JP2014063063A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display an image by a stable luminance even when the characteristic of a light source varies by a temperature change.SOLUTION: A display device displays an image by light from laser diodes 11 to 13 (LD), and includes: a light intensity detection part 20 for detecting an emission intensity of the LD; and a main control part 300. The main control part 300 supplies to the LD as needed a current in which a current value is gradually increased from the current value smaller than a current value threshold value via a control part 100, acquires in sequence the variation of the emission intensity of the LD for the variation in the predetermined period of the current, acquires the current value when the variation of the acquired emission intensity exceeds a predetermined amount as a driving current threshold value, and drives the LD by supplying the current having a value larger than the acquired driving current threshold value.

Description

  The present invention relates to a display device.

  Patent Document 1 discloses a display device that generates a display image by scanning laser light emitted from a laser light source on a screen using a scanning system.

  By the way, a laser light source has a characteristic that a current threshold value for laser oscillation changes due to heat generated when light is emitted, a change in outside air temperature, or the like. When the current threshold value changes, the current-light emission intensity characteristic of the light source (the relationship between the supplied current and the light emission intensity) changes, which causes a problem that the brightness of the displayed image is not stable.

  Therefore, in Patent Document 2, in order to stabilize the luminance of the image to be displayed, the current value supplied to the light source is supplied by changing two or more points, and based on the light intensity detected by the light detection unit at this time, There has been disclosed a display device that calculates a current-light emission intensity characteristic of a light source and adjusts a current supplied to the light source based on a calculation result.

JP-A-7-270711 JP 2009-244797 A

  In the display device according to Patent Document 2, the light intensity when the current less than the current threshold is supplied to the light source is not considered, and based on the light intensity detected when the current value greater than or equal to the current threshold is changed by two or more points. The amount of change in the light emission intensity of the light source with respect to the amount of current change is calculated as a slope, and the current threshold is calculated from the calculated slope. However, in this method, a deviation occurs between the calculated current threshold and the actual current threshold. Easy (especially, a current threshold lower than the actual current threshold is easily calculated). When the current supplied to the light source is adjusted based on the current-light emission amount (emission intensity) characteristic based on the current threshold value and the maximum current value calculated in this way, a current lower than the actual current threshold value is supplied to the light source In this case, the laser light source cannot oscillate stably, and as a result, the brightness of the display image is not stable.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a display device capable of displaying an image with stable luminance even when the characteristics of a light source change due to a temperature change.

In order to achieve the above object, a display device according to the first aspect of the present invention provides:
A display device comprising: a light source that emits laser light having an intensity according to a supplied current; and a scanning unit that displays a predetermined image on a display unit by scanning the laser light emitted from the light source,
A light intensity detection means for detecting the emission intensity of the laser light emitted from the light source;
Current supply means for supplying the light source with a current that gradually increases from a current value that is smaller than a current threshold that is a current value at which the light source oscillates;
Based on the light emission intensity of the light source by the current supply from the current supply means detected by the light intensity detection means, a change amount of the light emission intensity of the light source with respect to a change amount in a predetermined period of the current supplied by the current supply means. In-drive threshold acquisition means for sequentially acquiring and acquiring the current value when the acquired amount of change in emission intensity exceeds a predetermined amount as the in-drive current threshold;
Light source driving means for driving the light source by supplying a current having a value larger than the driving current threshold acquired by the driving threshold acquisition means;
It is characterized by that.

In order to achieve the above object, a display device according to the second aspect of the present invention provides:
A display device comprising: a light source that emits laser light having an intensity according to a supplied current; and a scanning unit that displays a predetermined image on a display unit by scanning the laser light emitted from the light source,
A light intensity detection means for detecting the emission intensity of the laser light emitted from the light source;
Current supply means for supplying the light source with a current that gradually decreases from a current value that is larger than a current threshold value that is a current value that causes the laser to oscillate;
Based on the light emission intensity of the light source by the current supply from the current supply means detected by the light intensity detection means, a change amount of the light emission intensity of the light source with respect to a change amount in a predetermined period of the current supplied by the current supply means. In-drive threshold value acquisition means for sequentially acquiring and acquiring the current value when the acquired amount of change in the emission intensity is equal to or less than a predetermined amount as a driving current threshold value;
Light source driving means for driving the light source by supplying a current having a value larger than the driving current threshold acquired by the driving threshold acquisition means;
It is characterized by that.

  According to the present invention, an image can be displayed with stable luminance even if the characteristics of the light source change due to temperature changes.

It is a figure for demonstrating the mounting aspect of the HUD apparatus which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the HUD apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the structure of a laser beam emission part. It is a figure for demonstrating the electrical constitution of the HUD apparatus which concerns on 1st Embodiment. (A) And (b) is a figure for demonstrating the signal waveform which drives a MEMS mirror. It is a figure for demonstrating a mode that an image is scanned on a screen. It is a flowchart of the gradation control process which concerns on 1st Embodiment. It is a flowchart of the threshold determination / output control data acquisition process which concerns on 1st Embodiment. It is a flowchart following FIG. 4 is a flowchart of threshold output control data comparison processing according to the first embodiment. It is a flowchart of the gradation control data generation process which concerns on 1st Embodiment. It is a flowchart following FIG. It is a flowchart of the gradation control data update process which concerns on 1st Embodiment. It is the figure which showed the electric current-light intensity characteristic of the laser diode. It is the figure which showed the gradation characteristic curve. It is a figure for demonstrating gradation control data. It is a flowchart of the threshold output control data comparison process which concerns on 2nd Embodiment of this invention. It is a flowchart of the gradation control data generation process which concerns on 2nd Embodiment. It is a flowchart following FIG. It is a flowchart of the gradation control data update process which concerns on 2nd Embodiment.

  A display device according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
The display device according to the first embodiment of the present invention is a head-up display (HUD) device 1 shown in FIG. As shown in the figure, the HUD device 1 is disposed on the dashboard of the vehicle 2 and emits display light L representing an image M (see FIG. 2) for notifying predetermined information toward the windshield 3. The display light L reflected by the windshield 3 is viewed as a virtual image V of an image formed in front of the windshield 3 by the observer 4 (mainly the driver of the vehicle 2). In this way, the HUD device 1 causes the observer 4 to visually recognize an image.

  As shown in FIG. 2, the HUD device 1 includes a laser light emitting unit 10, a light intensity detecting unit 20, a MEMS (Micro Electro Mechanical System) mirror 30, a screen 40, a first reflecting unit 60, a second The reflection part 70, the housing | casing 80, and the translucent part 90 are provided.

  The laser beam emitting unit 10 emits laser beam RGB, which will be described later, toward the MEMS mirror 30, and as shown in FIG. 2, laser diodes (hereinafter referred to as LD) 11, 12, 13 and a condensing optical system. 14, a multiplexing unit 15, and a permeable membrane 16.

The LD 11 emits red laser light R. The LD 12 emits green laser light G. The LD 13 emits blue laser light B. The LDs 11, 12, and 13 are supplied with a drive signal (drive current) from an LD control unit 100 described later, and each emits light at a predetermined light intensity and timing.
Note that the emission characteristics of the LDs 11 to 13 change due to heat generated when laser light is emitted, changes in the outside air temperature, and the like. Specifically, the current threshold value, which is the current value at which laser oscillation starts, changes due to a temperature change, thereby changing the relationship between the supplied current and the light emission luminance (current-light emission luminance characteristic). However, as will be described in detail later, according to the HUD device 1, even if the light emission characteristics change due to a temperature change, the LDs 11 to 13 can be driven while accurately reflecting the changed light emission characteristics (the supplied current is reduced). Can be adjusted).

  The condensing optical system 14 condenses each of the laser beams R, G, and B emitted from the LDs 11, 12, and 13, reduces the spot diameter, and forms convergent light. Specifically, the condensing optical system 14 includes condensing units 14a, 14b, and 14c each formed of a lens or the like. The condensing part 14a is located on the optical path of the laser light R emitted from the LD 11, the condensing part 14b is located on the optical path of the laser light G emitted from the LD 12, and the condensing part 14c is the laser light B emitted from the LD 13. Located on the optical path.

The multiplexing unit 15 combines the laser beams R, G, and B emitted from the LDs 11, 12, and 13 via the condensing optical system 14, and outputs the combined laser beams as a single laser beam RGB. . Specifically, the multiplexing unit 15 includes a reflection unit 15a, a multiplexing unit 15b, and a multiplexing unit 15c each formed of a dichroic mirror that reflects light of a specific wavelength but transmits light of other wavelengths. It is configured.
The reflection unit 15a reflects the incident laser light R toward the multiplexing unit 15b.
The multiplexing unit 15b transmits the laser beam R from the reflecting unit 15a as it is and reflects the incident laser beam G toward the multiplexing unit 15c. Thereby, the laser beam RG obtained by combining the laser beams R and G is emitted from the combining unit 15b toward the combining unit 15c.
The multiplexing unit 15 c transmits the laser beam RG from the multiplexing unit 15 b as it is and reflects the incident laser beam B toward the MEMS mirror 30. In this manner, the laser beam RGB obtained by combining the laser beams RG and B is emitted from the multiplexing unit 15 c toward the MEMS mirror 30.

  The transmissive film 16 is made of a transmissive member having a reflectivity of about 5%, for example, and transmits most of the laser light RGB from the multiplexing unit 15c as it is, but a part of the light of the light intensity detection unit 20 is transmitted. Reflect in the direction.

The light intensity detection unit 20 is made of a photodiode or the like, receives the laser light RGB reflected by the transmission film 16, and detects the light intensity of each of the laser lights R, G, and B from the received laser light RGB.
Specifically, the light intensity detection unit 20 outputs a detection signal (voltage) corresponding to the light intensity, and this detection signal is converted into a digital value by an A / D converter (not shown) to obtain light intensity information. The data is output to a main control unit 300 described later. The light intensity detection unit 20 only needs to be able to detect the light intensities of R, G, and B. For example, the laser light R and laser light G before being combined are not optical paths of the laser light RGB. The light intensity of each of the laser beams B may be provided at a location where the light intensity can be detected.

  The MEMS mirror 30 receives the laser light RGB from the laser light emitting unit 10 and receives the light under the control of the scanning control unit 200 described later (based on the scanning control signal supplied from the scanning control unit 200). Laser light RGB is scanned on the screen 40. As a result, the image M is displayed on the screen 40.

  The screen 40 receives the laser beam RGB from the MEMS mirror 30 on the back side and transmits and diffuses it to display the image M on the front side. The screen 40 includes a holographic diffuser, a microlens array, a diffusion plate, and the like. The

As shown in FIG. 6, the screen 40 has a display area 40 a that is an area that the viewer 4 can visually recognize as a virtual image V (that is, an area that emits the display light L reflected by the first reflection unit 60 and the like) It is classified into a non-display area 40b that is an area in which the observer 4 cannot visually recognize.
Here, as shown in FIG. 6, the MEMS mirror 30 scans the laser light RGB from the upper left corner S to the lower right corner T of the screen 40 in the left and right directions (see the dotted line indicated by reference numeral RGB). When it reaches T, it returns to the upper left corner S again (see the arrow indicated by reference numeral 40c) and scans. As shown in FIGS. 5A and 5B, the scanning period of the MEMS mirror 30 includes an actual scanning period 30a in which the display area 40a and the non-display area 40b are scanned, and a lower left corner T to an upper left corner. It is classified into a blanking period 30b (vertical blanking period) which is a period returning to S.

  The first reflection unit 60 includes a plane mirror or the like, receives display light L representing the image M displayed on the screen 40, and reflects the display light L toward the second reflection unit 70 side.

  The second reflecting unit 70 is formed of a concave mirror or the like, and reflects the display light L from the first reflecting unit 60 in the direction of the windshield 3. The display light L reflected by the second reflecting unit 70 reaches the windshield 3 via the light transmitting unit 90.

  The housing 80 houses the laser beam emitting unit 10, the light intensity detecting unit 20, the MEMS mirror 30, the screen 40, the first reflecting unit 60, the second reflecting unit 70, and the like, and is formed of a light shielding member. The

  The light transmitting portion 90 is made of a light transmitting resin such as acrylic and transmits the display light L from the second reflecting portion 70, and is fitted to the housing 80, for example. The translucent part 90 is formed in a curved shape so that the external light that has reached does not reflect in the direction of the observer 4.

  Next, the electrical configuration of the HUD device 1 will be described.

  In addition to the above, the HUD device 1 includes an LD control unit 100, a scan control unit 200, and a main control unit 300 that controls the LD control unit 100 and the scan control unit 200, as shown in FIG. These control units are mounted, for example, on a printed circuit board (not shown) disposed in the housing 80. Note that these control units may be disposed outside the HUD device 1 and electrically connected to the HUD device 1 (LDs 11 to 13, the light detection unit 20, the MEMS mirror 30, and the like) by wiring.

The LD control unit 100 drives the LDs 11 to 13 and includes a first drive unit 101 and a power feeding unit 102.
The first drive unit 101 is composed of a driver IC (Integrated Circuit) or the like, and each of the LDs 11 to 13 is controlled by a PWM (Pulse Width Modulation) control method under the control of the main control unit 300, or It is driven by a PAM (Pulse Amplitude Modulation) control method. Specifically, as will be described later, the first drive unit 101 drives the LDs 11 to 13 by the PWM method in the low gradation region shown in FIGS. 15 and 16 and by the PAM method in the main gradation region. The first drive unit 101 supplies a drive current to each of the LDs 11 to 13 based on the output control data supplied from the main control unit 300. That is, the output control data indicates a current value supplied to each of the LDs 11 to 13.
The power supply unit 102 supplies power to the LDs 11 to 13 through the first drive unit 101, and includes a power supply IC, a switching circuit using a transistor, and the like. Under the control of the main control unit 300, the power supply unit 102 switches between supply and non-supply of power to each of the LDs 11 to 13 (supply when on and non-supply when off). In addition, the electric power feeding part 102 may be independently provided in each of LD11-13, and may be shared by these.

The scanning control unit 200 drives the MEMS mirror 30 and includes a second driving unit 201 and a mirror position detection unit 202.
The second drive unit 201 includes a driver IC and the like, and drives the MEMS mirror 30 (based on scanning control data from the main control unit 300) under the control of the main control unit 300. The second drive unit 201 drives the MEMS mirror 30, acquires the scan position detection data output from the mirror position detection unit 202, calculates feedback data based on the acquired scan position detection data, and outputs the feedback data. Is output to the main control unit 300. The feedback data output from the second drive unit 201 is the measured resonance frequency that is the resonance frequency of the piezo element when the mirror of the MEMS mirror 30 is actually moved in the horizontal direction, and when the mirror is actually moved in the vertical direction. This is data such as the measured vertical drive frequency, which is the vertical frequency of the piezo element.
The mirror position detection unit 202 detects the shake position of the piezo element that moves the mirror of the MEMS mirror 30 for each time, and outputs the detected position to the second drive unit 201 as scanning position detection data.

The main control unit 300 includes a microcontroller, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), and the like, and includes a CPU 301 and a storage unit 302. The storage unit 302 stores programs and data necessary for the operation of the HUD device 1 and includes an EEPROM, a flash, and the like.
The CPU 301 reads out a program from the storage unit 302 and executes it to control each unit. In the CPU 301, vehicle information and an activation signal from an external device (not shown) such as an ECU (Electronic Control Unit) of the vehicle 2 and an LD current error signal indicating an abnormality of the LD from the LD control unit 100 flow to the LDs 11-13. Various information such as LD current data indicating a current value, light intensity information from the light intensity detector 20 and feedback data from the scanning controller 200 is input, and the CPU 301 drives the LD controller 100 based on these information. Output control data and scan control data for driving the scan control unit 200 are generated and output, and comprehensive control of the HUD 1 is performed. That is, the CPU 301 drives the LDs 11 to 13 and the MEMS mirror 30 via the LD control unit 100 and the scan control unit 200 according to the input information, and generates an image M. Thereby, the display light L representing the image M is emitted toward the windshield 3, and the observer 4 can visually recognize the image M as the virtual image V.

The HUD device 1 having the above configuration is activated when, for example, the activation switch of the vehicle 2 is turned on (by ignition, accessory, key unlocking, etc.). The storage unit 302 stores in advance a program for executing “gradation control processing” unique to the present embodiment. The CPU 301 reads, for example, the gradation control when the HUD device 1 is activated. Execute the process.
From here, the gradation control processing will be described with reference to FIGS.

(Gradation control processing)
First, the CPU 301 initializes various data.
Specifically, as shown in FIG. 7, the CPU 301 initializes a gradation control data generation request flag and a gradation control data update request flag (step S100), and subsequently controls R, G, and B_ Threshold value output control data, R, G, B current_threshold output control data and R, G, B current_tone control data are initialized (step S200). These request flags and other data will be described later.

  Subsequently, the CPU 301 executes “threshold judgment / output control data acquisition processing” (step S300). This process includes the processes of steps S301 to S318 shown in FIGS. The threshold determination / output control data acquisition process will be described below.

(Threshold judgment / output control data acquisition process)
In the threshold determination / output control data acquisition process, the CPU 301 determines a threshold (light intensity value) at which each of the LDs 11 to 13 starts laser oscillation, and threshold output control data at this threshold (data indicating a current value at the threshold). To get.

  First, the CPU 301 initializes data used in the threshold determination / output control data acquisition process (step S301). Specifically, the CPU 301 stores a threshold primary acquisition flag, light intensity_previous value, threshold determination data, threshold sampling value, and R, G, and B current_threshold output control stored in the storage unit 302 in advance. Initialize data. These data will be described later.

Subsequently, the CPU 301 determines whether or not the current scan is outside the execution area (step S302).
Specifically, based on the feedback data acquired from the mirror position detection unit 202, the CPU 301 determines that the scanning is not outside the execution area if the display area 40a is being scanned or if it is the blanking period 30b (step S302; No), the CPU 301 waits until the scanning in the display area 40a or the blanking period 30b ends.
On the other hand, if the scan is outside the execution area (step S302; Yes), the CPU 301 performs the process of step S303.

In step S <b> 303, the CPU 301 determines a color for threshold determination from the threshold primary acquisition flag stored in the storage unit 302 in advance. That is, among the LDs 11 to 13, the LD that determines the threshold value for starting laser oscillation is determined.
The “threshold primary acquisition flag” is a flag for three colors of R, G, and B, and is configured by 3 bits of 1 bit for each color. The color determination method is determined based on the establishment / non-establishment information of each color indicated by the threshold primary acquisition flag and the priority of R>G> B.

  The CPU 301 determines a threshold value for starting laser oscillation in the processing after step S304 for the color LD (any one of LD11 to 13) determined in step S303. In the threshold value determination / output control data acquisition process, the color determined in step S303 is also simply referred to as “determined color” below.

When the color to be subjected to the threshold determination is determined, the CPU 301 sets the light intensity_previous value data stored in advance in the storage unit 302 to 0 (zero) (step S304).
“Light intensity_previous value data” functions as a location for temporarily storing light intensity information from the light intensity detection unit 20, and is configured with, for example, 10 bits for each color.

  Subsequently, the CPU 301 turns on the power supply unit 102, then sets the output control data of R, G, and B to 0 (sets to the minimum value), and sends the output control data to the first drive unit 101 ( Step S305).

  Subsequently, the CPU 301 sends data having a value obtained by adding “1” to the output control data of the determined color to the first driving unit 101 (step S306), and the light intensity information (current light) from the light intensity detecting unit 20 is sent. (Indicating intensity) is acquired (step S307).

Subsequently, the CPU 301 calculates threshold determination data (step S308).
The “threshold judgment data” is calculated as the absolute value of the difference between the light intensity information acquired in step S307 and the light intensity_previous value, as shown in (Equation 1) below. Indicates the amount of change from the previous value to the current value.

When the threshold determination data is calculated, the CPU 301 compares the calculated threshold determination data with the threshold determination data stored in advance in the storage unit 302 (step S309).
The “threshold determination data” is arbitrary invariant data stored in advance in the storage unit 302 for each of R, G, and B colors (that is, for each of LD 11 to 13), and the amount of change in emission intensity in the vicinity of the current threshold. Is stored as a value that takes into account. This data is composed of, for example, 10 bits for each color.

When the threshold determination data is equal to or less than the threshold determination data (step S309; No), the CPU 301 can determine that the threshold has not yet been reached from the amount of change in the emission intensity, so the CPU 301 stores the light intensity stored in the storage unit 302. The light intensity information acquired in step S307 is written in the previous value data, and then the process returns to step S306.
On the other hand, when the threshold determination data is larger than the threshold determination data (step S309; Yes), since it can be determined that the threshold has been reached, the CPU 301 outputs the output control data created in the most recent step S306 (that is, the current output control data). ) Is determined as data to be written in the current_threshold value output control data (step S311). This time_threshold output control data will be described in step S312.

  That is, the CPU 301 acquires the light intensity information by adding the output control data to be output to the LD related to the determined color from 0 to 1 (by gradually adding from the minimum value) by the processing of step S306 to step S309, Threshold determination data indicating the amount of change in light intensity is obtained, and the light intensity value when the amount of change in light intensity exceeds a predetermined value is determined as the threshold value. Then, the output control data at this threshold value is written in the current_threshold value output control data.

Subsequently, the CPU 301 outputs the output control data determined in step S <b> 311 to the current color_threshold output control data of the determined color in “R_G, B current_threshold output control data” stored in the storage unit 302 in advance. Are averaged and written (step S312).
“R, G, B current_threshold output control data” is data used in a threshold output control data comparison process to be described later, and is composed of 10 bits for each color.
Further, as shown in the following (Equation 2), the averaging process divides the sum of the output control data determined in step S311 and the current color_threshold output control data of the determined color by 2 (only the first time) Divided by 1). By averaging in this way, even if the light intensity detection unit 20 is erroneously detected or the like, it is possible to prevent the current value (current threshold value) at the threshold value from being acquired in a sudden change, and to be stable. Thus, the current threshold value can be acquired.

  Subsequently, the CPU 301 sets (establishes) a determination color flag in the threshold primary acquisition flag stored in the storage unit 302 (step S313).

  Through the processing from step S303 to step S313 described above, a current threshold value at which the LD (any one of LDs 11 to 13) related to the determined color oscillates (that is, “current time_threshold output control data” related to the determined color) is obtained ( (See FIG. 14).

  Subsequently, as shown in FIG. 9, the CPU 301 determines whether or not the threshold primary acquisition flag is established for all the colors R, G, and B (step S314). When the threshold primary acquisition flag is not satisfied for all of R, G, and B (step S314; No), the CPU 301 returns to step S303 to perform threshold determination / output control data acquisition processing for the unsatisfied color in the threshold primary acquisition flag. Do. As a result, the processing from step S303 to step S313 is executed for all three colors of R, G, and B, and the current threshold value of each color can be acquired.

On the other hand, when the threshold primary acquisition flag is established for all of R, G, and B (step S314; Yes), the CPU 301 adds 1 to the threshold sampling value stored in the storage unit 302 (step S315).
The “threshold sampling value” is data for counting the number of times of sampling of the current_threshold control data for R, G, and B. This data indicates how many sets of R, G, and B current_threshold control data have been acquired when all the three colors R, G, and B are satisfied by the threshold primary acquisition flag. . For example, the threshold sampling value is composed of 3 bit data and can count up to a maximum of 8 sets.

  Subsequently, the CPU 301 lowers the threshold primary acquisition flag for all the colors (step S316).

Subsequently, the CPU 301 determines whether or not the threshold sampling value is greater than or equal to the first gradation control adjustment value stored in advance in the storage unit 302 (step S317).
The “first gradation control adjustment value” is data indicating an arbitrary value that determines how many times the threshold is sampled. The first gradation control adjustment value indicates the current_threshold output control data averaging count of R, G, and B. Therefore, when it is desired to increase the accuracy of threshold determination, the first gradation control adjustment value is used. In order to move to the next threshold value output control data comparison process (step S400) quickly, the first gradation control adjustment value may be decreased.

  When the threshold sampling value is less than the first gradation control value (step S317; No), the CPU 301 returns to step S303 to perform processing.

On the other hand, when the threshold sampling value is equal to or higher than the first gradation control value (step S317; Yes), the CPU 301 returns the threshold sampling value stored in the storage unit 302 to 0 (step S318), and threshold determination / output control is performed. The data acquisition process is terminated, and the next “threshold output control data comparison process” is executed (step S400). This process includes the processes in steps S401 to S409 shown in FIG.
Hereinafter, the threshold output control data comparison process will be described.

(Threshold output control data comparison process)
In the threshold output control data comparison process (step S400), the CPU 301 obtains the R_G_B current_threshold output control data acquired in the threshold determination / output control data acquisition process (step S300) and the R, G, B The in-control_threshold output control data is compared for each color, and it is determined whether or not tone control data generation is necessary.

  First, the CPU 301 makes a determination at startup. Specifically, the CPU 301 determines whether all the R_G_B control threshold_threshold output control data stored in advance in the storage unit 302 is 0 (step S <b> 401).

When the control_threshold value output control data is all 0 (step S401; Yes), that is, when it is determined that it is a start-up time, the CPU 301 sets a gradation control data generation request flag stored in advance in the storage unit 302. (Step S402).
The “gradation control data generation request flag” is determination data for determining whether to generate gradation control data for each of R, G, and B in a gradation control data generation process (step S500) described later, and is configured with 1 bit. Is done.
As described above, at the time of activation, the processing after step S403 is not executed, and the processing is forcibly shifted to the gradation control data generation processing (step S500) described later.

  On the other hand, if the in-control_threshold output control data is not 0 in any of the RGB colors (step S401; No), the CPU 301 stores the comparison completion flag, R, G, and B gradations stored in advance in the storage unit 302. The control data generation_determination data is initialized (step S403). These data will be described later.

In step S <b> 404, the CPU 301 determines a color for generating gradation control data from the comparison completion flag stored in advance in the storage unit 302.
The “comparison completion flag” is an R, G, B color flag, and is composed of 3 bits, 1 bit for each color. The color determination method is determined based on the establishment / non-establishment information of each color indicated by the comparison completion flag and the priority of R>G> B.
In the threshold output control data comparison process, the color determined in step S404 is also simply referred to as “determined color” below.

  When the color for generating the gradation control data is determined, the CPU 301 calculates gradation control data generation_determination data for the determined color (step S405).

  “Gradation control data generation_determination data” is the absolute value of the difference between the determined color being controlled_threshold output control data and the determined color's current_threshold output control data, as shown in the following (Equation 3): Is calculated as

  “During control_threshold output control data” is threshold output control data when the image M is actually displayed on the screen 40, and is 10-bit data, similarly to the current_threshold output control data. For example, if the determined color is R, the in-control_threshold output control data related to R is data necessary for the CPU 301 to light the LD 11. The same applies to the correspondence between G and LD12 and the correspondence between B and LD13. The in-control_threshold output control data is threshold output control data when R, G, B gradation control data is generated, as will be described later.

Subsequently, the CPU 301 calculates the gradation control data generation_determination data relating to the determined color in the R, G, B gradation control data generation_determination data stored in the storage unit 302 in advance, and calculation in step S405. The generated gradation control data_determination data is compared (step S406).
“R, G, B gradation control data generation_determination data” is arbitrary invariant data stored in advance in the storage unit 302 for each color of R, G, B (that is, for each of LD 11 to 13). Yes, it indicates the allowable value of gradation control data generation_determination data (that is, in-control_deviation amount from threshold output control data). This data is composed of, for example, 10 bits for each color. In this way, by providing R, G, B gradation control data generation_determination data for each color of R, G, B, the characteristics of the LDs 11 to 13 can be taken into consideration. In addition, since gradation control data generation_determination data depends on the frequency of gradation control data generation, the degree of gradation control data generation and update can be adjusted by increasing or decreasing the numerical value.

When the gradation control data generation_determination data is larger than the gradation control data generation_determination data (step S406; Yes), the CPU 301 sets a gradation control data generation request flag (step S402). That is, in any one of the LDs 11 to 13, if the gradation control data generation_determination data exceeds the allowable value, the current threshold value may change depending on the temperature, and an image may not be displayed with appropriate luminance. Therefore, gradation control data is forcibly generated for all colors.
On the other hand, when the gradation control data generation_determination data is equal to or less than the gradation control data generation_determination data (step S406; No), the CPU 301 sets the determination color flag in the comparison completion flag stored in the storage unit 302. It is established (step S407).

  Subsequent to step S407, the CPU 301 determines whether or not the comparison completion flag is satisfied for all the colors R, G, and B (step S408). If at least one of the comparison completion flags is not established among R, G, and B (step S408; No), the CPU 301 returns to step S404 to make a determination about the color that is not established in the comparison completion flag.

On the other hand, when the comparison completion flags are all established (step S408; Yes), the CPU 301 lowers the comparison completion flags for all the colors (step S409), and finishes the threshold output control data comparison processing. The “tone control data generation process” is executed (step S500). This process includes the processes in steps S501 to S526 shown in FIGS.
Hereinafter, the gradation control data generation process will be described.

(Tone control data generation processing)
In the gradation control data generation process (step S500), the CPU 301 generates gradation control data using the gradation control data generation request flag created in the threshold output control data comparison process (step S400).

First, the CPU 301 determines whether or not the gradation control data generation request flag stored in the storage unit 302 is set (step S501). When the gradation control data generation request flag is not set (step S501; No), the gradation control data generation process ends.
On the other hand, when the gradation control data generation request flag is set (step S501; Yes), the CPU 301 stores the I / L primary acquisition flag, I / L start_output control data, which are stored in the storage unit 302 in advance. R, G, B minimum luminance_output control data, R, G, B maximum luminance_output control data, and I / L sampling values are initialized (step S502). These data will be described later.

Subsequently, the CPU 301 determines whether or not the current scan is outside the execution area (step S503).
The determination method is the same as in step S302 described above. When it is determined that the scan is not outside the execution area (step S503; No), the CPU 301 waits until the scan in the display area 40a or the blanking period 30b ends. To do.
On the other hand, if the scan is outside the execution area (step S503; Yes), the CPU 301 performs the process of step S504.

In step S504, the CPU 301 obtains R, G, B minimum luminance_output control data and R, G, B maximum luminance_output control data from the I / L primary acquisition flag stored in the storage unit 302 in advance. Determine the color to get. In the gradation control data generation process, the color determined in step S504 is also simply referred to as “determined color” below.
The “I / L primary acquisition flag” is an R, G, B color flag, and is composed of 3 bits of 1 bit for each color. The color determination method is determined based on the establishment / non-establishment information of each color indicated by the I / L primary acquisition flag and the priority of R>G> B. Here, I / L is described as an abbreviation of the current-light intensity characteristic of the LD, that is, the slope when the light intensity is L and the current value is I.
“Minimum luminance of R, G, B_output control data” indicates a current value corresponding to the minimum light intensity value in the stable oscillation region of each of LD 11 to 13.
“Maximum brightness of R, G, B_output control data” indicates a current value corresponding to the maximum light intensity value in consideration of the white balance of each of LD 11 to 13.
The minimum luminance_output control data for R, G, and B and the maximum luminance_output control data for R, G, and B are composed of 10-bit data for each of R, G, and B. Both of them become sampling data necessary for calculating gradation control data.

  Subsequently, the CPU 301 turns on the power supply unit 102, then sets R, G, B output control data to 0, and sends the output control data to the first drive unit 101 (step S505).

Subsequently, the CPU 301 calculates I / L start_output control data for the determined color in “R, G, B I / L start_output control data” stored in the storage unit 302 in advance (step S506). ).
“I / L start_output control data” is composed of 10 bits for each color of R, G, and B, and as shown in the following (Equation 4), it is an arbitrary value predetermined in the current color_threshold output control data of the determined color It is obtained by adding a value (for example, 5). The I / L start_output control data indicates a value at which the LD stably starts laser oscillation beyond the unstable oscillation region. In addition, it is possible to cope with a change in the bit of the light source characteristics and the output control data by appropriately adjusting an arbitrary value.
The CPU 301 sends the calculated I / L start output control data to the first drive unit 101 as output control data.

  Subsequently, the CPU 301 sends data of a value obtained by adding “1” to the color output control data determined in step S504 to the first drive unit 101 (step S507), and the light intensity information from the light intensity detection unit 20. (Indicating the current light intensity) is acquired (step S508).

Subsequently, the CPU 301 compares the acquired light intensity information with the minimum light intensity information of the determined color in the “minimum light intensity information of R, G, B” stored in advance in the storage unit 302 (step S509). .
“Minimum light intensity information of R, G, B” is data indicating the minimum light intensity value in the stable oscillation region of each of LD 11 to 13, and is composed of 10 bits each.

  In step S509, a predetermined range for the minimum light intensity information of the determined color (for example, a range of “± 3” with respect to the value indicated by the minimum light intensity information of the determined color) is set as an allowable range, and the CPU 301 performs step S508. If the light intensity information acquired in step S5 is outside the allowable range (step S509; No), the process returns to step S507 and the output control data increase and the light intensity information acquisition are repeated until the light intensity information is within the allowable range.

  On the other hand, when the light intensity information acquired in step S508 is within the allowable range (step S509; Yes), the CPU 301 sets the output control data (that is, the current output control data) created in the latest step S507 to the minimum. The data to be written to the luminance_output control data is determined (step S510).

  That is, the CPU 301 acquires the light intensity information by adding the output control data to be output to the LD related to the determined color from 0 to 1 (by gradually adding from the minimum value) by the processing of step S507 to step S509, When the acquired light intensity information is within a predetermined allowable range, the current output control data is determined as data to be written in the minimum luminance_output control data.

Subsequently, the CPU 301 adds the output control data determined in step S510 to the minimum luminance_output control data of the determined color in “R, G, B minimum luminance_output control data” stored in the storage unit 302 in advance. Averaged and written (step S511).
In the averaging process, as shown in the following (Equation 5), the sum of the output control data determined in step S510 and the minimum luminance of the determined color_output control data is divided by 2 (note that the first time is 1 only) To be executed). By averaging in this way, the minimum light intensity value in the stable oscillation region can be stably acquired even if the light intensity detector 20 is erroneously detected.

  Subsequently, the CPU 301 sends data having a value obtained by adding “1” to the output control data of the color determined in step S504 to the first driving unit 101 (step S512), and the light intensity information from the light intensity detecting unit 20. Is acquired (step S513).

Subsequently, the CPU 301 compares the acquired light intensity information with the maximum light intensity information of the determined color in the “maximum light intensity information of R, G, B” stored in advance in the storage unit 302 (step S514). .
“Maximum light intensity information of R, G, B” is data indicating the maximum light intensity value in consideration of the white balance of each of LD 11 to 13, and is composed of 10 bits each.

  In step S514, a predetermined range for the maximum light intensity information of the determined color (for example, a range of “± 3” for the value indicated by the maximum light intensity information of the determined color) is set as an allowable range, and the CPU 301 performs step S513. If the light intensity information acquired in step S5 is outside the allowable range (step S514; No), the process returns to step S512, and the output control data increase and the light intensity information acquisition are repeated until the light intensity information is within the allowable range.

  On the other hand, when the light intensity information acquired in step S513 is within the allowable range (step S514; Yes), the CPU 301 sets the output control data (that is, the current output control data) created in the latest step S512 to the maximum. The data to be written in the luminance_output control data is determined (step S515).

  That is, the CPU 301 acquires the light intensity information while adding the output control data output to the LD related to the determined color one by one from 0 through the processing of steps S512 to S514, and the acquired light intensity information is predetermined. If it is within the allowable range, the current output control data is determined as data to be written in the maximum luminance_output control data.

Subsequently, the CPU 301 outputs the output control data determined in step S515 to the maximum brightness_output control data of the determined color in “R, G, B maximum brightness_output control data” stored in the storage unit 302 in advance. Averaged and written (step S516).
In the averaging process, as shown in the following (Equation 6), the sum of the output control data determined in step S515 and the maximum luminance of the determined color_output control data is divided by 2 (note that the first time is 1 only) To be executed). By averaging in this way, the maximum light intensity value in the stable oscillation region can be stably acquired even if the light intensity detector 20 is erroneously detected.

  Subsequently, the CPU 301 sets (establishes) a determination color flag in the I / L primary acquisition flag stored in the storage unit 302 (step S517).

  Through the processing from step S504 to step S517, “minimum luminance_output control data” and “maximum luminance_output control data” of the LD (any one of LD11 to 13) related to the determined color are obtained (FIG. 14). reference).

  Subsequently, as shown in FIG. 12, the CPU 301 determines whether or not the I / L primary acquisition flag is established for all the colors R, G, and B (step S518). When at least one of the R / G / B primary acquisition flags is not established (step 518; No), the CPU 301 returns to step S504 to determine that the I / L primary acquisition flag is not established. , The process from step S504 to step S517 is executed.

On the other hand, when the I / L primary acquisition flag is established for all of R, G, and B (step S518; Yes), the CPU 301 adds 1 to the I / L sampling value stored in the storage unit 302 (step S519). .
The “I / L sampling value” is data for counting the number of sampling times of the minimum luminance_output control data and the maximum luminance_output control data. This data indicates how many sets have passed when one set is made until all three colors of R, G, and B are established in the primary acquisition flag for I / L. For example, the I / L sampling value is composed of 3 bit data and can count up to 8 sets.

  Subsequently, the CPU 301 lowers the I / L primary acquisition flag for all the colors (step S520).

Subsequently, the CPU 301 determines whether or not the I / L sampling value is greater than or equal to the second gradation control adjustment value stored in advance in the storage unit 302 (step S521).
The “second gradation control adjustment value” is data indicating an arbitrary value that determines how many times the acquisition of the minimum luminance_output control data and the maximum luminance_output control data for R, G, and B is performed. Since the second gradation control adjustment value indicates the R, G, B current_threshold output control data averaging count, R, G, B minimum luminance_output control data and maximum luminance_output If it is desired to increase the accuracy of the control data, the second gradation control adjustment value is increased. If it is desired to proceed to the next gradation control data update process (step S600) quickly, the second gradation control adjustment value is decreased. Just do it.

  When the I / L sampling value is less than the second gradation control adjustment value (step S521; No), the CPU 301 returns to step S504 to perform processing.

On the other hand, when the I / L sampling value is equal to or greater than the second gradation control adjustment value (step S521; Yes), the CPU 301 is based on the minimum luminance_output control data and the maximum luminance_output control data of R, G, B. R, G, B gradation control data is generated (step S522).
Hereinafter, the gradation control data generation method will be described with reference to FIGS.

First, the gradation control data will be described with reference to the table shown in FIG.
As shown in FIG. 15, the “gradation control data area” is classified into a low gradation area and a main gradation area. 15 and 16, the minimum bit in the main gradation region is defined as the minimum oscillation gradation bit, and the maximum bit is defined as the maximum oscillation gradation bit. The minimum oscillation gradation bit is the minimum luminance_output control data acquired in steps S508 to S511. The minimum oscillation gradation bit may be different for each of the LDs 11 to 13. This is because it is related to the ratio of the minimum luminance_output control data and the maximum luminance_output control data of each of LD 11 to 13. The maximum oscillation gradation bit is maximum luminance_output control data acquired in steps S513 to S516.
The “number of gradations” is set to 6 bits, that is, 64 levels, for each color of R, G, B on the general gradation characteristic curve shown in FIG.
“Light intensity data” indicates light intensity values in 64 levels suitable for the LDs 11 to 13 respectively.
The gradation control data area, the number of gradations, and the light intensity data are stored in the storage unit 302 as numerical values that do not change for each of R, G, and B.

Next, the gradation control data generation procedure will be described.
(I) Main gradation area In the steps so far, the minimum luminance_output control data and the maximum luminance_output control data are obtained. Thereafter, the CPU 301 calculates the inclination α in the LD stable oscillation region shown in FIG.
The slope α is obtained by the following equation (Equation 7). The value indicated by the maximum light intensity information is Lmax, the value indicated by the minimum light intensity information is Lmin, the value indicated by the maximum brightness_output control data is Imax, and the value indicated by the minimum brightness_output control data is Imin.

  Then, Xn with respect to the value Ln indicated by the light intensity data in the main gradation region is calculated by the following equation (Equation 8), and the minimum luminance_output is output to the calculated Xn, as in the equation (Equation 9). By adding the control data Imin, the current_gradation control data In in the main gradation area is obtained. Note that n represents the number of gradations corresponding to any one of “minimum oscillation gradation bit” to “maximum oscillation gradation bit” shown in FIG.

(Ii) Low Gradation Area Next, a method for calculating current_gradation control data in the low gradation area will be described.
First, Duty_m is calculated based on the value Lm indicated by the light intensity data in the low gradation region and the minimum luminance_output control data Imin from the following equation (Equation 10). Note that m represents the number of gradations corresponding to any one of “0” to “one gradation below the minimum oscillation gradation bit” shown in FIG.

  Then, the minimum luminance_output control data Imin is modulated by the calculated Duty_m to drive the LDs 11 to 13 (PWM driving). That is, the current_tone control data in the low tone area is generated as indicating Duty_m and the minimum luminance_output control data Imin.

  As described above, according to the HUD device 1, the LDs 11 to 13 are driven by the PAM drive and the PWM drive method based on the current value in the stable oscillation region (in other words, the LD with the current threshold that may cause unstable oscillation). Therefore, the display brightness of the image becomes stable.

  Returning to FIG. 12, when the gradation control data for each color is calculated (generated) by the above method, the CPU 301 stores the current_gradation control data of R, G, B stored in the storage unit 302 in advance. The gradation control data of each color R, G, B generated in step S522 is written (step S523).

Subsequently, the CPU 301 resets the I / L sampling value to 0 (step S524) and sets a gradation control data update request flag stored in advance in the storage unit 302 (step S525).
The “gradation control data update request flag” is 1-bit data, and is data for determining whether or not the gradation control data is updated in the gradation control data update process (step S600).

Then, the CPU 301 lowers the gradation control data generation request flag stored in the storage unit 302 (step S526), ends the gradation control data generation process, and executes the next "gradation control data update process" ( Step S600). This process includes the processes in steps S601 to S605 shown in FIG.
Hereinafter, the gradation control data update process will be described.

(Gradation control data update process)
In the gradation control data update process (step S600), the current_gradation control data created by the gradation control data generation process (step S500) is reflected in the actual gradation control.

  First, the CPU 301 determines whether or not the gradation control data update request flag stored in the storage unit 302 is set (step S601). When the gradation control data update request flag is not set (step S601; No), the gradation control data update process ends.

On the other hand, when the gradation control data update request flag is set (step S601; Yes), the CPU 301 determines whether or not an update start trigger is detected (step S602).
Here, the update start trigger is detected based on information from the mirror position detection unit 202, and the CPU 301 has detected, for example, the start point (point T shown in FIG. 6) of the blanking period 30b as the update trigger. Is determined. Thereby, the gradation control data can be reliably updated before the start of scanning of the display area 40a.
The CPU 301 stagnates step S602 until it detects an update start trigger (step S602; No), and when it detects an update start trigger (step S602; Yes), it executes the process of the next step S603.

  In step S <b> 603, the CPU 301 rewrites the in-control R_G / B gradation control data stored in the storage unit 302 to the current_gradation control data R, G, B (that is, R, G, B). B) Rewrite all colors. Subsequently, in step S604, the CPU 301 rewrites the R_G_B in-control_threshold output control data stored in the storage unit 302 to R_G_B current_threshold output control data (that is, R , G, B for all colors). In this way, the comparison target of the threshold output control data from the next time is updated.

  When the data is updated as described above, the CPU 301 lowers the gradation control data update request flag stored in the storage unit 302 (step S605) and ends the gradation control data update process. Thereafter, until the power of the HUD device 1 is turned off (for example, the vehicle is turned off in response to the start switch of the vehicle 2 being turned off), the CPU 301 repeatedly executes the processing from step S300 to step 600.

The above is the gradation control process. The flow of this process is briefly described as follows.
First, in the threshold determination / output control data acquisition process (step S300), R_G_B current_threshold output control data is acquired. That is, the threshold value at which the LDs 11 to 13 perform laser oscillation is determined.
Next, in the threshold output control data comparison process (step S400), R, G, B in control_threshold output control data and R, G, B current_threshold output control data are converted into R, G, B A comparison is made for each color to determine whether or not gradation control data can be generated. In the threshold output control data comparison process (step S400), the process transitions to (step S501; No) and (step S601; No) until it is determined that generation of gradation control data is necessary. The output control data acquisition process (step S300) and the threshold output control data comparison process (step S400) are repeated.
Only when it is determined in the threshold output control data comparison process (step S400) that gradation control data generation is necessary, the process proceeds to the gradation control data generation process (step S500) to newly generate gradation control data. To do.
In the gradation control data update process (step S600), the gradation control data is surely updated before the display area 40a is scanned.

[Second Embodiment]
In the first embodiment, gradation control data is generated for all colors of R, G, and B when necessary in the gradation control process. From here, a second embodiment in which the gradation control data is generated by separating each color will be described. The configuration of the HUD device 1 and the flow of gradation control processing (see FIG. 7) are the same as those in the first embodiment. Each process constituting the gradation control process is different from the first embodiment. Therefore, in the following, steps similar to those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted as appropriate, and processing different from that in the first embodiment will be mainly described.

The processing from step S100 to step S300 shown in FIG. 7 is the same as that in the first embodiment.
When the threshold value determination / output control data acquisition process (step S300) is completed, the CPU 301 executes a threshold value output control data comparison process shown in FIG.

(Threshold output control data processing)
In the threshold output control data comparison process according to the second embodiment, the CPU 301 performs the R_G_B current_threshold output control data and R, G, B acquired in the threshold determination / output control data acquisition process (step S300). The B control in progress_threshold output control data is compared for each color, and a tone control data generation request is issued for each color.

As shown in FIG. 17, first, the CPU 301 makes a determination at startup (step S401).
If all in-control_threshold output control data is 0 (step S401; Yes), the CPU 301 sets a gradation control data generation request flag stored in advance in the storage unit 302 for all colors (step S2402). The gradation control data generation request flag here is composed of 3 bits each of R, G, and B1 bits.

  On the other hand, if the in-control_threshold output control data is not 0 among RGB colors (step S401; No), the CPU 301 executes the processes of steps S403 to S405 as in the first embodiment.

  Subsequently, the CPU 301 calculates the gradation control data generation_determination data relating to the determined color in the R, G, B gradation control data generation_determination data stored in the storage unit 302 in advance, and calculation in step S405. The generated gradation control data_determination data is compared (step S2406). About the comparison method of both data, it is the same as that of 1st Embodiment.

When the gradation control data generation_determination data is larger than the gradation control data generation_determination data (step S2406; Yes), the CPU 301 sets the color flag determined in step S404 in the gradation control data generation request flag. (Step S2407), the process of step S407 is executed.
On the other hand, when the gradation control data generation_determination data is equal to or less than the gradation control data generation_determination data (step S2406; No), the CPU 301 executes the process of step S407.

  The processing from step S407 to step S409 is the same as in the first embodiment. When the threshold value determination / output control data acquisition process (see FIG. 17) is finished, the CPU 301 executes the gradation control data generation process shown in FIGS.

(Tone control data generation processing)
In the gradation control data generation process according to the second embodiment, gradation control data generation is performed for a color for which a gradation control data generation request has been made, using a gradation control data generation request flag.

As shown in FIG. 18, first, the CPU 301 determines whether or not at least one gradation control data generation request flag stored in the storage unit 302 is set (step S2501). When the gradation control data generation request flag is not set (step S2501; No), the gradation control data generation process ends.
On the other hand, when even one gradation control data generation request flag is set (step S2501; Yes), the process of step S502 is executed.

  Subsequent to step S502, the CPU 301 determines a color for which there is no tone generation request from the tone control data generation request flag (step S2502). In the following, a color determined to be a color for which no tone generation request is made is referred to as a “non-requested color”.

  Subsequent to step S2502, the CPU 301 determines whether or not the current scan is outside the execution area (step S503). When it is determined that the scan is outside the execution area (step S503; No), the CPU 301 waits until the scan in the display area 40a or the blanking period 30b ends.

  On the other hand, if scanning is outside the execution area (step S503; Yes), the CPU 301 sets a flag for non-requested colors in the I / L primary acquisition flag stored in the storage unit 302 in advance (step S2503).

  Subsequent to step S2503, the CPU 301 determines the minimum luminance_output control data for R, G, B and the maximum luminance_output control for R, G, B from the I / L primary acquisition flag stored in advance in the storage unit 302. The color from which data is acquired is determined (step S2504). Here, the CPU 301 determines a bit of a color for which no flag is set in the I / L primary acquisition flag, and determines a color based on a priority of R> G> B.

After executing the process of step S2504, the CPU 301 executes the processes of step S505 to step S517 similar to those in the first embodiment. Then, as shown in FIG. 19, the CPU 301 determines whether or not the I / L primary acquisition flag is established for all the colors R, G, and B (step S518).
If the I / L primary acquisition flag is not all R, G, B (step 518; No), the CPU 301 returns to step S2503 shown in FIG. Steps S2504 and S505 to S517 are executed.

  On the other hand, when all of the R / G / B primary acquisition flags are established (step S518; Yes), the CPU 301 adds 1 to the I / L sampling value stored in the storage unit 302 (step S519). The I / L primary acquisition flag is lowered for each color (step S520).

  Subsequently, the CPU 301 determines whether or not the I / L sampling value is greater than or equal to the second gradation control adjustment value stored in advance in the storage unit 302 (step S521).

  When the I / L sampling value is less than the second gradation control adjustment value (step S521; No), the CPU 301 returns to step S2503 shown in FIG.

  On the other hand, when the I / L sampling value is greater than or equal to the second gradation control adjustment value (step S521; Yes), the CPU 301 executes the processing from step S522 to step S524 similar to the first embodiment.

Subsequently, the CPU 301 sets a gradation control data update request flag stored in advance in the storage unit 302 (step S2525).
The “gradation control data update request flag” here is composed of 3 bits of 1bi for each color of R, G, B, and whether or not to update the gradation control data in the subsequent gradation control data update processing. It is data for judging.

  Then, the CPU 301 lowers the gradation control data generation request flag stored in the storage unit 302 for all the colors (step S2526), ends the gradation control data generation process, and the floor according to the second embodiment shown in FIG. The key control data update process is executed.

(Gradation control data update process)
First, the CPU 301 determines whether or not any gradation control data update request flag stored in the storage unit 302 is set (step S2601). If no gradation control data update request flag is set (step S2601; No), the gradation control data update process ends.

  On the other hand, when the gradation control data update request flag is set (step S2601; Yes), the CPU 301 determines the color that needs to be updated from the gradation control data update request flag, and the update necessary color. (Step S2602).

  In step S602, the CPU 301 determines whether an update start trigger has been detected (step S602). The CPU 301 stagnates step S602 until it detects an update start trigger (step S602; No), and when it detects an update start trigger (step S602; Yes), it executes the processing of the next step S2603.

  In step 2603, the CPU 301 controls the R_G, B in control_gradation control data stored in the storage unit 302 _the current control_gradation control data for the update required color determined in step S <b> 2602 _ Rewrite to gradation control data.

  Subsequently, in step S <b> 2604, the CPU 301 stores the R_G, B in control_threshold output control data stored in the storage unit 302, while controlling the update required color determined in step S <b> 2602 _threshold output control data. This time, it is rewritten to _threshold output control data. In this way, the comparison target of the threshold output control data from the next time is updated.

  When the data is updated as described above, the CPU 301 lowers the gradation control data update request flag stored in the storage unit 302 for each color (step S2605), and ends the gradation control data update process.

  In the gradation control process according to the second embodiment described above, the process proceeds to the gradation control data generation process only when it is determined in the threshold output control data comparison process that gradation control data generation is necessary even for one color, The tone control data is newly generated only for the color requested to generate the tone control data.

  According to the HUD device 1 according to the first and second embodiments described above, as described above, the LDs 11 to 13 are driven based on the current value in the stable oscillation region (in other words, unstable oscillation occurs). Since it is possible to avoid driving the LD with a current threshold that may cause a problem, the display brightness of the image becomes stable. Further, since the current-light intensity characteristics during the driving of the LDs 11 to 13 are calculated based on the sensing by the light intensity detection unit 20 and can be reflected in the drive control of the LD, a large number of sensing and complex gradation data are required. Correction can be avoided. In addition, the current-luminescence intensity characteristics of laser light sources are temperature-dependent, but there is no linearity with respect to temperature changes, so the problem is that the temperature sensor cannot reflect the characteristics well. However, according to the above configuration, the gradation control data can be updated in a form that takes linearity into account by monitoring the amount of change in the current threshold (Ith). In addition, since each process (threshold judgment / output control data acquisition process, threshold output control data comparison process, gradation control data generation process, gradation control data update process) is separated, it is possible to execute each process. Judgment is possible. In addition, since each process can be started from the optimum timing, it does not adversely affect the display image, can be avoided after judging unnecessary work, and efficient gradation control is possible.

[Modification]
In addition, this invention is not limited by the above 1st, 2nd embodiment and drawing. Changes (including deletion of constituent elements) can be added to the embodiments and the drawings as appropriate without departing from the scope of the present invention. Below, an example of a modification is described.

  The update start trigger in step S602 is not limited to the start point of the blanking period 30b. Any update start trigger may be used as long as the update operation can be surely completed before the scanning of the display area 40a is started, and the update start trigger includes the end point of the return line period 30b, the start point of the non-display area 40b, and the vertical non-direction. It may be the end point of the display area 40a in the display area 40b.

In the above threshold determination / output control data acquisition process, a current that gradually increases from a current value smaller than the current threshold is supplied to the LD, and the amount of change from the previous value to the current value of the emission intensity is indicated. Although the current value when the threshold value determination data exceeds the threshold value determination data indicating a predetermined amount determined in advance (step S309; Yes) is determined as the current threshold value, the present invention is not limited to this.
A threshold value indicating a predetermined amount by which threshold judgment data indicating a change amount of the light emission intensity from the previous value to the current value is supplied to the LD with a current that gradually decreases from a current value larger than the current threshold value. You may make it judge the electric current value when it becomes below decision data as an electric current threshold value.

  Further, in the above embodiment, three LDs are disposed, and these emit laser beams R, G, and B, respectively, but the number of LDs is not limited to this. By arranging four LDs, the image M may be generated with four primary colors, or the image M may be generated with one LD.

  In the above description, the example in which the display light L is reflected by the first reflection unit 60 and the second reflection unit 70 and reaches the windshield 3 has been described, but the present invention is not limited thereto. The display light L from the screen 40 may be emitted toward the windshield 3 or the combiner dedicated to the apparatus without passing through such a reflection portion.

  In the above description, an example of a vehicle on which the HUD device 1 is mounted is a vehicle, but is not limited thereto. The HUD device 1 can also be installed on other vehicles (ships, airplanes, etc.). Furthermore, it is not restricted to what is installed in a vehicle.

  In the above, the example in which the HUD device 1 is configured integrally with the dashboard of the vehicle has been described. However, the HUD device 1 is, for example, a stationary type (retrofitted type) installed on the dashboard of the vehicle. May be.

  In the above, the HUD device 1 has been described as an example of the display device, but the present invention is not limited to this. Other display devices (car navigation device, portable terminal device, etc.) may be used. However, since the HUD device allows the display image to be visually recognized overlaid on the background (landscape), it is particularly necessary to adjust the display brightness, and since it is often mounted on the vehicle, the temperature change is particularly severe. In view of the above, the HUD device is suitable as the display device that executes the gradation control process as described above.

  In the above description, in order to facilitate the understanding of the present invention, the description of known unimportant technical matters is appropriately omitted.

1 HUD device 10 Laser beam emitting section 11, 12, 13 Laser diode (LD)
20 light intensity detection unit 30 MEMS mirror 30a actual scanning period 30b blanking period 40 screen 40a display area 40b non-display area 100 LD control unit 101 first drive unit 102 power supply unit 200 scan control unit 201 second drive unit 202 mirror position detection Unit 300 main control unit 301 CPU
302 Memory 2 Vehicle 3 Windshield 4 Observer M Image L Display Light V Virtual Image

Claims (5)

A display device comprising: a light source that emits laser light having an intensity according to a supplied current; and a scanning unit that displays a predetermined image on a display unit by scanning the laser light emitted from the light source,
A light intensity detection means for detecting the emission intensity of the laser light emitted from the light source;
Current supply means for supplying the light source with a current that gradually increases from a current value that is smaller than a current threshold that is a current value at which the light source oscillates;
Based on the light emission intensity of the light source by the current supply from the current supply means detected by the light intensity detection means, a change amount of the light emission intensity of the light source with respect to a change amount in a predetermined period of the current supplied by the current supply means. In-drive threshold acquisition means for sequentially acquiring and acquiring the current value when the acquired amount of change in emission intensity exceeds a predetermined amount as the in-drive current threshold;
Light source driving means for driving the light source by supplying a current having a value larger than the driving current threshold acquired by the driving threshold acquisition means;
A display device characterized by that. The light source driving means includes
When the difference between the driving current threshold acquired by the driving threshold acquisition means and a predetermined current threshold exceeds a predetermined value, a current having a value larger than the driving current threshold is supplied. Driving the light source;
When the difference between the driving current threshold acquired by the driving threshold acquisition unit and the predetermined current threshold is equal to or less than the predetermined value, a current having a value larger than the predetermined current threshold is supplied to drive the light source. To
The display device according to claim 1. The light source driving means includes
Based on the first current value and the second current value that are larger than the driving current threshold acquired by the driving threshold acquisition unit, a current-light emission intensity characteristic of the light source being driven is calculated and calculated. Adjusting the current supplied to the light source based on the current-luminescence intensity characteristic.
The display device according to claim 1 or 2. The light source driving means includes
When the difference between the driving current threshold acquired by the driving threshold acquisition unit and a predetermined current threshold exceeds a predetermined value, the light source is controlled based on the calculated current-luminescence intensity characteristic. Adjust the current supplied,
When the difference between the driving current threshold acquired by the driving threshold acquisition means and the predetermined current threshold is equal to or smaller than the predetermined value, the light source is based on a predetermined current-light emission intensity characteristic of the light source. Adjust the current supplied to the
The display device according to claim 3. A display device comprising: a light source that emits laser light having an intensity according to a supplied current; and a scanning unit that displays a predetermined image on a display unit by scanning the laser light emitted from the light source,
A light intensity detection means for detecting the emission intensity of the laser light emitted from the light source;
Current supply means for supplying the light source with a current that gradually decreases from a current value that is larger than a current threshold value that is a current value that causes the laser to oscillate;
Based on the light emission intensity of the light source by the current supply from the current supply means detected by the light intensity detection means, a change amount of the light emission intensity of the light source with respect to a change amount in a predetermined period of the current supplied by the current supply means. In-drive threshold value acquisition means for sequentially acquiring and acquiring the current value when the acquired amount of change in the emission intensity is equal to or less than a predetermined amount as a driving current threshold value;
Light source driving means for driving the light source by supplying a current having a value larger than the driving current threshold acquired by the driving threshold acquisition means;
A display device characterized by that.