Projection display system

Abstract

This invention provides a projection display system. It is capable of detecting anomalies in the projection display system caused by factors such as the wiring condition of the optical fiber and ambient temperature. The projection display system (10) includes a light source unit (100) comprising: a first control unit (110); an anomaly determination unit (113); an optical element unit (125) having multiple optical elements; an optical element driving unit (116); and a first light receiving unit (123) that detects the light intensity of the output light from each optical element. The projection unit (300) comprises: a second control unit (313); a light modulation device (322); and a second light receiving unit (324) that detects the light intensity for projected image formation. The anomaly determination unit (110) adjusts the driving value of the optical element driving unit (116) to satisfy a first condition that the light intensity received for projected image formation is within a first permissible range, and determines an anomaly state based on whether a second condition is met regarding whether the light intensity received by all or a predetermined number of the output lights from the multiple optical elements is within a second permissible range.

Description

Technical Field

[0001] The present invention relates to a projection display system, etc., which is mounted on a vehicle such as an automobile and forms a projected image on a road, etc. Background Technology

[0002] For example, patent documents 1 and 2 describe projection-type display devices in which the light source and the projection part are separated.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2010-78622 Patent Document 2: Japanese Patent Application Publication No. 2023-97755 Summary of the Invention

[0004] The technical problem that the invention aims to solve Through the inventor's research, the following issues have been identified.

[0005] (1) After the projection display system, which integrates the light source and the projection unit, is shipped from the factory, it is installed in the spare space of a vehicle. At this time, it is necessary to connect the light source and the projection unit through communication cables and optical fibers.

[0006] (2) After the operation, determine whether the projection display system is working properly. If an abnormal state is detected, appropriate measures such as stopping the light output and notifying the abnormality should be taken.

[0007] (3) As a method for determining the anomaly, a light-receiving element (photodiode, etc.) can be provided on the projection section side that receives the light for forming the projected image, to confirm whether the light for forming the projected image transmitted from the light source section via the optical fiber is received in the projection section with an appropriate amount of light.

[0008] (4) However, the transmission loss of optical fiber varies considerably depending on the fiber wiring conditions, the ambient temperature of the actual product being used, and the standard temperature (reference temperature) that was intended when the product was manufactured.

[0009] For example, in a fiber optic cable after cabling, the more bends there are, or the higher the ambient temperature, the greater the transmission loss tends to be.

[0010] Therefore, if a projection display system (product) is installed on-site and fiber optic cables are laid, the transmission loss will be greater than the standard transmission loss of the fiber optic cable as envisioned at the factory, depending on the cabling conditions, which can be expected to reduce the amount of light received on the projection side.

[0011] In other words, depending on the fiber optic cabling and other factors, the amount of light transmitted through the fiber optic cable can vary significantly. In such cases, it is not easy to determine whether it is normal or abnormal based solely on the light intensity received by the light-receiving part located on the projection side.

[0012] (5) Assuming that the amount of light received on the projection side is reduced, and a strict judgment is made based on the light intensity of the light-receiving element provided on the projection side, it is conceivable that a product that could originally be used would be judged as abnormal.

[0013] In such cases, it is necessary to reinstall the product, re-wire the fiber optic cable, or replace the product, making the on-site work inefficient.

[0014] (6) On the other hand, if the judgment criteria are relaxed appropriately and abnormal judgments are made, products that should have been judged as abnormal will be judged as normal, which will also lead to situations where the reliability and safety of the products cannot be guaranteed.

[0015] (7) Therefore, while ensuring the reliability and safety of the product, it is necessary to suppress the situation where the product becomes unusable due to being judged as abnormal on site, so as to suppress the reduction in efficiency of on-site operations.

[0016] (8) In addition, if light leaks from the optical fiber and shines into the operator's eyes during on-site product normal / abnormality determination, it may cause damage to the operator's eyes. Therefore, the method for determining the normal / abnormality of products on-site must also be able to prevent accidents and effectively ensure the safety of operators.

[0017] (9) There is no record of such a problem in the above-mentioned patent documents 1 and 2, nor is there any mention of such a countermeasure.

[0018] These issues were clarified through the inventor's research.

[0019] One of the objectives of this invention is to detect anomalies in a projection display system caused by factors such as the wiring condition of the optical fiber and ambient temperature.

[0020] Another object of the invention will be apparent to those skilled in the art from the following illustrated schemes and preferred embodiments, as well as the accompanying drawings.

[0021] Technical solutions adopted to solve technical problems The following examples illustrate the solutions of the present invention in order to facilitate understanding of the invention.

[0022] In the first embodiment, a projection display system has a light source and a projection unit separated, electrically connected via a communication cable. Light output from the light source for image formation is supplied to the projection unit via an optical fiber to form a projected image. The light source includes: a first control unit for controlling bidirectional communication with the projection unit; an anomaly detection unit for determining an anomaly caused by at least one of the installation condition of the optical fiber and ambient temperature; an optical element unit comprising multiple optical elements of different emission colors that generate the light for image formation; an optical element driving unit for driving the multiple optical elements; and a first light receiving unit for detecting the light intensity of each output light from the multiple optical elements of different emission colors. The projection unit includes: a second control unit for controlling bidirectional communication with the light source. The light modulation device modulates the light of each color for forming the projected image transmitted from the light source via the optical fiber to form the projected image; and the second light receiving unit detects the light intensity of the light of each color for forming the projected image transmitted from the light source via the optical fiber. The anomaly determination unit adjusts the drive value of the optical element driving unit to satisfy a first condition that the light intensity of each color for forming the projected image in the second light receiving unit is within a first allowable range. The anomaly determination unit performs the following anomaly determination process: determining whether a second condition is satisfied that the light intensity of all or a predetermined number of the output lights of the multiple optical elements with different emission colors detected by the first light receiving unit is within a second allowable range. If the second condition is not satisfied, an anomaly is determined.

[0023] In the first scheme, a first and a second light-receiving part are respectively provided in the separately configured light source part and projection part, and the normal / abnormal status of the projection display system (product) is determined based on the light intensity of each light-receiving part.

[0024] Specifically, the driving value of the light source driving unit in the light source unit (in other words, the light emission intensity of each color light element) is adjusted (calibrated) so that the light intensity of each color light used for projecting image formation in the first light receiving unit on the receiving side (projection side) of the optical fiber is within the first allowable range (in other words, the first condition is met).

[0025] For example, if the actual transmission loss in the fiber optic cable after wiring is within the range intended at the factory, then the luminous intensity (adjusted luminous intensity) of each color optical element on the transmitting side (light source side) of the fiber optic cable should also fall within the intended range. If the luminous intensity of all (or a predetermined number of) optical elements of each color is outside the intended range, then the optical elements will emit abnormal light.

[0026] The reasons for this include: problems with the installation of the optical fiber; for example, cracks in the cladding of the optical fiber causing light leakage; or a significant difference between the ambient temperature and the pre-determined standard temperature, resulting in an unexpected decrease in communication reliability.

[0027] With this in mind, in this solution, it is determined whether the luminous intensity (adjusted luminous intensity) of all (or a predetermined number of) light elements of each color falls within a predetermined second allowable range (in other words, whether the second condition is met). If the second condition is not met, it is determined that an abnormal state caused by the wiring condition of the optical fiber has occurred.

[0028] By properly detecting abnormal conditions, the light output of the light-emitting element can be stopped, or the abnormality can be notified to the user, for example, via the vehicle-side controller, so that appropriate measures can be taken quickly.

[0029] In the second embodiment, which is subordinate to the first embodiment, the anomaly determination unit may have: a low-emission mode in which each of the plurality of optical elements emits light at a brightness lower than the normal emission brightness; and a normal emission mode in which each of the plurality of optical elements emits light at the normal emission brightness. The anomaly determination process is performed in the low-emission mode to determine whether an anomaly exists in the low-emission mode. After determining that there is no anomaly in the low-emission mode, the anomaly determination process is performed in the normal emission mode to determine whether an anomaly exists in the normal emission mode.

[0030] In the second scheme, in the case of anomaly detection, in addition to the normal light emission mode, a low light emission mode in which the light element emits light at a lower brightness than the normal light emission mode can also be used.

[0031] For example, in the initial anomaly detection process after fiber optic cabling, if workers are present around the fiber, and light leaks from the fiber and shines into their eyes, it could cause eye damage. Therefore, suddenly implementing anomaly detection based on high-brightness emission is not preferable.

[0032] According to this solution, by utilizing a low-emission mode, the amount of light propagating in the optical fiber can be significantly reduced. Therefore, even if, for example, light leaks from the optical fiber and shines into the worker's eyes, the weak light ensures the worker's eye safety.

[0033] According to this solution, after confirming that the basic performance (minimum performance) of optical communication via optical fiber is ensured through a low emission mode, the emission power of the optical element can be restored to the normal level and anomaly detection processing based on the normal emission mode can be implemented. Therefore, high-precision anomaly detection can be implemented while ensuring the safety of the operator.

[0034] In the third scheme, which is subordinate to the first or second scheme, if the anomaly determination unit determines whether an abnormal state exists, APC (Automatic Power Control) can be implemented to stabilize the light output of the multiple light elements with different emission colors based on the light intensity of the light used for forming the projected image of each color in the second light receiving unit.

[0035] In the third approach, during anomaly detection, APC can stabilize the light output of each color optical element. Therefore, fluctuations in detection accuracy can be suppressed.

[0036] In the fourth scheme, which belongs to any one of the first to third schemes, the anomaly determination unit is pre-prepared with: a first reference light-receiving value in the first light-receiving unit for each color of light; a second reference light-receiving value in the second light-receiving unit for each color of light; and a reference threshold coefficient for determining the upper and lower limits of the second permissible range for each color of light. The anomaly determination unit has a calibration unit that calibrates the reference threshold coefficient to calculate a calibration threshold coefficient. The calibration unit calibrates the reference threshold coefficient to calculate the calibration threshold coefficient by comparing the ratio of the first and second reference light-receiving values ​​(i.e., a first ratio) with the ratio of the first and second measured light-receiving values ​​in the first and second light-receiving units (i.e., a second ratio). If the calculated calibration threshold coefficient is within a predetermined normal range, the calibration threshold coefficient is used to determine the upper and lower limits of the second permissible range.

[0037] In the fourth approach, a coefficient known as the “threshold coefficient” is used to determine the upper and lower limits of the second permissible range used to determine normal / abnormal conditions.

[0038] When the product leaves the factory, a reference threshold coefficient (standard threshold coefficient) is prepared in advance.

[0039] However, it is undeniable that immediately after fiber optic cabling is completed on-site, there is a tendency for increased transmission loss and reduced optical communication quality due to fiber bending and other factors. If this situation is ignored and the upper and lower limits determined by the baseline threshold coefficients prepared at the factory are used for anomaly detection, the detection process will become overly strict. Usable products will be deemed abnormal, and the number of products deemed unusable will increase. In such cases, reinstallation of products, re-laying of fiber optic cables, or replacement of products will be necessary, making on-site operations inefficient.

[0040] However, if the judgment criteria are relaxed appropriately, products that were originally judged as abnormal may be judged as normal, which may compromise the reliability and safety of the products.

[0041] Therefore, in this scheme, the reference threshold coefficient prepared at the factory is appropriately calibrated (corrected) using the measured values ​​of the first and second light-receiving parts on site. The threshold coefficient obtained as a result is called the "calibration threshold coefficient".

[0042] During this calibration, the reference threshold coefficient is calibrated by comparing the first ratio of the first and second reference light-receiving values ​​prepared at the factory with the second ratio of the first and second measured light-receiving values ​​in the first and second light-receiving sections, thereby calculating the calibration threshold coefficient.

[0043] For example, in a standard environment before the product leaves the factory, when the light elements of each color are driven by a reference driving value, the reference light receiving value in the first light receiving part on the light source side is a relative value of "1", and the reference light receiving value in the second light receiving part on the projection side is a relative value of "0.8".

[0044] Here, if the first ratio is set to "0.8:1", then the value of the ratio is "0.8 (=0.8 / 1)".

[0045] On the other hand, let the actual measured values ​​(measured values: expressed as relative values ​​here) in the first and second light-receiving sections be "1" and "0.4" respectively. Here, if the second ratio is set to "0.4:1", then the value of the ratio is "0.4 (=0.4 / 1)".

[0046] In the example above, immediately after the fiber optic cable was laid on site, the amount of light received at the projection end was half of the standard amount of light received at the factory. In other words, the communication quality of the light was reduced to half.

[0047] Therefore, in this scheme, the correction factor is determined by comparing the first ratio and the second ratio (specifically, the values ​​of the comparison ratios). In the example above, the correction factor is 2 (=0.8 / 0.4). The reference threshold coefficient is corrected (calibrated) using this correction factor.

[0048] For example, if the reference threshold coefficient for the upper limit of the second allowable range is set as γupper, and the reference threshold coefficient for the lower limit is set as γunder, then the calibration threshold coefficients obtained through calibration are “2·γupper” and “2·γunder”.

[0049] The upper limit of the second permissible range is (first light-receiving reference value · 2 · γupper), which is twice the normal value. On the other hand, the lower limit is "first light-receiving reference value / (2 · γunder)", which is half the normal value. Thus, the second permissible range is expanded to twice the normal range, making it easier to be judged as normal during anomaly detection. Therefore, it is possible to minimize the possibility of the product being judged as abnormal and becoming unusable in the field.

[0050] However, if the above calibration is allowed unconditionally, the reliability of the calibration threshold coefficient cannot be guaranteed in cases where the amount of light received on the projection side exceeds the normal range and is low.

[0051] Therefore, in this scheme, it is determined whether the calibration threshold coefficient obtained through calibration is within a predetermined normal range. If the result of this determination is that the calibration threshold coefficient is normal, the calibration threshold coefficient is used to determine the upper and lower limits of the second allowable range.

[0052] Furthermore, if the calibration threshold coefficient is outside the normal range, and calibration is not possible, measures such as notifying the user of the situation should be taken.

[0053] Thus, according to this solution, while ensuring the reliability and safety of the product, it is possible to minimize the situation where the product is judged to be abnormal and becomes unusable on-site, thereby suppressing the reduction of on-site operational efficiency.

[0054] In the fifth scheme, which belongs to any of the first to third schemes, the anomaly determination unit may pre-prepare: a first reference light-receiving value in the first light-receiving unit for each color of light; a second reference light-receiving value in the second light-receiving unit for each color of light; and a reference threshold coefficient for determining the upper and lower limits of the second allowable range for each color of light. The anomaly determination unit includes a calibration unit that calibrates the reference threshold coefficients used for anomaly determination to calculate a calibration threshold coefficient. The calibration unit operates as follows: the first reference light-receiving value for each color of light is set to pd1', the second reference light-receiving value for each color of light is set to pd2', the first measured light-receiving value for each color of light obtained through measurement in the first light-receiving unit is set to pd1'', the second measured light-receiving value for each color of light obtained through measurement in the second light-receiving unit is set to pd2'', and the reference threshold coefficient for the upper limit of the reference threshold coefficients is set to γupper. When the reference threshold coefficient for the lower limit value in the reference threshold coefficient is set to γunder, and γupper and γunder are allowed to have the same value, the calibration threshold coefficient for the upper limit value in the calibration threshold coefficient is set to γupper(cab), and the calibration threshold coefficient for the lower limit value in the calibration threshold coefficient is set to γunder(cab), γupper(cab) is calculated by the first expression represented by γupper･{(pd2' / pd1') / (pd2'' / pd1'')}, and γunder(cab) is calculated by the second expression represented by γunder･{(pd2' / pd1') / (pd2'' / pd1'')}. If the calculated γupper(cab) and γunder(cab) are within a predetermined normal range, the upper limit value and the lower limit value of the second allowable range of light of each color are determined using γupper(cab) and γunder(cab).

[0055] The fifth scheme contains a more detailed description of the content of the fourth scheme described earlier.

[0056] In this scheme, the first reference light-receiving value for each color of light is set as "pd1'", the second reference light-receiving value for each color of light is set as "pd2'", the first measured light-receiving value for each color of light obtained through the first light-receiving unit is set as "pd1''", the second measured light-receiving value for each color of light obtained through the second light-receiving unit is set as "pd2''", the upper limit value of the reference threshold coefficient is set as "γupper", and the lower limit value of the reference threshold coefficient is set as "γupper". Set the value coefficient to "γunder" (where γupper can also be γunder), set the calibration threshold coefficient for the upper limit value to "γupper(cab)", set the calibration threshold coefficient for the lower limit value to "γunder(cab)", set the first operation formula for calibration to "γupper·{(pd2' / pd1') / (pd2'' / pd1'')}", and set the second operation formula to "γunder·{(pd2' / pd1') / (pd2'' / pd1'')}".

[0057] In this scheme, when the obtained calibration threshold coefficients γupper(cab) and γunder(cab) are within a predetermined normal range, these calibration threshold coefficients are used to determine the upper and lower limits of the second permissible range for each color of light. Furthermore, if the calibration threshold coefficients are outside the normal range, since calibration is impossible, measures are taken, for example, to notify the user of this situation.

[0058] Thus, according to this solution, while ensuring the reliability and safety of the product, it is possible to minimize the situation where the product is judged to be abnormal and becomes unusable on-site, thereby suppressing the reduction of on-site operational efficiency.

[0059] In the sixth embodiment, which belongs to any of the first to fifth embodiments, the projection display system may also be a vehicle-mounted projection display system.

[0060] When a projection display system is installed in a vehicle, the ambient temperature changes in various ways depending on the vehicle's driving environment. In addition, the ambient temperature may also change drastically.

[0061] According to this solution, while ensuring the reliability and safety of the product, it can minimize the possibility of the product being judged as abnormal and becoming unusable in the field.

[0062] Therefore, it increases the possibility of using projection display systems (e.g., road projectors that display images on the road surface) in various environments.

[0063] Those skilled in the art will readily understand that further modifications can be made to the illustrated embodiments of the invention without departing from the spirit of the invention. Attached Figure Description

[0064] Figure 1 This is a diagram showing an example of the appearance of a projection display system, as well as an example of the internal structure of the light source and projection section.

[0065] Figure 2 This is a diagram showing an example of the structure of the anomaly detection unit, as well as an example of various reference values ​​and thresholds (including threshold coefficients) pre-existing in the anomaly detection unit.

[0066] Figure 3 This is a flowchart illustrating an example of the main steps in a low-emission determination process that utilizes a low-emission mode.

[0067] Figure 4 This is a flowchart illustrating an example of the main steps in a normal emission determination process that utilizes a normal emission mode. Detailed Implementation

[0068] The preferred embodiments described below are provided for ease of understanding of the invention. Therefore, those skilled in the art should note that the invention is not unreasonably limited to the embodiments described below.

[0069] (First Implementation) Reference Figure 1 . Figure 1 This diagram shows an example of the appearance of a projection display system, as well as an example of the internal structure of the light source and projection section. Figure 1 In the example, the projection display system 10 is an in-vehicle projection display system mounted on a vehicle (not shown).

[0070] In recent years, vehicle-mounted projection display systems (vehicle projectors) have required higher brightness to improve visibility.

[0071] However, in order to make the light source emit light more brightly, it is necessary to effectively dissipate the heat generated by the light source, leading to a tendency for the size of heat sinks and other heat dissipation devices to increase. As a result, vehicle-mounted projectors are becoming larger, and it is conceivable that they cannot be installed in the limited space of vehicles or other similar locations.

[0072] Therefore, in this invention, the light source and the projection part are separated by optical fiber-based optical transmission technology to construct a separate projection display system (projection system) 10.

[0073] By separating the light source 100 from the projection section 300, the light source, which generates a lot of heat, is placed in a space that can be installed in a vehicle or the like. On the other hand, the projection section that forms the projected image can be separated from the heat source and freely placed in an appropriate position, making it easy to install the projection display system 10 in a vehicle.

[0074] After installing the light source unit 100 and the projection unit 300 in a spare space such as a vehicle, it is necessary to connect the light source unit 100 and the projection unit 300 through the communication cable 210 and the optical fiber 220. After this operation, it is necessary to determine whether the projection display system 10 is working properly. If an abnormal state is detected, appropriate measures such as stopping the light output and notifying of the abnormality need to be taken.

[0075] However, depending on the wiring of the optical fiber 220, the ambient temperature, etc., the amount of light transmitted through the optical fiber 220 can sometimes vary greatly. In such cases, it is not easy to determine normal / abnormal based solely on the light intensity of the light-receiving part 324 located on the projection part 300 side.

[0076] Therefore, in this embodiment, a light-receiving unit 123 is also provided on the light source unit 100 side, and the measured light intensity information obtained from the light-receiving unit 123 on the light source side and the measured light intensity information obtained from the light-receiving unit 324 on the projection unit side are obtained. Anomaly detection processing is performed through predetermined steps using each piece of information, thereby enabling the detection of anomalies in the projection display system 10 caused by the wiring condition of the optical fiber 220, ambient temperature, etc.

[0077] The following is a detailed explanation with reference to the attached diagram.

[0078] like Figure 1 As shown in A-1, in the projection display system 10, the light source unit 100 and the projection unit 300 are separately configured. The light source unit 100 and the projection unit 300 are electrically connected via a communication cable 210. The light output by the light source unit 100 for forming the projected image is supplied to the projection unit 300 via an optical fiber cable (hereinafter, sometimes simply referred to as optical fiber) 220, and the projection unit 300 forms the projected image.

[0079] In addition, the communication cable 210 can be used to transmit power, control signals, video signals, etc.

[0080] The light source unit 100 includes a heat sink 101 serving as a heat dissipation unit, a control board 102, and a microcontroller (MCU) mounted on the control board 102 that serves as a first control unit. Figure 1 The integrated circuit device (IC) 103 (symbol 110 in A-2) and multiple reflectors 120 to 122 as optical elements, etc. On the other hand, the projection unit 300 has a projection port (emission port) 323 for projecting (emitting) display light for the image.

[0081] like Figure 1 As shown in A-2, 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 driver (LC driver) 116, multiple optical elements (here, laser diodes corresponding to each of the colors R (red), G (green), and B (blue)) 117 to 119 with different emission colors, multiple reflectors 120 to 122, a first light receiving unit (here, a first photodiode PD1) 123 for detecting the light intensity of the light for forming the projected image of each color output from the light source unit 125, an optical output interface 124, and a power circuit (power supply circuit) 130.

[0082] The MCU (microcontroller) 110, which serves 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 memory.

[0083] The MCU110 includes: a first light intensity measuring unit 111 that measures light intensity based on the measured values ​​(pd1(R'' / G'' / B'')) of red (R), green (G), and blue (B) light received from the first light receiving unit (PD1) 123; and an anomaly determination unit 113.

[0084] The optical element section 125 is composed of multiple optical elements 117-119 with different emitting colors, multiple reflectors 120-122, a first light receiving part (first photodiode PD1) 123, and an optical output interface 124.

[0085] The first serial interface section SIF1 is composed of serializer 112 and deserializer 114.

[0086] The projection unit 300 includes: a deserializer (serial / parallel converter) 312; a display controller (display control device) 313 serving as a second control unit; a serializer (parallel / serial converter) 314; an optical input interface 320; an optical modulation device (here, a DMD (digital micromirror device)) 322; a second light receiving unit (here, a second photodiode PD2) 324 for detecting the light intensity of each color of light used for forming the projected image transmitted via the optical fiber 220; and a power circuit (power supply circuit) 325.

[0087] The display controller 313, which serves as the second control unit, is a dedicated integrated circuit device that carries a sub-CPU (not shown) and performs display control in place of the MCU110.

[0088] The display controller 313 is provided with a second light intensity measuring unit 315 that measures light intensity based on the measured values ​​(pd2(R'' / G'' / B'')) of light of each color (R, G, B) sent from the second light receiving unit (PD2) 324.

[0089] The second serial interface section SIF2 is composed of a deserializer 312 and a serializer 314.

[0090] The light modulation device 322 includes a main body 319 with a built-in light modulation element, an input terminal 321 for the light modulation device that inputs image bitstream data VBSD supplied from the display controller 313, and a projection port (emission port) 323 for projecting display light onto an image.

[0091] The optical input interface 320 receives the light for projecting image formation sent from the light source unit 100 via the optical fiber 220, and supplies the received light (light of each color R, G, and B) to the main body 319 of the optical modulation device 322.

[0092] Next, the communication between the image signal and the control signal via the first serial interface unit SIF1 and the second serial interface unit SIF2 will be explained.

[0093] The serial communication signals transmitted and received between the first serial interface unit SIF1 and the second serial interface unit SIF2 include, for example, serial video signals (LVDS VideoS) transmitted from the light source unit 100 to the projection unit 300 via LVDS (Low Voltage Differential Signal) transmission, light emission enable signals (LDE: specifically LEDR / G / BLD Enable for each color) transmitted from the light source unit 100 to the projection unit 300 as signals that enable the light elements 117 to 119 to emit light, and various communication signals (CommunicationS1, CommunicationS2).

[0094] Next, an example of various communication signals will be explained. For example, the vehicle-side controller 90 mounted in a vehicle (not shown) can send various request commands C1 based on user settings to the MCU (first control unit) 110 of the light source unit 100.

[0095] As a request command, one could envision requests for things like instructing changes to display brightness, color balance, image size, image position, projection distortion correction, or turning the display on / off.

[0096] The MCU 110 sends the received request command as a communication signal C2 to the serializer 112, and the serializer 112 performs a parallel / serial conversion on the received communication signal C2 to generate a communication signal Communication S1, and sends the communication signal Communication S1 to the projection unit 300 via the communication cable 210. The deserializer 312 of the projection unit 300 performs a serial / parallel conversion on the received communication signal Communication S1 to generate a communication signal C3, and sends the communication signal C3 to the display controller (second control unit) 313.

[0097] 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 (e.g., a signal indicating normal processing completion, or a signal indicating a parameter value obtained as a result of the processing, etc.), and sends it to the serializer 314. The serializer 314 performs parallel / serial conversion on the communication signal C4 to generate a communication signal Communication S2, and sends 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 / 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.

[0098] 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.

[0099] Next, the transmission of the image signal will be described. The vehicle-side controller 90 transmits the image signal VideoS to the serializer 112 of the light source unit 100. The serializer 112 generates an LDVS-formatted image signal LDVS VideoS based on the received image 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-formatted image signal LDVS VideoS into a parallel digital image signal VD and sends the digital image signal VD to the display controller (second control unit) 313.

[0100] Next, the flow of signals related to anomaly detection and processing will be explained. The display controller 313 can send the measured value (pd2(R'' / G'' / B'')) in the second light intensity measurement unit 315 to the light source unit 100 as light intensity information LI.

[0101] The light intensity information LI sent from the display controller 313 is converted from parallel to serial by the serializer 314 and sent to the light source unit 100 as serial light intensity information LI (Light Intensity).

[0102] The deserializer 114 of the light source unit 100 performs serial-to-parallel conversion on the incoming serial light intensity information LI and sends it to the MCU 110 (more specifically, the fault determination unit 113) as a communication signal C5. In addition, the light intensity information LI is supplied to the optical element drive unit 116 in parallel.

[0103] The anomaly determination unit 113, which receives light intensity information LI, performs predetermined processing using the measured value (pd2(R'' / G'' / B'')) in the second light receiving unit (PD2) of the projection unit 300, generates a light source drive value control signal PCR as needed, and sends it to the light element drive unit 110 to appropriately control the luminous intensity of each color light element 117 to 119.

[0104] Furthermore, the light element drive unit 116 fine-tunes the luminous intensity of each color light element 117-119 so that the fluctuation of the received light intensity information LI (the measured value (pd2(R'' / G'' / B'')) in the second light receiving unit (PD2)) within a predetermined period falls within a predetermined level. This implements APC (Automatic Power Control) to stabilize the light output of the multiple light elements 117-119 with different luminous colors.

[0105] Additionally, power 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 power voltage to the power circuit 325 of the projection unit 300 via the communication cable 210. The power circuit 325 supplies power voltage to various parts within the projection unit 300.

[0106] Next, refer to Figure 2 . Figure 2 This is a diagram showing an example of the structure of the anomaly detection unit, as well as an example of various reference values ​​and thresholds (including threshold coefficients) pre-existing in the anomaly detection unit.

[0107] like Figure 2 As shown in A-1, the anomaly determination unit 113 includes: a reference value storage unit 151 that stores various reference values ​​152, a threshold storage unit 153 that stores various thresholds 154, a low light emission determination processing unit 160, a normal light emission determination processing unit 170, and an anomaly notification unit (including a light output stop unit 181) 180.

[0108] The low light emission determination processing unit 160 includes a light source intensity adjustment unit 162 for low light emission and an abnormality determination unit 164 for low light emission.

[0109] Normal light emission determination processing unit 170 includes: light source intensity adjustment unit 172 for normal light emission, calibration unit 174 for abnormality determination of reference threshold, abnormality determination unit 176 for normal light emission, and storage processing unit 178 for adjusted light source intensity and light source drive value.

[0110] Figure 2 Examples of various reference values ​​152 are shown in A-2. Various reference values ​​152 are prepared in advance at the product factory before shipment.

[0111] For example, regarding the red (R) light element (laser diode LD(R)), the following are prepared in advance: the normal driving value GDR' of the LD(R) when it emits light alone, the reference light receiving value pd1R' of the first light receiving part (first photodiode PD1: hereinafter sometimes referred to as "PD1"), and the reference light receiving value pd2R' of the second light receiving part (second photodiode PD2: hereinafter sometimes referred to as "PD2").

[0112] Similarly, for the green (G) light element (laser diode LD(G)), the following are prepared in advance: the normal driving value GDG' of LD(G) when it emits light alone, the reference light-receiving value pd1G' of PD1, and the reference light-receiving value pd2G' of PD2.

[0113] Similarly, for the blue (B) light element (laser diode LD(B)), the following are prepared in advance: the normal driving value GDB' of LD(B) when it emits light alone, the reference light-receiving value pd1B' of PD1, and the reference light-receiving value pd2B' of PD2.

[0114] Figure 2 Examples of various thresholds 154 are shown in A-3. Various thresholds 154 are prepared in advance at the product factory before shipment.

[0115] As thresholds for low luminescence determination processing, the following are prepared in advance: allowable threshold Δpd2 (low power R, G, B) for fluctuation of PD2's light-receiving value; and reference threshold coefficient βupper for the upper limit of the abnormal light-receiving value determination threshold of PD1, and reference threshold coefficient βunder for the lower limit (where βupper=βunder=β can also be set).

[0116] As thresholds for normal emission determination processing, the following are prepared in advance: allowable threshold Δpd2 (normal power R, G, B) for light-receiving value fluctuation of PD2; reference threshold coefficient γupper for the upper limit of abnormal light-receiving value determination threshold of PD1, and reference threshold coefficient γunder for the lower limit (wherein, γupper=γunder=γ can also be set); and normal determination thresholds for each reference threshold coefficient γupper(cab) and γunder(cab) after calibration.

[0117] Next, refer to Figure 3 This is a flowchart illustrating an example of the main steps in a low-emission determination process that utilizes a low-emission mode.

[0118] exist Figure 3 In the example, a low-emission mode is used to make each color light element 117-119 emit light at a brightness lower than normal, and a preliminary anomaly detection is performed (anomaly detection of basic performance such as poor fiber optic installation and light leakage from the fiber optic).

[0119] For example, in the first anomaly detection process after the installation of fiber optic cable 220 on-site, if workers are present around the fiber optic cable 220 and light leaks from it and shines into their eyes, it could cause eye damage. Therefore, it is not preferable to suddenly implement anomaly detection based on high-brightness emission (normal emission).

[0120] Therefore, in Figure 3 In the example, by using a low-emission mode to reduce the luminous intensity of each color light element 117-119, the amount of light propagating in the optical fiber 220 can be sufficiently reduced. Therefore, even if, for example, light leaks from the optical fiber 220 and shines into the operator's eyes, the weak light ensures the safety of the operator's eyes.

[0121] In step S1, the driving values ​​of the light elements 117 to 119 of each color are set to the normal driving values ​​( Figure 2 1 / α of GDR', GDG', GDB' shown in A-2 (α is an integer greater than 1: in a preferred example, α is set to 5 to 10).

[0122] In step S2, the light elements 117-119 of each color are emitted sequentially, and the measured light intensity (measured value) of PD1 and PD2 is detected. Here, the measured values ​​of PD1 and PD2 for red light are set as pd1R'' and pd2R'', the measured values ​​for green light are set as pd1G'' and pd2G'', and the measured values ​​for blue light are set as pd1B'' and pd2B''.

[0123] In step S3, the drive values ​​of each optical element 117 to 119 are adjusted to satisfy the following equations (1) to (3). The drive values ​​are adjusted by sequentially increasing or decreasing the drive current of each optical element 117 to 119 in units of Δi (the minimum change range of the current value), within the maximum allowable dynamic range, until the following equations (1) to (3) are satisfied. pd2R' / α-pd2R''≦Δpd2(low power R)…(1); pd2G' / α-pd2G''≦Δpd2(low power G) …(2); pd2B' / α-pd2B'' ≦ Δpd2(low power B)…(3).

[0124] In equation (1), firstly, the previously... Figure 2 The reference light-receiving value pd2R' in PD2 shown in A-2 is multiplied by (1 / α). This is because the driving value of optical element 117 has become 1 / α, so the reference light-receiving value in PD2 is also ideally assumed to become 1 / α.

[0125] Next, it is determined whether the difference between the obtained reference light-receiving value (pd2R' / α) of PD2 and the measured value in PD2 is below the allowable threshold Δpd2(low power R) for the fluctuation of the light-receiving value of PD2 with respect to red light in low power mode.

[0126] Assuming that equation (1) is satisfied, then the amount of light that can be measured is detected in PD2.

[0127] Furthermore, if equation (1) is not satisfied, although the driving value of the red optical element 117 is adjusted within the maximum dynamic range, the light that does not reach the minimum light quantity via the optical fiber 220 will not be able to proceed with the subsequent abnormality detection process.

[0128] Furthermore, the processing content of equations (2) and (3) is the same as that of equation (1), so the explanation is omitted.

[0129] Next, in step S4, it is determined whether the following relationships (4) to (6) are satisfied: (pd1R' / α) / βunder≦pd1R''≦(pd1R' / α)·βupper…(4); (pd1G' / α) / βunder≦pd1G''≦(pd1G' / α)·βupper…(5); (pd1B' / α) / βunder≦pd1B''≦(pd1B' / α)·βupper…(6).

[0130] In equation (4), it is determined whether the measured value pd1R'' of PD1 for red light is above the lower limit and below the upper limit of the delineated allowable range.

[0131] The lower limit of the delineation range is calculated by dividing the reference light received value (pd1R' / α) of PD1 in low emission mode by the threshold coefficient βunder (an integer greater than 1) used for the lower limit of low emission mode.

[0132] Similarly, the upper limit of the delineated allowable range is calculated by multiplying the reference light received value (pd1R' / α) of PD1 in low emission mode by the threshold coefficient βupper used for the upper limit value in low emission mode.

[0133] If equation (4) is satisfied, it means that the measured value of the output light PD1 of the red light element 117 whose drive value was adjusted in step S2 is within the allowable range specified based on the reference light value and reference threshold coefficient prepared at the time of factory delivery, and the basic performance (minimum performance) of the product is ensured.

[0134] If equation (4) is not satisfied, it means that the red light element 117 is emitting light rather barely outside the permissible range envisioned when the product leaves the factory.

[0135] Furthermore, the processing content of equations (5) and (6) is the same as that of equation (4), so the explanation is omitted.

[0136] In step S5, it is determined whether all or at least a predetermined number (here, at least two) of equations (4) to (6) are satisfied.

[0137] Furthermore, the reason for setting it to at least two is that if two of the equations (4) to (6) are satisfied and only one is not satisfied, it is judged as an abnormality that is too strict. Therefore, it is treated as a normal range here.

[0138] When S5 is Y, proceed to step S6, save the adjusted driving values ​​of each color light element 117-119 obtained in step S3, and end the low luminous emission determination process.

[0139] When step S5 is N, since it can be determined that some kind of abnormality related to basic performance has occurred (poor installation of fiber optic 220, light leakage from fiber optic 220, etc.), measures such as stopping light output and notifying of the abnormality are taken in step S7.

[0140] Furthermore, it was subsequently transferred to Figure 4 In step S10, the light emission power of the optical element is restored to the normal level and an anomaly determination process based on the normal light emission mode is implemented.

[0141] Based on the low-emission detection process described above, a low-emission mode can be used, taking into account operator safety and ensuring the basic performance (minimum performance) of optical communication, such as via fiber optic cables. It is possible to perform anomaly detection regarding basic performance while ensuring operator safety.

[0142] Next, refer to Figure 4 This is a flowchart illustrating an example of the main steps in a normal emission determination process that utilizes a normal emission mode.

[0143] In step S10, Figure 3 The adjusted driving values ​​of each color light element 117 to 119 saved in step S6 are multiplied by α to obtain the normal light emission driving values.

[0144] In addition, APC (Automatic Power Control) is implemented for each color light element 117-119. As a result, fluctuations in the amount of light received in PD2 are suppressed, and the light intensity is stabilized.

[0145] Next, step S11 will be performed. This step S11 corresponds to the previously described... Figure 3 Step S2. In step S11, the light elements of each color emit light sequentially, and the measured light intensity (measured value) of PD1 and PD2 is detected to obtain the values ​​of pd1R'', pd2R'', pd1G'', pd2G'', pd1B'', and pd2B''.

[0146] Next, we will proceed to step S12. This step S12 corresponds to the previously explained step S12. Figure 3 Step S3. The processing content is essentially the same as step S3, so detailed explanation is omitted.

[0147] However, in step S12, since it is the normal light emission mode, the reference light received value for PD2 is different from... Figure 3 Unlike step S3, it is not multiplied by (1 / α) but used as is.

[0148] In addition, as the allowable threshold for the fluctuation of the light received value of PD2, the allowable thresholds (Δpd2(normal power R), Δpd2(normal power G), Δpd2(normal power B)) used in the usual light emission determination process are used to implement the determination based on Equations (7) to (9).

[0149] In this specification, the allowable range for general light emission determination and processing shown by equations (7) to (9) is sometimes referred to as the "first allowable range", and the condition defined by equations (7) to (9) is referred to as the "first condition".

[0150] After steps S13 and S14, the process proceeds to step S15. Step S15 corresponds to the previous... Figure 3 Step S4 is described in the text.

[0151] However, in the usual emission determination process, before implementing step S15, the reference threshold coefficient is calibrated (step S13), and it is determined whether the reference threshold coefficient obtained through calibration is within the normal range (step S14).

[0152] In typical luminescence determination processing, and Figure 3 Similarly, the low luminous emission determination process is based on whether the light received by each color light element emitting light at the adjusted drive value in PD1 falls within a predetermined range to determine the abnormality.

[0153] However, it is undeniable that immediately after the fiber optic 220 is laid on-site, there is a tendency for increased transmission loss and reduced optical communication quality due to factors such as fiber optic bending and significant changes in ambient temperature. If this situation is ignored, and the upper and lower limits determined by the baseline threshold coefficients (γupper, γunder) prepared at the factory are used for anomaly detection, the detection process becomes overly strict. Usable products are increasingly being flagged as abnormal, and unusable products are being deemed unusable. In such cases, reinstallation of products, re-laying of fiber optic cables, or product replacement are necessary, making on-site operations inefficient.

[0154] However, if the judgment criteria are relaxed appropriately, products that were originally judged as abnormal may be judged as normal, which may compromise the reliability and safety of the products.

[0155] Therefore, in Figure 4 In the example, the measured values ​​of PD1 and PD2 on site are used to appropriately calibrate (correct) the reference threshold coefficients (γupper, γunder) prepared at the factory.

[0156] The threshold coefficient obtained as a result is called the "calibration threshold coefficient", denoted as "γupper(cab)" or "γunder(cab)".

[0157] The calibration of the threshold coefficients is explained below. In step S13, the calibration threshold coefficients γupper(cab) and γunder(cab) are calculated using the following formulas.

[0158] γupper(cab)={(pd2R' / pd1R') / (pd2R'' / pd1R'')}· γupper γunder(cab)={(pd2R' / pd1R') / (pd2R'' / pd1R'')}· γunder In the above formula, (pd2R' / pd1R') represents the first ratio of the reference light received values ​​for PD1 and PD2 prepared at the time of shipment from the factory.

[0159] Additionally, (pd2R'' / pd1R'') represents the second ratio, which is the ratio of the measured light received values ​​in PD1 and PD2.

[0160] Then, the magnification is determined by comparing the first ratio with the second ratio. The reference threshold coefficients γupper and γunder are calibrated using this magnification, thereby calculating the calibration threshold coefficients γupper(cab) and γunder(cab).

[0161] For example, under standard conditions before the product leaves the factory, it is assumed that when the light elements 117 to 119 of each color are driven with reference driving values, the reference light received value of PD1 is a relative value of "1", and the reference light received value of PD2 is a relative value of "0.8".

[0162] Here, if the first ratio is set to "0.8:1", then the value of the ratio is "0.8 (=0.8 / 1)".

[0163] On the other hand, let the actual measured values ​​(measured values: expressed as relative values ​​here) in PD1 and PD2 be "1" and "0.4" respectively. Here, if the second ratio is set to "0.4:1", then the value of the ratio is "0.4 (=0.4 / 1)".

[0164] In the example above, immediately after the fiber optic cable 220 is laid on site, the amount of light received on the projection unit 300 side is half of the standard amount of light received at the factory. In other words, the optical communication quality is reduced to half.

[0165] With this in mind, in Figure 4 In step S13, the first ratio and the second ratio (specifically, the values ​​of the comparison ratios) are compared to determine the correction factor. In the example above, the factor is 2 (=0.8 / 0.4). The reference threshold coefficients γupper and γunder are corrected (calibrated) using this factor. In the example above, the calibration threshold coefficients obtained by this calibration are "2·γupper" and "2·γunder".

[0166] In step S15, the calibration threshold coefficient is used to determine whether each of equations (10) to (12) is satisfied.

[0167] The upper limit for this determination is (light reception reference value for each color × 2 × γupper), which is twice the normal value. On the other hand, the lower limit is "light reception reference value for each color / (2 × γunder)", which is half the normal value. Therefore, the permissible range for determination is expanded to twice the normal range, making it easier to determine normality in cases of anomaly. Thus, it is possible to minimize situations where products are determined to be abnormal and become unusable on-site.

[0168] However, if the above calibration is allowed unconditionally, the reliability of the calculated calibration threshold coefficients γupper(cab) and γunder(cab) cannot be guaranteed, for example, in cases where the amount of light received on the projection section 300 side is lower than the normal range.

[0169] Therefore, in Figure 4 In step S14, use the previously mentioned... Figure 2 The normality determination shown in A-3 uses thresholds to determine whether the calibration threshold coefficients γupper(cab) and γunder(cab) obtained through calibration are within a predetermined normal range.

[0170] Then, as a result of this determination, if the calibration threshold coefficient is normal (Y in step S14), the upper and lower limits for anomaly determination in step S15 are determined using the calibration threshold coefficient.

[0171] Furthermore, if the calibration threshold coefficient is outside the normal range (in the case of N in step S14), since calibration is not possible, the process proceeds to step S18, and measures such as notifying the user of the detected anomaly are taken.

[0172] Step S15 corresponds to the previously described... Figure 3 Step S4. The processing content is essentially the same. However, in step S15, since the abnormal determination in the normal light emission determination process is performed, the reference light received value of PD1 for each color of light is not multiplied by (1 / α) in Equations (10) to (12) and is used as is.

[0173] This point is consistent with Figure 3 Step S4 is different.

[0174] Additionally, in step S15, the calibration threshold coefficients γupper(cab) and γunder(cab) obtained through calibration are used. This is also consistent with... Figure 3 Step S4 is different.

[0175] Furthermore, in this specification, the allowable range for the usual light emission determination process shown by equations (10) to (12) is sometimes referred to as the "second allowable range", and the conditions defined by equations (10) to (12) are referred to as the "second condition".

[0176] Step S16 corresponds to the previously explained... Figure 3 Step S5. The content is essentially the same.

[0177] If the result in step S16 is Y, proceed to step S17. In step S17, the calibrated drive values ​​of the optical elements 117 to 119 of each color obtained in step S12 are saved as the reference drive values ​​after the optical fiber is installed.

[0178] In addition, the measured light intensity (measured values) pd1R''~pd1B'' and pd2R''~pd2B'' corresponding to the driving value of PD1 and PD2 will be saved as the light reception reference values ​​after the fiber is installed.

[0179] These saved data can be used in subsequent anomaly detection.

[0180] If N is found in step S16, proceed to step S18 and take measures such as stopping the light output and notifying of the abnormality.

[0181] Thus, according to Figure 4 For example, while ensuring the reliability and safety of the product, we should try our best to prevent the product from being judged as abnormal and becoming unusable on the spot, thereby preventing the reduction of on-site operation efficiency.

[0182] Furthermore, in the above description, the reference light received values ​​of each color of light in PD1 are recorded as pd1R', pd1G', and pd1B', but when these are collectively referred to as the reference light received values ​​of PD1, they are sometimes simply recorded as "pd1'".

[0183] Similarly, the reference light received values ​​of each color in PD2 are recorded as pd2R', pd2G', and pd2B', but when these are collectively referred to as the reference light received values ​​of PD2, they are sometimes simply recorded as "pd2'".

[0184] Similarly, in the above description, the measured light intensity (measured value) of each color of light in PD1 is recorded as pd1R'', pd1G'', and Pd1'', but the measured light intensity (measured value) of these collectively referred to is sometimes only recorded as "Pd1''".

[0185] Similarly, in the above description, the measured light intensity (measured value) of each color of light in PD2 is recorded as pd2R'', pd2G'', and pd2B'', but the measured light intensity (measured value) of these collectively referred to is sometimes simply recorded as "Pd2''".

[0186] As described above, according to this embodiment, it is possible to detect anomalies caused by factors such as the condition of the fiber optic cabling and ambient temperature in a projection display system where the light source and projection parts are separated.

[0187] In addition, while ensuring the reliability and safety of the product, it can minimize the situation where the product is judged to be abnormal and becomes unusable on site, thereby suppressing the reduction of on-site operation efficiency.

[0188] Furthermore, by implementing a low-emission determination process prior to the normal emission determination process, it is possible to ensure the basic performance (minimum performance) of, for example, optical communication via fiber optic cables, while taking operator safety into account. Therefore, it is possible to perform anomaly determinations related to basic performance while ensuring operator safety.

[0189] Furthermore, when a projection display system is installed in a vehicle, the ambient temperature fluctuates in various ways, and there are also cases where the ambient temperature changes drastically. According to this embodiment, for example, changes in transmission loss in the optical fiber caused by ambient temperature are also considered, allowing for appropriate calibration of the reference threshold coefficient.

[0190] In other words, by taking countermeasures against changes in ambient temperature, this invention has high practical value in the field.

[0191] Furthermore, according to the present invention, by implementing accurate anomaly detection, the degradation of projected image quality can be effectively suppressed. Therefore, it is possible to suppress the decrease in reliability of vehicle-mounted projection display systems (e.g., road projectors that display images on the road surface).

[0192] Furthermore, by using this invention, the possibility of using vehicle-mounted projection display systems (e.g., road projectors that display images on the road surface) in various environments is increased.

[0193] This invention is not limited to the embodiments described above. Furthermore, those skilled in the art should be able to easily modify the exemplary embodiments within the scope contained in the claims.

[0194] Explanation of reference numerals in the attached figures 10: Projection-type 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 the first control unit; 111: First light intensity measuring unit; 112: Serializer (parallel / serial converter); 113: Anomaly detection unit; 114: Deserializer (parallel / serial converter); 116: Optical element driving unit (LC driver); 117-119: Multiple optical elements with different emission colors (laser diodes corresponding to R, G, and B colors); 120-122: Multiple reflectors; 123: The light source unit... The following components are included: a first light-receiving section composed of diode PD1; 124: light output interface; 125: optical element section; SIF1: first serial interface section; 130: power circuit (power supply circuit); 151: reference value storage section; 152: various reference values; 153: threshold storage section; 154: various thresholds; 160: low emission determination processing section; 162: light source intensity adjustment section for low emission; 164: abnormal determination section for low emission; 170: normal emission determination processing section; 172: light source intensity adjustment section for normal emission; 174: calibration section for reference thresholds for abnormal determination; 176: abnormal determination section for normal emission; 178: adjusted light source intensity and light... 180: Source drive value storage and processing unit; 181: Abnormal notification unit; 210: Optical output stop unit; 220: Communication cable; 300: Optical fiber cable (optical fiber); 312: Deserializer (serial / parallel converter); 314: Serializer (parallel / serial converter); 313: Display controller (display control device) as a second control unit; 315: Second light intensity measurement unit; 320: Optical input interface; 321: Input terminal of optical modulation device; 322: Optical modulation device (DMD (Digital Micromirror Device)); 323: Projection port (emission port); 324: Second light receiving unit composed of second photodiode PD2; 325: Power... Circuit (power supply circuit), SIF2: Second serial interface section, VideoS: Image signal, LVDSVideoS: Serial image signal transmitted via LVDS transmission mode, VD: Image digital signal, VBSD: Image bit stream data, CommunicationS1, CommunicationS2: Various communication signals, LI: Light intensity information (light intensity signal), pd1(R'' / G'' / B''): Measured light intensity (measured value) of each color of light in PD1, pd2(R'' / G'' / B''): Measured light intensity (measured value) of each color of light in PD2, PS: Power supply.

Claims

1. A projection display system, wherein a light source and a projection unit are separated, the light source and the projection unit are electrically connected via a communication cable, and light for forming a projected image output from the light source is supplied to the projection unit via an optical fiber, thereby forming a projected image through the projection unit, characterized in that... The light source unit has: The first control unit has the function of controlling bidirectional communication between the projection unit and the projection unit; An anomaly determination unit determines an abnormal state caused by at least one of the installation condition of the optical fiber and the ambient temperature. The optical element section includes multiple optical elements of different colors that generate light for forming the projected image; An optical element driving unit that drives the plurality of optical elements; as well as The first light-receiving unit detects the light intensity of each output light from the multiple light elements with different emitting colors. The projection part has: The second control unit has the function of controlling bidirectional communication between the light source unit and the light source unit; An optical modulation device that modulates light of various colors for forming the projected image transmitted from the light source via the optical fiber to form the projected image; as well as The second light-receiving unit detects the light intensity of the projected image-forming light of each color transmitted from the light source unit via the optical fiber. The anomaly determination unit adjusts the drive value of the optical element drive unit to satisfy the first condition that the light intensity of each color of the projected image forming light in the second light receiving unit is within a first allowable range. Furthermore, the anomaly determination unit performs the following anomaly determination process: it determines whether the light intensity of all or a predetermined number of the output lights of the multiple light elements with different emission colors detected by the first light receiving unit is within the second allowable range, and determines an abnormal state if the second condition is not met.

2. The projection display system according to claim 1, characterized in that, The anomaly detection unit includes: a low-emission mode in which each of the plurality of optical elements emits light at a brightness lower than the normal emission brightness; and a normal emission mode in which each of the plurality of optical elements emits light at the normal emission brightness. Furthermore, the anomaly detection process is implemented in the low-light-emitting mode to determine whether an anomaly exists in the low-light-emitting state. After determining that there is no abnormality in the low light emission state, the abnormality determination process is performed in the normal light emission mode to determine whether there is an abnormality in the normal light emission state.

3. The projection display system according to claim 1, characterized in that, When the anomaly determination unit determines whether an abnormal state exists, automatic power control (APC) is implemented to stabilize the light output of the multiple light elements with different emission colors based on the light intensity of each color of the light used for forming the projected image in the second light receiving unit.

4. The projection display system according to claim 1, characterized in that, The anomaly determination unit is pre-prepared with: Regarding the first reference light-receiving value in the first light-receiving part for each color of light; Regarding the second reference light-receiving value in the second light-receiving part for each color of light; as well as The reference threshold coefficients used to determine the upper and lower limits of the second permissible range for each color of light are... The anomaly determination unit includes a calibration unit that calibrates the reference threshold coefficient to calculate a calibration threshold coefficient. The calibration unit calculates the calibration threshold coefficient by calibrating the reference threshold coefficient using a magnification determined by comparing the ratio of the first and second reference light-receiving values ​​(i.e., the first ratio) with the ratio of the first and second measured light-receiving values ​​(i.e., the second ratio) of the first and second light-receiving units. If the calculated calibration threshold coefficient is within a predetermined normal range, the calibration threshold coefficient is used to determine the upper and lower limits of the second allowable range.

5. The projection display system according to claim 1, characterized in that, The anomaly determination unit is pre-prepared with: Regarding the first reference light-receiving value in the first light-receiving part for each color of light; Regarding the second reference light-receiving value in the second light-receiving part for each color of light; as well as The reference threshold coefficients used to determine the upper and lower limits of the second permissible range for each color of light are... The anomaly determination unit includes a calibration unit that calibrates the reference threshold coefficient used for anomaly determination to calculate a calibration threshold coefficient. The calibration unit is used in the following situations: The first reference light value for each color of light is set to pd1'. Set the second reference light value for each color of light to pd2'. The first measured light-receiving value for each color of light, obtained through actual measurement in the first light-receiving section, is set as pd1''. The second measured light-receiving value for each color of light, obtained through actual measurement in the second light-receiving section, is set as pd2''. The upper limit value in the benchmark threshold coefficient is set as γupper. The lower limit value in the benchmark threshold coefficient is set as γunder. Furthermore, it is permissible for γupper and γunder to have the same value. The calibration threshold coefficient used for the upper limit value in the calibration threshold coefficient is set to γupper(cab). When the lower limit value of the calibration threshold coefficient is set to γunder(cab), The γupper(cab) is calculated using the first expression represented by γupper･{(pd2' / pd1') / (pd2'' / pd1''){. The γunder(cab) is calculated using the second expression represented by γunder･{(pd2' / pd1') / (pd2'' / pd1'')}. If the calculated γupper(cab) and γunder(cab) are within a predetermined normal range, the upper and lower limits of the second permissible range for each color of light are determined using the γupper(cab) and γunder(cab).

6. The projection display system according to claim 1, characterized in that, The projection display system is an in-vehicle projection display system mounted on a vehicle.

Images