JP2018200811A - Light source drive device and head-up display apparatus - Google Patents

Abstract

To provide a light source drive device and head-up display apparatus which suppress the change in the chromaticity from the desired chromaticity when changing the display luminance.SOLUTION: A light source drive device 5 includes: voltage adjustment units 310, 320 which adjust the voltage Vr, Vg applied to light sources 11g, 11r; a lighting control processing unit 101 which performs voltage variable lighting control processing of adjusting the light emission luminance of each of the light sources 11g, 11r to the requested luminance from the present luminance so that the light intensity ratio of the green light G and red light R becomes the desired light intensity ratio by adjusting the voltage Vg and voltage Vr through the voltage adjustment units 310, 320; and a predicted time determination unit 102 which determines the predicted time that is predicted to be required for adjusting the luminance to the requested luminance from the present luminance. The lighting control processing unit 101 adjusts the light emission luminance of the light sources 11g, 11r to the requested luminance from the present luminance with the luminance adjustment time equal to or longer than the longer predicted time out of the predicted time for the light source 11g and the predicted time for the light source 11r.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a light source driving device and a head-up display device.

  Conventionally, for example, as disclosed in Patent Document 1, a plurality of light sources, a power supply unit that applies a common voltage to the plurality of light sources, and light from the light source to which the voltage is applied are displayed to display an image. A display device including a display element is known.

JP 2017-33645 A

  The inventor of the present application is considering providing a display device with a power supply control unit that generates a different voltage for each light source in order to achieve desired luminance and chromaticity particularly at low luminance. In order to smooth the fluctuation of the voltage generated for each light source, this power supply control unit is considered to include a capacitor for each light source. In this configuration, when reducing the luminance of the light source, it is necessary to discharge the charge charged in the capacitor to the outside. The time required to release this charge (charge discharge time) varies depending on the current luminance and the required luminance due to the nature of the capacitor. For this reason, the length of the charge discharge time may be different for each light source. In this case, when the display luminance is changed from the current luminance to the required luminance, the chromaticity may change from the desired chromaticity. is there.

  The present invention has been made in view of the above circumstances, and provides a light source driving device and a head-up display device in which a change in chromaticity from a desired chromaticity is suppressed when the display luminance is changed. Objective.

  In order to achieve the above object, a light source driving apparatus according to a first aspect of the present invention is a light source driving apparatus that emits first light from a first light source and emits second light from a second light source. A voltage adjusting unit for adjusting a first voltage applied to the first light source and a second voltage applied to the second light source; and adjusting the first voltage and the second voltage through the voltage adjusting unit. Thus, the emission luminance of each of the first light source and the second light source is determined from the current luminance so that the light intensity ratio between the first light and the second light becomes a desired light intensity ratio. A dimming processing unit that performs voltage-modulable light processing to adjust to the required luminance, and an expected time determination unit that determines an expected time that is expected to be required to adjust the emission luminance from the current luminance to the required luminance And the dimming processing unit performs the voltage-modulable light processing. A longer expected time is selected from the expected time for the first light source and the expected time for the second light source determined by the expected time determination unit, and the luminance is equal to or higher than the selected expected time. The emission luminance of each of the first light source and the second light source is adjusted from the current luminance to the required luminance over an adjustment time.

  In order to achieve the above object, a head-up display device according to a second aspect of the present invention includes the light source driving device, the first light source driven by the light source driving device, and the second light source. A light combining unit that combines the first light and the second light, a display element that generates an image on a screen based on the combined light combined by the light combining unit, and display light that represents the image from the display element. And an optical system that displays a virtual image by projecting toward the projection member.

  ADVANTAGE OF THE INVENTION According to this invention, in a light source drive device and a head-up display apparatus, when changing display brightness, it is suppressed that chromaticity changes from desired chromaticity.

It is a mimetic diagram of a vehicle carrying a head up display device concerning a 1st embodiment of the present invention. It is the schematic which shows the structure of the head-up display apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the structure of the illuminating device which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the electric constitution of the light source drive device which concerns on the 1st Embodiment of this invention. 1 is a circuit diagram showing an electrical configuration of a logic circuit according to a first embodiment of the present invention. It is a block diagram which shows a part of light source drive circuit which concerns on the 1st Embodiment of this invention, and the electrical structure of a power supply control unit. FIG. 3 is a circuit diagram showing a specific electrical configuration of the power supply control unit according to the first embodiment of the present invention. It is a timing chart which shows the state of the display element concerning the 1st Embodiment of this invention, and the electric current supplied to each light source. (A)-(f) which concerns on the 1st Embodiment of this invention is a timing chart which shows the various signals and drive current in a sub-frame. (A)-(f) which concerns on the 1st Embodiment of this invention is a timing chart which shows the various signals and drive current in a sub-frame. It is a flowchart which shows the process sequence of the light control process which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the process sequence of the brightness | luminance adjustment time setting process which concerns on the 1st Embodiment of this invention. (A) concerning the 1st Embodiment of this invention is a figure which shows the relationship between a request | requirement brightness | luminance and HUD brightness | luminance, (b) is a figure which shows a display period ratio data table, (c) is a current data table. (D) is a figure which shows a restriction | limiting data table, (e) is a figure which shows a voltage data table. It is a figure which shows the relationship between the request | requirement brightness | luminance and HUD brightness | luminance which concern on the 1st Embodiment of this invention. It is a figure which shows the estimated time data table which concerns on the 1st Embodiment of this invention. (A) And (b) which concerns on the 1st Embodiment of this invention is a graph which shows the relationship between light emission luminance and estimated time. It is a graph which shows the relationship between the light emission luminance and the estimated time which concern on the 1st Embodiment of this invention and its comparative example. It is a flowchart which shows the process sequence of the learning process which concerns on the 3rd Embodiment of this invention.

(First embodiment)
A first embodiment of a light source driving device and a head-up display (HUD) device according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the HUD device 1 is installed on a dashboard 2a of a vehicle 2, generates display light L representing an image M (see FIG. 2), and the generated display light L is an example of a projection member. The light is emitted toward the windshield 3. The display light L is reflected by the windshield 3 and then reaches the viewer 4 (mainly the driver of the vehicle 2). Thereby, the viewer 4 can visually recognize the virtual image V representing the image M formed in front of the windshield 3. In the image M, information related to the vehicle 2 (for example, engine speed, navigation information, etc.) is displayed.

(Configuration of HUD device 1)
As shown in FIG. 2, the HUD device 1 includes an illumination device 10, a light intensity detection unit 500, an illumination optical system 20, a display element 30, a light source driving device 5, a projection optical system 40, and a screen 50. , A plane mirror 61 and a concave mirror 62 corresponding to the optical system, a housing 70, and a translucent part 71.

The housing 70 is formed in a box shape from a light-shielding material, for example. The housing 70 accommodates the components of the HUD device 1 such as the illumination device 10 and the illumination optical system 20. The housing 70 is formed with an opening 70a through which the display light L passes.
The translucent portion 71 is made of a translucent resin such as acrylic and is provided so as to close the opening 70 a of the housing 70. The translucent part 71 is formed in, for example, a curved shape in order to prevent the external light that has reached from being reflected toward the viewer 4.

  The illumination device 10 generates the combined light C and emits the generated combined light C toward the illumination optical system 20. Specifically, as illustrated in FIG. 3, the lighting device 10 includes a light source unit 11, a circuit board 12, a light synthesis unit 13, a luminance unevenness reduction unit 14, and a transmission film 15.

The light source unit 11 includes, for example, three light sources 11r, 11g, and 11b each formed of an LED (Light Emitting Diode). The light source 11r emits red light R, the light source 11g emits green light G, and the light source 11b emits blue light B. Each of the light sources 11r, 11g, and 11b is driven by a light source driving device 5 as will be described later, and emits light at a predetermined light intensity (light emission luminance) and timing.
For example, the light source 11g corresponds to the first light source, and the green light G corresponds to the first light. The light source 11r corresponds to the second light source, and the red light R corresponds to the second light.

  The circuit board 12 is a printed circuit board. Light sources 11r, 11g, and 11b are mounted on the circuit board 12.

The dichroic mirror 13c generates the combined light C by aligning the optical axes of the red light R, the green light G, or the blue light B sequentially emitted from the light sources 11r, 11g, and 11b. 14 is emitted.
Specifically, the light combining unit 13 includes a reflecting mirror 13a and dichroic mirrors 13b and 13c that reflect light having a specific wavelength and transmit light having other wavelengths other than the specific wavelength. The reflection mirror 13a is located on the emission side of the light source 11b. The reflection mirror 13a reflects the incident blue light B toward the dichroic mirror 13b. The dichroic mirror 13b is located on the emission side of the light source 11g. The dichroic mirror 13b reflects the incident green light G toward the dichroic mirror 13c and transmits the blue light B from the reflection mirror 13a as it is. The dichroic mirror 13c is located on the emission side of the light source 11r. The dichroic mirror 13c reflects the incident red light R toward the luminance unevenness reducing unit 14 and transmits the light B and G from the dichroic mirror 13b as they are.

  The brightness unevenness reducing unit 14 includes a mirror box, an array lens, and the like, and reduces unevenness of light by irregularly reflecting, scattering, and refracting the synthesized light C from the light combining unit 13.

  The transmissive film 15 is made of a transmissive member having a reflectivity of, for example, about 5%, and transmits most of the synthesized light C that has arrived through the luminance unevenness reducing unit 14 as it is. Reflected toward the part 500.

  The light intensity detection unit 500 is formed of a light receiving element having a photodiode, for example, and is provided at a position for receiving the combined light C reflected by the transmission film 15. The light intensity detection unit 500 receives a part of the combined light C and detects the light intensities of the lights R, G, and B constituting the combined light C in a time division manner.

  The illumination optical system 20 is composed of a concave lens or the like, and adjusts the synthesized light C emitted from the illumination device 10 to a size corresponding to the display element 30 as shown in FIG.

  As shown in FIG. 2, the display element 30 is composed of a DMD provided with a plurality of movable micromirrors 30 a which are an example of a reflecting portion. The micromirror 30a includes an electrode (not shown), and is turned on / off by switching a voltage value applied to the electrode. When the micromirror 30a is on, the micromirror 30a takes a posture inclined, for example, by +12 degrees with the hinge as a fulcrum. At this time, the combined light C emitted from the illumination optical system 20 passes through the projection optical system 40 and the screen 50. Reflect towards When the micromirror 30a is off, the micromirror 30a takes a posture inclined, for example, -12 degrees with the hinge as a fulcrum, and then reflects the synthesized light C in a direction different from the projection optical system 40. Accordingly, the display element 30 individually drives each micromirror 30a under the control of the light source driving device 5 (specifically, a second control unit 200 described later), whereby the image M of the combined light C is displayed. Only light corresponding to is projected toward the projection optical system 40.

  The projection optical system 40 includes a concave lens or a convex lens, and efficiently projects the display light L from the display element 30 onto the screen 50.

  The screen 50 is composed of a translucent screen such as a holographic diffuser, a microlens array, and a diffusing plate. The screen 50 receives the display light L from the projection optical system 40 on the back surface (the lower surface in FIG. 2), and the front surface The image M is displayed on the upper surface in FIG.

The plane mirror 61 reflects the display light L representing the image M displayed on the screen 50 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 reaches the windshield 3 after passing through the light transmitting portion 71 of the housing 70. Thereby, the virtual image V to be formed is enlarged as compared with the image M displayed on the screen 50.

(Configuration of the light source driving device 5)
As shown in FIG. 4, the light source driving device 5 includes a power source control unit 300 that applies voltages Vr, Vg, and Vb to the light sources 11r, 11g, and 11b, a light source driving unit 400 that drives the light sources 11r, 11g, and 11b, A second control unit 200 that controls the display element 30 and a first control unit 100 that controls the light source driving unit 400 and the second control unit 200 are provided.

  As illustrated in FIG. 8, the light source driving device 5 performs control for each frame F that is a control cycle for displaying the image M. The frame F includes a display period Fa and a non-display period Fb. In the display period Fa, the light source driving device 5 drives each micromirror 30a and the light sources 11r, 11g, and 11b of the display element 30 so as to generate the image M. In the display period Fa, the light source driving device 5 sequentially turns on the light sources 11r, 11g, and 11b by supplying the current I (Ir, Ig, Ib) to the light sources 11r, 11g, and 11b that are different for each subframe Fs. The light source unit 11 is driven by a field sequential method. In the non-display period Fb, the light source driving device 5 turns off all the light sources 11r, 11g, and 11b, and the display element 30 is set so that the on period and the off period of the micromirror 30a in the frame F are substantially the same. The micromirror 30a is driven. By setting the non-display period Fb, failure of each micromirror 30a of the display element 30 is suppressed.

  The light source driving device 5 adjusts the display period ratio that the display period Fa occupies in the entire frame F. That is, this display period ratio is calculated by “(display period Fa / frame F) × 100%”. Specifically, as shown in FIG. 13B, the light source driving device 5 sets the display period ratio so as to decrease stepwise as the required luminance decreases. In addition, the lower limit of the display period ratio is set to 50% in order to make the on period and the off period substantially the same as described above.

As shown in FIG. 4, the first control unit 100 executes a memory 100a such as a ROM (Read Only Memory) in which an operation program is stored, a timer 100b for measuring time, and the stored operation program. And a CPU (Central Processing Unit) (not shown) that executes dimming processing and the like described later.
The first control unit 100 functions as a dimming processing unit 101 that performs dimming processing and an expected time that is required to reach the required luminance from the current luminance for each of the light sources 11r, 11g, and 11b. An expected time judging unit 102 for judging.

A video signal for displaying an image M is input to the first control unit 100 from a vehicle ECU (Electronic Control Unit) 6 of the vehicle 2 by LVDS (Low Voltage Differential Signal) communication or the like.
The first control unit 100 outputs the input video signal to the second control unit 200 via an image processing IC (Integrated Circuit) (not shown). Note that the video signal from the vehicle ECU 6 may be directly input to the second control unit 200 via an image processing IC (not shown) or the like without passing through the first control unit 100.
In addition, the first control unit 100 displays the display control data for displaying the display image M requested by the video signal on the display element 30, and the light sources 11r, The illumination control data for driving 11g and 11b is output to the second control unit 200.
In addition, an external light intensity signal (dimming signal) SL around the vehicle 2 detected through the external light intensity sensor 7 is input from the vehicle ECU 6 to the first control unit 100. This external light intensity signal SL has a value corresponding to the required luminance.

  In the memory 100a, various data tables are stored in addition to the above-described display control data and illumination control data. The various data tables include a display period ratio data table indicating the display period ratio with respect to the required luminance shown in FIG. 13B, and current data indicating the current Ig supplied to the light source 11g with respect to the required luminance shown in FIG. 13C. A table, a limit data table for limiting the period during which the current Ig is supplied to the light source 11g for the required luminance shown in FIG. 13D, and a voltage Vg applied to the light source 11g for the required luminance shown in FIG. A voltage data table, and an expected time data table associated with the luminance change and the luminance adjustment time shown in FIG.

The first control unit 100 adjusts the light emission intensity (light emission luminance) of the light sources 11r, 11g, and 11b via the light source driving unit 400, and consequently the HUD luminance (display luminance), according to the external light intensity signal SL.
The first control unit 100 recognizes the required luminance based on the external light intensity signal SL, and displays the display element at a display period ratio corresponding to the required luminance while referring to the display period ratio data table shown in FIG. 30 and the light sources 11r, 11g, and 11b are driven.
As shown in FIG. 4, the first control unit 100 generates a reference signal SA serving as a threshold based on the external light intensity signal SL from the vehicle ECU 6, and outputs the reference signal SA to the light source driving unit 400. Specifically, the first control unit 100 sets the duty ratio of the reference signal SA based on the external light intensity signal SL. The first control unit 100 outputs a reference signal SA that is a digital signal having a set duty ratio, and converts the reference signal SA into an analog signal by a digital-analog converter (not shown) including an integration circuit. The analog signal reference signal SA is output to the light source driver 400 (more precisely, a comparison circuit 410 described later).
The first control unit 100 can output a reference signal SA having a different magnitude for each subframe Fs, which is a period during which a selected one of the light sources 11r, 11g, and 11b emits light.

As shown in FIG. 6, the first control unit 100 generates PWM signals Sp <b> 1 to Sp <b> 3 and outputs the generated PWM signals Sp <b> 1 to Sp <b> 3 to the power supply control unit 300.
The first control unit 100 sets the on-duty ratio of the PWM signal Sp1, and outputs the PWM signal Sp1 having the set on-duty ratio to the first voltage adjustment unit 310 of the power supply control unit 300. As will be described later, the voltage Vg applied to the light source 11g is set according to the on-duty ratio of the PWM signal Sp1.
The first control unit 100 sets the on-duty ratio of the PWM signal Sp2, and outputs the PWM signal Sp2 having the set on-duty ratio to the second voltage adjustment unit 320 of the power supply control unit 300. As will be described later, a voltage Vr applied to the light source 11r is set according to the on-duty ratio of the PWM signal Sp2.
The first control unit 100 sets the on-duty ratio of the PWM signal Sp3 and outputs the PWM signal Sp3 having the set on-duty ratio to the third voltage adjustment unit 330 of the power supply control unit 300. As will be described later, the voltage Vb applied to the light source 11b is set in accordance with the on-duty ratio of the PWM signal Sp3.
For example, the voltage Vg corresponds to the first voltage, and the voltage Vr corresponds to the second voltage.

  The second control unit 200 is an LSI (Large Scale Integration) that realizes a desired function by hardware, and is configured by, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

As shown in FIG. 4, the second control unit 200 outputs a limiting signal SC to the light source driving unit 400 (more precisely, a logic circuit 420 described later) under the control of the first control unit 100. As shown in FIG. 9 (d) or FIG. 10 (d), the restriction signal SC is turned on to indicate that the lighting of the light sources 11r, 11g, and 11b is permitted, and the lighting of the light sources 11r, 11g, and 11b is prohibited. It is in an off state indicating.
The first control unit 100 sets the on-duty ratio of the limit signal SC in the subframe Fs based on the required luminance determined according to the external light intensity signal SL via the second control unit 200, and the set on-state A duty ratio limit signal SC is output. The limit signal SC2 in the example of FIG. 9D has a higher on-duty ratio because the external light intensity signal SL is larger than the limit signal SC1 in the example of FIG. In this example, as shown in FIGS. 13B and 13D, the first control unit 100 sets the on-duty ratio of the limit signal SC to 100 when the display period ratio is in the range of 60% to 100%. When the display period ratio is 50% and the required luminance is equal to or higher than the first threshold value Th1, the on-duty ratio of the limit signal SC is changed stepwise in this example according to the required luminance. . Further, when the required luminance is less than the first threshold Th1, the on-duty ratio of the limit signal SC is kept at the lower limit value.

As shown in FIG. 4, the second control unit 200 controls on / off of each micromirror 30a in the display element 30 by a PWM (Pulse Width Modulation) method based on the display control data from the first control unit 100. To do.
The second controller 200 is an enable signal EN (R-EN, G-EN, B-EN) that controls the light emission timing of the light sources 11r, 11g, and 11b in accordance with the illumination control data from the first controller 100. And the generated enable signal EN is output to the light source driver 400 (more precisely, a logic circuit 420 described later). The second control unit 200 uses the red enable signal R-EN corresponding to the light source 11r, the green enable signal G-EN corresponding to the light source 11g, and the blue enable signal B-EN corresponding to the light source 11b as the enable signal EN. Are output at different timings. The enable signal EN is either on indicating that the corresponding light sources 11r, 11g, and 11b are allowed to be turned on, and off indicating that the corresponding light sources 11r, 11g, and 11b are not allowed to be turned on. The second control unit 200 synchronizes the light emission timings of the light sources 11r, 11g, and 11b with the screen control of the display element 30 through the output of the enable signal EN.
Note that the first control unit 100 generates an enable signal EN (R-EN, G-EN, B-EN), and the generated enable signal EN does not pass through the second control unit 200, and the light source driving unit 400. May be output.

As shown in FIG. 4, the light source driving unit 400 is an LSI that realizes a desired function by hardware. For example, the light source driving unit 400 includes an ASIC, FPGA, or analog circuit independent of the second control unit 200. .
The light source drive unit 400 includes a comparison circuit 410 that compares the reference signal SA and the light intensity detection signal SFB, and a light source drive circuit 430 that includes switch units 431, 432, and 433 that turn on or off the light sources 11r, 11g, and 11b. And a logic circuit 420 that outputs a drive signal SD for controlling the switch units 431, 432, and 433.
In brief, the light source driver 400 includes a light intensity detection signal SFB from the light intensity detector 500, a reference signal SA from the first controller 100, an enable signal EN from the second controller 200, and In response to the limit signal SC, a drive signal SD for driving the light sources 11r, 11g, and 11b is generated based on the signals SFB, SA, EN, and SC, and the switch units 431 and 432 are generated based on the drive signal SD. , 433 are turned on or off to turn on or off the light sources 11r, 11g, and 11b.

Specifically, the comparison circuit 410 includes a comparator, compares the light intensity detection signal SFB from the light intensity detection unit 500 with the reference signal SA from the first control unit 100, and outputs the comparison signal SB as a comparison result. The data is output to the circuit 420 and the second control unit 200.
Specifically, as shown in FIGS. 9B and 9C, the comparison circuit 410 turns off the comparison signal SB when the light intensity detection signal SFB exceeds the reference signal SA. When the comparison signal SB is turned off as described above, the current I (current Ir in the figure) flowing through the light sources 11r, 11g, and 11b decreases as shown in FIG. The light intensity detection signal SFB, which is feedback data of the emission intensity of 11g and 11b, decreases until it becomes less than the reference signal SA.
Further, as shown in FIGS. 9B and 9C, the comparison circuit 410 turns on the comparison signal SB when the light intensity detection signal SFB is equal to or lower than the reference signal SA. When the comparison signal SB is thus turned on, the current I (current Ir in the figure) flowing through the light sources 11r, 11g, and 11b increases as shown in FIG. The light intensity detection signal SFB, which is feedback data of the emission intensity of 11g and 11b, increases until it exceeds the reference signal SA.
In this manner, the comparison circuit 410 is a comparison that is a pulse signal that repeatedly turns on and off by repeatedly repeating the light intensity detection signal SFB below the reference signal SA or the light intensity detection signal SFB exceeding the reference signal SA. A signal SB is generated, and a value of the current I corresponding to the reference signal SA is generated.
An amplification circuit (not shown) is provided between the light intensity detection unit 500 and the comparison circuit 410, and the light intensity detection signal SFB is amplified by the amplification circuit and input to the comparison circuit 410. Also good.

The logic circuit 420 receives the limit signal SC, the enable signal EN, and the comparison signal SB, and turns on or off the switch units 431, 432, and 433 corresponding to the light sources 11r, 11g, and 11b based on the signals SC, EN, and SB. To do.
Specifically, as shown in FIG. 5, the logic circuit 420 includes a first AND circuit 421, a red AND circuit 422, a green AND circuit 423, and a blue AND circuit 424.

The first AND circuit 421 receives the limit signal SC from the second control unit 200 and the comparison signal SB from the comparison circuit 410, and outputs a drive signal SD that is an AND signal of the limit signal SC and the comparison signal SB to each AND circuit. To 422, 423, and 424.
That is, as shown in FIGS. 10C to 10E, the first AND circuit 421 outputs the drive signal SD having substantially the same waveform as the comparison signal SB during the on time Ton when the limit signal SC is on. . Therefore, in the on time Ton of the limit signal SC, the drive signal SD is turned on when the comparison signal SB is on, and the drive signal SD is turned off when the comparison signal SB is off. The first AND circuit 421 turns off the drive signal SD regardless of whether the comparison signal SB is on or off during the off time Tof when the limit signal SC is off.

  As shown in FIG. 5, the red AND circuit 422 receives the red enable signal R-EN from the second controller 200 and the drive signal SD from the first AND circuit 421, and receives the red enable signal R-EN and the drive. A red drive signal SDR that is an AND signal of the signal SD is output to the red switch unit 431. Further, the green AND circuit 423 receives the green enable signal G-EN from the second controller 200 and the drive signal SD from the first AND circuit 421, and the AND signal of the green enable signal G-EN and the drive signal SD. Is output to the green switch unit 432. The blue AND circuit 424 receives the blue enable signal B-EN from the second controller 200 and the drive signal SD from the first AND circuit 421, and is an AND signal of the blue enable signal B-EN and the drive signal SD. The blue drive signal SDB is output to the blue switch unit 433.

  In the predetermined subframe Fs shown in FIGS. 9A and 10A, only the red enable signal R-EN among the enable signals EN is turned on. In this case, as shown in FIGS. 9E and 10E, the red AND circuit 422 outputs a red drive signal SDR having the same waveform as the drive signal SD from the first AND circuit 421. In this subframe Fs, the green AND circuit 423 and the blue AND circuit 424 receive the green enable signal G-EN and the blue enable signal B-EN in the off state, respectively, so that the green drive signal SDG and the blue drive in the off state are input. The signal SDB is output.

The switch units 431, 432, and 433 are, for example, switching elements using n-type channel FETs (Field Effect Transistors). The switch units 431, 432, and 433 are switched to an on state or an off state in accordance with the drive signals SDR, SDG, and SDB from the logic circuit 420.
As shown in FIG. 6, the red switch unit 431 is connected to the cathode side of the light source 11r, the green switch unit 432 is connected to the cathode side of the light source 11g, and the blue switch unit 433 is connected to the cathode side of the light source 11b. The red switch unit 431 is turned on when the red drive signal SDR from the red AND circuit 422 is turned on. When the red switch unit 431 is in the ON state, the current Ir is supplied from the power supply control unit 300 to the light source 11r, whereby the light source 11r emits red light R. The red switch unit 431 is turned off when the red drive signal SDR from the red AND circuit 422 is turned off. When the red switch unit 431 is in the off state, the light source 11r is turned off. Similarly, in the green switch unit 432 and the blue switch unit 433, the light source 11g and the light source 11b are turned on or off depending on whether the green drive signal SDG and the blue drive signal SDB are turned on or off.
The first control unit 100 and the light source driving unit 400 correspond to a first current adjustment unit that adjusts the current Ig supplied to the light source 11g and a second current adjustment unit that adjusts the current Ir supplied to the light source 11r. To do.

  As shown in FIG. 4, the power supply control unit 300 is connected to the anode side of each light source 11r, 11g, 11b. The power supply control unit 300 receives the power supply voltage from the battery 700 as the power supply of the vehicle 2 and applies the voltages Vr, Vg, and Vb to the light sources 11r, 11g, and 11b, respectively, under the control of the first control unit 100. To do.

  As shown in FIG. 6, the power supply control unit 300 controls the first to third voltages that control the voltages Vr, Vg, and Vb applied to the light sources 11r, 11g, and 11b under the control of the first control unit 100. Adjustment units 310 to 330 are provided.

When receiving the PWM signal Sp1 from the first control unit 100, the first voltage adjustment unit 310 applies a voltage Vg corresponding to the on-duty ratio of the PWM signal Sp1 to the light source 11g.
When receiving the PWM signal Sp2 from the first control unit 100, the second voltage adjustment unit 320 applies a voltage Vr corresponding to the on-duty ratio of the PWM signal Sp2 to the light source 11r. In this example, the second voltage adjustment unit 320 generates the voltage Vr using the voltage Vg from the first voltage adjustment unit 310 as a power source. This voltage Vr is set to a voltage value equal to or lower than the voltage Vg.
When receiving the PWM signal Sp3 from the first control unit 100, the third voltage adjustment unit 330 applies a voltage Vb corresponding to the on-duty ratio of the PWM signal Sp3 to the light source 11b. In this example, the third voltage adjustment unit 330 generates the voltage Vb using the voltage Vg from the first voltage adjustment unit 310 as a power source. This voltage Vb is set to a voltage value equal to or lower than the voltage Vg.

As shown in FIG. 7, the first voltage adjustment unit 310 includes a power supply IC (Integrated Circuit) 316, a D / A conversion circuit 311 including a resistor R4 and a capacitor 315, resistors R1 to R3, a smoothing capacitor 318, . The D / A conversion circuit 311 receives the PWM signal Sp1, which is a digital signal, and generates an analog signal Sa1 having a current value corresponding to the on-duty ratio of the PWM signal Sp1.
The power supply IC 316 is, for example, a step-down DC / DC converter. The power supply IC 316 receives the power supply voltage from the battery 700, generates a voltage Vg corresponding to the analog signal Sa1, and applies the generated voltage Vg to the light source 11g. The power supply IC 316 receives the voltage divided by the resistors R1 and R2 and performs feedback control. One end of the smoothing capacitor 318 is connected to the connection line Lg connecting the power supply IC 316 and the light source 11g, and the other end is connected to the ground. The smoothing capacitor 318 smoothes the fluctuation of the voltage Vg.
Note that the smoothing capacitor 318 may be omitted.

The second voltage adjustment unit 320 includes a D / A conversion circuit 321 including a resistor R8 and a capacitor 325, a non-inverting amplifier circuit 326, a resistor R7, a switch unit 329, and a smoothing capacitor 328.
The D / A conversion circuit 321 receives the PWM signal Sp2, generates a sine wave analog signal Sa2 corresponding to the period of the PWM signal Sp2, and outputs the generated analog signal Sa2 to the non-inverting amplifier circuit 326.
The non-inverting amplifier circuit 326 generates an amplified PWM signal Sp2 based on the input of the analog signal Sa2, and outputs the amplified PWM signal Sp2 to the switch unit 329. The non-inverting amplifier circuit 326 includes an operational amplifier 327 and resistors R5 and R6. Since the non-inverting amplifier circuit 326 is known, a detailed description thereof is omitted.
The switch unit 329 is composed of a switching element using, for example, an FET. The switch unit 329 switches to an on state or an off state in accordance with the amplified PWM signal Sp2. Thus, the switch unit 329 outputs the voltage Vg from the power supply IC 316 to the light source 11r side when in the on state, and stops outputting the voltage Vg to the light source 11b side when in the off state. Thereby, a rectangular wave is generated. One end of the smoothing capacitor 328 is connected to the connection line Lr connecting the non-inverting amplifier circuit 326 and the light source 11r, and the other end is connected to the ground. The smoothing capacitor 328 generates the voltage Vr by smoothing the rectangular wave, and applies the voltage Vr to the light source 11r.
The resistor R7 is provided to protect the switch unit 329, for example.

The third voltage adjustment unit 330 includes a D / A conversion circuit 331 including a resistor R12 and a capacitor 335, a non-inverting amplifier circuit 336, a resistor R11, a switch unit 339, and a smoothing capacitor 338.
The D / A conversion circuit 331 receives the PWM signal Sp3, generates a sine wave analog signal Sa3 corresponding to the period of the PWM signal Sp3, and outputs the generated analog signal Sa3 to the non-inverting amplifier circuit 336.
The non-inverting amplifier circuit 336 generates an amplified PWM signal Sp3 based on the input of the analog signal Sa3, and outputs the amplified PWM signal Sp3 to the switch unit 339. The non-inverting amplifier circuit 336 includes an operational amplifier 337 and resistors R9 and R10. Since the non-inverting amplifier circuit 336 is known, a detailed description thereof is omitted.
The switch unit 339 is composed of a switching element using, for example, an FET. The switch unit 339 switches to an on state or an off state according to the amplified PWM signal Sp3. Accordingly, the switch unit 339 outputs the voltage Vg from the power supply IC 316 to the light source 11b side when in the on state, and stops outputting the voltage Vg to the light source 11b side when in the off state. Thereby, a rectangular wave is generated. One end of the smoothing capacitor 338 is connected to the connection line Lb connecting the non-inverting amplifier circuit 336 and the light source 11b, and the other end is connected to the ground. The smoothing capacitor 338 generates the voltage Vg by smoothing the rectangular wave, and applies the voltage Vg to the light source 11b.
The resistor R11 is provided to protect the switch unit 339, for example.

(Light control processing)
Next, the dimming process executed by the first controller 100 (the dimming processor 101) will be described along the flowchart of FIG.
First, the first control unit 100 acquires an external light intensity signal SL through the external light intensity sensor 7 (step S101). The external light intensity signal SL has a value corresponding to the required luminance, that is, the required luminance increases as the external light intensity signal SL increases. The first control unit 100 determines whether or not the required luminance corresponding to the external light intensity signal SL is equal to or greater than the first threshold Th1 (step S102). When the first control unit 100 determines that the required luminance is equal to or higher than the first threshold Th1 (step S102: YES), the first control unit 100 shifts to the high luminance mode (step S103). After shifting to the high luminance mode, the first control unit 100 sets the voltages Vr, Vg, and Vb applied to the light sources 11r, 11g, and 11b to the constant voltage Vn (step S104). As described above, the constant voltage Vn is maintained by fixing the on-duty ratio of the PWM signals Sp1 to Sp3. Thereby, in the high luminance mode, a constant voltage Vn is always applied to each of the light sources 11r, 11g, and 11b. Then, the first control unit 100 sets the display period ratio according to the requested luminance by referring to the display period ratio data table of FIG. 13B, and refers to the limit data table of FIG. Thus, the on-duty ratio of the limit signal SC is set (step S105), and the current Ig supplied to the light source 11g is set according to the required luminance by referring to the current data table of FIG. 13C (step S106). ).
Note that the order of the processing in steps S104 to S106 may be changed as appropriate, or may be performed simultaneously.

  Next, the first controller 100 sets the currents Ir and Ib so as to realize a desired light intensity ratio stored in advance in the memory 100a with reference to the set current Ig (step S107). The desired light intensity ratio is, for example, a light intensity ratio that maintains white balance. Then, the first controller 100 supplies the set currents Ir, Ig, and Ib to the corresponding light sources 11r, 11g, and 11b (step S108). The process in step S108 is performed, for example, in the non-display period Fb shown in FIG.

Next, the first controller 100 recognizes the actual light intensity ratio via the light intensity detector 500 (step S109). Then, the first control unit 100 determines whether or not the actual light intensity ratio matches the desired light intensity ratio (step S110).
If the actual light intensity ratio does not match the desired light intensity ratio (step S110: NO), the first control unit 100 returns to the processing of step S107 so as to realize the desired light intensity ratio. The currents Ir and Ib are set again. Thereafter, the processes in steps S107 to S110 are repeated until the actual light intensity ratio matches the desired light intensity ratio.

  When the actual light intensity ratio matches the desired light intensity ratio (step S110: YES), the first control unit 100 ends the dimming process. As a result, in the high luminance mode, the set currents Ir, Ig, and Ib are supplied to the light sources 11r, 11g, and 11b, thereby realizing HUD luminance corresponding to the required luminance as shown in FIG. However, desired chromaticity can be realized.

  On the other hand, when determining that the requested luminance is less than the first threshold Th1 (step S102: NO), the first controller 100 shifts to the low luminance mode (step S111). The first control unit 100 sets the currents Ir, Ig, and Ib to the constant current In after shifting to the low luminance mode (step S112). This constant current In is set to a value that is not buried in noise. Then, the first control unit 100 sets the display period ratio according to the requested luminance by referring to the display period ratio data table of FIG. 13B, and refers to the limit data table of FIG. Thus, the on-duty ratio of the limit signal SC is set (step S113), and the voltage Vg corresponding to the required luminance is set by referring to the voltage data table of FIG. 13E (step S114). As shown in the voltage data table of FIG. 13E, in the region where the required luminance is less than the first threshold Th1, the voltage Vg is set to be linearly smaller as the required luminance is smaller.

  The first controller 100 sets the voltages Vr and Vb so as to realize the desired light intensity ratio described above with reference to the set voltage Vg (step S115). Then, the first control unit 100 performs a luminance adjustment time setting process for setting the luminance adjustment time Tc for reaching the requested luminance from the current luminance for each of the light sources 11r, 11g, and 11b (step S116).

The procedure of the brightness adjustment time setting process executed by the first control unit 100 (expected time determination unit 102) will be described with reference to FIG.
First, the first control unit 100 determines whether or not the required luminance is lower than the current luminance, that is, whether or not the light emission luminance of each of the light sources 11r, 11g, and 11b is decreased (step S201). When it is determined that the required brightness is lower than the current brightness, that is, the light emission brightness of each of the light sources 11r, 11g, and 11b is decreased (step S201: YES), the light sources 11r, 11g, The current luminance is recognized every 11b, and the luminances D1 to D5 closest to the recognized current luminance are determined (step S202). For example, as shown in FIG. 14, the luminances D1 to D5 have a magnitude relationship of “luminance D1 <luminance D2 <luminance D3 <luminance D4 <luminance D5” in a low luminance region less than the first threshold Th1. Next, the first controller 100 determines the luminances D1 to D5 that are closest to the required luminance for each of the light sources 11r, 11g, and 11b (step S203).

  Then, the first control unit 100 refers to the expected time data table stored in the memory 100a, for each of the light sources 11r, 11g, and 11b, the current luminance (luminance D1 to D2) and the required luminance (luminance D1 to D1). The expected time corresponding to D4) is read (step S204). This expected time is a time expected to reach the required brightness from the current brightness, and is set in advance by simulation, experiment, or the like. Then, the longest time among the three predicted times corresponding to the light sources 11r, 11g, and 11b is set as the brightness adjustment time Tc (step S205), the brightness adjustment time setting process is terminated, and the dimming process in FIG. The process proceeds to step S117.

  On the other hand, when the first control unit 100 determines that the required luminance is not lower than the current luminance, that is, the light emission luminance of each of the light sources 11r, 11g, and 11b increases (NO in step S201), the luminance adjustment time Tc. Is not set (step S206), the brightness adjustment time setting process is terminated, and the process proceeds to the process of step S117 of FIG. 11 in the dimming process.

  In the predicted time data table, as shown in FIG. 15, predicted times T5-4, T5-3, T5-2, corresponding to all combinations of the luminances D1 to D5 when the required luminance decreases from the current luminance. T5-1, T4-3, T4-2, T4-1, T3-2, T3-1, and T2-1 are stored. Note that the difference in the length of the expected time is caused by the difference in the charge discharge time of the smoothing capacitors 318, 328, and 338 as described in the above-mentioned “Problem to be Solved by the Invention”.

As shown in FIG. 16A, the expected time is the expected time T5-1 from the brightness D5 to the brightness D1, the expected time T4-1 from the brightness D4 to the brightness D1, and the expected time T3 from the brightness D3 to the brightness D1. -1 and the expected time T2-1 from the luminance D2 to the luminance D1 are set longer in this order. That is, the long / short relationship of “T5-1 <T4-1 <T3-1 <T2-1” is established.
Further, as shown in FIG. 16B, the expected time is the expected time T5-1 from the brightness D5 to the brightness D1, the expected time T5-2 from the brightness D5 to the brightness D2, and the expected time from the brightness D5 to the brightness D3. The time becomes shorter in the order of time T5-3 and expected time T5-4 from luminance D5 to luminance D4. That is, the long / short relationship of “T5-1>T5-2>T5-3> T5-4” is established.

  For example, assume that the current luminance of the light source 11r is closest to the luminance D5 and the required luminance is closest to the luminance D1. Then, it is assumed that the current luminance of the light sources 11g and 11b is closest to the luminance D3 and the required luminance is closest to the luminance D1. In this case, in step S204 of the luminance adjustment time setting process, the first control unit 100 refers to the expected time data table, and the current luminance in the light source 11r is the luminance D5 and the required luminance is the luminance D1. Of the light source 11g, 11b and the expected time T3-1 when the current luminance is the luminance D1 and the required luminance is the luminance D1, which is the longer time. Determine whether. Since there is a relationship of “T5-1 <T3-1” as described above, the first control unit 100 sets the longer expected time T3-1 as the luminance adjustment time Tc.

  Then, referring back to FIG. 11, the first control unit 100 takes the set luminance adjustment time Tc and applies the voltages applied to the light sources 11r, 11g, and 11b to the current voltages Vr and Vg corresponding to the current luminance. , Vb are linearly changed to the voltages Vr, Vg, Vb set in steps S114 and S115 corresponding to the required luminance (step S117). Thereby, the light emission luminances of the light sources 11r, 11g, and 11b change from the current luminance to the required luminance, respectively. The process in step S117 is performed, for example, in the non-display period Fb shown in FIG.

  Next, the first controller 100 recognizes the actual light intensity ratio via the light intensity detector 500 (step S118). Then, the first control unit 100 determines whether or not the actual light intensity ratio matches the desired light intensity ratio (step S119).

  If the actual light intensity ratio does not match the desired light intensity ratio (step S119: NO), the first control unit 100 returns to the process of step S115 so as to realize the desired light intensity ratio. The voltages Vr and Vb are set again. Thereafter, the processes in steps S115 to S119 are repeated until the actual light intensity ratio matches the desired light intensity ratio.

  When the actual light intensity ratio matches the desired light intensity ratio (step S119: YES), the first control unit 100 ends the dimming process. By the light control processing, as shown in FIG. 13A, desired chromaticity can be realized while realizing HUD luminance corresponding to the required luminance.

  The processes in steps S112 to S119 correspond to a voltage adjustment process, and the processes in steps S104 to S110 correspond to a current-modulable light process.

  According to the above, as shown in FIGS. 13A to 13E, the voltage Vg is changed while the display period ratio, the current Ig, and the on-duty ratio of the limiting signal SC are kept constant in the low luminance mode. As a result, HUD luminance corresponding to the required luminance is realized. Also, when in the high luminance range of the high luminance mode, the HUD luminance corresponding to the required luminance is realized by changing the display period ratio and the current Ig while keeping the on-duty ratio and voltage Vg of the limiting signal SC constant. Is done. Also, when in the low luminance range of the high luminance mode, the HUD luminance corresponding to the required luminance is realized by changing the on-duty ratio and current Ig of the limit signal SC while keeping the display period ratio and the voltage Vg constant. Is done.

Next, a comparative example when the brightness adjustment time setting process shown in FIG. 12 is not performed will be described. In this comparative example, the luminance adjustment time in the light control processing can be different for each of the light sources 11r, 11g, and 11b due to the properties of the smoothing capacitors 318, 328, and 338.
For example, as shown in FIG. 17, in the dimming process, the emission luminance of the light source 11r decreases linearly from the current luminance D5 to the required luminance D1 over the expected time T5-1, and the emission luminances of the light sources 11g and 11b are reduced. It is assumed that the current luminance D3 decreases linearly from the required luminance D1 over the expected time T3-1. In this case, the difference in slope between the brightness change slope A of the light source 11r and the brightness change slope E of the light sources 11g and 11b is large, and desired chromaticity (for example, white) in the process of reducing the HUD brightness in the dimming process. The chromaticity may change.

  In this regard, in the present embodiment, the first control unit 100 compares the lengths of the predicted time T5-1 and the predicted time T3-1 in step S205, and adjusts the brightness of the longer predicted time T3-1. Set to time Tc. In step 117, the luminance is linearly changed from the current luminance to the required luminance over the luminance adjustment time Tc set for the emission luminance of all the light sources 11r, 11g, and 11b. As a result, as indicated by the two-dot chain line in FIG. 17, the emission luminance of the light source 11r also decreases from the current luminance D5 to the required luminance D1 over time T3-1. Accordingly, the gradient A ′ of the luminance change of the light source 11r can be brought close to the gradient E of the luminance change of the light sources 11g and 11b to reduce the difference in gradient, and in the process of reducing the HUD luminance, the color from the desired chromaticity can be reduced. The degree is suppressed from changing.

(effect)
As mentioned above, according to 1st Embodiment demonstrated, there exist the following effects.

(1) The light source driving device 5 emits green light G (first light) from the light source 11g (first light source) and red light R (second light) from the light source 11r (second light source). To fire. The light source driving device 5 includes a first voltage adjusting unit 310 and a second voltage adjusting unit 320 that adjust a voltage Vg (first voltage) applied to the light source 11g and a voltage Vr (second voltage) applied to the light source 11r, The light source 11g and the light source are adjusted so that the light intensity ratio between the green light G and the red light R becomes a desired light intensity ratio by adjusting the voltage Vg and the voltage Vr through the first voltage adjusting unit 310 and the second voltage adjusting unit 320. A dimming processing unit 101 that performs voltage-modulable light processing for adjusting the light emission luminance of each of 11r from the current luminance to the required luminance, and an expected time that is required to adjust the luminance from the current luminance to the required luminance An expected time determination unit 102 for determining When the dimming processing unit 101 performs the voltage-modulable light processing, the dimming processing unit 101 selects and selects the longest expected time of the predicted time for the light source 11g and the predicted time for the light source 11r determined by the predicted time determination unit 102. The light emission luminance of each of the light source 11g and the light source 11r is adjusted from the current luminance to the required luminance over a luminance adjustment time Tc that is longer than the expected time.
According to this configuration, as described above with reference to FIG. 17, it is possible to reduce the difference in the slope of the luminance change for each of the light sources 11r, 11g, and 11b, so that it is desirable when changing the display luminance (HUD luminance). The change in chromaticity from the chromaticity of is suppressed.

(2) The light source driving device 5 includes a memory 100a that stores an expected time data table related to an expected time corresponding to the current brightness and the required brightness, and the expected time determination unit 102 includes an expected time data table stored in the memory 100a. The expected time is determined by referring to.
According to this configuration, the estimated time can be easily determined.

(3) The light source driving device 5 adjusts the current Ig (first current) supplied to the light source 11g and the current Ir (second current) supplied to the light source 11r. The dimming processing unit 101 performs voltage-modulable light processing when the required luminance is less than the first threshold Th1, and adjusts the current Ig and the current Ir when the required luminance is equal to or higher than the first threshold Th1. Thus, the current-modulable light processing for adjusting the light emission luminance of each of the light source 11g and the light source 11r from the current luminance to the required luminance so that the light intensity ratio of the green light G and the red light R becomes a desired light intensity ratio. Do.
According to this configuration, since the voltage-modulable light processing is performed at low luminance, the color from the desired chromaticity can be changed when changing the display luminance even at low luminance where the viewer can easily perceive a change in chromaticity. The degree is suppressed from changing.

(4) The light source driving device 5 includes smoothing capacitors 318 and 328 that smooth the voltage Vg and the voltage Vr adjusted by the first voltage adjustment unit 310 and the second voltage adjustment unit 320, respectively.
According to this configuration, even when the luminance adjustment time Tc required for adjusting the emission luminance from the current luminance to the required luminance is different for each of the light sources 11r, 11g, and 11b by the smoothing capacitors 318 and 328, the display is performed. When the luminance is changed, the change in chromaticity from the desired chromaticity is suppressed.

(5) The predicted time determination unit 102 increases the predicted time as the current brightness decreases.
According to this configuration, the luminance adjustment time Tc that matches the properties of the smoothing capacitors 318 and 328 is set.

(6) When performing the voltage-modulable light processing, the dimming processing unit 101 linearly decreases the light emission luminances of the light source 11g and the light source 11r from the current luminance to the required luminance over a luminance adjustment time Tc that is longer than the expected time. Let
According to this configuration, when the display luminance (HUD luminance) is changed, the chromaticity is prevented from changing from the desired chromaticity.

(7) The HUD device 1 is synthesized by the light combining unit 13, the light combining unit 13 that combines the light R, G, and B from the light sources 11 r, 11 g, and 11 b driven by the light source driving unit 5. The display element 30 that generates an image on the screen 50 based on the combined light C, and the optical that displays the virtual image V by projecting the display light L representing the image from the display element 30 toward the windshield 3 that is a projection member. The system includes a plane mirror 61 and a concave mirror 62.
According to this configuration, the chromaticity is prevented from changing from the desired chromaticity when the HUD luminance is changed. Therefore, the visibility of the virtual image V can be improved.

(Second Embodiment)
A second embodiment of the light source driving device and the HUD device according to the present invention will be described.
In the present embodiment, the predicted time data table includes only predicted times T5-1, T4-1, T3-1, and T2-1 from the brightness D2 to D5 as the current brightness to the minimum brightness D1 as the requested brightness. It is remembered. That is, the expected time data table does not store the expected times T5-4, T5-3, T5-2, T4-3,.

Next, the brightness adjustment time setting process in the present embodiment will be described.
When the first control unit 100 determines that the required luminance is closest to the minimum luminance D1 (step S203), the first control unit 100 refers to the predicted time data table and predicts the expected times T5-1 and T4 as in the first embodiment. Any one of -1, T3-1, and T2-1 is read (step S204).

On the other hand, when the first control unit 100 determines that the requested luminance is closest to the luminances D2 to D5 other than the lowest luminance D1 (step S203), the predicted times T5-1 and T4-1 read from the predicted time data table. , T3-1, T2-1, the expected time is calculated.
Specifically, when the current brightness is the brightness D5, the expected time is calculated by subtracting the correction value from the expected time T5-1. When the current brightness is the brightness D4, the correction value is calculated from the expected time T4-1. The predicted time is calculated by subtracting, and when the current luminance is the luminance D3, the predicted time is calculated by subtracting the correction value from the predicted time T3-1. When the current luminance is the luminance D2, the predicted time T2 is calculated. The expected time is calculated by subtracting the correction value from -1. The larger the difference between the required luminance and the minimum luminance D1, the larger the correction value is set. That is, the correction value when the required luminance is close to the luminance D4 is larger than the correction value when the required luminance is close to the luminance D3. Henceforth, it is the same as that of 1st Embodiment.

(effect)
As mentioned above, according to 2nd Embodiment demonstrated, there exist the following effects.

(1) When the predicted time corresponding to the required luminance is not stored in the predicted time data table, the first control unit 100 reads the predicted times T5-1, T4-1, T3-1 read from the predicted time data table. , T2-1, an expected time corresponding to the required luminance is calculated.
According to this configuration, it is possible to reduce the amount of data related to the expected time data table.

(Third embodiment)
A third embodiment of the light source driving device and the HUD device according to the present invention will be described with reference to FIG. The present embodiment is different from the second embodiment in that a learning process for storing the predicted time in the predicted time data table is performed.

The learning process will be described with reference to FIG. This learning process is performed by the first control unit 100 in parallel with the dimming process.
The first control unit 100 starts adjusting the light emission luminance of the light sources 11r, 11g, and 11b from the current luminance (step S301). The process of step S301 is realized by the process of step S117 of the light control process described above. Simultaneously with the start of the brightness adjustment, time measurement is started through the timer 100b (step S302). Then, the first control unit 100 waits for the current luminance of each of the light sources 11r, 11g, and 11b to reach the required luminance based on the detection result of the light intensity detection unit 500 (step S303: NO). When it is determined that the luminance has reached the required luminance (step S303: YES), the time measurement is ended through the timer 100b (step S304). Then, the first control unit 100 stores the measured time in the predicted time data table as the predicted time (step S305), and ends the learning process.

  For example, as in the second embodiment, it is assumed that the predicted time when the current luminance is the luminance D5 and the required luminance is the luminance D3 is not stored in the predicted time data table. In this case, when the luminance of any of the light sources 11r, 11g, and 11b is reduced from the current luminance D5 to the required luminance D3 by the learning process, the time measured at that time is estimated time data as the expected time. Stored in a table.

(effect)
As mentioned above, according to 3rd Embodiment demonstrated, there exist the following effects.

(1) The first control unit 100 measures the time required to adjust the light emission luminance of the light sources 11r, 11g, and 11b from the current luminance to the required luminance, and stores the measured time in the memory 100a as an expected time. .
According to this configuration, the expected time required to reach the required brightness from the current brightness is stored in the memory 100a by actual measurement. Therefore, it is possible to store the predicted time with higher accuracy according to the individual difference of the HUD device 1.

(Modification)
In addition, each said embodiment can be implemented with the following forms which changed this suitably.

  In each of the above embodiments, when the first control unit 100 determines that the luminance increases from the current luminance to the required luminance (step S201: NO), the luminance adjustment time Tc has not been set. The luminance adjustment time Tc may also be set when the luminance increases from the luminance to the required luminance. In this case, the expected time data table also stores the expected time corresponding to the combination of the luminances D1 to D5 when the required luminance increases from the current luminance. For example, the expected time when the current luminance is the luminance D1 and the required luminance is the luminance D5 is also stored.

  In each of the above embodiments, the first control unit 100 sets the longest time among the three predicted times corresponding to the light sources 11r, 11g, and 11b as the luminance adjustment time Tc (step S205). The luminance adjustment time Tc may be set longer than the longest time among the two expected times.

  In each of the above embodiments, the required luminance is determined according to the external light intensity signal SL. However, the present invention is not limited to this. For example, the operation signal for turning on or off the headlight of the vehicle 2 and the type of display image You may decide according to.

  In each of the above embodiments, the processes according to steps S108 and S117 are performed in the non-display period Fb, but may be performed in a period in which the display element 30 in the display period Fa is off.

  In the above embodiments, the second and third voltage adjustment units 320 and 330 generate the voltages Vr and Vb based on the voltage Vg from the power supply IC 316 of the first voltage adjustment unit 310. Each of the three voltage adjustment units 320 and 330 may include a power supply IC.

  In each said embodiment, although the 1st-3rd voltage adjustment part 310-330 was provided for every light source 11r, 11g, 11b, it is not restricted to this, Any two of light sources 11r, 11g, 11b are provided. A shared voltage adjustment unit may be provided. For example, one voltage adjusting unit may be provided in the light sources 11g and 11b, and this voltage adjusting unit may apply the same voltage to the light sources 11g and 11b.

  In each of the above embodiments, the voltages Vr and Vb are set so as to realize a desired light intensity ratio with the voltage Vg as a reference, but the reference voltage is either the voltage Vr or Vb. Also good.

  Further, the limit signal SC that determines the ON period Ton in each subframe Fs of the light sources 11r, 11g, and 11b is used as the enable signal EN (R-EN, G-EN, B- EN) may be substituted.

  In each of the above embodiments, when the required luminance is less than the first threshold Th1, the first control unit 100 linearly decreases the voltage Vg as the required luminance decreases, but the required luminance decreases. Accordingly, the voltage Vg may be lowered stepwise.

In each of the embodiments described above, the first control unit 100 holds the current Ig constant when the required luminance is less than the first threshold Th1, but the current Ig may also be changed according to the required luminance. .
In each of the above embodiments, the first control unit 100 holds the voltage Vg at the constant voltage Vn through the first voltage adjustment unit 310 when the required luminance is equal to or higher than the first threshold Th1. The voltage Vg may be changed according to the required luminance.

  In each said embodiment, the 1st control part 100 performed the voltage adjustment light control process which concerns on the said steps S111-S119 only at the time of low luminance mode. However, the first control unit 100 may perform this voltage adjustment dimming process regardless of the required luminance.

  In each of the above-described embodiments, the second control unit 200 may execute a part of the control content of the first control unit 100, or conversely, a part of the control content of the second control unit 200. The first control unit 100 may execute. The first and second control units 100 and 200 may be configured as one control unit.

In each of the embodiments described above, the light sources 11r, 11g, and 11b are configured as independent light sources, but may emit a plurality of colors of light from a common light source. Further, the light source may be any light source that emits light of a plurality of colors, may be composed of only two colors, and may be composed of four or more colors (including white).
In addition, when a plurality of colors of light are emitted from one light source, the light combining unit 13 that aligns the optical axes of the light sources 11r, 11g, and 11b may be omitted.

  In the above embodiment, the light intensity detection unit 500 is installed in a part of the optical path of the combined light C. However, it is sufficient that the light intensity of each of the light R, G, and B can be detected. It may be provided at a location where the light intensity of each of the lights R, G, B before being detected can be detected. In addition, the light intensity detection unit 500 may be appropriately provided at a location where a part of the combined light C emitted from the illumination optical system 20 can be detected.

  Although the HUD device 1 in the above embodiment is for in-vehicle use, the HUD device 1 is not limited to in-vehicle use, but may be a HUD device 1 mounted on a vehicle such as an airplane or a ship. Moreover, although the display light L from the HUD device 1 is projected onto the windshield 3 as a projection member, it may be projected onto a dedicated combiner. The light source driving device 5 may be applied to various display devices other than the HUD device 1, such as a projector.

  In each of the above embodiments, the desired light intensity ratio is set in advance according to the required luminance. However, the present invention is not limited to this. For example, the calculation formula is stored in the memory 100a in advance, and the first control unit 100 Using this calculation formula, a desired light intensity ratio may be calculated based on the required luminance.

  In each of the above embodiments, the light source driving device 5 drives the light sources 11r, 11g, and 11b by the field sequential method. However, the present invention is not limited to this. For example, juxtaposed additive color mixture, simultaneous additive color mixture, continuous additive color mixture, or the like The light sources 11r, 11g, and 11b may be driven by other methods.

1 HUD device 2 Vehicle 3 Windshield 5 Light source drive device 6 Vehicle ECU
7 External light intensity sensor 10 Illumination device 11 Light source unit 11b, 11g, 11r Light source 12 Circuit board 13 Photosynthesis unit 13a Reflection mirror 13b, 13c Dichroic mirror 14 Brightness unevenness reduction unit 15 Transmission film 20 Illumination optical system 30 Display element 30a Micro mirror 40 Projection optical system 50 Screen 61 Plane mirror 62 Concave mirror 70 Housing 70a Opening 71 Translucent unit 100 First control unit 100a Memory 100b Timer 101 Dimming processing unit 102 Expected time determination unit 200 Second control unit 300 Power supply control unit 310 -330 1st-3rd voltage adjustment part 316 Power supply IC
320 Second voltage adjustment unit 400 Light source drive unit 410 Comparison circuit 420 Logic circuit 430 Light source drive circuit 500 Light intensity detection unit 700 Battery

Claims (9)

A light source driving device that emits first light from a first light source and emits second light from a second light source,
A voltage adjusting unit that adjusts a first voltage applied to the first light source and a second voltage applied to the second light source;
By adjusting the first voltage and the second voltage through the voltage adjustment unit, the first light and the second light may have a desired light intensity ratio, so that the first light intensity ratio and the second light intensity ratio become the desired light intensity ratio. A dimming processing unit for performing voltage-modulable light processing for adjusting the light emission luminance of each of the light source and the second light source from the current luminance to the required luminance;
An expected time determination unit that determines an expected time that is expected to be required to adjust the light emission luminance from the current luminance to the required luminance;
The dimming processing unit, when performing the voltage-modulable light processing, out of the predicted time for the first light source and the predicted time for the second light source determined by the predicted time determination unit Selecting the long expected time, and adjusting the emission luminance of each of the first light source and the second light source from the current luminance to the required luminance over a luminance adjustment time equal to or greater than the selected expected time;
Light source drive device. A memory for storing data relating to the expected time corresponding to the current luminance and the required luminance;
The expected time determination unit determines the expected time by referring to the data stored in the memory;
The light source driving device according to claim 1. The dimming processing unit measures a time required to adjust the light emission luminance of the first light source or the second light source from the current luminance to the required luminance, and the measured time is the estimated time. As stored in the memory as
The light source driving device according to claim 2. The memory stores the expected time when the required brightness is a preset minimum brightness,
The expected time determination unit, when the required brightness is greater than the minimum brightness, determines the expected time according to the required brightness based on the expected time when the required brightness is the minimum brightness stored in the memory. Calculate,
The light source driving device according to claim 2. A current adjusting unit for adjusting a first current supplied to the first light source and a second current supplied to the second light source;
The light control processing unit
If the required brightness is less than a threshold, perform the voltage-modulable light processing,
When the required brightness is equal to or higher than the threshold, the light intensity ratio between the first light and the second light is set to a desired value by adjusting the first current and the second current through the current adjustment unit. Performing current-modulable light processing for adjusting the emission luminance of each of the first light source and the second light source from the current luminance to the required luminance so as to obtain a light intensity ratio;
The light source driving device according to any one of claims 1 to 4. A capacitor for smoothing the first voltage or the second voltage adjusted by the voltage adjustment unit;
The light source driving device according to claim 1. The predicted time determination unit increases the predicted time as the current brightness decreases.
The light source driving device according to claim 1. The dimming processing unit linearly changes the emission luminance of each of the first light source and the second light source from the current luminance to the required luminance.
The light source driving device according to claim 1. The light source driving device according to any one of claims 1 to 8,
A light combining unit that combines the first light and the second light from the first light source and the second light source driven by the light source driving device;
A display element that generates an image on a screen based on the combined light combined by the light combining unit;
An optical system that displays a virtual image by projecting display light representing the image from the display element toward a projection member,
Head-up display device.

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