Field sequential projector device, head-up display device, program product, and voltage measurement method

Abstract

The present invention provides a field sequential projector device, a head-up display device, a program product, and a voltage measurement method capable of measuring the forward voltage of a light-emitting diode (LED) during an appropriate lighting duration. The projector device includes: a storage unit (450) that stores lighting mode information (D) representing a time series of lighting start timings of LEDs and lighting durations from the lighting start timings; a drive control unit (421) that lights the LEDs based on the lighting mode information (D); and a voltage measurement unit (422). The voltage measurement unit (422) refers to the lighting mode information (D) and determines a lighting duration that is longer than a predetermined set period as a target period. The voltage measurement unit (422) measures the forward voltage (Vr, Vg, Vb) at a timing after the set period has passed since the start of the target period within the determined target period.

Description

Technical Field

[0001] The present disclosure relates to a field sequential projector device, a head-up display device, a program product, and a voltage measuring method. Background Art

[0002] An example of a field sequential projector device is the one described in Patent Document 1. The projector device described in Patent Document 1 generates display light representing an image using a display element composed of a DMD (Digital Micromirror Device) based on light emitted by multiple light-emitting diodes (LEDs) with different red, green, and blue lighting colors. Field sequential projection utilizes the afterimage phenomenon to create mixed colors by sequentially lighting multiple LEDs for short periods measured in microseconds (hereinafter referred to as the lighting duration).

[0003] Prior art literature

[0004] Technical Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-33645 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the projector device described above, the forward voltage of the LED is measured during the on-time period to diagnose the LED status. To avoid the period of voltage instability immediately after the LED is first illuminated, the forward voltage is measured after a set period has elapsed since the LED was illuminated. However, the timing of the intermittent on-time period during which the forward voltage should be measured is generally predetermined by the supplier of the IC (Integrated Circuit) that drives and controls the LEDs as part of the IC specifications. Using the measurement timing based on the IC specifications as is may not allow for adequate forward voltage measurement when the on-time period is very short, such as tens of microseconds.

[0008] The present disclosure has been made in view of the above-mentioned actual situation, and its object is to provide a field sequential projector device, a head-up display device, a program product, and a voltage measurement method capable of measuring the forward voltage of a light-emitting diode during an appropriate lighting duration.

[0009] Means for solving problems

[0010] In order to achieve the above-mentioned object, a field sequential projector device according to a first aspect of the present disclosure comprises:

[0011] light-emitting diodes;

[0012] a storage unit storing lighting pattern information for lighting the light emitting diode in a predetermined lighting pattern, the lighting pattern information indicating a time series of a lighting start timing of the light emitting diode and a lighting continuation period from the lighting start timing;

[0013] a drive control unit configured to light the light emitting diode in the lighting mode based on the lighting mode information;

[0014] a display element that generates display light representing an image based on the light emitted by the light emitting diode; and

[0015] a voltage measuring unit for measuring the forward voltage of the light emitting diode;

[0016] The voltage measuring unit:

[0017] Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period,

[0018] During the determined target period, a voltage measurement process is executed to measure the forward voltage at a timing after the set period has elapsed from the start of the period.

[0019] In order to achieve the above-mentioned object, a head-up display device according to a second aspect of the present disclosure includes:

[0020] The projector device includes the projector device, and displays a virtual image of the image by radiating the display light toward a light-transmitting member.

[0021] In order to achieve the above-mentioned object, a computer program product according to a third aspect of the present disclosure is provided.

[0022] It includes a computer program that causes a computer to function as:

[0023] a drive control mechanism for lighting the light-emitting diodes provided in the field sequential projector device in a predetermined lighting pattern based on lighting pattern information for lighting the light-emitting diodes in the predetermined lighting pattern; and

[0024] a voltage measuring mechanism for measuring the forward voltage of the light emitting diode;

[0025] The lighting pattern information indicates a time series of a lighting start timing of the light emitting diode and a lighting duration period from the lighting start timing.

[0026] The voltage measuring mechanism:

[0027] Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period,

[0028] The forward voltage is measured at a timing after the set period has elapsed from the start of the determined target period.

[0029] In order to achieve the above-mentioned object, a voltage measuring method according to a fourth aspect of the present disclosure comprises:

[0030] Based on lighting pattern information for lighting a light emitting diode included in a field sequential projector device in a predetermined lighting pattern, lighting the light emitting diode in the lighting pattern; and

[0031] a voltage measuring step of measuring the forward voltage of the light emitting diode,

[0032] The lighting pattern information indicates a time series of a lighting start timing of the light emitting diode and a lighting duration period from the lighting start timing.

[0033] In the voltage measuring step,

[0034] Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period,

[0035] The forward voltage is measured at a timing after the set period has elapsed from the start of the determined target period.

[0036] Effects of the Invention

[0037] According to the present disclosure, the forward voltage of a light emitting diode can be measured during an appropriate lighting duration. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of a vehicle equipped with a head-up display (HUD) device according to one embodiment of the present disclosure.

[0039] Figure 2 Schematic diagram showing the structure of the HUD device according to this embodiment.

[0040] Figure 3 Schematic diagram showing the structure of the lighting device according to this embodiment.

[0041] Figure 4 Schematic diagram showing the structure of a display unit according to this embodiment.

[0042] Figure 5 This is a block diagram for explaining the configuration of the control device according to this embodiment.

[0043] Figure 6 This is a block diagram for explaining the functions of the display control unit of this embodiment.

[0044] Figure 7 This is a circuit diagram for explaining the function of the voltage measuring unit of this embodiment.

[0045] Figure 8 1 is a diagram showing a configuration example of lighting pattern information according to this embodiment.

[0046] Figure 9 It shows that according to Figure 8 A diagram showing the supply timing of the driving current according to the lighting pattern information.

[0047] Figure 10 This is a schematic diagram for explaining the voltage measurement timing in this embodiment.

[0048] Figure 11 : is a flowchart showing the LED diagnostic process of this embodiment. DETAILED DESCRIPTION

[0049] One embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0050] like Figure 1 As shown, a head-up display (HUD) device 1 is mounted on the instrument panel of a vehicle 2 and radiates display light L toward a windshield 3 of the vehicle 2. The display light L reflected by the windshield 3 allows a user 4 (e.g., the driver of the vehicle 2) to visually recognize a virtual image V representing the image represented by the display light L. The virtual image V is displayed in front of the vehicle 2 across the windshield 3. Thus, the user 4 can visually recognize the virtual image V displayed superimposed on the scenery ahead. The virtual image V displays various information related to the vehicle 2, such as vehicle speed and engine speed.

[0051] like Figure 2 As shown, the HUD device 1 includes: a projector device 100, which radiates display light L; a screen 200, on which an image M represented by the display light L is projected; a plane mirror 150, which reflects the display light L radiated from the projector device 100 toward the screen 200; a light guide device 300, which guides the display light L passing through the screen 200 to the windshield 3; and a control device 400, which controls the operation of the HUD device 1.

[0052] The projector device 100 includes an illumination device 10 and a display unit 20 that is illuminated by the illumination device 10 and radiates display light L.

[0053] The lighting device 10 generates illumination light C and radiates the generated illumination light C toward the display unit 20. Figure 3 As shown, the lighting device 10 includes a light source unit 11 and a light combining unit 13 .

[0054] The light source unit 11 is composed of three light-emitting diodes 11r, 11g, and 11b (hereinafter referred to as LEDs) with different lighting colors. When illuminated, LED 11r emits red light R. When illuminated, LED 11g emits green light G. When illuminated, LED 11b emits blue light B. Each of LEDs 11r, 11g, and 11b is driven by a control device 400 to emit light at a predetermined intensity and timing.

[0055] The light combining unit 13 aligns the optical axes of the red light R, green light G, and blue light B sequentially emitted from the LEDs 11r, 11g, and 11b to generate illumination light C, and then radiates the generated illumination light C toward the display unit 20. The light combining unit 13 includes a reflector 13a and dichroic mirrors 13b and 13c. The reflector 13a reflects the incident blue light B toward the dichroic mirror 13b. The dichroic mirror 13b reflects the incident green light G toward the dichroic mirror 13c, while allowing the blue light B from the reflector 13a to pass directly. The dichroic mirror 13c reflects the incident red light R toward the display unit 20, while allowing the green light G and blue light B from the dichroic mirror 13b to pass directly. Thus, the dichroic mirror 13c radiates the illumination light C, which is a composite of the red light R, green light G, and blue light B, toward the display unit 20.

[0056] like Figure 4 As shown, the display unit 20 includes a plane mirror 21 , a prism 22 , a lens 23 , a display element 30 that generates display light L, and a light intensity detection unit 40 .

[0057] The plane mirror 21 reflects the illumination light C from the lighting device 10 toward the prism 22. The prism 22 is formed in a triangular prism shape and includes an inclined surface 22a facing the plane mirror 21, a right-angled surface 22b facing the display element 30, and a right-angled surface 22c facing the lens 23. The inclined surface 22a allows most of the illumination light C from the plane mirror 21 to enter the prism 22, while reflecting a portion of the illumination light C from the plane mirror 21 toward the light intensity detection unit 40. The illumination light C incident on the prism 22 is emitted toward the display element 30 via the right-angled surface 22b of the prism 22.

[0058] The light intensity detection unit 40 is composed of a photodiode or a phototransistor, and detects the luminous intensity of each of the light R, G, and B constituting the illumination light C incident on the prism 22 in a time-sharing manner. Figure 5 As shown, the light intensity detection unit 40 outputs the detection result as a light intensity detection signal S FB to a display control unit 420 of the control device 400 , which will be described later.

[0059] The display element 30 is composed of a DMD (Digital Micromirror Device) and includes a plurality of movable micromirrors 30a. The plurality of micromirrors 30a are arranged in a matrix to correspond to the pixels of the image M projected onto the screen 200. The micromirrors 30a are controlled by the control device 400 to be either open or closed. A micromirror 30a in the open state reflects the illumination light C toward the screen 200. A micromirror 30a in the closed state reflects the illumination light C in a direction that does not reach the screen 200. Each micromirror 30a represents the color of each pixel of the image M by adjusting the period during which it is in the open state. As described above, the display element 30 generates display light L representing the image M based on the illumination light C by combining the micromirrors 30a in the open and closed states.

[0060] The display light L generated by the display element 30 is incident on the right-angled surface 22 b of the prism 22, reflected by the inclined surface 22 a, and emitted from the lens 23 to the outside of the projector device 100. The lens 23 is composed of a convex lens, a concave lens, or the like, and amplifies the display light L. The amplified display light L transmitted by the lens 23 is reflected by the plane mirror 150 and directed toward the screen 200.

[0061] The screen 200 is a transmissive screen composed of a holographic diffuser, a microlens array, a diffusion plate, etc. Display light L emitted from the projector device 100 is projected onto the screen 200 as an image M, and passes through the screen 200 toward the light guide device 300 .

[0062] The light guide device 300 includes a reflecting unit 60 that reflects the display light L emitted from the screen 200 toward the windshield 3, and a housing 70 that houses the reflecting unit 60. The reflecting unit 60 includes a plane mirror 61 and a concave mirror 62. The plane mirror 61 reflects the display light L from the screen 200 toward the concave mirror 62. The concave mirror 62 reflects the display light L from the plane mirror 61 toward the windshield 3. The display light L reflected by the concave mirror 62 magnifies the virtual image V to be visually recognized by the user 4 compared to the image M projected onto the screen 200. The housing 70 is formed into a box shape from, for example, a light-blocking material and has an opening 70a through which the display light L reflected by the concave mirror 62 passes. A cover glass 71 is provided on the housing 70 to block the opening 70a and transmit the display light L. Furthermore, the housing (not shown) of the projector device 100 is connected to the housing 70 of the light guide device 300, for example.

[0063] like Figure 5As shown, the control device 400 includes an MCU (Micro Controller Unit) 410 and a display control unit 420 that communicate with each other, an LED driver 430 and a switch element 440 that operate under the control of the display control unit 420 , and a storage unit 450 connected to the display control unit 420 .

[0064] The LED driver 430 is constituted by, for example, a driver IC, and adjusts a voltage value applied to the light source unit 11 based on power from a battery (not shown) mounted on the vehicle 2 .

[0065] The switching element 440 is composed of a switching circuit using, for example, an n-channel or p-channel FET (Field Effect Transistor). The switching element 440 includes switches 44r, 44g, and 44b connected to the cathode sides of the LEDs 11r, 11g, and 11b. Switches 44r, 44g, and 44b are each switched between an on state and an off state under the control of the display control unit 420. When switch 44r is in the on state, a drive current Ir is supplied from the LED driver 430 to the LED 11r, lighting the LED 11r. On the other hand, when switch 44r is in the off state, the drive current Ir supplied to the LED 11r is cut off, turning off the LED 11r. The same applies to the correspondence between the state of switch 44g and the drive current Ig supplied to the LED 11g, and the correspondence between the state of switch 44b and the drive current Ib supplied to the LED 11b.

[0066] Based on the ambient light intensity around the vehicle 2 detected by an illuminance sensor (not shown), the MCU 410 generates a target brightness signal indicating the target brightness of the light source unit 11 for appropriately displaying the virtual image V, and outputs the signal to the display control unit 420. To adjust the display position of the virtual image V, the MCU 410 may also control the rotational or parallel movement of the concave mirror 62 via a mechanism (not shown).

[0067] The display control unit 420 is an LSI (Large Scale Integration) that implements the required functions through hardware, and is comprised of, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The ROM (Read Only Memory) built into the display control unit 420 stores programs for driving the light source unit 11 and the display element 30, as well as a program PG for executing the LED diagnostic process described later. The display control unit 420 receives inputs such as a video signal for displaying the image M from an external device such as an ECU (Electronic Control Unit) mounted on the vehicle 2, and receives a light intensity detection signal SFB from the light intensity detection unit 40.

[0068] The storage unit 450 is a nonvolatile memory composed of flash memory, EEPROM (Electrically Erasable Programmable ROM), or the like. It stores fixed data used by the display control unit 420 to execute various processes, such as the lighting pattern information D described later. Alternatively, the storage unit 450 may be built into the display control unit 420.

[0069] The display control unit 420 controls the opening / closing of each micro mirror 30a of the display element 30 based on the image signal. Figure 6 As shown, the display control unit 420 includes a drive control unit 421 and a voltage measuring unit 422 .

[0070] The drive control unit 421 controls the driving of the light source unit 11. The drive control unit 421 refers to the lighting mode information D stored in the storage unit 450 and lights up the LEDs 11r, 11g, and 11b in the lighting mode indicated by the lighting mode information D. The lighting mode information D is information for lighting each LED 11r, 11g, and 11b in a predetermined lighting mode so as to emit display light L in a desired color. The drive control unit 421 refers to the lighting mode information D and selects an appropriate lighting mode corresponding to the image signal. Figure 8 As shown, the lighting pattern information D indicates the lighting start timing of each LED 11r, 11g, 11b ( Figure 8 Start) and the lighting duration from the lighting start timing ( Figure 8 Duration) time series recorded in.

[0071] Figure 9 is shown with Figure 8 11b. The diagram shows the supply timing of the driving currents Ir, Ig, and Ib corresponding to the lighting start timing and the lighting duration recorded in the lighting mode information D. From the lighting start timing of the red light R until the lighting duration has passed, the drive control unit 421 turns on the switch 44r and supplies the driving current Ir to the LED 11r. As a result, the LED 11r is lit during the lighting duration of the red light R. On the other hand, the drive control unit 421 turns off the switch 44r during periods other than the lighting duration of the red light R. As a result, the LED 11r is extinguished during periods other than the lighting duration of the red light R. The drive control unit 421 controls the LEDs 11g and 11b in the same manner, lighting the LED 11g from the lighting start timing of the green light G until the lighting duration has passed, and lighting the LED 11b from the lighting start timing of the blue light B until the lighting duration has passed. In this way, the drive control unit 421 selectively illuminates any one of the LEDs 11r, 11g, and 11b, and drives the light source unit 11 in a field-sequential manner, sequentially switching the illuminated states of the LEDs 11r, 11g, and 11b. In the field-sequential method, a frame (frame period) representing the display cycle of an image M is composed of a display period Ton during which the display control unit 421 sequentially illuminates the light source unit 11 and causes the display element 30 to generate the image M; and a non-display period Toff during which the display control unit 421 continuously turns off the light source unit 11 and does not cause the display element 40 to generate the image M. A single display period Ton and a single non-display period Tof constitute a single frame.

[0072] Furthermore, the drive control unit 421 compares the target brightness indicated by the target brightness signal with the emission brightness indicated by the light intensity detection signal SFB, and performs feedback control on the current value supplied from the LED driver 430 to the light source unit 11 so that the light source unit 11 emits light at the target brightness.

[0073] The voltage measuring unit 422 measures the forward voltages Vr, Vg, and Vb of the LEDs 11 r , 11 g , and 11 b . Figure 7A circuit schematic diagram is shown to illustrate the function of the voltage measuring unit 422 for measuring the forward voltage Vr of LED 11r. The anode of LED 11r is connected to LED driver 430 via resistor Rr. The cathode of LED 11r is grounded via switch 44r. The anode of LED 11r is connected to the A / D (Analog to Digital) port of the display control unit 420 via terminal TA connected between the anode and resistor Rr. The display control unit 420, thus connected, obtains the anode voltage of LED 11r from terminal TA through the function of the voltage measuring unit 422. The voltage measuring unit 422 measures the anode voltage while switch 44r is on. Therefore, the anode voltage measured by the voltage measuring unit 422 is the voltage between the cathode and anode of LED 11r, i.e., the forward voltage Vr (also called the forward voltage). Using a similar structure, the voltage measuring unit 422 also measures the forward voltage Vg of LED 11g and the forward voltage Vb of LED 11b.

[0074] The voltage measuring unit 422 refers to the lighting pattern information D and determines the lighting duration that is longer than the predetermined set period Pm as the target period Pr, Pg, and Pb for measuring the forward voltages Vr, Vg, and Vb. In this embodiment, the longest lighting duration within a frame is determined as the target period Pr, Pg, and Pb. Figure 8 This is an example showing a portion of the lighting pattern for one frame. In the lighting color R, it is assumed that the lighting duration of "370μs" starting from the lighting timing t4 is the longest lighting duration in one frame. In this case, the voltage measuring unit 422 determines the lighting duration starting from the lighting timing t4 as the object period Pr. In the lighting color G, it is assumed that the lighting duration of "300μs" starting from the lighting timing t5 is the longest lighting duration in one frame. In this case, the voltage measuring unit 422 determines the lighting duration starting from the lighting timing t5 as the object period Pg. In the lighting color B, it is assumed that the lighting duration of "400μs" starting from the lighting timing t8 is the longest lighting duration in one frame. In this case, the voltage measuring unit 422 determines the lighting duration starting from the lighting timing t8 as the object period Pb. In addition, the determination of the object periods Pr, Pg, and Pb in a specified frame is performed before the start of the specified frame.

[0075] Then, the voltage measuring unit 422 performs a voltage measuring process of measuring the forward voltages Vr, Vg, and Vb at a timing after the set period Pm has elapsed from the start of the specified target period Pr, Pg, and Pb. Figure 10The measurement timing Tm of the forward voltage Vr within the determined object period Pr is shown. The voltage measuring unit 422 measures the forward voltage Vr at the timing Tm after the set period Pm has passed from the lighting timing t4. The set period Pm is, for example, a period of about 20 to 60 μs, and is determined as an appropriate period until the voltage to be measured stabilizes. The measurement of the forward voltages Vg and Vb within the determined object periods Pg and Pb is also performed at the same timing as above. In addition, the set period Pm can be an appropriate value determined for each LED11r, 11g, 11b, or a value common to LED11r, 11g, 11b. Below, refer to Figure 11 The LED diagnostic process including the voltage measurement process is described in the flowchart of FIG. The LED diagnostic process is executed by the display control unit 420 functioning as the voltage measurement unit 422.

[0076] When to start Figure 11 In the LED diagnosis process shown in the flowchart, first, the voltage measuring unit 422 refers to the lighting pattern information D and determines the longest period among the lighting durations in one frame as the target period Pr, Pg, or Pb (step S1).

[0077] Next, the voltage measuring unit 422 determines whether the frame including the object period Pr, Pg, and Pb (hereinafter referred to as the object frame) has started (step S2). The voltage measuring unit 422 can determine whether the object frame has started based on, for example, the vertical synchronization signal included in the image signal. When the object frame has not started (step S2; No), the voltage measuring unit 422 stands by. On the other hand, when the object frame has started (step S2; Yes), the voltage measuring unit 422 determines whether any one of the object periods Pr, Pg, and Pb has started (step S3). In the following, for ease of understanding, it is assumed that the object periods Pr, Pg, and Pb are started according to Figure 8 In this case, in step S3, it is determined whether the target period Pr has started (whether it has reached the lighting start timing t4).

[0078] If the target period Pr has not started (step S3; No), the voltage measuring unit 422 waits. On the other hand, if the target period Pr has started (step S3; Yes), the voltage measuring unit 422 determines whether the set period Pm has elapsed since the start of the target period Pr (lighting timing t4) (step S4).

[0079] If the setting period Pm has not elapsed (step S4; No), the voltage measuring unit 422 waits. On the other hand, if the setting period Pm has elapsed (step S4; Yes), the voltage measuring unit 422 performs a voltage measurement process to measure the forward voltage Vr of the LED 11r (step S5).

[0080] Next, the voltage measuring unit 422 determines whether all forward voltages Vr, Vg, and Vb corresponding to the lighting colors of each dot (i.e., red light R, green light G, and blue light B) have been measured in the target frame (step S6). If all forward voltages Vr, Vg, and Vb have not been measured (step S6; No), the voltage measuring unit 422 repeats the processing of steps S3 to S5 until all forward voltages Vr, Vg, and Vb are obtained. Figure 8 In the lighting pattern shown, after measuring the forward voltage Vr, the voltage measuring unit 422 repeatedly executes the processing of steps S3 to S5. Thus, the forward voltage Vg of LED 11g is measured at a timing when the set period Pm has elapsed from the start of the target period Pg (lighting timing t5), and the forward voltage Vb of LED 11b is measured at a timing when the set period Pm has elapsed from the start of the target period Pb (lighting timing t8). In this way, the voltage measuring unit 422 performs the voltage measurement process for each lighting color of LEDs 11r, 11g, and 11b.

[0081] When all forward voltages Vr, Vg, and Vb are measured in the target frame (step S6: Yes), the voltage measuring unit 422 determines whether or not an abnormality exists in the LEDs 11r, 11g, and 11b based on the measured forward voltages Vr, Vg, and Vb (step S7). For example, the ROM of the display control unit 420, which functions as the voltage measuring unit 422, stores threshold values ​​for determining a short circuit and a threshold value for determining a poor connection, respectively, corresponding to the LEDs 11r, 11g, and 11b. The voltage measuring unit 422 determines whether or not an abnormality exists in each of the LEDs 11r, 11g, and 11b based on these threshold values.

[0082] If at least one of LEDs 11r, 11g, and 11b is abnormal (step S7: Yes), voltage measurement unit 422 reports the abnormal LED and the details of the abnormality to MCU 410 (step S8). If all LEDs 11r, 11g, and 11b are normal (step S7: No), after executing step S8, voltage measurement unit 422 returns the process to step S1. Voltage measurement unit 422 continues to perform the above LED diagnostic process while the HUD device 1 is operating.

[0083] The present disclosure is not limited to the above-described embodiments and drawings, and can be appropriately modified (including deletion of components) without changing the gist of the present disclosure.

[0084] In the above, the drive control unit 421 and the voltage measuring unit 422 are implemented as functions of the display control unit 420. However, at least part of the functions of the drive control unit 421 and the voltage measuring unit 422 may be implemented by the MCU 410. Furthermore, the display control unit 420 and the MCU 410 may be constituted by a single control unit.

[0085] The above example shows that the longest lighting duration of each LED 11r, 11g, 11b within a frame period is determined as the target period Pr, Pg, Pb, but the present invention is not limited thereto. The target period Pr, Pg, Pb may be any period longer than the set period Pm.

[0086] The above example shows that the voltage measuring unit 422 performs the voltage measurement process on each of the LEDs 11r, 11g, and 11b once during a frame period, but the present invention is not limited thereto and the voltage measuring unit 422 may perform the voltage measurement process on each of the LEDs 11r, 11g, and 11b a plurality of times during a frame period.

[0087] The voltage measuring unit 422 may also measure the forward voltage of the light intensity detection unit 40, which is composed of a photodiode or a phototransistor, at at least one of the timings for measuring the forward voltages Vr, Vg, and Vb of the LEDs 11r, 11g, and 11b. Furthermore, the voltage measuring unit 422 may determine an abnormality in the light intensity detection unit 40 based on the measured forward voltage of the light intensity detection unit 40. For example, if an abnormality occurs in the light intensity detection unit 40, feedback control of the current value cannot be performed, and the display control unit 420 may shut down the system.

[0088] The configuration of the optical system provided in the process of generating the display light L from the illumination light C and guiding the display light L to the light guide device 300 can be arbitrarily changed. Furthermore, the configuration of the reflecting portion 60 that reflects the display light L toward the windshield 3 is also arbitrarily configured.

[0089] While the HUD device 1 is shown above as being mounted on a vehicle 2, the HUD device 1 may also be mounted on vehicles other than the vehicle 2, such as aircraft and ships. Furthermore, the light-transmitting component from which the HUD device 1 emits display light L may be a component other than the windshield 3, such as a dedicated combiner.

[0090] The program PG that executes the LED diagnostic processing described above is pre-stored in the ROM of the display control unit 420, but it can also be distributed and provided on a removable recording medium. Alternatively, the program PG can be downloaded from another device connected to the display control unit 420. Furthermore, the lighting pattern information D data can also be downloaded from another device connected to the display control unit 420. Furthermore, the display control unit 420 can execute various processes in accordance with the program by exchanging various data with other devices via a telecommunications network or the like.

[0091] (1) In the field sequential projector device 100 described above, the voltage measuring unit 422 refers to the lighting pattern information D and determines a lighting duration that is longer than a predetermined set period Pm as a target period Pr, Pg, or Pb. Furthermore, the voltage measuring unit 422 performs a voltage measurement process for measuring the forward voltages Vr, Vg, or Vb at a timing after the set period Pm has elapsed from the start of the determined target period Pr, Pg, or Pb.

[0092] This configuration avoids the period of voltage instability immediately after the lighting timing of LEDs 11r, 11g, and 11b, and prevents the forward voltages Vr, Vg, and Vb from being measured when LEDs 11r, 11g, and 11b are off. Therefore, the forward voltage of the light-emitting diodes can be measured during the appropriate lighting duration.

[0093] (2) Specifically, the lighting duration is shorter than the frame period, which is the display cycle of the image M, and exists intermittently in a plurality of frames. The voltage measuring unit 422 performs the voltage measurement process once or more in the frame period (in one frame).

[0094] (3) Furthermore, the voltage measuring unit 422 determines the longest lighting continuation period in the frame period as the target period Pr, Pg, or Pb.

[0095] (4) Furthermore, there are a plurality of light-emitting diodes that light up in different colors, and the voltage measuring unit 422 performs voltage measurement processing for each of the light-emitting diodes' lighting colors (R, G, B).

[0096] (5) The HUD device 1 described above includes the projector device 100 , and displays the virtual image V of the image M by radiating the display light L toward the light-transmitting member (eg, the windshield 3 ).

[0097] The HUD device 1 can also measure the forward voltage of the light-emitting diode during an appropriate lighting duration.

[0098] (6) The program PG described above causes the computer to function as: a drive control unit (e.g., the drive control unit 421) that, based on lighting pattern information D for lighting the light-emitting diodes included in the field sequential projector device 100 in a predetermined lighting pattern, causes the light-emitting diodes to light in the lighting pattern; and a voltage measurement unit (e.g., the voltage measurement unit 422) that measures the forward voltage of the light-emitting diodes. The voltage measurement unit refers to the lighting pattern information D, determines a lighting duration that is longer than the predetermined set period Pm as a target period Pr, Pg, or Pb, and measures the forward voltages Vr, Vg, or Vb at a timing after the set period Pm has elapsed from the start of the determined target period Pr, Pg, or Pb within the determined target period Pr, Pg, or Pb.

[0099] This program PG can also measure the forward voltage of the light-emitting diode during an appropriate lighting duration.

[0100] (7) The voltage measurement method using the display control unit 420 described above includes: a step of lighting the light-emitting diodes provided in the field sequential projector device 100 in a predetermined lighting pattern based on lighting pattern information D for lighting the light-emitting diodes in the lighting pattern; and a voltage measurement step of measuring the forward voltage of the light-emitting diodes. In the voltage measurement step, the lighting pattern information D is referenced, and a lighting duration that is longer than a predetermined set period Pm is determined as a target period Pr, Pg, or Pb. Within the determined target period Pr, Pg, or Pb, the forward voltages Vr, Vg, or Vb are measured at a timing after the set period Pm has elapsed from the start of the target period.

[0101] This voltage measurement method can also measure the forward voltage of the light-emitting diode during an appropriate lighting duration.

[0102] In the above description, in order to facilitate understanding of the present invention, descriptions of well-known technical contents have been appropriately omitted.

[0103] Description of Reference Numerals

[0104] 1: HUD device; 2: Vehicle; 3: Windshield; 4: User;

[0105] 100: Projector device;

[0106] 10: lighting device; 11r, 11g, 11b: light-emitting diodes (LEDs);

[0107] 20: display unit; 30: display element; 40: light intensity detection unit;

[0108] 200: screen;

[0109] 300: light guide device;

[0110] 400: control device;

[0111] 410: MCU;

[0112] 420: display control unit; PG: program;

[0113] 421: drive control unit;

[0114] 422: voltage measuring unit;

[0115] 430: LED driver;

[0116] 440: switch element; 44r, 44g, 44b: switch;

[0117] 450: storage unit; D: lighting mode information;

[0118] C: illumination light; R: red light; G: green light; B: blue light;

[0119] L: display light; M: image; V: virtual image;

[0120] Pr, Pg, Pb: target period; Pm: setting period;

[0121] Vr, Vg, Vb: forward voltage; Ir, Ig, Ib: driving current.

Claims

1. A field sequential projector device comprising: light-emitting diodes; a storage unit storing lighting pattern information for lighting the light emitting diode in a predetermined lighting pattern, the lighting pattern information indicating a time series of a lighting start timing of the light emitting diode and a lighting continuation period from the lighting start timing; a drive control unit configured to light the light emitting diode in the lighting mode based on the lighting mode information; a display element that generates display light representing an image based on the light emitted by the light-emitting diode; as well as a voltage measuring unit for measuring the forward voltage of the light emitting diode; The voltage measuring unit: Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period, During the determined target period, a voltage measurement process is executed to measure the forward voltage at a timing after the set period has elapsed from the start of the period.

2. The projector device according to claim 1, wherein The lighting duration is shorter than the display cycle of the image, that is, the frame period, and there are multiple lighting durations intermittently within the frame period. The voltage measuring unit performs the voltage measuring process one or more times within the frame period.

3. The projector device according to claim 2, wherein The voltage measuring unit determines the longest of the lighting continuation periods within the frame period as the target period.

4. The projector device according to any one of claims 1 to 3, wherein: There are multiple light-emitting diodes, which light up in different colors. The voltage measuring unit executes the voltage measuring process for each lighting color of the light emitting diode. 5 . A head-up display device comprising the projector device according to claim 1 , wherein a virtual image of the image is displayed by radiating the display light toward a light-transmitting member.

6. A computer program product comprising a computer program, the computer program causing a computer to function as: a drive control mechanism for lighting the light-emitting diodes provided in the field sequential projector device in a predetermined lighting pattern based on lighting pattern information for lighting the light-emitting diodes in the predetermined lighting pattern; and a voltage measuring mechanism for measuring the forward voltage of the light emitting diode; The lighting pattern information indicates a time series of a lighting start timing of the light emitting diode and a lighting duration period from the lighting start timing. The voltage measuring mechanism: Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period, The forward voltage is measured at a timing after the set period has elapsed from the start of the determined target period.

7. A voltage measurement method comprising: Based on lighting pattern information for lighting a light emitting diode included in a field sequential projector device in a predetermined lighting pattern, lighting the light emitting diode in the lighting pattern; and a voltage measuring step of measuring the forward voltage of the light emitting diode, The lighting pattern information indicates a time series of a lighting start timing of the light emitting diode and a lighting duration period from the lighting start timing. In the voltage measuring step, Referring to the lighting pattern information, the lighting duration period that is longer than a predetermined setting period is determined as a target period, The forward voltage is measured at a timing after the set period has elapsed from the start of the determined target period.

Images