitting elements 21, the drive frequency of the liquid crystal panel 62, the operation time, the standby period, threshold values ​​for determining various malfunction differences, etc.

[0078] In step S302, the drive control device 130 transmits a synchronization signal to the light-source output control device 110 and the rotation control device 120. In step S303, in response to electrical signals from the light-source output control device 110 and the rotation control device 120, white light WL is periodically emitted from the light-emitting element 21 of the light source device 20, the light-transmitting member 42 of the optical scanning device 40 rotates about the rotation axis CX, and the three color lights contained in the white light WL are converted into image light IL by the liquid crystal of each pixel of the liquid crystal panel 62 of the light modulation device 60. At this time, errors representing deviations from the set values ​​of the light amount and output of the white light WL from the light-emitting element 21 and the rotation speed of the light-transmitting member 42 are constantly detected and fed back to the drive control device 130.

[0079] If the error in the output of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 exceeds a target error range of, for example, about 0.5% in step S304, black is displayed in each pixel of the liquid crystal panel 62 until the error falls within the target error range in step S305. Once the error in the output of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 falls within the target error range, color light is converted into image light IL in each pixel of the liquid crystal panel 62 in step S306.

[0080] In step S307, the amount of missynchronization between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is detected at regular cycles, i.e., regular time intervals, when the image light IL is generated in each pixel of the liquid crystal panel 62. While it is detected that the amount of missynchronization between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is less than a predetermined value, each setting condition and setting value is maintained.

[0081] If it is detected that the amount of synchronization error between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is equal to or greater than a predetermined value, the drive frequency of the liquid crystal panel 62 is changed in step S308 to reduce the amount of synchronization error. As an example, if the drive frequency of the liquid crystal panel 62 on the Y axis is 1080 / 1124 lines, there is approximately 97% room for adjustment. After the drive frequency of the liquid crystal panel 62 is changed in step S308, the process returns to step S306, and modulation and video display on the liquid crystal panel 62 based on the input image are performed under the changed conditions.

[0082] The projector 201 of the first embodiment described above includes a light source device 20, an optical scanning device 40, an optical modulation device 60, and a projection optical system 80. The light source device 20 periodically emits white light (first light) WL. The optical scanning device 40 periodically scans the white light WL emitted from the light source device 20. The optical modulation device 60 modulates the white light WL scanned by the optical scanning device 40 and emitted from the optical scanning device 40 according to image information to generate image light IL. The projection optical system 80 projects the image light IL emitted from the optical modulation device 60 onto a projection surface such as a screen. The light source device 20 has a light-emitting element (first light-emitting element) 21 that emits white light WL. The optical scanning device 40 includes a light-transmitting member (transmissive optical element) 42 having side surfaces (incident surfaces) 54A, 54B, 54C, and 54D onto which the white light WL emitted from the light source device 20 is incident, and side surfaces (exit surfaces) 54C, 54D, 54A, and 54B from which the white light WL is emitted and which face the aforementioned side surfaces 54. The light modulation device 60 includes a liquid crystal panel (liquid crystal element) 62 that forms an image along the first direction parallel to the Y axis by converting the white light WL, which is irradiated along the first direction according to input image information, into image light IL. The liquid crystal panel 62 includes a liquid crystal layer that changes the amount of phase modulation for each color light according to an input electrical signal. Specifically, in the liquid crystal layer, the amount of phase modulation for each color light changes as the refractive index of the liquid crystal for the white light WL changes. In the projector 201 of the first embodiment, the modulation period TAL during which the three color lights (first lights) included in the white light WL are modulated in the liquid crystal layer of the liquid crystal panel 62 includes a rise period (first period) T1 from the time when the electrical signal is input to the time when the modulation amount of the liquid crystal layer changes to a predetermined value, and a fixed period (second period) T2 during which the modulation amount of the liquid crystal layer is maintained at the predetermined value. In the projector 201 of the first embodiment, the white light WL emitted from the light source device 20 is incident on the light modulation device 60 during the fixed period T2.

[0083] In the projector 201 of the first embodiment, in scan illumination, the image formation cycle of the light modulation device 60, the scanning cycle of the optical scanning device 40 of the white light WL from the light source device 20, and the light emission cycle of the light emitting element 21 of the light source device 20 are synchronized. For example, if the light emitting element 21 is constantly lit rather than periodically lit like a lamp, a specific pixel of the liquid crystal panel is constantly irradiated with illumination light (first light) from the start of the response, i.e., the start time of the rise of the modulation amount, to the completion of the response, i.e., the completion time of the fall of the modulation amount. In other words, because illumination light continues to be incident until the liquid crystal is completely opened or closed, uneven illuminance occurs on the projection surface such as a screen, and video quality and image quality deteriorate. According to the projector 201 of the first embodiment, as described above, the image formation cycle of the light modulation device 60, the scanning cycle of the white light WL from the light source device 20 by the light scanning device 40, and the light emission cycle of the light emitting element 21 of the light source device 20 are synchronized, and the white light WL emitted from the light source device 20 is made incident on the light modulation device 60 for a certain period T2, thereby reliably suppressing the occurrence of uneven illuminance in the projected image on the projection surface.

[0084] Fig. 11 corresponds to Fig. 6 and is a time chart in which the horizontal axis represents time t and the vertical axis represents the liquid crystal response rate and the light intensity of color light in each region when the modulation surface of the liquid crystal panel of a conventional projector with full-area illumination is divided into five along the scanning direction. Fig. 12 is a schematic diagram showing the distribution of each color region on the modulation surface divided into five regions of the liquid crystal panel of a conventional projector with full-area illumination.

[0085] As shown in Figures 11 and 12, in the case of full-surface illumination, in the center of the Y axis of the modulation surface of the liquid crystal panel, that is, in the second region Y2 to the fourth region Y4 of the five divisions, the red irradiation period TR', the green irradiation period TG', and the blue irradiation period TB' do not overlap with the liquid crystal rise period T1 and fall period T3 corresponding to the color light of any color region.

[0086] However, at the top end of the modulation surface of the liquid crystal panel, i.e., the end on the +Y side, i.e., the first region Y1 of the five divisions, the red irradiation period TR' overlaps with the liquid crystal fall period T3 corresponding to the color light of the red region R and the liquid crystal rise period T1 corresponding to the color light of the green region G. At the same end, the green irradiation period TG' overlaps with the liquid crystal fall period T3 corresponding to the color light of the green region G and the liquid crystal rise period T1 corresponding to the color light of the blue region B. The blue irradiation period TB' overlaps with the liquid crystal fall period T3 corresponding to the color light of the blue region B and the liquid crystal rise period T1 corresponding to the color light of the red region R. As a result, at the top end of the modulation surface of the liquid crystal panel, i.e., the first region Y1 of the five divisions, the color of the input video is not reproduced, and uneven illuminance and color mixing occur in the projected image on the projection surface.

[0087] At the bottom end of the modulation surface of the liquid crystal panel, i.e., the end on the -Y side, i.e., the fifth region Y5 of the five divisions, the red irradiation period TR' overlaps with the liquid crystal fall period T3 corresponding to the color light of the blue region B. At the same end, the green irradiation period TG' overlaps with the liquid crystal fall period T3 corresponding to the color light of the red region R. The blue irradiation period TB' overlaps with the liquid crystal fall period T3 corresponding to the color light of the green region G. As a result, even at the bottom end of the modulation surface of the liquid crystal panel, i.e., the fifth region Y5 of the five divisions, the color of the input image is not reproduced, resulting in uneven illuminance and color mixing in the projected image.

[0088] In conventional projectors with surface illumination, the longer the red irradiation period TR', green irradiation period TG', and blue irradiation period TB' are, the stronger the illuminance unevenness and color mixing of the projected image become. However, if the red irradiation period TR', green irradiation period TG', and blue irradiation period TB' are shortened in order to suppress the illuminance unevenness and color mixing of the projected image, the brightness of the image light IL decreases. As described above, the projector 201 of the first embodiment can suppress the illuminance unevenness and color mixing of the projected image while ensuring the brightness of the image light IL.

[0089] In the projector 201 of the first embodiment, the light-transmitting member 42 of the optical scanning device 40 has end faces (first faces) 51, 52 parallel to the Y axis and the first direction, and 2×m side faces (second faces) 54 in contact with the end faces 51, 52.

[0090] In the projector 201 of the first embodiment, the light-transmitting member 42 has an even number of side surfaces 54 (four or more), and all of the side surfaces 54 are opposed to each other across the central axis JX and are parallel to each other. According to the projector 201 of the first embodiment, the white light WL emitted from the light source device 20 and incident on the optical scanning device 40 can be emitted from the optical scanning device 40 in a direction parallel to the incident direction.

[0091] The projector 201 of the first embodiment further includes a drive control device 130 that transmits an electrical signal to the liquid crystal panel 62 of the light modulation device 60 to drive the liquid crystal of the liquid crystal layer of each pixel. The drive control device 130 is electrically connected to a light-source output control device 110 that controls the output power and output cycle of the white light WL emitted from the light-emitting element 21 of the light source device 20 by outputting an electrical signal related to a drive voltage or a drive current to the light-emitting element 21. The drive control device 130 is connected to a rotation control device 120 that is connected to the light-transmissive member 42 of the optical scanning device 40 via a motor or the like and controls the rotation speed of the light-transmissive member 42 about the rotation axis CX. The drive control device 130 transmits an electrical signal (synchronization signal) to the light source device 20 and the optical scanning device 40 to synchronize the output power of the white light WL from the light-emitting element 21 with the rotation speed of the light-transmissive member 42 based on the electrical signal output to the liquid crystal panel 62.

[0092] The projector 201 of the first embodiment includes the drive control device 130, and thus can easily synchronize the output power of the white light WL emitted from the light-emitting element 21 with the rotation speed of the light-transmissive member 42.

[0093] In the projector 201 of the first embodiment, when the error in the scanning period of the optical scanning device 40 relative to the image formation period of the liquid crystal panel 62 is a predetermined value or more, and when the error in the light emission period of the light source device 20 relative to the image formation period of the liquid crystal panel 62 is a predetermined value or more, the light modulation device 60 does not emit image light IL and displays black.

[0094] According to the projector 201 of the first embodiment, it is possible to prevent the display of an unexpected image that is not based on the image information or video information input to the drive control device 130.

[0095] In the projector 201 of the first embodiment, when an error in the scanning period of the optical scanning device 40 with respect to the image formation period of the liquid crystal panel 62 of the light modulation device 60 becomes equal to or greater than a predetermined value, the drive control device 130 changes the scanning period of the optical scanning device 40. The scanning period of the optical scanning device 40 is determined by the rotation speed of the light-transmitting member 42.

[0096] According to the projector 201 of the first embodiment, the light emission period of the light source device 20, the scanning period of the optical scanning device 40, and the image formation period of the optical modulation device 60 can be smoothly maintained in a synchronized state, thereby suppressing deterioration of image quality over time.

[0097] In the projector 201 of the first embodiment, when the error in the scanning period of the optical scanning device 40 relative to the image formation period of the liquid crystal panel 62 of the optical modulation device 60 becomes equal to or greater than a predetermined value, the drive control device 130 changes the image formation period of the liquid crystal panel 62 of the optical modulation device 60.

[0098] According to the projector 201 of the first embodiment, even when controlled as described above, a synchronized state can be smoothly maintained in which the light emission period of the light source device 20, the scanning period of the optical scanning device 40, and the image formation period of the optical modulation device 60 are synchronized with each other, thereby suppressing deterioration in image quality over time.

[0099] In the projector 201 of the first embodiment, the modulation period TAL in which the three colored lights (first lights) contained in the white light WL are modulated in the liquid crystal layer of the liquid crystal panel 62 further includes the aforementioned rise period T1, a fixed period T2, and a fall period T3 from the time when the modulation amount of the liquid crystal layer reaches a predetermined value to the time when it completely returns to the initial value.

[0100] The rise period T1 represents the period from when the liquid crystal layer of the liquid crystal panel 62 starts to rise to when it finishes rising. The fall period T3 represents the period from when the liquid crystal layer of the liquid crystal panel 62 starts to fall to when it finishes falling. In the projector 201 of the first embodiment, the white light WL emitted from the light source device 20 does not enter the light modulation device 60 during a period that overlaps with the fall period T3 of the other color region within the fixed period T2 in each color region of the liquid crystal panel 62 and during a period that overlaps with the rise period T1 of the other color region within the fixed period T2.

[0101] In the projector 201 of the first embodiment, the modulation period TAL for each pixel of the liquid crystal panel 62 of the light modulation device 60 includes a rise period (first period) T1, a fixed period (second period) T2, and a fall period (third period) T3. The rise period T1 is the period from the time when the modulation amount of the phase of the colored light in the liquid crystal layer of the liquid crystal panel 62 changes from an initial value to a predetermined value and starts to rise until the time when the predetermined value is reached. The fixed period T2 is the period during which the modulation amount of the phase of the colored light in the liquid crystal layer of the liquid crystal panel 62 is kept constant at a predetermined value. The fall period T3 is the period from the time when the modulation amount of the phase of the colored light in the liquid crystal layer of the liquid crystal panel 62 changes from a predetermined value to an initial value and starts to fall until the time when the initial value is reached.

[0102] In the projector 201 of the first embodiment, preferably, the white light WL emitted from the light source device 20 and manipulated by the optical scanning device 40 in a first direction along the Y axis is incident on the liquid crystal panel 62 of the light modulation device 60 during a certain period T2 of the red region R of the pixel for red light (first color light) contained in the white light WL, which does not overlap with the rising period T1 or falling period T3 of green light (second color light) or blue light (second color light) contained in the white light WL and having a wavelength band different from that of the red light. Similarly, the white light WL emitted from the light source device 20 is incident on the liquid crystal panel 62 during a certain period T2 of the green region G of the pixel for green light (first color light), which does not overlap with the rising period T1 or falling period T3 of blue light (second color light) or red light (second color light) contained in the white light WL and having a wavelength band different from that of the green light. The white light WL emitted from the light source device 20 is incident on the liquid crystal panel 62 during a certain period T2 of the blue region B of the pixel for blue light (first color light), which does not overlap with the rise period T1 or fall period T3 of red light (second color light) or green light (second color light) that is included in the white light WL and has a wavelength band different from that of the blue light.

[0103] That is, the projector 201 of the first embodiment can be controlled so that white light WL does not enter pixels of the liquid crystal panel 62 during a rise period T1 or a fall period T3 during which the liquid crystal molecules in the liquid crystal layer rotate with respect to red, green, or blue light, changing the phase modulation amount φ. In other words, one of the colored lights is incident on pixels of the liquid crystal panel 62 during a certain period T2 of red, green, or blue light that does not overlap with the rise period T1 or fall period T3 of the other colored light. Depending on whether the phase modulation amount φ is increased or decreased, the liquid crystal layer functions as a color filter, increasing or decreasing the light intensity I and the amount of light of the colored light passing through the liquid crystal layer in each pixel of the liquid crystal panel 62. The projector 201 of the first embodiment controlled in this manner can accurately reproduce the colors of the input image, suppress uneven illuminance of the projected image on the projection surface, and reduce color mixing between colored light intended for display and colored light not intended for display.

[0104] [Second embodiment] Next, a second embodiment of the present invention will be described with reference to Fig. 13. In the description of the second embodiment, description of the contents common to the first embodiment will be omitted, and only the contents different from the first embodiment will be described. Furthermore, with regard to the configuration of the projector 202 of the second embodiment, the same reference numerals as the corresponding configuration of the projector 201 of the first embodiment will be used for the components common to the projector 201 of the first embodiment, and description thereof will be omitted.

[0105] Fig. 13 is a schematic diagram of a projector 202 according to a second embodiment of the present invention. As shown in Fig. 13, the projector 202, like the projector 201, includes a light source device 220, an optical scanning device 40, an optical modulation device 60, a projection optical system 80, light source output control devices 111, 112, and 113, a rotation control device 120, a drive control device 130, a central processing unit 140, a user interface 150, a video processing circuit 160, and a video interface 170.

[0106] The light source device 220 periodically emits white light WL and includes a light emitting element 22 that emits blue light BL, a light emitting element 23 that emits green light GL, a light emitting element 24 that emits red light RL, collimating lenses 27, 28, and 29, and dichroic mirrors 31 and 32.

[0107] The light-emitting element 22 corresponds to a first light-emitting element described in the claims below. The blue light BL corresponds to a first light described below. The light-emitting element 22 emits the blue light BL from the emission surface 22e toward the +Z side along the Z axis. The light-emitting element 22 is, for example, a blue LD or a blue LED.

[0108] The collimating lens 27 is disposed on the optical path of the blue light BL emitted from the light-emitting element 22, and is disposed at the same position as the emission surface 22e of the light-emitting element 22 in the X and Y axes, and is disposed on the +Z side of the emission surface 22e of the light-emitting element 22. The central axis of the collimating lens 27 overlaps with the optical axis of the blue light BL emitted from the light-emitting element 22. The collimating lens 27 converts the blue light BL emitted from the light-emitting element 22 into parallel light parallel to the Z axis and emits it along the optical axis AX.

[0109] The collimating lens 27 is, for example, a biconvex lens. The collimating lens 27 may also be a plano-convex lens having a flat entrance surface parallel to the XY plane and an exit surface convex on the +Z side. In Fig. 13, the collimating lens 27 is disposed away from the exit surface 22e of the light-emitting element 22, but if the collimating lens 27 is a plano-convex lens, the collimating lens 27 may be in contact with the exit surface 22e of the light-emitting element 22.

[0110] The light-emitting element 23 corresponds to a second light-emitting element, which will be described later. The green light GL corresponds to a second light, which will be described later. The light-emitting element 23 is disposed at the same position on the X-axis as the light-emitting element 22, and is disposed on the -Y side of the light-emitting element 22, on the +Z side of the light-emitting element 22, and on the -Z side of the light-transmitting member 42 of the optical scanning device 40. The light-emitting element 23 emits green light GL from the emission surface 23e toward the +Y side along the Y-axis. The light-emitting element 23 is, for example, a green LD or a green LED.

[0111] The collimating lens 28 is disposed on the optical path of the green light GL emitted from the light-emitting element 23, and is disposed at the same position as the emission surface 23e of the light-emitting element 23 along the X and Z axes, and is disposed between the emission surface 23e of the light-emitting element 23 and the emission surface 22e of the light-emitting element 22 along the Y axis. The central axis of the collimating lens 28 overlaps with the optical axis of the green light GL emitted from the light-emitting element 23 and intersects with the central axis of the collimating lens 27. The collimating lens 28 emits the green light GL emitted from the light-emitting element 23 to the +Y side as parallel light parallel to the Y axis.

[0112] The collimating lens 28 is, for example, a biconvex lens. The collimating lens 28 may also be a plano-convex lens having a flat entrance surface parallel to the XZ plane including the X-axis and the Z-axis and an exit surface that is convex on the +Y side. In Fig. 13, the collimating lens 28 is disposed away from the exit surface 23e of the light-emitting element 23, but if the collimating lens 28 is a plano-convex lens, the collimating lens 28 may be in contact with the exit surface 23e of the light-emitting element 23.

[0113] The light-emitting element 24 corresponds to a second light-emitting element, which will be described later. The red light RL corresponds to a second light, which will be described later. The light-emitting element 24 is disposed at the same position on the X-axis as the light-emitting elements 22 and 23, and is disposed on the -Y side of the light-emitting element 22, on the +Z side of the light-emitting element 23, and on the -Z side of the light-transmitting member 42 of the optical scanning device 40. The light-emitting element 24 emits red light RL from the emission surface 24e toward the +Y side along the Y-axis. The light-emitting element 24 is, for example, a red LD or a red LED.

[0114] The collimating lens 29 is disposed on the optical path of the red light RL emitted from the light-emitting element 24, is disposed at the same position as the emission surface 24e of the light-emitting element 24 in the X-axis and Z-axis, and is disposed between the emission surface 24e of the light-emitting element 24 and the emission surface 22e of the light-emitting element 22 in the Y-axis. The central axis of the collimating lens 29 overlaps with the optical axis of the red light RL emitted from the light-emitting element 24 and intersects with the central axis of the collimating lens 27. The collimating lens 29 emits the red light RL emitted from the light-emitting element 24 to the +Y side as parallel light parallel to the Y-axis.

[0115] The collimating lens 28 is, for example, a biconvex lens. The collimating lens 28 may also be a plano-convex lens having a flat entrance surface parallel to the XZ plane including the X-axis and the Z-axis and an exit surface that is convex on the +Y side. In Fig. 13, the collimating lens 28 is disposed away from the exit surface 23e of the light-emitting element 23, but if the collimating lens 28 is a plano-convex lens, the collimating lens 28 may be in contact with the exit surface 23e of the light-emitting element 23.

[0116] Dichroic mirror 31 is disposed in a region where the optical path of blue light BL emitted from collimating lens 27 overlaps with the optical path of green light GL emitted from collimating lens 28. The center of dichroic mirror 31 in the XY plane substantially overlaps with the intersection point between the optical axis of blue light BL emitted from light-emitting element 22 and the optical axis of green light GL emitted from light-emitting element 23.

[0117] The dichroic mirror 31 has a reflective surface that transmits the blue light BL and reflects the green light GL. The reflective surface of the dichroic mirror 31 is inclined so that it moves from the -Y side to the +Y side as it moves from the -Z side to the +Z side when viewed along the X axis. The blue light BL emitted from the collimating lens 27 passes through the dichroic mirror 31 and is emitted to the +Z side along the Z axis. The green light GL emitted from the collimating lens 28 is incident on the dichroic mirror 31 and is reflected by the reflective surface of the dichroic mirror 31 to the +Z side along the Z axis, where it is superimposed on the blue light BL.

[0118] Dichroic mirror 32 is disposed in a region where the optical paths of blue light BL and green light GL emitted from dichroic mirror 31 overlap with the optical path of red light RL emitted from collimating lens 29. The center of dichroic mirror 32 in the XY plane substantially overlaps with the intersection of the optical axis of blue light BL emitted from light-emitting element 22 and the optical axis of red light RL emitted from light-emitting element 24.

[0119] The dichroic mirror 32 has a reflective surface that transmits the blue light BL and the green light GL and reflects the red light RL. The reflective surface of the dichroic mirror 32 is inclined so that, when viewed along the X axis, it moves from the -Y side to the +Y side as it moves from the -Z side to the +Z side. The blue light BL and the green light GL emitted from the dichroic mirror 32 are transmitted through the dichroic mirror 32 and emitted to the +Z side along the Z axis. The red light RL emitted from the collimating lens 29 is incident on the dichroic mirror 32 and reflected by the reflective surface of the dichroic mirror 32 to the +Z side along the Z axis, where it is superimposed on the blue light BL and the green light GL.

[0120] The blue light BL, green light GL, and red light RL emitted from the dichroic mirror 32 are combined as white light WL, which is emitted from the light source device 20 to the +Z side along the optical axis AX, and is incident as white light WL on the light-transmitting member 42 of the optical scanning device 40. The behavior of the white light WL emitted from the light source device 220 in the projector 202 is similar to the behavior of the white light WL emitted from the light source device 20 in the projector 201.

[0121] The light source device 220 , the optical scanning device 40 , the light modulation device 60 and the projection optical system 80 described above constitute the optical section 10 of the projector 202 .

[0122] The light source output control device 111 is electrically connected to the light emitting element 22 of the light source device 220 by wire or wirelessly, and controls the amount of blue light BL emitted from the light emitting element 22. Specifically, the light source output control device 111 outputs an electrical signal related to a drive voltage or drive current to the light emitting element 22 for controlling the amount of blue light BL emitted from the light emitting element 22, causing the light emitting element 22 to periodically emit the blue light BL. The light source output control device 111 is, for example, an LD driver or an LED driver. A program for setting a periodic drive voltage value or drive current value to the light emitting element 22 corresponding to an elapsed time and a time t is stored and saved in the driver, which is the light source output control device 111.

[0123] The light source output control device 112 is electrically connected to the light emitting element 23 of the light source device 220 by wire or wirelessly, and controls the amount of green light GL emitted from the light emitting element 23. Specifically, the light source output control device 112 outputs an electrical signal related to a drive voltage or drive current to the light emitting element 23 for controlling the amount of green light GL emitted from the light emitting element 23, causing the light emitting element 23 to periodically emit the green light GL. The light source output control device 112 is, for example, an LD driver or an LED driver. A program for periodic drive voltage values ​​or drive current values ​​to the light emitting element 23 corresponding to elapsed time and time t is stored and saved in the driver, which is the light source output control device 112.

[0124] The light source output control device 113 is electrically connected to the light emitting element 24 of the light source device 220 by wire or wirelessly, and controls the amount of red light RL emitted from the light emitting element 24. Specifically, the light source output control device 113 outputs an electrical signal related to a drive voltage or drive current to the light emitting element 24 for controlling the amount of red light RL emitted from the light emitting element 24, causing the light emitting element 24 to periodically emit the red light RL. The light source output control device 113 is, for example, an LD driver or an LED driver. A program for periodic drive voltage values ​​or drive current values ​​to the light emitting element 24 corresponding to elapsed time and time t is stored and saved in the driver, which is the light source output control device 113.

[0125] The drive control device 130 is electrically connected to the light source output control devices 111, 112, and 113 and the rotation control device 120, and is also electrically connected by wire or wirelessly to the liquid crystal panel 62 of the light modulation device 60. The drive control device 130 outputs electrical signals to each of the light source output control devices 111, 112, and 113 and the rotation control device 120, and controls the position, area, and timing on the XY plane at which the blue light BL emitted from the light emitting element 22, the green light GL emitted from the light emitting element 23, and the red light RL emitted from the light emitting element 24 of the light source device 220 are scanned as white light WL by the light-transmitting member 42 of the optical scanning device 40 and irradiated on the modulation surface 64 of the liquid crystal panel 62 of the light modulation device 60. The drive control device 130 supplies electrical signals to each pixel of the liquid crystal panel 62 on the modulation surface 64 in accordance with the irradiation position, irradiation area, and timing of the white light WL.

[0126] The above-described light source output control devices 111, 112, and 113, rotation control device 120, drive control device 130, central processing unit 140, user interface 150, video processing circuit 160, and video interface 170 constitute a control unit 100 of the projector 202. The control that the control unit 100 of the projector 202 performs on the optical unit 10 is similar to the control that the control unit 100 of the projector 201 performs on the optical unit 10.

[0127] 10, the central processing unit 140 transmits various initial values ​​to the drive control device 130 based on the image information received from the image processing circuit 160 and the refresh rate of the liquid crystal of the liquid crystal panel 62 set by the user interface 150 or the like. The various initial values ​​include image information of the projection target, the drive frequency of the light-emitting elements 22, 23, and 24, the drive frequency of the liquid crystal panel 62, the operation time, the standby period, threshold values ​​for determining various malfunction differences, and the like.

[0128] In step S303, electrical signals are received from the light source output control device 110 and the rotation control device 120, and blue light BL is periodically emitted from the light emitting element 22 of the light source device 220, green light GL is periodically emitted from the light emitting element 23, and red light RL is periodically emitted from the light emitting element 24, so that white light WL is periodically emitted from the light source device 220.

[0129] If the error in the output of light source device 220 and the rotation speed of light-transmitting member 42, which depend on the output of light-emitting elements 22, 23, and 24, exceeds a target error range of, for example, about 0.5% in step S304, black is displayed in each pixel of liquid crystal panel 62 until the error falls within the target error range in step S305. Once the error in the output of light source device 220 and the rotation speed of light-transmitting member 42 falls within the target error range, colored light is converted into image light IL in each pixel of liquid crystal panel 62 in step S306.

[0130] In step S307, when image light IL is generated in each pixel of the liquid crystal panel 62, the amount of missynchronization between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is detected at a constant period, i.e., at constant time intervals. While it is detected that the amount of missynchronization between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is less than a predetermined value, each setting condition and setting value are maintained. If it is detected that the amount of missynchronization between the output period of the light-emitting element 21 and the rotation speed of the light-transmitting member 42 is equal to or greater than a predetermined value, in step S308, the drive frequency of the liquid crystal panel 62 is changed so as to reduce the amount of missynchronization.

[0131] The projector 202 of the second embodiment described above includes a light source device 220, an optical scanning device 40, an optical modulation device 60, and a projection optical system 80. The light source device 220 periodically emits white light (first light) WL. The optical scanning device 40 periodically scans the white light WL emitted from the light source device 220. The light source device 220 includes a light-emitting element (first light-emitting element) 22 that emits blue light BL included in the white light WL, a light-emitting element 23 that emits green light GL included in the white light WL, and a light-emitting element 24 that emits red light RL included in the white light WL. In the projector 202 of the second embodiment, the modulation period TAL during which the three color lights contained in the white light WL are modulated in the liquid crystal layer of the liquid crystal panel 62 includes a rise period (first period) T1 from the time when the electrical signal is input to the time when the modulation amount of the liquid crystal layer changes to a predetermined value, and a fixed period (second period) T2 during which the modulation amount of the liquid crystal layer is maintained at the predetermined value. Also in the projector 202 of the second embodiment, the white light WL emitted from the light source device 220 is incident on the light modulation device 60 during the fixed period T2.

[0132] In the projector 202 of the second embodiment, similarly to the projector 201 of the first embodiment, in scan illumination, the image formation cycle of the light modulation device 60, the scanning cycle of the optical scanning device 40 of white light WL from the light source device 220, and the light emission cycle of the light emitting elements 22, 23, and 24 of the light source device 220 are synchronized. According to the projector 202 of the second embodiment, the image formation cycle of the light modulation device 60, the scanning cycle of the white light WL from the light source device 220 by the optical scanning device 40, and the light emission cycle of the light emitting elements 22, 23, and 24 of the light source device 220 are synchronized, and the white light WL emitted from the light source device 220 is made incident on the light modulation device 60 for a fixed period T2, thereby reliably suppressing the occurrence of uneven illuminance of the projected image on the projection surface.

[0133] As with the projector 201 of the first embodiment, the projector 202 of the second embodiment can be controlled so that white light WL does not enter pixels of the plurality of pixels of the liquid crystal panel 62 of the light modulation device 60 during a rise period T1 or a fall period T3 in which the phase modulation amount φ of the liquid crystal layer changes for red light, green light, or blue light. In other words, among the plurality of pixels of the liquid crystal panel 62, light of one of the aforementioned colors is incident on pixels during a certain period T2 of light of one of the colors of red light, green light, or blue light that does not overlap with the rise period T1 or fall period T3 of light of the other color. The projector 202 of the second embodiment can reproduce the colors of an input image well, and can suppress uneven illuminance in the projected image as well as color mixing between light of a color intended for display and light of a color not intended for display.

[0134] In a projector 202 of the second embodiment, a light source device 220 has a light-emitting element (first light source) 22 that emits blue light (first light) BL, and further has a light-emitting element (second light source) that emits green light (second light) GL and a light-emitting element (second light source) that emits red light (second light) RL. The blue light BL, green light GL, and red light RL emitted from the light source device 220 are manipulated by an optical scanning device 40 and enter a light modulation device 60 collectively. In each pixel of a liquid crystal panel 62 of the light modulation device 60, a color filter or the like causes red light RL to enter a red region R, green light GL to enter a green region G, and blue light BL to enter a blue region B. The red light RL, green light GL, and blue light BL are controlled to enter the liquid crystal layer for a fixed time T2 that is different from one another in each color region, and therefore enter the light modulation device 60 for different periods from one another.

[0135] The projector 202 of the second embodiment individually includes a light emitting element 22 that emits red light RL and a light source output control device 111 connected to the light emitting element 22, a light emitting element 23 that emits green light GL and a light source output control device 112 connected to the light emitting element 23, and a light emitting element 24 that emits blue light BL and a light source output control device 113 connected to the light emitting element 24. According to the projector 202 of the second embodiment, red light RL is made incident on each pixel of the liquid crystal panel 62 of the light modulation device 60 in accordance with the red irradiation period TR, green light GL is made incident on each pixel of the liquid crystal panel 62 of the light modulation device 60 in accordance with the green irradiation period TG, and blue light BL is made incident on each pixel of the liquid crystal panel 62 of the light modulation device 60 in accordance with the blue irradiation period TB, thereby improving the quality and color reproducibility of the projected image.

[0136] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as set forth in the claims. Furthermore, the components of multiple embodiments can be combined as appropriate.

[0137] For example, in the above-described embodiments, a projector that projects a multicolor (i.e., full-color) projection image that can be displayed using white light including red, green, and blue light is presented. However, the configuration of the projector in the above-described embodiments may also be applied to a projector that projects a monochromatic projection image. Even in a monochromatic projector, by providing the configuration described in the above-described embodiments, the emission period of the first light from the light source device's light-emitting element, the scanning period of the optical scanning device of the monochromatic first light emitted from the light source device, and the image formation period of the optical modulation device are synchronized. The first light is irradiated onto the liquid crystal layer of the pixel of the liquid crystal element for a certain period during which the modulation rate of the color light of the liquid crystal layer of the pixel is maintained constant at a predetermined value. This reliably reduces uneven illuminance of the projected image on the projection surface.

[0138] Summary of this disclosure A summary of this disclosure is provided below. (Supplementary Note 1) A projection optical system includes a light source device that periodically emits a first light, an optical scanning device that periodically scans the first light emitted from the light source device, an optical modulation device that modulates the first light emitted from the optical scanning device in accordance with image information, and a projection optical system that projects the image light emitted from the optical modulation device, wherein the light source device has a first light-emitting element that emits the first light, the optical scanning device has a transmissive optical element that has an incident surface onto which the first light emitted from the light source device is incident and an exit surface from which the first light incident from the incident surface exits, and the optical modulation device converts the first light irradiated along a first direction in accordance with the input image information into image light. a liquid crystal element that forms an image by scanning the first light in the first direction, a direction in which the optical scanning device scans the first light in synchronization with a drive cycle of the light source device and an image formation cycle of the light modulation device, the liquid crystal element has a liquid crystal layer in which an amount of modulation for the first light changes in response to an input electrical signal, a modulation period in which the first light is modulated in the liquid crystal layer includes a first period from a time when the electrical signal is input to a time when the amount of modulation reaches a predetermined value, and a second period in which the amount of modulation is maintained at the predetermined value, and the first light emitted from the light source device is incident on the light modulation device in the second period.

[0139] With the configuration of Appendix 1, the color light to be modulated is incident during the second period in which the liquid crystal response and phase modulation amounts are maintained at predetermined values ​​in some of the multiple pixels of the liquid crystal element of the optical modulation device, thereby improving the color reproducibility of the projected image relative to the input image and suppressing uneven illuminance in the projected image.

[0140] (Supplementary Note 2) The projector according to Supplementary Note 1, wherein the transmissive optical element has a first surface parallel to the first direction and 2×m second surfaces tangent to the first surface, where m is a natural number greater than or equal to 2.

[0141] With the configuration of Supplementary Note 2, the first light beam scanned by the optical scanning device and emitted from the optical scanning device can be emitted parallel to the principal ray of the first light beam incident on the optical scanning device.

[0142] (Supplementary Note 3) The projector of Supplementary Note 1 or Supplementary Note 2, wherein the light source device further includes a second light source that emits second light, and the first light and the second light are incident on the light modulation device in different periods.

[0143] With the configuration of Appendix 3, for example, the first light and the second light having a wavelength band different from that of the first light are incident on the pixels of the liquid crystal element of one light modulation device of a single-panel projector at irradiation periods and cycles corresponding to each color light, thereby improving the quality of the projected image.

[0144] (Appendix 4) Any of the projectors of Appendix 1 to Appendix 3, further comprising a drive control device that transmits the electrical signal to the light modulation device, and the drive control device transmits a synchronization signal based on the electrical signal to the light source device and the optical scanning device.

[0145] The configuration of Appendix 4 makes it possible to easily synchronize the power, period, and timing of the first light emitted from the light source device with the scanning period of the optical modulation device that scans the first light emitted from the light source device onto the modulation surface of the optical modulation device.

[0146] (Appendix 5) A projector according to any one of Appendices 1 to 4, wherein the light modulation device does not emit image light when the error in the scanning period of the optical scanning device relative to the image formation period of the light modulation device is equal to or greater than a predetermined value, and when the error in the light emission period of the light source device relative to the image formation period of the light modulation device is equal to or greater than a predetermined value.

[0147] The configuration of Supplementary Note 5 makes it possible to prevent unexpected images or videos that are not based on image information or video information transmitted from a user interface or the like from being projected or displayed on the projection surface.

[0148] (Appendix 6) Any of the projectors according to Appendix 4, wherein when an error in the scanning period of the optical scanning device relative to the image formation period of the optical modulation device becomes equal to or greater than a predetermined value, the drive control device changes the scanning period of the optical scanning device.

[0149] The configuration of Appendix 6 adjusts the degree of linkage between the power, light emission period and timing of the first light emitted from the light source device, the scanning period of the light modulation device that scans the first light emitted from the light source device onto the modulation surface of the light modulation device, and the fluctuation period and image formation period of the modulation amount for color light at each pixel of the liquid crystal element of the light modulation device, thereby synchronizing the aforementioned periods and timings and suppressing the display of images that are not based on the image information input to the light modulation device.

[0150] (Appendix 7) Any of the projectors of Appendix 4, wherein when an error in the scanning period of the optical scanning device relative to the image formation period of the optical modulation device becomes equal to or greater than a predetermined value, the drive control device changes the scanning period of the optical scanning device.

[0151] The configuration of Appendix 7 adjusts the degree of linkage between the power, light emission period and timing of the first light emitted from the light source device, the scanning period of the light modulation device that scans the first light emitted from the light source device onto the modulation surface of the light modulation device, and the fluctuation period and image formation period of the modulation amount for color light at each pixel of the liquid crystal element of the light modulation device, thereby synchronizing the aforementioned periods and timings and suppressing the display of images that are not based on the image information input to the light modulation device.

[0152] (Appendix 8) A projector according to any one of Appendices 1 to 7, wherein the modulation period further includes a third period from the time when the modulation amount of the liquid crystal layer reaches the predetermined value to the time when it reaches the initial value, and the first light emitted from the light source device is incident on the light modulation device during the second period for first color light contained in the first light, in a period that does not overlap with the first period or the third period for second color light having a different wavelength band from the first color light contained in the first light.

[0153] The configuration of Appendix 8 prevents the modulation period for the first color light, i.e., the second period, in the liquid crystal panel of the optical modulation device from overlapping with the rise period for the second color light, i.e., the first period, and the fall period, i.e., the third period, so that uneven illumination in the projected image as well as the occurrence of color mixing can be reliably suppressed. [Explanation of symbols]

[0154] 20, 220...light source device, 21, 22...light-emitting element (first light-emitting element), 40...optical scanning device, 42...light-transmitting member (transmitting optical element), 60...light modulation device, 62...liquid crystal panel (liquid crystal element), 80...projection optical system, 201, 202...projector.

Claims

1. a light source device that periodically emits a first light; an optical scanning device that periodically scans the first light emitted from the light source device; a light modulation device that modulates the first light emitted from the optical scanning device in accordance with image information; a projection optical system that projects image light emitted from the light modulation device; Equipped with the light source device has a first light-emitting element that emits the first light, the optical scanning device includes a transmissive optical element having an incident surface onto which the first light emitted from the light source device is incident and an exit surface from which the first light incident from the incident surface exits, the light modulation device has a liquid crystal element that forms an image by converting the first light irradiated along a first direction into image light in accordance with the input image information, a direction in which the optical scanning device scans the first light is the first direction; the optical scanning device scans the first light in synchronization with a drive cycle of the light source device and an image formation cycle of the light modulation device; the liquid crystal element has a liquid crystal layer whose modulation amount for the first light changes in response to an input electrical signal; a modulation period during which the first light is modulated in the liquid crystal layer includes a first period from a time when an electrical signal is input to a time when a modulation amount reaches a predetermined value, and a second period during which the modulation amount is maintained at the predetermined value; the first light emitted from the light source device is incident on the light modulation device during the second period; projector.

2. The transmissive optical element is a first surface parallel to the first direction; 2×m second surfaces tangent to the first surface; having The projector according to claim 1 . Here, m is a natural number of 2 or more.

3. the light source device further includes a second light source that emits second light, the first light and the second light are incident on the light modulation device in different periods from each other; The projector according to claim 1 or 2.

4. a drive control device that transmits the electrical signal to the optical modulation device; the drive control device transmits a synchronization signal based on the electrical signal to the light source device and the optical scanning device; The projector according to claim 1 or 2.

5. when an error in the scanning period of the optical scanning device with respect to the image formation period of the optical modulation device is equal to or greater than a predetermined value and an error in the light emission period of the light source device with respect to the image formation period of the optical modulation device is equal to or greater than a predetermined value, the optical modulation device does not emit image light; The projector according to claim 1 or 2.

6. when an error in the scanning period of the optical scanning device with respect to the image formation period of the optical modulation device becomes equal to or greater than a predetermined value, the drive control device changes the scanning period of the optical scanning device; The projector according to claim 4 .

7. when an error in the scanning period of the optical scanning device with respect to the image formation period of the optical modulation device becomes equal to or greater than a predetermined value, the drive control device changes the image formation period of the optical modulation device; The projector according to claim 4 .

8. the modulation period further includes a third period from a time when the modulation amount reaches the predetermined value to a time when the modulation amount reaches an initial value, the first light emitted from the light source device is incident on the light modulation device during the second period for first color light included in the first light, the period not overlapping with the first period or the third period for second color light having a wavelength band different from that of the first color light included in the first light; The projector according to claim 1 or 2.

Images