JPWO2018101121A1 - Light source driving device and head-up display device - Google Patents

Abstract

Provided are a light source driving device and a head-up display device that can further ensure the stability of light. The light source driving device (5) drives the light source (11g) that emits green light (G) and the light source (11r) that emits red light (R). The light source driving device (5) has a first voltage adjustment unit (310) for adjusting a voltage (Vg) applied to the light source (11g) based on a power supply voltage from the battery (700), and the voltage (Vg) as a power source. A second voltage adjustment unit (320) that generates a voltage (Vr) to be applied to the light source (11r), and a first control unit (100) that performs voltage-modulable light processing. In the voltage-modulable light processing, the voltage (Vg) and the voltage (Vr) are set so that the light intensity ratio between the green light (G) and the red light (R) becomes a desired light intensity ratio, and the first voltage adjustment unit (310) and the second voltage adjustment unit (320), the set voltage (Vg) and voltage (Vr) are applied to the light source (11g) and the light source (11r), respectively.

Description

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

  Conventionally, as a display device, for example, a configuration in which a DMD (Digital Micro-mirror Device) as a display element is provided is known. For example, the display device described in Patent Document 1 generates image light by reflecting illumination light with a plurality of micromirrors included in the DMD. The display device includes a light source driving device including a control unit that drives a light source. The control unit selectively emits one of three light sources that emit red, green, and blue light, and emits light. It operates by a so-called field sequential method in which illumination light of a desired color is generated by switching the light source for each subframe at high speed.

  For example, when supplying current to the light source, this control unit changes PWM (Pulse Width Modulation) control that changes the on-duty ratio indicating the current supply period in the subframe, and PAM (Pulse Amplitude Modulation) changes the current value. And control at the same time. Specifically, the control unit performs PWM control so as to reduce the on-duty ratio stepwise as the required luminance of the light source, that is, the required luminance decreases, and when the on-duty ratio is at a predetermined value. PAM control is performed to reduce the current value supplied to the light source as the required brightness decreases. Thereby, the display brightness according to the required brightness is realized.

JP 2014-066920 A

  In the display device described in Patent Document 1, the control unit realizes display luminance corresponding to the required luminance by controlling the current value when performing the PAM control. However, in a situation where stable control of the current value is difficult, it is difficult to ensure the stability of light. As an example, when the required luminance is low, the current value supplied to the light source is also reduced according to the required luminance. For this reason, the current value is easily affected by noise, so that it is difficult to ensure the stability of light, and it is difficult to realize desired luminance and chromaticity.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light source driving device and a head-up display device that can further ensure the stability of light.

  In order to achieve the above object, a light source driving apparatus according to a first aspect of the present invention includes a first light source that emits first light and a second light that emits second light having a color different from that of the first light. A light source driving device for driving the light source, a first voltage adjusting unit that adjusts a first voltage applied to the first light source based on a power source voltage from a power source, and the power source voltage or the first voltage. And a second voltage adjusting unit that generates a second voltage to be applied to the second light source, and a light intensity ratio between the first light and the second light is a desired light intensity ratio. The first voltage and the second voltage are set to the first light source and the second voltage through the first voltage adjustment unit and the second voltage adjustment unit, respectively. A control unit that performs voltage-modulable light processing applied to the second light source.

  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 and a light combining unit that combines the light from the light sources 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, and an optical system that displays a virtual image by projecting display light representing the image from the display element toward a projection member; .

  According to the present invention, it is possible to further ensure the stability of light.

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. (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 voltage data table corresponding to each light source which concerns on the 2nd Embodiment of this invention. (A) which concerns on the 2nd Embodiment of this invention is a figure which shows the waveform of the electric current supplied to a light source when a request | requirement brightness | luminance exists in a 1st threshold value, (b) is a request | requirement brightness | luminance in a 2nd threshold value It is a figure which shows the waveform of the electric current supplied to the light source at the time, (c) is a figure which shows the waveform of the electric current supplied to the light source when the request | requirement brightness | luminance is less than a 2nd threshold value. It is a circuit diagram which shows the specific electric constitution of the power supply control unit which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of the light control process which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of the delay time setting process which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of the voltage fluctuation process which concerns on the 3rd Embodiment of this invention. It is a figure which shows the delay time data table which concerns on the 3rd Embodiment of this invention. (A) is a graph which shows the voltage fluctuation of the light source with progress of time which concerns on a comparative example, (b) is a graph which shows the voltage fluctuation of the light source with progress of time concerning the 3rd Embodiment of this invention. is there. It is a graph which shows the voltage fluctuation of the light source with progress of time which concerns on the modification of this invention.

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

  As shown in FIG. 1, the HUD device 1 is installed on a dashboard of a vehicle 2, generates display light L representing an image M (see FIG. 2), and the generated display light L is a window that is an example of a projection member. The light is emitted toward the shield 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 the light source driving device 5 as described later, and emits light at a predetermined light intensity 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 light source 11b corresponds to the third light source, and the blue light B corresponds to the third light.

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

The light combining unit 13 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 reflection mirror 13a and dichroic mirrors 13b and 13c that reflect light of a specific wavelength and transmit light of other wavelengths other than the specific wavelength. ing. 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.

  As shown in FIG. 2, the illumination optical system 20 includes a concave lens or the like, and adjusts the combined light C emitted from the illumination device 10 to a size corresponding to the display element 30.

  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 an attitude tilted, for example, by -12 degrees with the hinge as a fulcrum, and at this time, 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 rear surface (the lower surface in FIG. 2) and receives the front surface (the lower surface in FIG. 2). 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. Each configuration of the light source driving device 5 is mounted on, for example, a printed circuit board (not shown) other than the circuit board 12 disposed in the housing 70. A part or all of the configuration of the light source driving device 5 may be mounted on the circuit board 12. The first and second control units 100 and 200 are examples of control units.

  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. 12B, 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 is a ROM (Read
A memory 100a such as a Only Memory), a timer 100b that measures time, and a processing unit 100c such as a CPU (Central Processing Unit) that executes a dimming process described later by executing a stored operation program. Prepare. 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 adjusts the light sources 11r and 11g according to the display control data for displaying the image M requested by the video signal on the display element 30 and the driving of the display element 30 based on the display control data. , 11b to the second control unit 200 is output.
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. 12B, and current data indicating the current Ig supplied to the light source 11g with respect to the required luminance shown in FIG. 12 shows 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. 12D, and a voltage Vg applied to the light source 11g for the required luminance shown in FIG. A voltage data table.

The first control unit 100 adjusts the light emission intensity of the light sources 11r, 11g, and 11b via the light source driving unit 400, and thus the HUD luminance (display luminance), according to the external light intensity signal SL.
The first control unit 100 recognizes the required brightness based on the external light intensity signal SL, and displays the display element at a display period ratio corresponding to the required brightness 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). Although described in detail later, the values of currents Ir, Ig, and Ib supplied to the light sources 11r, 11g, and 11b are set according to the duty ratio of the reference signal SA.

  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. 8, the first control unit 100 may change the reference signal SA for each subframe Fs having a different emission color.

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, the voltage Vr corresponds to the second voltage, and the voltage Vb corresponds to the third 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. 12B and 12D, 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%. Set to%. Further, when the display period ratio is 50% and the required luminance is equal to or higher than the first threshold 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, n-channel FETs (Field Effect
It consists of switching elements using 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, for 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 on or off.
The first control unit 100 and the light source driving unit 400 include a first current adjusting unit that adjusts the current Ig supplied to the light source 11g, a second current adjusting unit that adjusts the current Ir supplied to the light source 11r, and a light source 11b. A third current adjusting unit that adjusts the supplied current Ib.

  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 an analog signal Sa2 corresponding to 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 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 an analog signal Sa3 having a current value corresponding to 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 a PWM signal Sp3 amplified based on the input 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.

(Control contents of the first control unit 100)
Next, the dimming processing procedure by the first control unit 100 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 required luminance by referring to the display period ratio data table in FIG. 12B, and refers to the limit data table in 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. 12C (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). For example, this light intensity ratio is the first light intensity ratio that is the light intensity ratio of the light source 11g and the light intensity of the light source 11r, and the second light intensity ratio that is the light intensity ratio of the light source 11g and the light source 11b. Consists of. 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 controller 100 supplies the set currents Ir, Ig, Ib to the light sources 11r, 11g, 11b. Thus, as shown in FIG. 12A, desired chromaticity can be achieved while realizing HUD luminance corresponding to the required luminance.

  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 in FIG. 12B, and refers to the limit data table in 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. 12D (step S114). As shown in the voltage data table of FIG. 12D, in the region where the required luminance is less than the first threshold Th1, the voltage Vg is set to decrease linearly as the required luminance decreases.

  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 applies the set voltages Vr, Vg, and Vb to the actually corresponding light sources 11r, 11g, and 11b (step S116). The process in step S116 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 S117). Then, the first control unit 100 determines whether or not the actual light intensity ratio matches the desired light intensity ratio (step S118).

  If the actual light intensity ratio does not match the desired light intensity ratio (step S118: 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 S118 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 S118: YES), the first controller 100 applies the set voltages Vr, Vg, Vb to the light sources 11r, 11g, 11b. Thus, as shown in FIG. 12A, desired chromaticity can be achieved while realizing HUD luminance corresponding to the required luminance. Above, the light control process which concerns on the said flowchart is complete | finished.
Note that the processing in steps S112 to S118 corresponds to voltage adjustment processing, and the processing in steps S104 to S110 corresponds to current-modulable light processing.

  In step S115 after NO in step S118 or in step S107 after NO in step S110, the first control unit 100 selects the first light intensity ratio (light source 11g) from the desired light intensity ratio. The light intensity ratio of the light source 11r and the light intensity ratio of the light source 11r match the actual light intensity ratio, and the second light intensity ratio (the light intensity ratio of the light source 11g and the light intensity of the light source 11b) matches the actual light intensity ratio. If not, only the voltage Vb corresponding to the light source 11b may be adjusted. Similarly, the first control unit 100 determines that the second light intensity ratio in the desired light intensity ratio matches the actual light intensity ratio, and the first light intensity ratio matches the actual light intensity ratio. If not, only the voltage Vr corresponding to the light source 11r may be adjusted.

  According to the above, as shown in FIGS. 12A to 12E, when in the low luminance mode, the voltage Vg is changed while the display period ratio, the current Ig, and the on-duty ratio of the limit signal SC are kept constant. 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.

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

(1) The light source driving device 5 drives the light source 11g that emits green light G and the light source 11r that emits red light R. The light source driving device 5 generates a voltage Vr to be applied to the light source 11r by using the first voltage adjusting unit 310 that adjusts the voltage Vg applied to the light source 11g based on the power supply voltage from the battery 700 and the voltage Vg as a power source. 2 voltage adjustment part 320 and the 1st control part 100 which performs voltage modulation light processing are provided. In the voltage-modulable light processing, the voltage Vg and the voltage Vr are set so that the light intensity ratio between the green light G and the red light R becomes a desired light intensity ratio, and the first voltage adjusting unit 310 and the second voltage adjusting unit 320 are set. In this process, the set voltage Vg and voltage Vr are applied to the light source 11g and the light source 11r, respectively.
According to the above configuration, by performing voltage value control for controlling the voltage Vg and the voltage Vr applied to the light source 11g and the light source 11r, it is possible to maintain a current value that is not buried in noise. As a result, the stability of light can be further ensured, and as a result, desired luminance and chromaticity can be realized.

(2) The first controller 100 adjusts the current Ig supplied to the light source 11g and adjusts the current Ir supplied to the light source 11r. When the required luminance is less than the first threshold Th1, the first control unit 100 responds to the required luminance while the light intensity ratio between the green light G and the red light R becomes a desired light intensity ratio in the voltage-modulable light processing. Set the voltage Vg and the voltage Vr. The first control unit 100 performs current-modulable light processing when the required luminance is equal to or higher than the first threshold Th1. This current-modulable light processing sets the current Ig and the current Ir according to the required luminance while the light intensity ratio of the green light G and the red light R becomes a desired light intensity ratio, and the set current Ig and current Ir are set. It is the process which supplies to the light source 11g and the light source 11r, respectively.
According to this configuration, since the voltage-modulable light processing is performed at low luminance, it is not necessary to reduce the current Ig and the current Ir so as to be buried in noise. Therefore, the stability of light can be further secured, and as a result, desired luminance and chromaticity can be realized.

(3) The light source driving device 5 includes a memory 100a in which a voltage data table indicating the value of the voltage Vg applied to the light source 11g according to the required luminance is stored, the light intensity of the green light G, and the light intensity of the red light R. A light intensity detection unit 500 for detection. In the voltage-modulable light processing, the first control unit 100 sets the voltage Vg corresponding to the required luminance with reference to the stored voltage data table, and green light based on the detection result of the light intensity detection unit 500. The voltage Vr is set on the basis of the set voltage Vg so that the light intensity ratio of G and red light R becomes a desired light intensity ratio.
According to this configuration, another voltage Vr is set based on the voltage Vg. Here, the green light G from the light source 11g has the greatest influence on human vision. Therefore, it becomes easy to realize desired luminance and chromaticity by using the voltage Vg as a reference.

(4) The memory 100a stores a current data table indicating the value of the current Ig supplied to the light source 11g corresponding to the required luminance. In the current-modulable light processing, the first control unit 100 sets the current Ig corresponding to the required luminance with reference to the current data table, and based on the detection result of the light intensity detection unit 500, the green light G and the red light The current Ir is set based on the set current Ig so that the light intensity ratio of the light R becomes a desired light intensity ratio.
According to this configuration, another current Ir is set based on the current Ig. Here, the green light G from the light source 11g has the greatest influence on human vision. Therefore, desired luminance and chromaticity can be easily realized by using the current Ig as a reference.

(5) The first control unit 100 holds the voltage Vg at the constant voltage Vn through the first voltage adjustment unit 310 in the case of current-modulable light processing, that is, when the required luminance is the first threshold Th1 or more, In the modulated light processing, that is, when the required luminance is less than the first threshold Th1, the voltage Vg is gradually decreased through the first voltage adjustment unit 310 as the required luminance decreases.
According to this configuration, the change in the voltage Vg can be kept to the minimum necessary, and light stability can be ensured.

(6) The first control unit 100 holds the current Ig at a constant current In when the voltage-modulable light processing, that is, the required luminance is less than the first threshold Th1, and the current-modulable light processing, that is, the required luminance is In the case of the first threshold Th1 or more, the current Ig corresponding to the required luminance is set. The constant current In is set to a value that is not buried in noise, for example.
According to this configuration, since the current Ig is suppressed to be equal to or less than the constant current In, light stability can be ensured.

(7) The light source driving device 5 drives the light source 11b that emits the blue light B in addition to the light source 11g and the light source 11r. Furthermore, the light source driving device 5 includes a third voltage adjusting unit 330 that generates the voltage Vb applied to the light source 11b using the voltage Vg as a power source, and adjusts the current Ib supplied to the light source 11b. In the voltage-modulable light processing, the first control unit 100 performs the voltage Vg, the voltage Vr, and the voltage Vb so that the light intensity ratio of the green light G, the red light R, and the blue light B becomes a desired light intensity ratio. And the current Ig, the current Ir, and the current Ib are set so that the light intensity ratio of the green light G, the red light R, and the blue light B becomes a desired light intensity ratio.
According to this configuration, the light intensity ratio of the green light G, the red light R, and the blue light B is set to be a desired light intensity ratio in both cases of voltage-modulable light processing and current-modulable light processing. The

(8) The first voltage adjustment unit 310 adjusts the voltage Vg by stepping down the power supply voltage from the battery 700, and the second voltage adjustment unit 320 receives the voltage Vg adjusted through the first voltage adjustment unit 310 and receives the voltage The third voltage adjustment unit 330 receives the voltage Vg adjusted through the first voltage adjustment unit 310 and generates the voltage Vb.
According to this configuration, since the second and third voltage adjustment units 320 and 330 do not need to step down the power supply voltage from the battery 700, the second and third voltage adjustment units 320 and 330 are configured more simply. be able to.

  (9) The desired light intensity ratio is preset according to the required luminance. According to this configuration, the first control unit 100 can quickly specify a desired light intensity ratio.

(Second Embodiment)
A second embodiment in which the light source driving device according to the present invention is embodied in a HUD device will be described with reference to FIGS. This embodiment is mainly different from the first embodiment in that a different current data table and voltage data table are set for each of the light sources 11r, 11g, and 11b. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The memory 100a stores not only the current data table corresponding to the light source 11g shown in FIG. 12C in the first embodiment but also the current data table corresponding to the light source 11r and the current data table corresponding to the light source 11b. Has been. Each current data table is generated by calibration at the time of manufacture in consideration of individual differences of the light sources 11r, 11g, and 11b.

  The memory 100a stores a first voltage data table Tg corresponding to the light source 11g, a second voltage data table Tr corresponding to the light source 11r, and a third voltage data table Tb corresponding to the light source 11b. Yes. As shown in FIG. 13, each voltage data table Tr, Tg, Tb is a region in which the required luminance is equal to or higher than the second threshold Th2 (in other words, a region in which the voltage applied to the light sources 11r, 11g, 11b is Vl to Vn. ) Takes the same voltage value and decreases uniformly as the required luminance decreases. In the region where the required luminance is less than the second threshold Th2, each voltage data table Tr, Tg, Tb changes linearly in this example so that the voltage value decreases as the required luminance decreases. Each voltage data table Tr, Tg, Tb changes with a different slope in a region where the required luminance is less than the second threshold Th2. In this example, the second voltage data table Tr has a larger slope than the third voltage data table Tb, and the third voltage data table Tb has a larger slope than the first voltage data table Tg. This second threshold value Th2 takes a value smaller than the first threshold value Th1, which is a criterion for determining the high luminance mode and the low luminance mode. This second threshold value Th2 is set within the range of voltages Vr, Vg, Vb in which the rising times Tr1, Tr2 shown in FIGS. 14 (a) and 14 (b) are substantially constant, for example, the lower limit value of the range. The rise times Tr1, Tr2, Tr3 are times from when the voltages Vr, Vg, Vb are applied to the light sources 11r, 11g, 11b to the peak current values Ip1, Ip2, Ip3.

For example, the rising time Tr1 when the required luminance shown in FIG. 14A is at the first threshold Th1 is substantially the same as the rising time Tr2 when the required luminance shown in FIG. 14B is at the second threshold Th2. is there. Further, the peak current value Ip1 when the required luminance shown in FIG. 14A is at the first threshold Th1 is larger than the peak current value Ip2 when the required luminance shown in FIG. 14B is at the second threshold Th2. large.
Therefore, in the region above the second threshold Th2, the peak current values Ip1, Ip2, and consequently the luminance of the light sources 11r, 11g, 11b can be adjusted by adjusting the voltages Vr, Vg, Vb.

On the other hand, the rise time Tr3 when the required luminance shown in FIG. 14C is less than the second threshold Th2 is longer than the rise times Tr1 and Tr2. The rise time Tr3 differs for each of the light sources 11r, 11g, and 11b. For example, the rise time Tr3 of the light source 11r is longer than the rise time Tr3 ′ of the light sources 11g and 11b in the waveform shown by the broken line in FIG. . In consideration of this point, the voltage data tables Tr, Tg, Tb described above are set to different voltage values for each voltage data table Tr, Tg, Tb in a region where the required luminance is less than the second threshold Th2. ing.
Therefore, for example, when the light source 11r and the light source 11g emit light with the same luminance, the first control unit 100 refers to the first voltage data table Tg and the second voltage data table Tr, and the voltage Vg of the light source 11g. Is set to a voltage value larger than the voltage Vr of the light source 11r.

In the present embodiment, the first control unit 100 sets the voltages Vr, Vg, and Vb by referring to the voltage data tables Tr, Tg, and Tb in step S114 of FIG. 11 of the first embodiment. In the present embodiment, the process according to step S115 of the first embodiment may be omitted. Furthermore, in the present embodiment, the processing according to steps S115 to S118 of the first embodiment may be omitted.
Similarly, in the present embodiment, the first control unit 100 refers to the voltage data tables Tr, Tg, Tb in step S106 of FIG. 11 of the first embodiment to obtain the currents Ir, Ig, Ib. Set. In the present embodiment, the process according to step S107 of the first embodiment may be omitted. Furthermore, in the present embodiment, the processing according to steps S107 to S110 of the first embodiment may be omitted.

(effect)
As mentioned above, according to 2nd Embodiment demonstrated, there exist the following effects.
(1) The light source driving device 5 includes a first voltage data table Tg indicating the value of the voltage Vg applied to the light source 11g according to the required luminance, and a first value indicating the value of the voltage Vr applied to the light source 11r according to the required luminance. A memory 100a in which a two-voltage data table Tr is stored is provided. The first voltage data table Tg and the second voltage data table Tr take the same value when the required luminance is equal to or higher than the second threshold Th2 set to a value smaller than the first threshold Th1, and the required luminance is the second threshold. When it is less than Th2, the voltage Vg and the voltage Vr that achieve display luminance corresponding to the required luminance are different from each other. The first controller 100 refers to the first voltage data table Tg and the second voltage data table Tr so as to obtain 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. The corresponding voltage Vg and voltage Vr are set.
According to this configuration, a desired light intensity ratio can be maintained even in a low luminance region where the required luminance is less than the second threshold Th2. In addition, when setting the voltage Vg and the voltage Vr, it is only necessary to refer to the first voltage data table Tg and the second voltage data table Tr based on the required luminance, so that dimming can be performed quickly.

(Third embodiment)
A third embodiment in which the light source driving device according to the present invention is embodied in a HUD device will be described with reference to FIGS. The present embodiment is mainly different from the first and second embodiments in that the electric charge charged in the smoothing capacitor is discharged at different timings. Hereinafter, the difference from the first and second embodiments will be mainly described.

As shown in FIG. 15, the first voltage adjustment unit 310 further includes a discharge line L1, a resistor Rg, and a switch unit Swg.
The resistor Rg and the switch unit Swg are provided in series with the discharge line L1. One end of the discharge line L1 is connected to the connection line Lg, and the other end of the discharge line L1 is connected to the ground. The resistor Rg and the switch unit Swg are connected in parallel to the smoothing capacitor 318.
The switch part Swg is made of a switching element using, for example, an FET. The switch unit Swg is switched between an on state and an off state under the control of the first control unit 100. When the switch unit Swg is switched from the off state to the on state, the charge charged in the smoothing capacitor 318 flows to the ground via the discharge line L1.
The resistor Rg is for current limitation and is provided between the switch unit Swg and the connection line Lg.

The second voltage adjustment unit 320 further includes a discharge line L2, a resistor Rr, and a switch unit Swr.
The resistor Rr and the switch unit Swr are provided in series with the discharge line L2. One end of the discharge line L2 is connected to the connection line Lr, and the other end of the discharge line L2 is connected to the ground. The resistor Rr and the switch unit Swr are connected in parallel to the smoothing capacitor 328.
The switch unit Swr is composed of a switching element using an FET, for example. The switch unit Swr switches between an on state and an off state under the control of the first control unit 100. When the switch unit Swr is switched from the off state to the on state, the electric charge charged in the smoothing capacitor 328 flows to the ground via the discharge line L2.
The resistor Rr is for current limitation, and is provided between the switch unit Swr and the connection line Lr.

The third voltage adjustment unit 330 further includes a discharge line L3, a resistor Rb, and a switch unit Swb.
The resistor Rb and the switch unit Swb are provided in series with the discharge line L3. One end of the discharge line L3 is connected to the connection line Lb, and the other end of the discharge line L3 is connected to the ground. The resistor Rb and the switch unit Swb are connected in parallel to the smoothing capacitor 338.
The switch unit Swb is composed of a switching element using an FET, for example. The switch unit Swb is switched between an on state and an off state under the control of the first control unit 100. When the switch unit Swb is switched from the off state to the on state, the charge charged in the smoothing capacitor 338 flows to the ground through the discharge line L3.
The resistor Rb is for current limitation and is provided between the switch unit Swb and the connection line Lb.

The resistors Rr, Rg, and Rb have different resistance values. For example, the resistance values of the resistors Rr, Rg, and Rb are set to have the following magnitude relationship.
Resistance value of resistor Rg> resistance value of resistor Rb> resistance value of resistor Rr The smaller the resistance value of each resistor Rr, Rg, Rb, the smoothing capacitor 318 when the switch units Swr, Swg, Swb are in the ON state, The speed at which the charges charged in 328 and 338 are released increases. As the speed at which charges are released increases, as shown in FIG. 20 (a), when the voltages Vr, Vg, Vb decrease, the decreasing speed of the voltages Vr, Vg, Vb increases, and the voltages Vr, Vg, Vb decrease. The absolute value of the slope increases.
Here, the light source 11r has a lower forward voltage when a specified forward current flows than the other light sources 11g and 11b. For this reason, in order to reduce the current supplied to the light source 11r, it is necessary to apply a voltage Vr lower than the voltages Vg and Vb of the other light sources 11g and 11b. Therefore, when dimming to low luminance (for example, luminance less than the second threshold Th), the required voltage Vr1 of the light source 11r is lower than the required voltages Vg1 and Vb1 of the other light sources 11g and 11b. Therefore, by setting the resistance value of the resistor Rr of the light source 11r to be smaller than the resistance values of the resistors Rg and Rb of the light sources 11g and 11b, the rate of decrease in the voltage Vr of the light source 11r can be increased, and the voltage Vr , Vg, Vb can approach the required voltages Vr1, Vg1, Vb1.

In the memory 100a of the first control unit 100, as shown in FIG. 19, delay time data in which the dimming change amounts Δ1 to Δn and the current luminances D1 to Dn are associated with the delay times Tg1 to Tgn and Tb1 to Tbn. The table is stored. “N” is an arbitrary natural number.
The dimming change amounts Δ1 to Δn are differences between the current luminance and the required luminance, and the numerical range of each dimming change amount Δ1 to Δn can be set as appropriate. The current luminances D1 to Dn are set at predetermined intervals.
As shown in FIG. 20B, the delay times Tb1 to Tbn are times from the time ta at which the voltage Vr of the light source 11r starts to decrease to the time tb at which the voltage Vb of the light source 11b starts to decrease. Is set to match the time td when the voltage Vr reaches the required voltage Vr1 and the time td when the voltage Vb of the light source 11b reaches the required voltage Vb1.
Similarly, the delay times Tg1 to Tgn are the time from the time ta at which the voltage Vr of the light source 11r starts to decrease to the time tc at which the voltage Vg of the light source 11g starts to decrease, and the voltage Vr of the light source 11r is the required voltage Vr1. Is set to match the time td when the voltage Vg of the light source 11g reaches the required voltage Vg1.
Due to the nature of the smoothing capacitors 318, 328, and 338, the delay times Tg1 to Tgn and Tb1 to Tbn become longer as the dimming change amounts Δ1 to Δn increase in a state where the current luminance is fixed. The higher the current luminance D1 to Dn, the longer. The delay times Tg1 to Tgn and Tb1 to Tb1 are set in advance by calculation, simulation, experiment, or the like.

(Control contents of the first control unit 100)
Next, the dimming processing procedure by the first control unit 100 will be described along the flowchart of FIG. In the present embodiment, after step S115 similar to the first embodiment, the delay time setting process according to step S20 and the voltage variation process according to step S30 are continuously performed.

First, the processing procedure of the delay time setting process will be described with reference to FIG.
The first control unit 100 acquires the dimming change amount and the current luminance (step S201). The current luminance is acquired through the detection result of the light intensity detection unit 500. The dimming change amount is derived by calculating the difference between the current luminance and the required luminance. Then, 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 S202). 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 reduced (step S202: YES), the dimming change amount acquired in step S201 and the current brightness Based on the above, the delay times Tg1 to Tgn and Tb1 to Tbn are read with reference to the delay time data table (step S203).
Specifically, as shown in FIG. 19, among the dimming change amounts Δ1 to Δn stored in the delay time data table, the one closest to the dimming change amount acquired in step S201 is selected. Here, for example, when the dimming change amount Δ1 is selected, next, the current luminance D1 to Dn corresponding to the dimming change amount Δ1 that is closest to the current luminance acquired in step S201 is selected. select. Here, for example, when the dimming change amount Δ1 and the current luminance D1 are selected, the delay times Tg1 and Tb1 corresponding to the dimming change amount Δ1 and the current luminance D1 among the delay times Tg1 to Tgn and Tb1 to Tbn are set. read out. Hereinafter, an example in which the delay times Tg1 and Tb1 are read will be described.
The first control unit 100 sets the read delay times Tg1 and Tb1 as delay times (step S204), ends the delay time setting process, and proceeds to the voltage fluctuation process according to step S30.

  On the other hand, when the first control unit 100 determines that the requested luminance is not lower than the current luminance, that is, the light emission luminance of each of the light sources 11r, 11g, and 11b is increased (step S202: NO), the delay time is set. Without (step S205), the delay time setting process ends, and the process proceeds to the voltage fluctuation process according to step S30.

Next, the processing procedure of the voltage variation process will be described with reference to FIG. At the start of this voltage variation process, the switch units Swr, Swg, and Swb are in an off state.
First, the first controller 100 determines whether a delay time is set (step S301). If it is determined that the delay time is not set (step S301: NO), the voltage Vr, Vg, Vb of the light sources 11r, 11g, 11b is started to change simultaneously (step S313), and the process proceeds to step S312 described later. To do. On the other hand, when it is determined that the delay time is set (step S301: YES), time measurement is started through the timer 100b (step S302). Below, the case where delay time Tg1, Tb1 is set as delay time is demonstrated.

Then, with the start of time measurement, the first control unit 100 switches the switch unit Swr from the off state to the on state (step S303), and changes the voltage Vr of the light source 11r toward the required voltage Vr1 corresponding to the required luminance. Is started (step S304). As a result, as shown in FIG. 20B, at time ta, the voltage Vr of the light source 11r starts to decrease linearly toward the required voltage Vr1.
The first controller 100 reduces the voltage Vr of the light source 11r by reducing the on-duty ratio of the PWM signal Sp2.

Next, the first control unit 100 determines whether or not the delay time Tb1 of the light source 11b for which the measured time (measurement time) is set has elapsed (step S305). When it is determined that the measurement time has passed the delay time Tb1 (step S305: YES), the switch unit Swb is switched from the off state to the on state (step S306), and the light source 11b is turned toward the required voltage Vb1 corresponding to the required luminance. The change of the voltage Vb is started (step S307). As a result, as shown in FIG. 20B, at time tb, the voltage Vb of the light source 11b starts to decrease linearly toward the required voltage Vb1.
The first controller 100 reduces the voltage Vb of the light source 11b by reducing the on-duty ratio of the PWM signal Sp3.

Next, the first control unit 100 determines whether or not the delay time Tg1 of the light source 11g for which the measurement time is set has elapsed (step S308). When it is determined that the measurement time has passed the delay time Tg1 (step S308: YES), the switch unit Swg is switched from the off state to the on state (step S309), and the light source 11g is turned toward the required voltage Vg1 corresponding to the required luminance. The change of the voltage Vg is started (step S310). Accordingly, as shown in FIG. 20B, at time tc, the voltage Vg of the light source 11g starts to decrease linearly toward the required voltage Vg1.
The first controller 100 reduces the voltage Vg of the light source 11g by reducing the on-duty ratio of the PWM signal Sp1.

  When the first control unit 100 determines that the measurement time has not elapsed the delay time Tb1 (step S305: NO), the first control unit 100 proceeds to the process of step S308 without passing through steps S306 and S307. Further, when the first control unit 100 determines that the measurement time has not passed the delay time Tg1 (step S308: NO), the first control unit 100 proceeds to the process of step S311 described later without passing through steps S309 and S310. .

  Next, the first control unit 100 determines whether or not the measurement time has passed both of the two delay times Tg1 and Tb1 (step S311), and the measurement time is at least one of the delay times Tg1 and Tb1. Is determined not to have elapsed (step S311: NO), the process returns to step S305. That is, the processes in steps S305 to 311 are repeated until the measurement time has passed both of the two delay times Tg1 and Tb1.

The first control unit 100 determines that the measurement time has passed both of the two delay times Tg1 and Tb1 (step S311: YES), or after starting the change of the voltages Vr, Vg, and Vb simultaneously (step S311). S313) Waits for the voltages Vr, Vg, Vb of the light sources 11r, 11g, 11b to reach the required voltages Vr1, Vg1, Vb1 (step S312: NO). When the first control unit 100 determines that the voltages Vr, Vg, and Vb of the light sources 11r, 11g, and 11b have reached the required voltages Vr1, Vg1, and Vb1 (step S312: YES), the voltage control process ends. Thus, the process proceeds to step S117 in FIG. Since the processing after step S117 is the same as that of the first embodiment, the description thereof is omitted.
Note that the first control unit 100 returns the switch units Swr, Swg, and Swb from the on state to the off state when the required luminance becomes equal to or higher than the first threshold value Th1 or the second threshold value Th2.

Next, when the smoothing capacitors 318, 328, and 338 are provided, the following points are concerned.
When the luminance of the light sources 11r, 11g, and 11b is decreased, the charges charged in the smoothing capacitors 318, 328, and 338 inhibit the decrease in the voltages Vr, Vg, and Vb of the light sources 11r, 11g, and 11b. For this reason, it is necessary to discharge the charges of the smoothing capacitors 318, 328, and 338. The time required for discharging the electric charge varies depending on the current luminance and the required luminance due to the nature of the smoothing capacitor. For this reason, the length of the charge discharge time may be different for each of the light sources 11r, 11g, and 11b. In this case, the time required for reducing the voltages Vr, Vg, and Vb for each of the light sources 11r, 11g, and 11b. Different. In this case, as shown in FIG. 20A, when the voltages Vr, Vg, and Vb start to decrease at the same time t1, immediately before the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1, White balance may be lost. For example, at time t2 when the voltage Vg of the light source 11g reaches the required voltage Vg1, the voltages Vr and Vb of the other light sources 11r and 11b do not reach the required voltages Vr1 and Vb1. Therefore, at time t2, the light intensity of the red light R and the blue light B with respect to the green light G is strong, and the white balance is lost. In particular, at a low luminance, a change in the color tone of the synthesized light C due to a loss of white balance is easily recognized by a viewer.
In this regard, in the present embodiment, as shown in FIG. 20B, the delay times Tg1 to Tgn, Tb1 so that the voltages Vr, Vg, Vb reach the required voltages Vr1, Vg1, Vb1 at the same time td. Tbn is set. Therefore, in this embodiment, the white balance is prevented from being lost immediately before the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1. At time tc, the voltage Vr, Vb of the light sources 11r, 11b has started to decrease, but the voltage Vg of the light source 11g has not started to decrease. For this reason, although the white balance is lost at the time tc, the luminance at the time tc is higher than the luminance at the time td. Therefore, the change in the color tone of the synthesized light C due to the white balance is difficult to be visually recognized by the viewer. .

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

(1) The light source driving device 5 includes a smoothing capacitor 318 (first smoothing capacitor) that smoothes the voltage Vg (first voltage) adjusted by the first voltage adjustment unit 310, and a second voltage adjustment unit 320. A smoothing capacitor 328 (second smoothing capacitor) that smoothes the adjusted voltage Vr (second voltage) and a smoothing capacitor that smoothes the voltage Vb (third voltage) adjusted by the third voltage adjustment unit 330. A switch unit that switches between an on state in which the capacitor 338 (third smoothing capacitor) and the discharge line L1 (first discharge flow path) from the smoothing capacitor 318 to the ground are conducted and an off state in which the discharge line L1 is cut off. Between the SWG (first switch unit) and the ON state in which the discharge line L2 (second discharge flow path) from the smoothing capacitor 328 to the ground is conducted and the OFF state in which the discharge line L2 is cut off. Switching is performed between a switch part Swr (second switch part) to be switched and an ON state in which the discharge line L3 (third discharge flow path) from the smoothing capacitor 338 to the ground is conducted and an OFF state in which the discharge line L3 is cut off. A switch unit Swb (third switch unit). The first control unit 100 switches the switch units Swr, Swg, and Swb from the off state to the on state when reducing the voltages Vr, Vg, and Vb to the required voltages Vr1, Vg1, and Vb1 corresponding to the required luminance, respectively.
According to this configuration, the charges charged in the smoothing capacitors 318, 328, and 338 can be released, and the voltages Vr, Vg, and Vb can be quickly reduced, and as a result, dimming can be completed quickly. .

(2) When the first controller 100 reduces the voltages Vr, Vg, and Vb to the required voltages Vr1, Vg1, and Vb1 corresponding to the required luminance, the voltages Vr, Vg, and Vb are the required voltages Vr1, Vg1, and Vb1, respectively. The switch units Swr, Swg, and Swb are switched from the off state to the on state at different timings (time ta, tb, and tc) so that the timings of arriving at may be made closer to or coincide with each other. Specifically, the first control unit 100 switches the switch unit Swr corresponding to the light source 11r from the off state to the on state at a timing (time ta) faster than the switch units Swg and Swb corresponding to the other light sources 11g and 11b. Switch.
According to this configuration, the white balance immediately before the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1 is suppressed. Therefore, the change in the color tone of the synthesized light C when the luminance is reduced is suppressed, the stability of the synthesized light C can be ensured, and the visibility can be improved.

(3) The light source driving device 5 includes a resistor Rg (first resistor) provided on the discharge line L1, a resistor Rr (second resistor) provided on the discharge line L2, and a resistor Rb (third resistor) provided on the discharge line L3. Resistance). The resistance values of the resistors Rr, Rg, and Rb are close to the timing at which the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1 when the voltages Vr, Vg, and Vb are reduced to the required voltages Vr1, Vg1, and Vb1, respectively. Alternatively, different values are set so as to match. Specifically, the resistance value of the resistor Rr of the light source 11r is set to be smaller than the resistance values of the resistors Rg and Rb of the light sources 11g and 11b.
According to this configuration, the decreasing speeds of the voltages Vr, Vg, Vb, that is, the gradients of the voltages Vr, Vg, Vb can be set by the resistance values of the resistors Rr, Rg, Rb. For this reason, the timing at which the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1 can be brought closer or matched. Therefore, white balance is prevented from being lost immediately before the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1. Therefore, the change in the color tone of the synthesized light C when the luminance is reduced is suppressed, the stability of the synthesized light C can be ensured, and the visibility can be improved.

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

  In the third embodiment, the delay time is set and the resistance values of the resistors Rr, Rg, and Rb are set to different values, so that the voltages Vr, Vg, and Vb are simultaneously changed to the required voltages Vr1, Vg1, and so on. It reached Vb1. However, the present invention is not limited to this, by setting the resistance values of the resistors Rr, Rg, and Rb to different values without setting the delay time, and simultaneously switching the switch units Swr, Swg, and Swb to the on state. As shown in FIG. 21, the voltages Vr, Vg, and Vb may be made to reach the required voltages Vr1, Vg1, and Vb1 simultaneously at time te. In this case, it is desirable to set a larger difference between the resistance values of the resistors Rr, Rg, and Rb than in the third embodiment. In this configuration, it is only necessary to control the switch units Swr, Swg, and Swb at the same time, so that the control burden on the first control unit 100 can be reduced.

  In the third embodiment, the resistance values of the resistors Rr, Rg, and Rb may be set to the same value.

  In the third embodiment, the voltages Vr, Vg, and Vb started to decrease at different timings (time ta, tb, and tc). For example, the voltages Vg and Vb decrease at the same speed. In this case, the decrease in the voltages Vg and Vb may be started at the same timing. In this case, the voltage drop starts at a timing when the voltage Vr and the voltages Vg and Vb are different.

In the third embodiment, the resistance values of the resistors Rr, Rg, and Rb are fixed values. However, by using a variable resistor that can change the resistance values, the resistance values of the resistors Rr, Rg, and Rb are changed. May be. For example, the first control unit 100 can change the slopes of the decreasing voltages Vr, Vg, and Vb by changing the resistance values of the resistors Rr, Rg, and Rb. Thus, as shown in FIG. 21, the slopes of the voltages Vr, Vg, Vb are set so that the voltages Vr, Vg, Vb reach the required voltages Vr1, Vg1, Vb1 at the same time at the time te. Adjusted.
Further, as an example, the first control unit 100 measures the variation in timing at which the voltages Vr, Vg, Vb reach the required voltages Vr1, Vg1, Vb1, and corrects the measured variation. , Rg, Rb may be changed in resistance value. Further, the first control unit 100 may change the slopes of the voltages Vr, Vg, and Vb while the voltages Vr, Vg, and Vb are decreasing.

  In the third embodiment, the first control unit 100 may have a function of automatically correcting the delay times Tg1 to Tgn and Tb1 to Tbn stored in the delay time data table. For example, the first control unit 100 measures delays when the voltages Vr, Vg, and Vb reach the required voltages Vr1, Vg1, and Vb1, and corrects the measured variations so that the delay times Tg1 to Tgn are corrected. , Tb1 to Tbn may be corrected.

  In the third embodiment, the delay time data table associates the dimming change amounts Δ1 to Δn and the current luminances D1 to Dn with the delay times Tg1 to Tgn and Tb1 to Tbn. The current luminance values D1 to Dn may be associated with the delay times Tg1 to Tgn and Tb1 to Tbn.

  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 S109 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 time 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-) that controls the light emission timing of the light sources 11r, 11g, and 11b. EN) may be substituted.

  In each of the above embodiments, as shown in FIGS. 12B and 12C, the HUD device 1 continuously changes current while the display period ratio is constant while changing the display period ratio stepwise. As shown in FIGS. 12 (d) and 12 (c), the on-duty ratio of the limit data is constant while changing the on-duty ratio of the limit data stepwise. The required luminance area for continuously changing the current is provided separately, but the display luminance ratio, the on-duty ratio of the limit data, and the required luminance area for changing the current may be provided. . Specifically, for example, the HUD device 1 changes the on-duty ratio of the limit data while changing the on-duty ratio of the limit data stepwise while the display period ratio is constant while changing the display period ratio stepwise. The current may be continuously changed while the ratio is constant.

  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 of the above embodiments, the first control unit 100 performs the voltage adjustment dimming processing according to steps S104 to S110 only in the 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, and 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 100c Processing unit 200 Second control unit 300 Power supply control unit 310 First voltage adjustment unit 318, 328,338 Smoothing capacitor 316 Power supply IC
320 Second voltage adjustment unit 330 Third 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 (13)

A light source driving device that drives a first light source that emits first light and a second light source that emits second light having a color different from that of the first light,
A first voltage adjusting unit for adjusting a first voltage applied to the first light source based on a power supply voltage from a power supply;
A second voltage adjusting unit that generates a second voltage to be applied to the second light source using the power supply voltage or the first voltage as a power source;
The first voltage and the second voltage are set so that a light intensity ratio between the first light and the second light becomes a desired light intensity ratio, and the first voltage adjustment unit and the second voltage adjustment are performed. A control unit that performs voltage-modulable light processing to apply the set first voltage and the second voltage to the first light source and the second light source, respectively, through a unit;
Light source drive device. A first current adjustment unit for adjusting a first current supplied to the first light source;
A second current adjusting unit that adjusts a second current supplied to the second light source,
The controller is
When the required luminance is less than the first threshold, in the voltage-modulable light processing, the light intensity ratio between the first light and the second light is the desired light intensity ratio, and the required luminance is satisfied. Setting the first voltage and the second voltage;
When the required luminance is equal to or greater than the first threshold, the first current and the second light according to the required luminance while the light intensity ratio of the first light and the second light is the desired light intensity ratio A second current is set, and the set first current and second current are supplied to the first light source and the second light source through the first current adjustment unit and the second current adjustment unit, respectively. Perform current-modulable light processing,
The light source driving device according to claim 1. A memory that stores a voltage data table indicating a value of the first voltage applied to the first light source according to the required luminance;
A light intensity detector that detects the light intensity of the first light and the light intensity of the second light,
In the voltage-modulable light processing, the control unit sets the first voltage according to the required luminance with reference to the voltage data table, and based on the detection result of the light intensity detection unit, the first voltage The second voltage is set with reference to the set first voltage so that the light intensity ratio of the second light and the second light becomes the desired light intensity ratio.
The light source driving device according to claim 2. The memory stores a current data table indicating a value of the first current supplied to the first light source according to the required luminance,
In the current-modulable light processing, the control unit sets the first current according to the required luminance with reference to the current data table, and based on the detection result of the light intensity detection unit, the first current The second current is set with reference to the set first current so that the light intensity ratio of the second light and the second light becomes the desired light intensity ratio.
The light source driving device according to claim 3. The controller is
In the current-modulable light processing, the first voltage is held constant through the first voltage adjustment unit,
In the voltage-modulable light processing, the first voltage is gradually reduced through the first voltage adjustment unit as the required luminance decreases.
The light source driving device according to any one of claims 2 to 4. The controller is
In the voltage-modulable light processing, the first current is kept constant through the first current adjustment unit,
In the current-modulable light processing, the first current corresponding to the required luminance is set through the first current adjustment unit.
The light source driving device according to claim 2. The light source driving device drives a third light source that emits third light of a color different from the first light and the second light, in addition to the first light source and the second light source,
Furthermore, the light source driving device includes:
A third voltage adjusting unit that generates a third voltage to be applied to the third light source using the power supply voltage or the first voltage as a power source;
A third current adjusting unit that adjusts a third current supplied to the third light source,
The controller is
In the voltage-modulable light processing, the first voltage, the second voltage, and the like so that the light intensity ratio of the first light, the second light, and the third light becomes a desired light intensity ratio. And setting the third voltage,
In the current-modulable light processing, the first current, the second light, and the second light are adjusted so that a light intensity ratio of the first light, the second light, and the third light becomes the desired light intensity ratio. Setting a current and the third current;
The light source driving device according to claim 2. A first voltage data table indicating a value of the first voltage applied to the first light source according to the required luminance, and a value of the second voltage applied to the second light source according to the required luminance. And a second voltage data table to be stored.
The first voltage data table and the second voltage data table are:
When the required brightness is equal to or higher than a second threshold set to a value smaller than the first threshold, each takes the same value,
When the required luminance is less than the second threshold value, the first voltage and the second voltage that achieve display luminance according to the required luminance are different from each other,
The controller is
According to the required luminance with reference to the first voltage data table and the second voltage data table so that the light intensity ratio of the first light and the second light becomes the desired light intensity ratio. Setting the first voltage and the second voltage;
The light source driving device according to claim 2. The first voltage adjustment unit generates the first voltage by stepping down the power supply voltage,
The second voltage regulator receives the first voltage generated through the first voltage regulator and generates the second voltage;
The light source driving device according to any one of claims 1 to 8. A first smoothing capacitor for smoothing the first voltage adjusted by the first voltage adjustment unit;
A second smoothing capacitor for smoothing the second voltage adjusted by the second voltage adjustment unit;
A first switch section that switches between an on state that conducts the first discharge flow path from the first smoothing capacitor to the ground and an off state that shuts off the first discharge flow path;
A second switch unit that switches between an on state that conducts the second discharge flow path from the second smoothing capacitor to the ground and an off state that shuts off the second discharge flow path;
The control unit switches the first switch unit and the second switch unit from the off state to the on state when reducing the first voltage and the second voltage to a required voltage corresponding to the required luminance, respectively.
The light source driving device according to claim 1. The controller is configured to reduce or match the timing at which the first voltage and the second voltage reach the required voltage when reducing the first voltage and the second voltage to the required voltage, respectively. Switching each of the first switch unit and the second switch unit from the off state to the on state at different timings;
The light source driving device according to claim 10. A first resistor provided in the first discharge flow path;
A second resistor provided in the second discharge flow path,
The resistance value of the first resistor and the resistance value of the second resistor are set such that when the first voltage and the second voltage are reduced to the required voltage, respectively, the first voltage and the second voltage are changed to the required voltage. Set to different values so that the arrival timings are close or match,
The light source driving device according to claim 10 or 11. The light source driving device according to any one of claims 1 to 12,
A light combining unit that combines the light from the light sources 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.

Images