Projection-type display system

Abstract

The present invention makes it possible to detect an abnormality in a projection-type display system due to the optical fiber wiring situation, environmental temperature, or the like.　A light source unit 100 of a projection-type display system 10 includes: a first control unit 110; an abnormality determination unit 113; an optical element unit 125 that is provided with a plurality of optical elements; an optical element drive unit 116; and a first light reception unit 123 that detects the light intensities of output light beams from the respective optical elements. A projection unit 300 includes a second control unit 313, a light modulation device 322, and a second light reception unit 324 that detects the light intensity of light for forming a projection image. The abnormality determination unit 110 adjusts the drive value of the optical element drive unit 116 such that a first condition in which the light reception intensity of the light for forming a projection image falls within a first allowable range is satisfied, and determines an abnormal state depending on whether a second condition in which the light reception intensities of all of the respective output light beams from the plurality of optical elements or a prescribed number of output light beams from among the respective output light beams falls within a second allowable range is satisfied.

Description

Projection Display System

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

[0002] Projection display devices in which the light source unit and the projection unit are separated are described in, for example, Patent Documents 1 and 2.

[0003] JP 2010-78622 A JP 2023-97755 A

[0004] The inventors' investigations revealed the following problems. (1) A projection display system, in which the light source unit and the projection unit are separate, is installed in an empty space in a vehicle, for example, after being shipped from a factory. This requires connecting the light source unit and the projection unit via a communication cable and optical fiber. (2) After this installation, it is necessary to determine whether the projection display system is operating normally. If an abnormality is detected, appropriate measures, such as stopping the optical output and issuing an abnormality alert, must be taken. (3) One method for determining this abnormality is to provide a light-receiving element (e.g., a photodiode) on the projection unit side that receives the light for forming the projection image, and to confirm whether the light for forming the projection image, transmitted from the light source unit via the optical fiber, is received by the projection unit in an appropriate amount. (4) However, the transmission loss of optical fiber varies considerably depending on factors such as the condition of the optical fiber wiring and whether the environmental temperature in which the product is actually used is significantly different from the standard temperature (reference temperature) assumed at the time of product shipment. For example, the more bends in an optical fiber cable or the higher the environmental temperature, the greater the optical fiber transmission loss. Therefore, when a projection display system (product) is installed and the optical fiber cable is installed on-site, depending on the wiring conditions, it is entirely possible that a transmission loss greater than the standard optical fiber transmission loss assumed at the time of factory shipment will occur, resulting in a decrease in the amount of light received by the projection unit. In other words, the amount of light transmitted through the optical fiber can vary significantly depending on the wiring conditions, etc. Under such circumstances, it is not easy to determine whether the product is normal or abnormal based solely on the light intensity received by the light-receiving element installed on the projection unit. (5) If a strict evaluation were performed based on the light intensity received by the light-receiving element installed on the projection unit when the amount of light received by the projection unit was reduced, it is likely that a product that is otherwise usable would be determined to be abnormal. In this case, the product would need to be reinstalled, the optical fiber cable rewired, or the product replaced, resulting in inefficient on-site work.(6) On the other hand, if the judgment criteria are loosened appropriately to perform an abnormality judgment, a product that should be judged as abnormal may be judged as normal, which may result in failure to ensure product reliability and safety. (7) Therefore, while ensuring product reliability and safety, it is necessary to minimize the number of cases in which a product is judged as abnormal and becomes unusable in the field, thereby preventing inefficiencies in on-site work. (8) Furthermore, if light leaks from an optical fiber during on-site product normality / abnormality judgment and is incident on a worker's eyes, it could cause eye damage. Therefore, a method for determining whether a product is normal or abnormal in the field is also required to prevent accidents and ensure the safety of workers. (9) The above-mentioned Patent Documents 1 and 2 do not mention such issues or any countermeasures.

[0005] Such a problem was made clear through investigations by the inventors of the present invention.

[0006] One of the objects of the present invention is to make it possible to detect abnormalities in a projection display system caused by the wiring conditions of optical fiber, the environmental temperature, and the like.

[0007] 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.

[0008] 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.

[0009] In a first aspect, a 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 electrically connected via a communication cable, 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 has a first control unit having a function of controlling two-way communication with the projection unit, an abnormality determination unit that determines an abnormal state caused by at least one of an attachment status of the optical fiber and an ambient temperature, a light element unit that generates light for forming the projection image and has a plurality of light elements with different emission colors, a light element drive unit that drives the plurality of light elements, and a first light receiving unit that detects the light intensity of each output light of the plurality of light elements with different emission colors, and the projection unit has a function of controlling two-way communication with the light source unit. a second control unit having 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 second light receiving unit that detects the light intensity of the light for forming the projection image of each color sent from the light source unit via the optical fiber, wherein the abnormality determination unit adjusts the drive value of the light element drive unit so that a first condition is satisfied that the received light intensity of each of the light for forming the projection image of each color at the second light receiving unit is within a first allowable range, and determines whether a second condition is satisfied that the received light intensity of all of the output light of the plurality of light elements having different light emission colors, or for a predetermined number of output light of the output light, is within a second allowable range, and performs abnormality determination processing to determine that an abnormal state exists if the second condition is not satisfied.

[0010] In the first aspect, a first and a second light receiving unit are provided for each of the light source unit and projection unit, which are arranged separately, and the normality / abnormality of the projection display system (product) is determined based on the light receiving intensity of each light receiving unit.

[0011] Specifically, the drive value of the light source drive unit in the light source unit (in other words, the light emission intensity of the light elements of each color) is adjusted (calibrated) so that the received light intensity at the first light receiving unit of the light for forming the projection image of each color on the receiving side (projection unit side) of the optical fiber is within a first allowable range (in other words, the first condition is satisfied).

[0012] Here, for example, if the actual transmission loss of the wired optical fiber is within the expected range at the time of shipment from the factory, the light emission intensity (adjusted light emission intensity) of the optical elements of each color on the transmitting side (light source side) of the optical fiber should also be within the expected range. If the light emission intensity of all (or a predetermined number of) the optical elements of each color is outside the expected range, the optical elements are emitting abnormal light. This can be caused by problems with the optical fiber installation, for example, cracks in the cladding layer of the optical fiber causing light leakage, or a significant difference between the ambient temperature at the site and the expected standard temperature, resulting in an unexpected decrease in communication reliability. In light of this, in this embodiment, the light emission intensity (adjusted light emission intensity) of all (or a predetermined number of) the optical elements of each color is determined to be within a predetermined second allowable range (in other words, whether the second condition is satisfied). If the second condition is not satisfied, it is determined that an abnormal state has occurred due to the optical fiber wiring conditions, etc. By properly detecting an abnormal condition, the light output of the light-emitting element can be stopped or the user can be notified of the abnormality via, for example, a controller on the vehicle, allowing appropriate measures to be taken quickly.

[0013] In a second aspect dependent on the first aspect, the abnormality determination unit has a low light emission mode in which each of the plurality of optical elements emits light at a brightness lower than a normal light emission brightness, and a normal light emission mode in which each of the plurality of optical elements emits light at a normal light emission brightness, and may perform the abnormality determination process in the low light emission mode to determine whether or not an abnormality exists in the low light emission state, and after it is determined that no abnormality exists in the low light emission state, perform the abnormality determination process in the normal light emission mode to determine whether or not an abnormality exists in the normal light emission state.

[0014] In the second aspect, in addition to the normal light emission mode, a low light emission mode can be used when performing an abnormality determination. This mode causes the optical element to emit light at a lower brightness than the normal light emission. For example, when performing the first abnormality determination process after laying optical fiber at a site, there may be workers around the optical fiber. If light leaks from the optical fiber and irradiates the worker's eyes, it could cause eye damage. Therefore, it is considered undesirable to immediately perform an abnormality determination process using high-brightness light emission. According to this aspect, by using the low light emission mode, the amount of light propagating through the optical fiber can be sufficiently reduced. Therefore, even if light leaks from the optical fiber and irradiates the worker's eyes, the light is weak, ensuring the safety of the worker's eyes. According to this aspect, after confirming that the basic performance (minimum performance) of optical communication via optical fiber is ensured using the low light emission mode, the light emission power of the optical element can be returned to a normal level and an abnormality determination process can be performed using the normal light emission mode. This allows for highly accurate abnormality determination while ensuring the safety of the worker.

[0015] In a third aspect dependent on the first or second aspect, when the abnormality determination unit determines whether or not an abnormal state exists, APC (Automatic Power Control) may be performed to stabilize the light output of the plurality of optical elements having different light emission colors based on the received light intensity of each of the lights for forming the projection image of each color at the second light receiving unit.

[0016] In the third aspect, the optical output of the optical elements of each color can be stabilized by APC when determining whether an abnormality has occurred, thereby suppressing variations in the accuracy of the determination.

[0017] In a fourth aspect dependent on any one of the first to third aspects, the abnormality determination unit may be provided with a first reference light-receiving value at the first light-receiving unit for each color of light, a second reference light-receiving value at the second light-receiving unit for each color of light, and a reference threshold coefficient used to determine upper and lower limit values ​​that define the second allowable range for each color of light, the abnormality determination unit having a calibration unit that calibrates the reference threshold coefficient to calculate a calibration threshold coefficient, the calibration unit calibrating the reference threshold coefficient with a magnification determined by comparing a first ratio that is a ratio between the first and second reference light-receiving values ​​and a second ratio that is a ratio between the first and second actual measured light-receiving values ​​at the first and second light-receiving units to calculate the calibration threshold coefficient, and if the calculated calibration threshold coefficient is within a predetermined normal range, the calibration threshold coefficient may be used to determine the upper and lower limit values ​​that define the second allowable range.

[0018] In the fourth aspect, the upper and lower limits defining the second tolerance range for determining normality / abnormality are determined using coefficients called "threshold coefficients." A standard threshold coefficient (a standard threshold coefficient) is pre-set when the product is shipped from the factory. However, immediately after optical fiber wiring in the field, there is a tendency for transmission loss to increase due to bending of the optical fiber, leading to a decrease in the quality of optical communication. If such conditions are ignored and an abnormality determination is performed using the upper and lower limits determined by the standard threshold coefficient pre-set at the factory, the determination may become too strict, resulting in an increase in the number of cases where a usable product is determined to be abnormal and therefore unusable. In this case, the product must be reinstalled, the optical fiber wiring must be redone, or the product must be replaced, resulting in inefficient on-site work.

[0019] However, if the judgment conditions are relaxed too much, a product that should be judged as abnormal may be judged as normal, which may result in a failure to ensure product reliability and safety. Therefore, in this embodiment, the actual measured values ​​of the first and second light receiving units at the site are used to properly calibrate the standard threshold coefficients prepared at the time of shipment from the factory. The threshold coefficients obtained as a result are referred to as "calibration threshold coefficients."

[0020] During this calibration, the reference threshold coefficient is calibrated using a magnification determined by comparing a first ratio of the first and second reference light-receiving values, which are prepared at the time of shipment from the factory, with a second ratio, which is the ratio of the first and second actual light-receiving values ​​at the first and second light-receiving units, and the calibration threshold coefficient is calculated based on this. For example, under a standard environment before product shipment, when the optical elements of each color are driven at the reference drive value, the reference light-receiving value at the first light-receiving unit on the light source side becomes a relative value of "1," and the reference light-receiving value at the second light-receiving unit on the projection unit side becomes a relative value of "0.8." Here, if the first ratio is "0.8:1," the value of this ratio is "0.8 (= 0.8 / 1)." Meanwhile, suppose the actual measurement values ​​(actual values: expressed as relative values ​​here) at the first and second light-receiving units are "1" and "0.4." Here, if the second ratio is "0.4:1", the value of the ratio is "0.4 (=0.4 / 1)". In the above example, immediately after the optical fiber is laid on-site, the amount of light received on the projection unit side is half of the standard amount of light received at the time of factory shipment, in other words, the optical communication quality is reduced to half.

[0021] Therefore, in this embodiment, the first ratio and the second ratio are compared (specifically, the ratio values ​​are compared) to determine a calibration magnification. In the above example, the magnification is 2 (= 0.8 / 0.4). The reference threshold coefficient is calibrated using this magnification. For example, if the reference threshold coefficient defining the upper limit of the second allowable range is γupper and the reference threshold coefficient defining the lower limit is γunder, the calibration threshold coefficients obtained by calibration are “2·γupper” and “2·γunder.” The upper limit of the second allowable range is (first light-receiving reference value·2·γupper), which is twice the normal value, while the lower limit is “first light-receiving reference value / (2·γunder),” which is half the normal value. This expands the second allowable range to twice the normal range, making it easier to determine a product as normal during an abnormality determination. This minimizes the likelihood of a product being determined as abnormal and rendered unusable in the field.

[0022] However, if the above calibration is allowed unconditionally, the reliability of the calibration threshold coefficient cannot be guaranteed in cases such as when the amount of light received by the projection unit is lower than the normal range. Therefore, in this aspect, it is determined whether the calibration threshold coefficient obtained by calibration is within a predetermined normal range, and 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 limit values ​​that define the second allowable range. Note that if the calibration threshold coefficient is outside the normal range, calibration is impossible, and measures are taken, for example, to notify the user of this fact.

[0023] In this way, according to this aspect, while ensuring the reliability and safety of the product, it is possible to minimize the number of cases where the product is determined to be abnormal and becomes unusable on site, thereby preventing inefficiencies in work on site.

[0024] In a fifth aspect dependent on any one of the first to third aspects, the abnormality determination unit is provided 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 used to determine an upper limit value and a lower limit value that define the second allowable range for each color of light, and the abnormality determination unit is configured to calibrate the reference threshold coefficient for abnormality determination and calculate a calibration threshold coefficient. the calibration unit defines the first reference light-receiving value for each color of light as pd1', the second reference light-receiving value for each color of light as pd2', the first measured light-receiving value for each color of light obtained by actual measurement in the first light-receiving unit as pd1'', the second measured light-receiving value for each color of light obtained by actual measurement in the second light-receiving unit as pd2'', a reference threshold coefficient for the upper limit value in the reference threshold coefficient as γupper, The reference threshold coefficient for the lower limit value is γunder, and it is permitted that the γupper and the γunder are the same value. The calibration threshold coefficient for the upper limit value in the calibration threshold coefficients is γupper(cab), and the calibration threshold coefficient for the lower limit value in the calibration threshold coefficients is γunder(cab). Then, The γupper(cab) may be calculated by the first arithmetic expression, the γunder(cab) may be calculated by the second arithmetic expression expressed as γunder·{(pd2′ / pd1′) / (pd2″ / pd1″)}, and when the calculated γupper(cab) and γunder(cab) are within a predetermined normal range, the γupper(cab) and γunder(cab) may be used to determine upper and lower limit values ​​that define the second allowable range for light of each color.

[0025] In the fifth aspect, the content of the fourth aspect described above is described more specifically. In this aspect, the first reference light-receiving value for each color of light is "pd1'", the second reference light-receiving value for each color of light is "pd2'", the first measured light-receiving value for each color of light obtained by actual measurement in the first light-receiving unit is "pd1"", the second measured light-receiving value for each color of light obtained by actual measurement in the second light-receiving unit is "pd2"", the reference threshold coefficient for the upper limit value in the reference threshold coefficient is "γupper", the reference threshold coefficient for the lower limit value in the reference threshold coefficient is " In this embodiment, the calibration threshold coefficients γupper(cab) and γunder(cab) are set to "γupper·{(pd2' / pd1') / (pd2" / pd1")}" and "γunder·{(pd2' / pd1') / (pd2" / pd1")}", respectively. In this embodiment, 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 limit values ​​that define the second allowable range for each color of light. Note that when the calibration threshold coefficients are outside the normal range, calibration is impossible, and measures are taken, for example, to notify the user of this fact.

[0026] In this way, according to this aspect, while ensuring the reliability and safety of the product, it is possible to minimize the number of cases where the product is determined to be abnormal and becomes unusable on site, thereby preventing inefficiencies in work on site.

[0027] In a sixth aspect dependent on any one of the first to fifth aspects, the projection display system may be an in-vehicle projection display system mounted on a vehicle.

[0028] When a projection display system is installed in a vehicle, the ambient temperature varies depending on the vehicle's driving environment, and the ambient temperature may also change suddenly. According to this aspect, it is possible to minimize the possibility of the product being determined to be abnormal and becoming unusable in the field, while ensuring the reliability and safety of the product. This increases the possibility that the in-vehicle projection display system (e.g., a road projector that displays images on the road surface) can be used in a variety of environments.

[0029] 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.

[0030] Fig. 1 is a diagram showing an example of the appearance of a projection display system, and an example of the internal configuration of a light source unit and a projection unit. Fig. 2 is a diagram showing an example of the configuration of an abnormality determination unit, and an example of various reference values ​​and various thresholds (including threshold coefficients) that are pre-installed in the abnormality determination unit. Fig. 3 is a flowchart showing an example of main procedures in low light emission determination processing using low light emission mode. Fig. 4 is a flowchart showing an example of main procedures in normal light emission determination processing using normal light emission mode.

[0031] 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.

[0032] First Embodiment Referring to Fig. 1, Fig. 1 shows an example of the external appearance of a projection display system 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 mounted on a vehicle (not shown).

[0033] 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, and the size of heat sinks and other devices used for heat dissipation tends to increase. As a result, it is conceivable that in-vehicle projectors will become larger and will no longer be able to be installed in the limited space of a vehicle. Therefore, in the present invention, optical fiber optical transmission technology is used to separate the light source unit and the projection unit, thereby constructing a separate projection display system (projector system) 10.

[0034] 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, which 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.

[0035] 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 the communication cable 210 and the 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, it is necessary to take appropriate measures such as stopping the light output and notifying the abnormality. However, the amount of light transmitted through the optical fiber 220 can vary greatly depending on the wiring condition of the optical fiber 220, the environmental temperature, etc., and under such circumstances, it is not easy to determine whether the system is normal or abnormal based solely on the light receiving intensity of the light receiving unit 324 provided on the projection unit 300 side. Therefore, in this embodiment, a light receiving unit 123 is also provided on the light source unit 100 side, and information on the actually measured received light intensity obtained from the light receiving unit 123 on the light source side and information on the actually measured received light intensity obtained from the light receiving unit 324 on the projection unit side are acquired, and by using each piece of information to perform an abnormality determination process in a predetermined procedure, it becomes possible to detect abnormalities in the projection display system 10 caused by the wiring status of the optical fiber 220, the ambient temperature, etc.

[0036] A specific description will be given below with reference to the drawings.

[0037] 1A-1, in the projection display system 10, a light source unit 100 and a 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, and light for forming a projection image output by the light source unit 100 is supplied to the projection unit 300 via an optical fiber cable (hereinafter sometimes simply referred to as an optical fiber) 220, and a projection image is formed by the projection unit 300. The communication cable 210 can be used to transmit power, control signals, video signals, etc.

[0038] The light source unit 100 has a heat sink 101 as a heat dissipation unit, a control board 102, an integrated circuit device (IC) 103 mounted on the control board 102 and including a microcontroller (MCU: reference numeral 110 in A-2 of FIG. 1) as a first control unit, and a plurality of mirrors 120-122 as optical elements. On the other hand, the projection unit 300 has a projection aperture (exit aperture) 323 that projects (exits) display light for an image.

[0039] 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 that detects 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.

[0040] 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 memory.

[0041] The MCU 110 is provided with a first light intensity measuring unit 111 that measures light intensity based on the actual measured values ​​(pd1(R'' / G'' / B'')) of light of each color, red (R), green (G), and blue (B), sent from a first light receiving unit (PD1) 123, and an abnormality determination unit 113.

[0042] An optical element section 125 is configured by a plurality of optical elements 117 to 119 that emit light of different colors, a plurality of mirrors 120 to 122, a first light receiving section (first photodiode PD1) 123, and an optical output interface .

[0043] The serializer 112 and the deserializer 114 form a first serial interface unit SIF1.

[0044] 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, a light 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 used to form a projection image sent via the optical fiber 220, and a power circuit (power supply circuit) 325.

[0045] 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 .

[0046] The display controller 313 is provided with a second light intensity measuring unit 315 that measures the light intensity based on the actual measured values ​​(pd2(R'' / G'' / B'')) of light of each color R, G, and B sent from the second light receiving unit (PD2) 324.

[0047] The deserializer 312 and the serializer 314 form a second serial interface unit SIF2.

[0048] The optical modulation device 322 includes a main body 319 incorporating an optical modulation element, 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 the image is projected (exited).

[0049] 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, and B) to the main body unit 319 of the optical modulation device 322.

[0050] 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.

[0051] 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).

[0052] 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.

[0053] 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.

[0054] 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 a display controller (second control unit) 313.

[0055] 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 results 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 it to the serializer 314. The serializer 314 performs parallel-to-serial conversion of the communication signal C4 to generate a communication signal Communication S2, and transmits this 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 of the received communication signal Communication S2 to generate a communication signal C5, and sends this communication signal C5 to the MCU (first control unit) 110.

[0056] 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.

[0057] 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 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 video signal LDVS VideoS into a parallel digital video signal VD and transmits the digital video signal VD to a display controller (second control unit) 313.

[0058] Next, the flow of signals related to the abnormality determination process will be described. 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.

[0059] 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 serial light intensity information LI (Light Intensity).

[0060] The deserializer 114 of the light source unit 100 converts the received serial-format light intensity information LI from serial to parallel 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 light element driving unit 116.

[0061] 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.

[0062] Furthermore, the optical element driving unit 116 finely adjusts the light emission intensity of the optical elements 117 to 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 achieves APC (Automatic Power Control) that stabilizes the light output of the multiple optical elements 117 to 119 that emit different light colors.

[0063] Furthermore, power supply PS is supplied from the vehicle-side controller 90 to a power circuit 130 of the light source unit 100. The power circuit 130 supplies a power supply voltage to a power circuit 325 of the projection unit 300 via a communication cable 210. The power circuit 325 supplies the power supply voltage to each unit within the projection unit 300.

[0064] Next, reference will be made to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the abnormality determination unit, and an example of various reference values ​​and various threshold values ​​(including threshold coefficients) that are provided in advance in the abnormality determination unit.

[0065] As shown in A-1 of Figure 2, the abnormality determination unit 113 has a reference value memory unit 151 that stores various reference values ​​152, a threshold memory unit 153 that stores various threshold values ​​154, a low light emission determination processing unit 160, a normal light emission determination processing unit 170, and an abnormality notification unit (including a light output stop unit 181) 180.

[0066] The low light emission determination processing unit 160 includes a light source intensity adjustment unit 162 for low light emission and a malfunction determination unit 164 for low light emission.

[0067] The normal light emission determination processing unit 170 has a light source intensity adjustment unit 172 during normal light emission, a calibration unit 174 for a reference threshold value for abnormality determination, an abnormality determination unit 176 during normal light emission, and a storage processing unit 178 for the light source intensity and light source drive value after adjustment.

[0068] 2A-2 shows examples of various reference values ​​152. Various reference values ​​152 are prepared in advance when the product is shipped from the factory.

[0069] For example, with regard to a red (R) optical element (laser diode LD(R)), the normal drive value GDR' when the LD(R) emits light alone, the reference light reception value pd1R' of the first light receiving unit (first photodiode PD1: hereinafter, sometimes simply referred to as "PD1"), and the reference light reception value pd2R' of the second light receiving unit (second photodiode PD2: hereinafter, sometimes simply referred to as "PD2") are prepared in advance.

[0070] Similarly, for the green (G) optical element (laser diode LD(G)), a normal drive value GDG' for single light emission of LD(G), a reference light reception value pd1G' for PD1, and a reference light reception value pd2G' for PD2 are prepared in advance.

[0071] Similarly, for the blue (B) optical element (laser diode LD(B)), a normal drive value GDB' for single emission of LD(B), a reference light reception value pd1B' for PD1, and a reference light reception value pd2B' for PD2 are prepared in advance.

[0072] 2A-3 shows examples of the various thresholds 154. The various thresholds 154 are prepared in advance when the product is shipped from the factory.

[0073] As thresholds for the low light emission determination process, an allowable threshold value Δpd2 (low power R, G, B) for the variation in the light reception value of PD2, a reference threshold coefficient βupper for the upper limit value as an abnormality determination threshold value for the light reception value of PD1, and a reference threshold coefficient βunder for the lower limit value (however, βupper = βunder = β may also be used).

[0074] As thresholds for the normal light emission determination process, there are prepared in advance an allowable threshold value Δpd2 (normal power R, G, B) for the variation in the light reception value of PD2, a reference threshold coefficient γupper for the upper limit value as a threshold for determining whether the light reception value of PD1 is abnormal, a reference threshold coefficient γunder for the lower limit value (however, γupper = γunder = γ), and thresholds for determining whether each of the reference threshold coefficients γupper(cab) and γunder(cab) after calibration is normal.

[0075] Next, reference is made to Fig. 3. This is a flowchart showing an example of the main steps in the low light emission determination process using the low light emission mode.

[0076] In the example of Figure 3, a low light emission mode in which the optical elements 117 to 119 of each color emit light at a brightness lower than normal light emission is used to perform preliminary abnormality determination (determination of abnormalities related to basic performance such as improper installation of optical fiber or light leakage from optical fiber).

[0077] For example, when the first abnormality determination process is performed after laying the optical fiber 220 at the site, there will be workers around the optical fiber 220, and if light leaks from the optical fiber 220 and shines into the eyes of the workers, it could cause damage to the workers' eyes. Therefore, it is considered undesirable to suddenly perform the abnormality determination process using high-intensity light emission (normal light emission).

[0078] 3, the light emission intensity of the optical elements 117 to 119 of each color is reduced using the low light emission mode, thereby making it possible to sufficiently reduce the amount of light propagating through the optical fiber 220. Therefore, even if light leaks from the optical fiber 220 and irradiates the eyes of an operator, the light is weak and the safety of the operator's eyes can be ensured.

[0079] In step S1, the drive values ​​of the optical elements 117 to 119 of each color are set to 1 / α (α is an integer greater than 1; in a preferred example, α is set to 5 to 10) of the normal drive values ​​(GDR', GDG', GDB' shown in A-2 of Figure 2).

[0080] In step S2, the optical elements 117 to 119 for each color are sequentially turned on to detect the actual light reception intensities (actual values) of PD1 and PD2. Here, the actual measured values ​​of red light at PD1 and PD2 are designated as pd1R" and pd2R", the actual measured values ​​of green light are designated as pd1G" and pd2G", and the actual measured values ​​of blue light are designated as pd1B" and pd2B".

[0081] In step S3, the drive value of each of the optical elements 117 to 119 is adjusted so as to satisfy the following equations (1) to (3). The drive value adjustment is performed by sequentially increasing or decreasing the drive current of each of the optical elements 117 to 119 in units of Δi (the minimum change amount 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)

[0082] In equation (1), first, the reference light-receiving value pd2R' at PD2, shown in A-2 of FIG. 2, is multiplied by (1 / α). This is because, since the drive value of the optical element 117 is 1 / α, it is assumed that the reference light-receiving value at PD2 is also ideally 1 / α. Next, it is determined whether the difference between the obtained reference light-receiving value of PD2 (pd2R' / α) and the actual measured value at PD2 is equal to or less than the allowable threshold value Δpd2 (low power R) for the variation in the light-receiving value of PD2 for red light in low light emission mode. If equation (1) is satisfied, it means that PD2 detected a light amount sufficient for measurement. Furthermore, if equation (1) is not satisfied, it means that, although the drive value of the red optical element 117 was adjusted within the maximum dynamic range, the minimum amount of light did not reach via the optical fiber 220, and subsequent abnormality determination processing is impossible. The processing contents of equations (2) and (3) are the same as the processing contents of equation (1), and therefore the explanation will be omitted.

[0083] 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)

[0084] In equation (4), it is determined whether the actual measurement value pd1R'' of red light at PD1 is greater than or equal to a lower limit value and less than or equal to an upper limit value that defines an acceptable range. The lower limit value that defines the acceptable range is calculated by dividing the reference light reception value of PD1 in low light emission mode (pd1R' / α) by a threshold coefficient βunder (an integer greater than 1) for the lower limit value for low light emission mode. Similarly, the upper limit value that defines the acceptable range is calculated by multiplying the reference light reception value of PD1 in low light emission mode (pd1R' / α) by a threshold coefficient βupper for the upper limit value for low light emission mode. If equation (4) is satisfied, it means that the actual measurement value at PD1 of the output light of the red optical element 117, whose drive value has been adjusted in step S2, is within an acceptable range that is determined based on the reference light reception value and the reference threshold coefficient that are prepared at the time of shipment from the factory, and the basic performance (minimum performance) of the product is ensured. If formula (4) is not satisfied, the red light element 117 will be emitting light at a considerable level outside the allowable range assumed at the time of shipment from the factory. Note that the processing contents of formulas (5) and (6) are the same as the processing contents of formula (4), and therefore will not be described here.

[0085] In step S5, it is determined whether all or at least a predetermined number (here, at least two) of equations (4) through (6) are satisfied. The requirement of at least two means that if two of equations (4) through (6) are satisfied but only one is not, it would be too strict to determine that an abnormality has occurred, and therefore the result is treated as within the normal range. If the result in step S5 is Y, the process proceeds to step S6, where the adjusted drive values ​​of the optical elements 117 through 119 for each color obtained in step S3 are saved, and the low light emission determination process ends. If the result in step S5 is N, it may be determined that some basic performance abnormality (e.g., improper installation of the optical fiber 220, light leakage from the optical fiber 220, etc.) has occurred, and measures such as stopping the optical output and reporting the abnormality are taken in step S7. After this, the process proceeds to step S10 in FIG. 4, where the light emission power of the optical elements is returned to the normal level and the abnormality determination process is performed in the normal light emission mode.

[0086] According to the low light emission determination process described above, it is possible to use the low light emission mode to check that the basic performance (minimum performance) of optical communication via optical fiber, for example, is ensured while taking into consideration the safety of the operator. This makes it possible to determine abnormalities in basic performance while ensuring the safety of the operator.

[0087] Next, reference is made to Fig. 4. This is a flowchart showing an example of the main steps in the normal light emission determination process using the normal light emission mode.

[0088] In step S10, the drive values ​​of the optical elements 117-119 of each color after adjustment, which were saved in step S6 in Fig. 3, are multiplied by α to obtain normal light emission drive values. Furthermore, automatic power control (APC) is performed on the optical elements 117-119 of each color. This suppresses variations in the amount of light received by PD2, stabilizing the intensity of the received light.

[0089] Next, step S11 is carried out. This step S11 corresponds to step S2 in Fig. 3 described above. In step S11, the optical elements of each color are sequentially caused to emit light, and the actual received light intensities (actual measured values) of PD1 and PD2 are detected to obtain the values ​​of pd1R'', pd2R'', pd1G'', pd2G'', pd1B'', and pd2B''.

[0090] Next, step S12 is performed. This step S12 corresponds to step S3 in FIG. 3 described above. The processing content is substantially the same as step S3, so a detailed description will be omitted. However, because step S12 is the normal light emission mode, the reference light reception value for PD2 is used as is without being multiplied by (1 / α), unlike step S3 in FIG. 3. Furthermore, the allowable thresholds for the normal light emission determination process (Δpd2 (normal power R), Δpd2 (normal power G), Δpd2 (normal power B)) are used as allowable thresholds for the variation in the light reception value of PD2, and determination is performed using equations (7) to (9). In this specification, the allowable range for the normal light emission determination process shown in equations (7) to (9) may be referred to as the "first allowable range," and the conditions defined by equations (7) to (9) may be referred to as the "first condition."

[0091] Thereafter, the process proceeds to step S15 via steps S13 and S14. Step S15 corresponds to step S4 previously described with reference to Fig. 3. However, in the normal light emission determination process, before step S15 is performed, calibration of the reference threshold coefficient (step S13) is performed, and a determination is made as to whether the reference threshold coefficient obtained by calibration is within a normal range (step S14).

[0092] In the normal light emission determination process, as in the low light emission determination process of Figure 3, an abnormality is determined based on whether the light reception value at PD1 for the light elements of each color that are emitting light at the adjusted drive value falls within a predetermined range, and this is a common point.

[0093] However, immediately after laying the optical fiber 220 in the field, for example, bending of the optical fiber 220 or large changes in environmental temperature can increase transmission loss and degrade the quality of optical communication. If such conditions were ignored and anomaly detection were performed using the upper and lower limits determined by the factory-prepared standard threshold coefficients (γupper, γunder), the detection would be too strict, potentially resulting in an increase in cases where usable products are determined to be abnormal and unusable. This would require re-installation of the product, rewiring the optical fiber, or product replacement, resulting in inefficient on-site work. However, if the detection criteria were relaxed too much, a product that would otherwise be determined to be abnormal could be determined to be normal, potentially making it impossible to ensure product reliability and safety. Therefore, in the example of FIG. 4 , the factory-prepared standard threshold coefficients (γupper, γunder) are properly calibrated using the actual measured values ​​of PD1 and PD2 in the field. The resulting threshold coefficients are called "calibration threshold coefficients" and are denoted as "γupper(cab)" and "γunder(cab)."

[0094] The calibration of the threshold coefficients will be described below. In step S13, the calibration threshold coefficients γupper(cab) and γunder(cab) are calculated by the following formula: γupper(cab)={(pd2R' / pd1R') / (pd2R'' / pd1R'')}·γupperγunder(cab)={(pd2R' / pd1R') / (pd2R'' / pd1R'')}·γunder

[0095] In the above equation, (pd2R' / pd1R') represents a first ratio of the reference light-receiving values ​​of PD1 and PD2, which is prepared at the time of shipment from the factory. Furthermore, (pd2R'' / pd1R'') represents a second ratio, which is the ratio of the measured light-receiving values ​​of PD1 and PD2. The magnification is determined by comparing the first ratio with the second ratio. This magnification is used to calibrate the reference threshold coefficients γupper and γunder, and thereby calculate the calibration threshold coefficients γupper(cab) and γunder(cab).

[0096] For example, assume that under standard conditions before product shipment, when the optical elements 117-119 of each color are driven at the standard drive values, the reference light reception value of PD1 is a relative value of "1" and the reference light reception value of PD2 is a relative value of "0.8." If the first ratio is "0.8:1," the ratio becomes "0.8 (=0.8 / 1)." Meanwhile, assume that the actual measured values ​​(actual measured values: expressed as relative values ​​here) of PD1 and PD2 are "1" and "0.4." If the second ratio is "0.4:1," the ratio becomes "0.4 (=0.4 / 1)." In the above example, immediately after the optical fiber 220 is installed on-site, the amount of light received on the projection unit 300 side is half of the standard amount of light received at the time of factory shipment. In other words, the optical communication quality is reduced to half.

[0097] Taking this into consideration, in step S13 of FIG. 4, the first ratio and the second ratio are compared (specifically, the ratio values ​​are compared) to determine a magnification factor for calibration. In the above example, the magnification factor is 2 (=0.8 / 0.4). The reference threshold coefficients γupper and γunder are calibrated using this magnification factor. In the above example, the calibration threshold coefficients obtained by this calibration are "2·γupper" and "2·γunder."

[0098] In step S15, this calibration threshold coefficient is used to determine whether each of the formulas (10) to (12) is satisfied.

[0099] The upper limit used in this judgment is (light receiving reference value of each color light × 2 × γupper), which is twice the normal value, while the lower limit is "light receiving reference value of each color light / (2 × under)", which is half the normal value. This expands the allowable range for judgment to twice the normal range, making it easier to judge a product as normal when judging an abnormality. Therefore, it is possible to minimize the number of products in the field that are judged to be abnormal and become unusable.

[0100] However, if the above calibration is allowed unconditionally, for example, in cases where the amount of light received on the projection unit 300 side is lower than the normal range, the reliability of the calculated calibration threshold coefficients γupper(cab) and γunder(cab) cannot be guaranteed.

[0101] Therefore, in step S14 of FIG. 4, it is determined whether the calibration threshold coefficients γupper(cab) and γunder(cab) obtained by calibration are within a predetermined normal range using the normality determination threshold shown in A-3 of FIG. 2. If the result of this determination is that the calibration threshold coefficients are normal (Y in step S14), the calibration threshold coefficients are used to determine the upper and lower limit values ​​used in the abnormality determination in step S15. If the calibration threshold coefficients are outside the normal range (N in step S14), calibration is impossible, and the process proceeds to step S18, where, for example, a measure is taken to notify the user of the detected abnormality.

[0102] Step S15 corresponds to step S4 in FIG. 3 described above. The processing is substantially the same. However, in step S15, an abnormality determination is performed in the normal light emission determination process, and therefore, in equations (10) to (12), the reference light reception values ​​of PD1 for each color of light are used as is without being multiplied by (1 / α). This differs from step S4 in FIG. 3. Furthermore, step S15 uses the calibration threshold coefficients γupper(cab) and γunder(cab) obtained by calibration. This also differs from step S4 in FIG. 3. Note that in this specification, the allowable range for the normal light emission determination process shown in equations (10) to (12) may be referred to as the "second allowable range," and the conditions defined in equations (10) to (12) may be referred to as the "second conditions."

[0103] Step S16 corresponds to step S5 in FIG. 3 described above. The contents are substantially the same. If the answer is Y in step S16, the process proceeds to step S17. In step S17, the post-calibration drive values ​​of the optical elements 117-119 of each color obtained in step S12 are saved as reference drive values ​​after the optical fiber is attached. In addition, the actual received light intensities (actual values) pd1R"-pd1B" and pd2R"-pd2B" of PD1 and PD2 corresponding to those drive values ​​are saved as reference light received values ​​after the optical fiber is attached. These saved data can be used in subsequent abnormality determinations.

[0104] If the answer is N in step S16, the process proceeds to step S18, where measures such as stopping the optical output or reporting an abnormality are taken.

[0105] In this way, according to the example of Figure 4, while ensuring the reliability and safety of the product, it is possible to minimize the number of cases where the product is determined to be abnormal and becomes unusable on site, thereby preventing inefficiencies in work on site.

[0106] In the above description, the reference light-receiving values ​​of light of each color at PD1 are referred to as pd1R', pd1G', and pd1B', but when these are collectively referred to as the reference light-receiving values ​​of PD1, they may be simply referred to as "pd1'". Similarly, the reference light-receiving values ​​of light of each color at PD2 are referred to as pd2R', pd2G', and pd2B', but when these are collectively referred to as the reference light-receiving values ​​of PD2, they may be simply referred to as "pd2'". Similarly, in the above description, the actual received light intensities (actual values) of light of each color at PD1 are referred to as pd1R'', pd1G'', and pd1'', but when these are collectively referred to as the actual received light intensities (actual values), they may be simply referred to as "pd1''". Similarly, in the above explanation, the measured light intensity (measured value) of each color of light at PD2 is described as pd2R'', pd2G'', and pd2B'', but the measured light intensity (measured value) collectively referring to these may be simply described as "pd2''.

[0107] As described above, according to this embodiment, it is possible to detect abnormalities caused by the wiring conditions of optical fiber, the ambient temperature, etc. in a projection display system in which the light source unit and the projection unit are separated.

[0108] Furthermore, while ensuring product reliability and safety, the system minimizes the likelihood of a product being determined to be abnormal and rendered unusable in the field, thereby preventing inefficiencies in on-site work. Furthermore, by performing the low light emission determination process before the normal light emission determination process, it is possible to confirm that the basic performance (minimum performance) of optical communication via optical fiber is ensured while taking into consideration the safety of the worker. This enables abnormality determination regarding basic performance while ensuring the safety of the worker. Furthermore, when a projection display system is installed in a vehicle, the environmental temperature (ambient temperature) fluctuates widely and may change suddenly. According to this embodiment, the reference threshold coefficient can be appropriately calibrated, taking into account, for example, changes in transmission loss in the optical fiber due to the environmental temperature. In other words, measures are taken against changes in the environmental temperature, making the present invention highly practical in the field. Furthermore, according to the present invention, accurate abnormality determination can be performed, thereby effectively preventing degradation of the quality of the projected image. Therefore, degradation of the reliability of an in-vehicle projection display system (e.g., a road projector that displays images on the road surface) can be prevented. Furthermore, the use of the present invention increases the possibility that a projection display system (such as a road projector that displays an image on the road surface) can be used in a variety of environments.

[0109] 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.

[0110] 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 first control unit, 111...First light intensity measurement unit, 112...Serializer (parallel / serial converter), 113...Abnormality determination unit, 114...Deserializer (parallel / serial converter), 116...Light element driving unit (LC driver), 117-119...Multiple light sources with different light emission colors a plurality of optical elements (laser diodes corresponding to the respective colors of R, G, and B), 120 to 122: a plurality of mirrors, 123: a first light receiving unit constituted by a first photodiode PD1, 124: an optical output interface, 125: an optical element unit, SIF1: a first serial interface unit, 130: a power circuit (power supply circuit), 151: reference value storage units 151 and 152: various reference values, 153: a threshold storage unit, 154: various thresholds, 160: a low light emission determination processing unit, 162: a light source intensity adjustment unit at low light emission, 64: Abnormality determination unit at low light emission, 170: Normal light emission determination processing unit, 172: Light source intensity adjustment unit at normal light emission, 174: Calibration unit for reference threshold for abnormality determination, 176: Abnormality determination unit at normal light emission, 178: Storage processing unit for light source intensity and light source drive value after adjustment, 180: Abnormality notification unit, 181: Optical output stopping unit, 210: Communication cable, 220: Optical fiber cable (optical fiber), 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 measuring unit, 320: optical input interface, 321: input terminal of light modulation device, 322: light modulation device (DMD (digital mirror device)), 323: projection port (output port), 324: second light receiving unit composed of second photodiode PD2, 325: power circuit (power supply circuit), SIF2: second serial interface unit, VideoS: video signal, LVDS VideoS: serial video signal transmitted by 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'')...actually measured received light intensity of each color of light at PD1 (actual measured value), pd2 (R'' / G'' / B'')...actually measured received light intensity of each color of light at PD2 (actual measured value), PS...power supply.

Claims

1. A projection type display system in which a light source unit and a projection unit are separated and electrically connected to each other via a communication cable, 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, wherein the light source unit has: a first control unit having a function of controlling two-way communication with the projection unit; an abnormality determination unit that determines an abnormal state caused by at least one of the installation status of the optical fiber and the ambient temperature; a light element unit having a plurality of light elements with different light emission colors that generates light for forming the projection image, a light element drive unit that drives the plurality of light elements, and a first light receiving unit that detects the light intensity of each output light of the plurality of light elements with different light emission colors; and the projection unit has: a second control unit that has a function of controlling two-way communication with the light source unit; and a light modulation device that forms the projection image by modulating the light for forming the projection image of each color sent from the light source unit via the optical fiber. a second light receiving unit that detects the light intensity of the light for forming the projection image of each color sent from the light source unit via the optical fiber, wherein the abnormality determination unit adjusts a drive value of the light element drive unit so that a first condition is satisfied that the received light intensity of each of the light for forming the projection image of each color at the second light receiving unit is within a first tolerance range, and performs abnormality determination processing to determine whether a second condition is satisfied that the received light intensity of all of the output light of each of the plurality of light elements having different light emission colors, or for a predetermined number of output lights among the output lights, is within a second tolerance range, and determines that an abnormality exists if the second condition is not satisfied.

2. The projection display system of claim 1, wherein the abnormality determination unit has a low light emission mode in which each of the plurality of light elements emits light at a luminance lower than a normal light emission luminance, and a normal light emission mode in which each of the plurality of light elements emits light at a normal light emission luminance, and performs the abnormality determination process in the low light emission mode to determine whether or not there is an abnormal state in the low light emission state, and after it is determined that there is no abnormal state in the low light emission state, performs the abnormality determination process in the normal light emission mode to determine whether or not there is an abnormal state in the normal light emission state.

3. The projection display system of claim 1, wherein when the abnormality determination unit determines whether or not an abnormal state exists, APC (Automatic Power Control) is performed to stabilize the light output of the multiple light elements having different light emission colors based on the received light intensity of each of the lights for forming the projection image of each color at the second light receiving unit.

4. The projection type display system of claim 1, wherein the abnormality determination unit is provided with in advance a first reference light receiving value at the first light receiving unit for each color of light, a second reference light receiving value at the second light receiving unit for each color of light, and a reference threshold coefficient used to determine upper and lower limit values ​​that define the second allowable range for each color of light, the abnormality determination unit having a calibration unit that calibrates the reference threshold coefficient to calculate a calibration threshold coefficient, the calibration unit calibrates the reference threshold coefficient at a magnification determined by a comparison between a first ratio that is a ratio between the first and second reference light receiving values ​​and a second ratio that is a ratio between the first and second actual measured light receiving values ​​at the first and second light receiving units to calculate the calibration threshold coefficient, and when the calculated calibration threshold coefficient is within a predetermined normal range, determines upper and lower limit values ​​that define the second allowable range using the calibration threshold coefficient.

5. The abnormality determination unit is provided in advance with: a first reference light receiving value at the first light receiving unit for each color of light; a second reference light receiving value at the second light receiving unit for each color of light; and a reference threshold coefficient used to determine an upper limit value and a lower limit value that define the second tolerance range for each color of light; and the abnormality determination unit has a calibration unit that calibrates the reference threshold coefficient for abnormality determination to calculate a calibration threshold coefficient, and the calibration unit: defines the first reference light receiving value for each color of light as pd1', the second reference light receiving value for each color of light as pd2', the first measured light receiving value for each color of light obtained by actual measurement at the first light receiving unit as pd1'', the second measured light receiving value for each color of light obtained by actual measurement at the second light receiving unit as pd2'', a reference threshold coefficient for the upper limit value in the reference threshold coefficient is defined as γupper, and a reference threshold coefficient for the lower limit value in the reference threshold coefficient is defined as γunder, and it is permitted that the γupper and the γunder are equal in value, and in the case where a calibration threshold coefficient for the upper limit value in the calibration threshold coefficient is γupper(cab), and a calibration threshold coefficient for the lower limit value in the calibration threshold coefficient is γunder(cab), the γupper(cab) is calculated by a first arithmetic expression represented by γupper·{(pd2' / pd1') / (pd2'' / pd1'')}, and the γunder(cab) is calculated by a second arithmetic expression represented by γunder·{(pd2' / pd1') / (pd2'' / pd1'')}, 2. The projection display system of claim 1, wherein, when the calculated γupper(cab) and γunder(cab) are within a predetermined normal range, the γupper(cab) and γunder(cab) are used to determine upper and lower limit values ​​that define the second tolerance range for each color of light.

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

Images