Projection display system

Abstract

To provide a projection display system which enables quick adjustment of the output light intensity of each of multiple optical elements.SOLUTION: A light source unit 100 comprises multiple optical elements 117-119 with different emission colors. A projection unit 300 comprises a light modulation device 322 configured to form a projection image by modulating projection image-forming light (outgoing light) of each color emitted from the light source unit 100 via an optical fiber 220. The projection unit 300 has a reflective unit 326 for reflecting a portion of the ongoing light toward the optical fiber 220 as light intensity adjustment light (returning light). On the light source unit 100 side, a light sensor 324 detects intensity of the returning light, and an optical element drive unit 116 adjusts intensity of each output light (returning light) of the multiple optical elements 117-119 according to a detection result (light intensity information LI) of the light sensor 324.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a projection display system that is mounted on a vehicle such as an automobile and that projects an image onto a road or the like. [Background technology]

[0002] Projection-type display devices in which the light source unit and the projection unit are separated are described, for example, in Patent Documents 1 and 2. A configuration for detecting the intensity of the light source unit is described, for example, in Patent Document 3. In Patent Document 3, light from the light source unit is incident on an optical fiber, and the intensity of the light emitted from the optical fiber is detected by a second photodiode, and the power (brightness) of the light source unit can be adjusted based on the detection result (paragraph

[0099] of Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-78622 [Patent Document 2] Japanese Patent Application Publication No. 2023-97755 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-164483 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a projection display device in which the light source unit and the projection unit are separated, when transmitting or feeding back information for controlling the power of the light source unit from the projection unit to the light source unit, problems such as noise arise with analog signals, so the information is passed from the projection unit to the light source unit as a digital signal. In other words, in order to transmit information from the projection unit to the light source unit, the detection result of the photodiode needs to be converted from analog to digital on the projection unit side, and this conversion causes a delay in transmission.

[0005] One object of the present invention is to enable rapid adjustment of the power of a light source unit.

[0006] Other objects of the present invention will become apparent to those skilled in the art by referring to the following exemplary aspects and best modes, as well as the accompanying drawings. [Means for solving the problem]

[0007] In order to facilitate an understanding of the outline of the present invention, the following examples are given of embodiments according to the present invention.

[0008] In a first aspect, the projection display system is a projection display system in which a light source unit and a projection unit are separated, the light source unit and the projection unit are controlled based on a video signal, and light for forming a projection image output by the light source unit is supplied to the projection unit via an optical fiber, and a projection image is formed by the projection unit, the light source unit having a plurality of optical elements with different luminous colors that generate the light for forming the projection image, an optical sensor that detects the intensity of light for adjusting the light intensity that is returned from the projection unit to the light source unit via the optical fiber, and an optical element drive unit that adjusts the intensity of each output light of the plurality of optical elements based on the detection result of the optical sensor, and the projection unit has a light modulation device that modulates the light for forming the projection image of each color sent from the light source unit via the optical fiber to form the projection image, and a reflection unit that reflects the portion of the light for forming the projection image supplied to the light modulation unit via the optical fiber towards the optical fiber as light for adjusting the light intensity.

[0009] In the first aspect, when light for forming a projection image output from a light source unit is supplied to a projection unit via an optical fiber, the intensity of the light is not detected on the projection unit side, but rather a portion of the light is returned to the optical fiber by a reflector of the projection unit and reaches the light source unit. That is, in the first aspect, the intensity of the light is not detected on the projection unit side and the detection result is not fed back to the light source unit side via a communication cable, but the light itself (reflecting the intensity of the light for forming a projection image output from the optical fiber to the projection unit) is transmitted to the light source unit side via the optical fiber. Because information (light intensity) from the projection unit to the light source unit is transmitted optically via the optical fiber, there is almost no delay in the transmission, and the optical element driver of the light source unit can quickly adjust the intensity of the output light of each of the multiple optical elements.

[0010] In a second aspect dependent on the first aspect, the optical fiber is a double-clad fiber including a core, a first clad outside the core, and a second clad outside the first clad, and the light for forming the projection image output by the light source unit may propagate within the core, and the light for adjusting the light intensity reflected from the reflecting unit may propagate within the first clad.

[0011] In the second aspect, the light for forming a projection image output from the light source unit is supplied to the projection unit via the core of the double-clad fiber, and a portion of the light for forming the projection image (outgoing light) returns to the light source unit via the first clad of the double-clad fiber as light for adjusting light intensity (returning light).The optical element driver of the light source unit can quickly adjust the intensity of the output light of each of the multiple optical elements by using the detection result of the light for adjusting light intensity (returning light) returned from the first clad.

[0012] In a third aspect dependent on the first or second aspect, the light source unit may include a light condensing unit that condenses the light for adjusting the light intensity onto the optical sensor.

[0013] In the third aspect, the light collecting section can prevent a reduction in the intensity of the light for adjusting the light intensity (returning light) detected by the optical sensor.

[0014] In a fourth aspect dependent on any one of the first to third aspects, the video signal may be communicated between the light source unit and the projection unit via the optical fiber.

[0015] In the fourth aspect, a separate communication cable (and connectors at both ends of the communication cable, etc.) is not required between the light source side and the projection side, and by using optical fiber, it is possible to prevent the projection display system from increasing in size.

[0016] In a fifth aspect dependent on the fourth aspect, the light source unit may have a first communication optical element that generates a first light for communication, which is infrared light, and a first multiplexing unit that multiplexes the first light for communication with the light for forming the projection image, and the projection unit may have a first demultiplexing unit that demultiplexes the first light for communication and the light for forming the projection image, which are supplied from the light source unit via the optical fiber.

[0017] In the fifth aspect, communication data (optical signals) such as video signals can be supplied from the light source unit to the projection unit using optical communication technology that multiplexes and transmits multiple light beams (optical signals) of different wavelengths through a single fiber.

[0018] In a sixth aspect dependent on the fifth aspect, the projection unit may have a second communication optical element that generates a second light for communication, which is infrared light, and a second multiplexing unit that multiplexes the second light for communication and the light for light intensity adjustment, and the light source unit may have a second demultiplexing unit that demultiplexes the second light for communication and the light for light intensity adjustment supplied from the projection unit via the optical fiber.

[0019] In the sixth aspect, communication data (optical signals) can be supplied from the projection unit to the light source unit.

[0020] In a seventh aspect dependent on any one of the first to sixth aspects, the projection display system may be an in-vehicle projection display system mounted on a vehicle.

[0021] Because a portion of the light used to form the projection image (outgoing light) returns to the light source unit via the fiber as light used to adjust the light intensity (returning light), there is no need to provide an optical sensor on the projection unit to detect the intensity of the light used to form the projection image (outgoing light). In other words, the space occupied by the projection unit can be reduced, and when the projection display system is installed in a vehicle, there is greater freedom in designing the layout of the light source unit, optical fiber, and projection unit.

[0022] Those skilled in the art will easily understand that the exemplified embodiments according to the present invention can be further modified without departing from the spirit of the present invention. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing an example of the appearance of a projection display system as a comparative example, and an example of the internal configuration of a light source unit and a projection unit. [Figure 2] 2A and 2B are diagrams showing an example of the configuration of a projection display system. [Figure 3] FIG. 3 is a diagram illustrating the propagation of light in a double clad fiber used in the projection display system of FIG. [Figure 4] FIG. 10 is a diagram showing another example of the configuration of a projection display system. DETAILED DESCRIPTION OF THE INVENTION

[0024] The best mode described below is used to facilitate understanding of the present invention, and therefore, those skilled in the art should be aware that the present invention is not unduly limited by the embodiments described below.

[0025] Please refer to Fig. 1. Fig. 1 is a diagram showing an example of the external appearance of a projection display system as a comparative example, and an example of the internal configuration of a light source unit and a projection unit. In the example of FIG. 1, the projection display system 10 is an in-vehicle projection display system that is mounted on a vehicle (not shown).

[0026] In recent years, there has been a demand for higher brightness in in-vehicle projection display systems (in-vehicle projectors) to improve visibility. However, to make the light source shine brighter, it is necessary to efficiently dissipate the heat generated by the light source, which tends to increase the size of heat sinks and other devices used for heat dissipation. As a result, in-car projectors become larger, and it is possible that they will no longer be able to be installed in the limited space of a vehicle. Therefore, in the comparative example, a light source unit and a projection unit are separated using optical fiber light transmission technology, and a separate projection display system (projector system) 10 is constructed.

[0027] By separating the light source unit 100 and the projection unit 300, the light source unit, which dissipates a large amount of heat, can be installed in any available space in a vehicle, etc., while the projection unit that forms the projected image can be separated from the heat source and installed freely in an appropriate location, making it easier to install the projection display system 10 in a vehicle.

[0028] On the other hand, after the light source unit 100 and the projection unit 300 are installed in an empty space in a vehicle or the like, it is necessary to connect the light source unit 100 and the projection unit 300 with a communication cable 210 and an optical fiber 220. After this work, it is necessary to determine whether the projection display system 10 is operating normally, and if an abnormal state is detected, appropriate measures such as stopping the light output and notifying the abnormality must be taken. However, the amount of light transmitted through the optical fiber 220 may vary greatly depending on the wiring condition of the optical fiber 220, the ambient temperature, etc., and under such circumstances, normality / abnormality may be determined based solely on the intensity of light received by the light receiving unit 324 provided on the projection unit 300 side. In addition, in the comparative example, a light receiving unit 123 is also provided on the light source unit 100 side, and normal / abnormality can be determined based only on information on the actually measured received light intensity obtained from the light receiving unit 123 on the light source side 100, or based on information on the actually measured received light intensity obtained from the light receiving units 123, 324 on the light source side 100 and the projection unit 300 side.

[0029] Such a normal / abnormal determination is not essential, and assuming that the condition is normal, in the comparative example, the light element driving unit 116 can adjust the light emission intensity of the light elements 117 to 119 of each color based only on the light receiving intensity of the light receiving unit 324 provided on the projection unit 300 side. In the comparative example, similar to the projection display system of Patent Document 3, the light emission intensity of the optical elements 117 to 119 of each color may be adjusted based on the received light intensity of the light receiving units 324 and 123 provided on the projection unit 300 side and the light source 100 side.

[0030] A specific description of the comparative example of FIG. 1 will be given later, and the embodiment will be described below with reference to FIGS.

[0031] Please refer to Fig. 2. Figs. 2(A) and (B) are diagrams showing an example of the configuration of a projection display system. In Fig. 2, the same functions as or corresponding to those in Fig. 1 are assigned the same reference numerals. Furthermore, in Fig. 2, the same functions as or corresponding to those in Fig. 1 may not be shown or described.

[0032] As shown in the first embodiment of FIG. 2(A), the present invention also makes it possible to separate the light source unit 100 and the projection unit 300 by utilizing optical transmission technology using an optical fiber 220, and to construct a separate projection display system (projector system) 10.

[0033] In the first embodiment, when light (outgoing light) for forming a projection image output from the light source unit 100 is supplied to the projection unit 300 via the optical fiber 220, the intensity of the light (outgoing light) is not detected on the projection unit 300 side, but a part of the light (returning light) is returned to the optical fiber 220 by the reflector 326 of the projection unit 300 and reaches the light source unit 100. That is, in the first embodiment, the intensity of the light is not detected on the projection unit 300 side in the comparative example of FIG. 1 and the detection result is not fed back to the light source unit 100 side via the communication cable 210, but the light (returning light) itself (reflecting the intensity of the light (outgoing light) for forming a projection image output from the optical fiber 220 to the projection unit 300) is transmitted to the light source unit 100 side via the optical fiber 220.

[0034] Since information (light intensity information LI) from the projection unit 300 to the light source unit 100 is transmitted by light (return light) via the optical fiber 220, there is almost no delay in the transmission, and the light element driving unit 116 of the light source unit 100 can quickly adjust the intensity of the output light of each of the multiple light elements 117, 118, and 119 based on the detection result of the light sensor 324 (e.g., a light receiving unit configured with a photodiode) on the light source unit 100 side. The light element driving unit 116 can control the emission timing of the RGB laser light (outgoing light) in a time-division manner.

[0035] In the first embodiment, as in the comparative example, a first light receiving unit (first photodiode PD1) 123 as an optical sensor may be provided on the light source unit 100 side to detect the intensity of the light (outgoing light) for forming a projection image output by the light source unit 100 before it is incident on the optical fiber 220.

[0036] In the first embodiment, the light source unit 100 has a condenser 127 that condenses light for adjusting light intensity (outgoing light) onto the optical sensor 324, and the condenser 127 can prevent a reduction in the intensity of the light for adjusting light intensity (returning light) detected by the optical sensor 324. As shown in FIG. 2A, the condenser 127 is formed of, for example, a concave mirror, and the concave mirror includes a through-hole or a hole in the center so as not to block the light for forming a projection image (outgoing light), and the concave mirror directs reflected light toward the optical sensor 324. The concave mirror may be replaced with a convex lens having a through hole or aperture in the center, and the light condenser 127 may direct the refracted light of the convex lens toward the optical sensor 324 .

[0037] In the first embodiment, the light source unit 100 has an incident lens (condenser lens) 126 , and the projection unit 300 has an exit lens (condenser lens) 318 and an incident lens (condenser lens) 327 .

[0038] The operation of the first embodiment will be described below. As shown in Fig. 2(A), the light source unit 100 has a plurality of optical elements 117-119 that emit different light colors (here, laser diodes corresponding to the colors R (red), G (green), and B (blue)). Specifically, similar to the comparative example, the plurality of optical elements 117-119 that emit different light colors (outgoing light) can be used to configure an optical element unit 125 together with a plurality of mirrors 120-122 and an optical output interface 124.

[0039] 2(A), the projection unit 300 has a light modulation device (here, a DMD (Digital Mirror Device) is used) 322 that forms a projection image by modulating light for forming a projection image of each color (outgoing light) sent from the light source unit 100 via the optical fiber 220. Specifically, similar to the comparative example, the light modulation device 322 includes a projection port (exit port) 323 that projects (exits) display light of the image (ON light of the DMD).

[0040] In the first embodiment, the projection unit 300 has a reflector 326 that reflects a portion of the light for forming a projection image (outgoing light) (OFF light of the DMD (light not used to display an image)) toward the optical fiber 220 as light for adjusting light intensity (returning light). The light for adjusting light intensity (returning light) returns from the projection unit 300 to the light source unit 110 via the optical fiber 220. On the light source unit 100 side, an optical sensor 324 detects the intensity of the light for adjusting light intensity (returning light), and the optical element driver 116 can adjust the intensity of each output light (outgoing light) of the multiple optical elements 117 to 119 based on the detection result (light intensity information LI) of the optical sensor 324.

[0041] Next, reference is made to FIG. 2(B). The second embodiment differs from the first embodiment in that a half mirror 328 is provided between the optical fiber 220 and the optical modulator 322. The differences from the configuration of the first embodiment will be described below. As shown in FIG. 2(B), in the second embodiment, the projection unit 300 has a reflecting unit 326 that reflects a portion of the light for forming a projection image (outgoing light) (reflected light from the half mirror 328) toward the optical fiber 220 as light for adjusting the light intensity (returning light).

[0042] In the second embodiment, as in the first embodiment, light for adjusting the light intensity (return light) returns from the projection unit 300 to the light source unit 110 via the optical fiber 220. On the light source unit 100 side, the optical element driving unit 116 can adjust the intensity of each output light (outgoing light) of the multiple optical elements 117 to 119 based on the detection result (light intensity information LI) of the optical sensor 324.

[0043] Next, reference is made to Figure 3. Figure 3 is a diagram illustrating the propagation of light in a double clad fiber used in the projection display system of Figure 2.

[0044] The optical fiber 22 is a double-clad fiber and includes a core 221, a first clad 222 outside the core 221, and a second clad 223 outside the first clad 222. Light for forming a projection image output by the light source unit 100 propagates within the core 221. In addition, light for adjusting the light intensity reflected from the reflector 326 propagates within the first clad 222.

[0045] The refractive index of the first cladding 222 is higher than the refractive index of the second cladding 223, and the refractive index of the core 221 is higher than the refractive index of the first cladding 222. When light for forming a projection image (outgoing light) is incident on the optical fiber 220 from the light source unit 100, the light has a maximum incident angle NA1 by the incident lens (condenser lens) 126, and in order to be totally reflected at the boundary between the core 221 and the first cladding 222, the maximum incident angle NA1 is set to be smaller than the numerical aperture NAcore of the core 221 (NA1 <NAcore)。

[0046] When the light for adjusting the light intensity (return light) is incident from the projection unit 300 to the optical fiber 220, the light has a minimum incident angle NA2 and a maximum incident angle NA3 by the incident lens (condenser lens) 327. In order to cause total reflection at the boundary between the first clad 222 and the second clad 223, the minimum incident angle NA2 is set to be larger than the numerical aperture NAcore of the core 221 (NA2>NAcore), and the maximum incident angle NA3 is set to be smaller than the numerical aperture NAclad of the first clad 222 (NA3 <NAclad)。

[0047] In the first and second embodiments, the light for forming the projection image output by the light source unit 100 is supplied to the projection unit 300 via the core 221 of the double-clad fiber, and a portion of the light for forming the projection image (outgoing light) returns to the light source unit 100 via the first clad 222 of the double-clad fiber as light for adjusting the light intensity (returning light).

[0048] Next, reference is made to FIG. 4. FIG. 4 is a diagram showing another example of the configuration of a projection display system. The third embodiment differs from the first embodiment in that communication is performed between the light source unit 100 and the projection unit 300 via an optical fiber (optical fiber cable) 220. In other words, instead of transmitting the video signal (VideoS) via the communication cable 210 as in the first comparative example, in the third embodiment, communication data such as the video signal (VideoS) and control signals can be transmitted via the optical fiber 220. Below, the differences from the configuration of the first embodiment will be described.

[0049] 4, the light source unit 100 includes a communication optical element (first communication optical element) LD that generates infrared communication light (first light), and a multiplexing unit (first multiplexing unit) 128 that multiplexes the communication light with light for forming a projection image (outgoing light). In contrast, the projection unit 300 includes a demultiplexing unit (first demultiplexing unit) 317 that demultiplexes the communication light (first light) supplied from the light source unit 100 via an optical fiber 220 into the light for forming a projection image (outgoing light). Communication data such as a video signal (VideoS) and a communication signal (CommunicationS1) can be supplied from the light source unit 100 to the projection unit 300 via the optical fiber 220 (optical signal), thereby eliminating the need for the communication cable 210 of the first comparative example.

[0050] Similarly, communication data such as a communication signal (Communication S2) can be supplied from the projection unit 300 to the light source unit 100 via the optical fiber 220 (optical signal), and the projection unit 300 has a communication optical element (second communication optical element) LD that generates infrared light for communication (second light), and a multiplexing unit (second multiplexing unit) 329 that multiplexes the light for communication (second light) with light for light intensity adjustment (return light).In addition, the light source unit 100 has a demultiplexing unit (second demultiplexing unit) 330 that demultiplexes the light for communication (second light) supplied from the projection unit 300 via the optical fiber 220 from the light for light intensity adjustment (return light).

[0051] The light source unit 100 may have, for example, a serializer (parallel / serial converter) 112, and the communication optical element (first communication optical element) LD may be included in the serializer 112. The emission wavelength of the communication optical element (first communication optical element) LD may be set to, for example, a range of 800 [nm] to 1600 [nm], and the communication optical element LD may be configured as, for example, a light emitting diode or laser capable of emitting light having a wavelength of 1310 [nm] or 1550 [nm]. Furthermore, the light source unit 100 may include, in the serializer 112, a communication superposition unit that superposes multiple pieces of communication data, for example, a video signal (VideoS) and a communication signal (CommunicationS1).

[0052] The communication optical element (first communication optical element) LD can be driven by a dedicated optical element driver (not shown) or by an optical element driver 116 that drives a plurality of optical elements 117-119.

[0053] The projection unit 300 may have, for example, a deserializer (serial / parallel converter) 312, and an optical sensor (for example, a light receiving unit PD configured with a photodiode) corresponding to the communication optical element (first communication optical element) LD may be included in the deserializer 312. The projection unit 300 may also include, in the deserializer 312, a communication extraction unit that extracts each of the multiple pieces of communication data.

[0054] Similarly, the projection unit 300 may have, for example, a serializer 314, and the communication optical element (second communication optical element) LD may be included in the serializer 314. The emission wavelength of the communication optical element (second communication optical element) LD may be set to, for example, a range of 800 [nm] to 1600 [nm], and the communication optical element LD may be configured as, for example, a light emitting diode or laser capable of emitting light having a wavelength of 850 [nm] or 1300 [nm]. Furthermore, the projection unit 300 may include, in the serializer 314, a communication superposition unit that superposes multiple pieces of communication data, such as a communication signal (Communication S2).

[0055] The communication optical element (second communication optical element) LD can be driven by a dedicated optical element driver (not shown) or the optical modulator 322.

[0056] The light source unit 100 may have, for example, a deserializer 114, and an optical sensor (for example, a light receiving unit PD configured with a photodiode) corresponding to the communication optical element (second communication optical element) LD may be included in the deserializer 114. Furthermore, the light source unit 100 may include, in the deserializer 114, a communication extraction unit that extracts each of the multiple pieces of communication data.

[0057] Referring again to Figure 1, as shown in A-1 of Figure 1, in the projection display system 10, the light source unit 100 and the projection unit 300 are arranged separately, and the light source unit 100 and the projection unit 300 are electrically connected via a communication cable 210. The light for forming a projection image output by the light source unit 100 is supplied to the projection unit 300 via an optical fiber 220, and the projection image is formed by the projection unit 300. In the comparative example, the first embodiment, and the second embodiment, the communication cable 210 can be used to transmit power, control signals, video signals, etc. In the third embodiment, the transmission of control signals, video signals, etc. can be performed by the optical fiber 220 (first clad 222).

[0058] 1A-1, the light source unit 100 includes a heat sink 101 as a heat dissipation unit, a control board 102, an integrated circuit device (IC) 103 including a microcontroller (MCU: reference numeral 110 in A-2 of FIG. 1A) as a first control unit mounted on the control board 102, and a plurality of mirrors 120-122 as optical elements. On the other hand, the projection unit 300 includes a projection aperture (exit aperture) 323 for projecting (exiting) display light for an image.

[0059] As shown in A-2 of FIG. 1, the light source unit 100 includes an MCU 110 as a first control unit, a serializer (parallel / serial converter) 112, a deserializer (parallel / serial converter) 114, an optical element driving unit (LC driver) 116, a plurality of optical elements (here, laser diodes corresponding to the colors R (red), G (green), and B (blue)) 117-119 emitting different light, a plurality of mirrors 120-122, a first light receiving unit (here, a first photodiode PD1 is used) 123 detecting the light intensity of light for forming a projection image of each color output from the light source unit 125, an optical output interface 124, and a power circuit (power supply circuit) 130.

[0060] The MCU (microcontroller) 110 serving as the first control unit is an integrated circuit device that integrates a processor that functions as a main CPU (host CPU) with peripheral circuits such as a memory.

[0061] The MCU 110 is provided with a first light intensity measuring unit 111 that measures light intensity based on the actual measurement values ​​(pd1(R'' / G'' / B'')) of the light (outgoing light) of each color of red (R), green (G), and blue (B) sent from the first light receiving unit (PD1) 123, and an abnormality judgment unit 113. In the first to third embodiments, the actual measured values ​​of red (R), green (G), and blue (B) light (return light) sent from the optical sensor 324 in Figure 2 or Figure 4 can be processed by the MCU 110.

[0062] As shown in A-2 of FIG. 1, a plurality of optical elements 117-119 emitting light of different colors, a plurality of mirrors 120-122, a first light receiving section (first photodiode PD1) 123, and a light output interface 124 constitute an optical element section 125.

[0063] The serializer 112 and the deserializer 114 form a first serial interface unit SIF1.

[0064] In the comparative example shown in A-2 of Figure 1, the projection unit 300 has a deserializer (serial / parallel converter) 312, a display controller (display control device) 313 as a second control unit, a serializer (parallel / serial converter) 314, an optical input interface 320, an optical modulation device (here, a DMD (digital mirror device) is used) 322, a second light receiving unit (here, a second photodiode PD2 is used) 324 that detects the light intensity of each color of light for forming a projection image sent via the optical fiber 220, and a power circuit (power supply circuit) 325. In the first to third embodiments, as shown in FIG. 2 or 4, the optical sensor 324 is provided on the light source unit 100 side.

[0065] As shown in A-2 of FIG. 1, the display controller 313 as a second control unit is a dedicated integrated circuit device that includes a sub-CPU (not shown) and performs display control in place of the MCU 110.

[0066] In the comparative example, the display controller 313 is provided with a second light intensity measuring unit 315 that measures light intensity based on the actual measured values ​​of light of each color R, G, and B (pd2(R'' / G'' / B'')) sent from the second light receiving unit (PD2) 324.

[0067] The deserializer 312 and the serializer 314 form a second serial interface unit SIF2.

[0068] As shown in A-2 of Figure 1, the optical modulation device 322 includes a main body 319 in which an optical modulation element is built, an input terminal 321 of the optical modulation device to which video bitstream data VBSD supplied from the display controller 313 is input, and a projection port (exit port) 323 from which display light of an image is projected (exited).

[0069] The optical input interface 320 receives light for forming a projection image transmitted from the light source unit 100 via the optical fiber 220, and supplies the received light (light of each color R, G, B) to the main body unit 319 of the optical modulation device 322.

[0070] Next, the contents of communication of video signals and control signals via the first serial interface unit SIF1 and the second serial interface unit SIF2 will be described.

[0071] As shown in A-2 of FIG. 1, the serial communication signals transmitted and received between the first serial interface unit SIF1 and the second serial interface unit SIF2 include, for example, a serial video signal (LVDS VideoS) transmitted from the light source unit 100 to the projection unit 300 using an LVDS (Low Voltage Differential Signal) transmission method, a light emission enable signal (LDE: specifically, LEDR / G / B LD Enable for each color) which is transmitted from the light source unit 100 to the projection unit 300 and enables the light elements 117 to 119 to emit light, and various communication signals (Communication S1, Communication S2).

[0072] Next, an example of various communication signals will be described. For example, a vehicle-side controller 90 mounted on a vehicle (not shown) can transmit various request commands C1 based on user settings to an MCU (first control unit) 110 of the light source unit 100.

[0073] Possible request commands include, for example, request commands to change the display brightness, change the color balance, change the image size, change the image position, correct projection distortion, turn the display on / off, and the like.

[0074] The MCU 110 sends the received request command as a communication signal C2 to the serializer 112, and the serializer 112 performs parallel / serial conversion on the received communication signal C2 to generate a communication signal Communication S1 and transmits this communication signal Communication S1 to the projection unit 300 via the communication cable 210. The deserializer 312 of the projection unit 300 performs serial / parallel conversion on the received communication signal Communication S1 to generate a communication signal C3 and sends this communication signal C3 to the display controller (second control unit) 313. In the third embodiment, an optical fiber 220 can be used instead of the communication cable 210 .

[0075] 1 , the display controller (second control unit) 313 performs processing in response to various requests from the MCU (first control unit) 110 of the light source unit 100, and generates a signal C4 indicating the result of the processing (for example, a signal indicating that the processing was successful, or a signal indicating a parameter value obtained as a result of the processing) and sends the signal C4 to the serializer 314. The serializer 314 performs parallel-to-serial conversion on the communication signal C4 to generate a communication signal Communication S2, and transmits the communication signal Communication S2 to the light source unit 100 via the communication cable 210. The deserializer 114 of the light source unit 100 performs serial-to-parallel conversion on the received communication signal Communication S2 to generate a communication signal C5, and sends the communication signal C5 to the MCU (first control unit) 110.

[0076] In this way, the MCU (first control unit) 110 and the display controller (second control unit) 313 can transmit and receive various signals via the first and second serial interface units SF1 and SF2.

[0077] Next, transmission of a video signal will be described. The vehicle-side controller 90 transmits a video signal VideoS to the serializer 112 of the light source unit 100. The serializer 112 generates an LDVS-type video signal LDVS VideoS based on the received video signal VideoS and transmits it to the projection unit 300 via the communication cable 210. The deserializer 312 of the projection unit 300 converts the received LDVS-type video signal LDVS VideoS into a parallel-format digital video signal VD and transmits the digital video signal VD to a display controller (second control unit) 313. In the third embodiment, an optical fiber 220 can be used instead of the communication cable 210 .

[0078] Next, the flow of signals related to the abnormality determination process will be described. As shown in A-2 of FIG. 1, the display controller 313 can transmit the actual measurement value (pd2(R'' / G'' / B'')) of the second light intensity measurement unit 315 to the light source unit 100 as light intensity information LI.

[0079] The light intensity information LI sent from the display controller 313 is converted from parallel to serial by the serializer 314 and transmitted to the light source unit 100 as light intensity information LI (Light Intesity) in serial format.

[0080] The deserializer 114 of the light source unit 100 performs serial / parallel conversion on the received serial-format light intensity information LI and transmits it as a communication signal C5 to the MCU 110 (more specifically, the abnormality determination unit 113), and in parallel with this, supplies the light intensity information LI to the optical element driving unit 116.

[0081] The abnormality determination unit 113, which receives the light intensity information LI, performs a predetermined process using the actual measurement value (pd2(R'' / G'' / B'')) at the second light receiving unit (PD2) of the projection unit 300, and, if necessary, generates a light source drive value control signal PCR and sends it to the light element drive unit 110, thereby appropriately controlling the light emission intensity of the light elements 117 to 119 of each color.

[0082] Furthermore, the optical element driver 116 finely adjusts the light emission intensity of the optical elements 117-119 of each color so that the variation in the light intensity information LI (actual measurement value (pd2(R'' / G'' / B'') at the second light receiving unit (PD2)) within a predetermined period falls within a predetermined level. This allows for APC (Automatic Power Control) to be performed, which stabilizes the light output of the multiple optical elements 117-119 that emit different colors of light. In the first to third embodiments, the light intensity information LI corresponds to the detection result of the optical sensor 324 in FIG. 2 or FIG.

[0083] 1, power supply PS is supplied from the vehicle-side controller 90 to the power circuit 130 of the light source unit 100. The power circuit 130 supplies a power supply voltage to the power circuit 325 of the projection unit 300 via the communication cable 210. The power circuit 325 supplies the power supply voltage to each unit in the projection unit 300. In the third embodiment, the power source PS does not need to use the communication cable 210. In other words, the power source PS may be supplied to the projection unit 300 from a device other than the light source unit 100.

[0084] The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent that they fall within the scope of the claims. [Explanation of symbols]

[0085] 10 Projection display system, 90 Vehicle-side controller, 100 Light source unit, 101 Heat sink (heat dissipation unit), 102 Control board, 103 Integrated circuit device (IC), 110 Microcontroller (MCU) as first control unit, 111 First light intensity measurement unit, 112 Serializer (parallel / serial converter), 113 Abnormality determination unit, 114 Deserializer (parallel / serial converter), 116 Optical element drive unit (LC driver), 117 to 119 Multiple optical elements (R, 120-122: a plurality of mirrors; 123: a first light receiving section including a first photodiode PD1; 124: an optical output interface; 125: an optical element section; 126: an incident lens (condenser lens); 127: a condenser section; 128: a multiplexing section (first multiplexing section); SIF1: a first serial interface section; 130: a power circuit (power supply circuit); 210: a communication cable; 220: an optical fiber cable (optical fiber); 221: a core; 222: a first cladding; clad, 223...second clad, NA1...maximum angle of incidence of outgoing light, NA2...minimum angle of incidence of return light, NA3...maximum angle of incidence of return light, 300...projection unit, 312...deserializer (serial / parallel converter), 314...serializer (parallel / serial converter), 313...display controller (display control device) as second control unit, 315...second light intensity measurement unit, 317...demultiplexing unit (first demultiplexing unit), 318...output lens (condenser lens), 320...optical input interface, 321...optical modulation device input terminal, 322...optical modulation device (DMD (digital mirror device)), 323...projection port (output port), 324...optical sensor arranged in the second light receiving section or light source section constituted by the second photodiode PD2, 325...power circuit (power supply circuit), 326...reflection section, 327...incident lens (condenser lens), 328...half mirror, 329...multiplexing section (second multiplexing section), 330...demultiplexing section (second demultiplexing section), SIF2...second serial interface section, VideoS...video signal, LD...communication optical element, LVDSVideoS...Serial video signal transmitted using the LVDS transmission method, VD...Video digital signal, VBSD...Video bit stream data, CommunicationS1, CommunicationS2...Various communication signals, LI...Light intensity information (light intensity signal), pd1(R'' / G'' / B'')...Measured received light intensity of each color of light at PD1 (actual measured value), pd2(R'' / G'' / B'')...Measured received light intensity of each color of light at PD2 (actual measured value), PS...Power supply.

Claims

1. A projection display system in which a light source unit and a projection unit are separated, the light source unit and the projection unit are controlled based on a video signal, and light for forming a projection image output from the light source unit is supplied to the projection unit via an optical fiber, and a projection image is formed by the projection unit, The light source unit is a plurality of light elements each having a different emission color that generate light for forming the projection image; an optical sensor for detecting the intensity of light for adjusting the light intensity, which is a part of the light for forming the projection image from the projection unit and returns to the light source unit via the optical fiber; an optical element driver that adjusts the intensity of the output light of each of the plurality of optical elements based on the detection result of the optical sensor; The projection unit includes: a light modulation device that modulates the light for forming the projection image of each color sent from the light source unit through the optical fiber to form the projection image; a reflecting section that reflects the part of the light for forming the projection image, which is supplied to the light modulation device through the optical fiber, toward the optical fiber as the light for adjusting the light intensity, Projection display system.

2. the optical fiber is a double-clad fiber including a core, a first clad outside the core, and a second clad outside the first clad; the light for forming the projection image output from the light source unit propagates within the core, the light for adjusting the light intensity reflected from the reflecting portion propagates within the first clad; 10. The projection display system of claim 1.

3. the light source unit has a light condensing unit that condenses the light for adjusting the light intensity onto the optical sensor; 10. The projection display system of claim 1.

4. the video signal is communicated between the light source unit and the projection unit via the optical fiber; 10. The projection display system of claim 1.

5. the light source unit includes a first communication optical element that generates a first light for communication, which is infrared light, and a first multiplexing unit that multiplexes the first light for communication and the light for forming the projection image; the projection unit has a first demultiplexing unit that demultiplexes the first light for communication supplied from the light source unit through the optical fiber and the light for forming the projection image; 5. The projection display system of claim 4.

6. the projection unit includes a second communication optical element that generates second light for communication, which is infrared light, and a second multiplexing unit that multiplexes the second light for communication and the light for light intensity adjustment, the light source unit has a second demultiplexing unit that demultiplexes the second light for communication supplied from the projection unit through the optical fiber and the light for light intensity adjustment, 6. The projection display system of claim 5.

7. The projection display system is an in-vehicle projection display system mounted on a vehicle.

7. A projection display system according to any one of claims 1 to 6.

Images