Drawing device for vehicle

Abstract

To provide a drawing device for a vehicle that can improve visibility of drawing under a bright environment.SOLUTION: Provided is a drawing device 1 for a vehicle mounted in a vehicle 100 and including: a light source part that includes a plurality of light sources that emit pieces of light having different wavelengths and emits drawing light L of a color tone according to a ratio of pieces of light emitted from each light source; a scanning part that scans the drawing light L emitted from the light source part and forms a drawing pattern P; and a control part that controls the plurality of light sources to be turned on to control the color tone and the drawing pattern P of the drawing light L to be variable. When an outer light illuminance of an emission range to which the drawing light L is emitted exceeds a threshold, the control part turns off one light source that emits the longest wavelength among the plurality of light sources and control the other light sources to be turned on.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drawing device for a vehicle. [Background technology]

[0002] In recent years, laser light sources such as laser diodes (LDs) capable of producing high-brightness, high-output light have been used to project drawings onto road surfaces and the like while scanning the laser light emitted from the laser light source (see, for example, Patent Document 1 below).

[0003] Furthermore, some laser light sources are configured with an LD package including a red LD chip that emits red light, a green LD chip that emits green light, and a blue LD chip that emits blue light.

[0004] In such a laser light source, it is possible to control the ratio of red light, green light, and blue light emitted by each LD chip in the LD package, and to arbitrarily change the color tone (emission color) of the laser light obtained by combining (mixing) these colored lights. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-122365 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in order to improve the visibility of images in bright environments such as daytime, it is necessary to perform drawing by increasing the output of the laser light.

[0007] On the other hand, an investigation into the effect of the drive current on the output of laser light revealed that the output of the red LD chip is more susceptible to the effects of temperature than the output of the green LD chip and blue LD chip mentioned above, and that the temperature of the LD chip is also more likely to rise as the drive current increases, resulting in a decrease in the light extraction efficiency from the LD chip and insufficient output being obtained even when the drive current is increased.

[0008] For this reason, in a conventional drawing device or drawing system, even if the output of the three colors of laser light from the red LD chip, green LD chip, and blue LD chip is increased simultaneously, the output of the red LD chip cannot keep up, and the brightness of the drawing is insufficient, the chromaticity is deviated from the intended chromaticity, and contrast is insufficient, making it difficult to improve visibility. For this reason, drawing is generally performed in a dark environment such as at night.

[0009] The present invention has been proposed in view of the above-mentioned conventional circumstances, and has an object to provide a drawing device for a vehicle that is capable of improving the visibility of drawings in bright environments. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides the following means. [1] A vehicle-mounted drawing device, a light source unit including a plurality of light sources emitting light of different wavelengths, the light source unit emitting drawing light of a color tone corresponding to a ratio of light emitted from each light source; a scanning unit that forms a drawing pattern by scanning the drawing light emitted from the light source unit; a control unit that variably controls a color tone of the drawing light and the drawing pattern by controlling lighting of the plurality of light sources, The control unit is characterized in that, when the external light illuminance in the irradiation range where the drawing light is irradiated exceeds a threshold value, it turns off one of the multiple light sources that emits light with the longest wavelength, and controls the lighting of the other light sources. [2] The vehicle drawing device described in [1], wherein the control unit performs control to increase the output of the other light sources when the external light illuminance exceeds a threshold value compared to before the threshold value is exceeded. [3] The light source unit includes a red light source that emits red light, a green light source that emits green light, and a blue light source that emits blue light, The control unit is characterized in that, when the external light illuminance exceeds a threshold value, it turns off the red light source and controls the lighting of the green light source and the blue light source. [4] The imaging device for a vehicle according to [1], wherein the wavelength of the light emitted by the one light source is 620 nm or more. [5] The vehicle imaging device according to [1], wherein the wavelength of the light emitted by the other light source is 565 nm or less. [6] The imaging device for a vehicle according to [5], wherein the other light source includes at least a GaN-based light-emitting element. [7] The other light source includes a green light source that emits green light and a blue light source that emits blue light, the green light source includes a GaN-based or InGaN-based light-emitting element; The vehicle imaging device according to [6], wherein the blue light source includes a GaN-based light-emitting element. [8] The vehicle drawing device according to [1], wherein the drawing pattern is formed by a border drawing pattern or a negative-positive drawing pattern obtained by using lights of different colors. [9] The vehicle imaging device according to [1], wherein the plurality of light sources are laser light sources.

[10] The vehicle drawing device described in [1], wherein the control unit determines whether or not the external light illuminance detected by an illuminance sensor mounted on the vehicle exceeds a threshold value.

[11] The vehicle drawing device described in [1], wherein the control unit determines whether the external light illuminance exceeds a threshold value based on external light illuminance information supplied via a communication unit installed in the vehicle.

[12] The control unit sets a first threshold and a second threshold higher than the first threshold, When the external light illuminance exceeds the first threshold, the drawing light is set to a first color tone; The vehicle drawing device described in [1] is characterized in that, when the external light illuminance exceeds the second threshold, the drawing light is controlled to be a second color tone having a higher hue or saturation contrast than the first color tone.

[13] The drawing light of the first color tone is a monochromatic light obtained by mixing green light, blue light, or green light and blue light, The drawing light of the second color tone is green light, blue light, or a monochromatic light obtained by mixing green light and blue light, having a contrast with a higher hue or saturation than the drawing light of the first color tone.

[14] The vehicle drawing device according to [1], characterized in that the drawing pattern is projected onto a road surface.

[15] The vehicle drawing device according to [1], characterized in that the drawing pattern is projected onto a vehicle body. Effect of the Invention

[0011] As described above, according to the present invention, a drawing device for a vehicle is provided that is capable of improving the visibility of a drawing in a bright environment. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an example of road surface drawing performed by a vehicle drawing device according to an embodiment of the present invention; [Diagram 2] 1 is a block diagram showing a configuration of a drawing device for a vehicle; [Diagram 3] 2 is a schematic diagram showing the configuration of a light source unit and a scanning unit included in the vehicle imaging device; FIG. [Figure 4] FIG. 2 is a schematic diagram showing a configuration of a light source unit. [Diagram 5] FIG. 4 is a flowchart for explaining road surface drawing by the vehicle drawing device. [Figure 6]1 is a schematic diagram illustrating a drawing pattern by a drawing device for a vehicle; [Figure 7] FIG. 11 is a flowchart for explaining an application example of road surface drawing by the vehicle drawing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make each component easier to see, the dimensions of the components may be shown at different scales, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0014] As an embodiment of the present invention, a vehicle drawing device 1 shown in, for example, FIGS. 1 to 7 will be described.

[0015] FIG. 1 is a schematic diagram showing an example of road surface drawing by the vehicle drawing device 1. FIG. 2 is a block diagram showing the configuration of the vehicle drawing device 1. FIG. 3 is a schematic diagram showing the configuration of the light source unit 2 and the scanning unit 3 provided in the vehicle drawing device 1. FIG. 4 is a schematic diagram showing the configuration of the light source unit 2. FIG. 5 is a flowchart for explaining road surface drawing by the vehicle drawing device 1. FIG. 6 is a schematic diagram illustrating a drawing pattern P by the vehicle drawing device 1. FIG. 7 is a flowchart for explaining an application example of road surface drawing by the vehicle drawing device 1.

[0016] The vehicle drawing device 1 of this embodiment is installed on the door mirror 101 of a vehicle 100, as shown in FIG. 1, and performs road surface drawing by projecting a drawing pattern P, such as letters or images, using drawing light L irradiated toward the road surface T on the side of the vehicle when the vehicle is stopped.

[0017] In this embodiment, the drawing pattern P is displayed as the word "welcome" to the passenger H.

[0018] Specifically, the vehicle imaging device 1 includes a light source unit 2, a scanning unit 3, and a control unit 4 electrically connected to the light source unit 2 and the scanning unit 3, as shown in FIGS.

[0019] As shown in FIG. 4, the light source unit 2 includes multiple (three in this embodiment) light sources 5R, 5G, and 5B that emit light of different wavelengths, and emits drawing light L of a color tone (emission color) according to the proportion of light emitted from each light source 5R, 5G, and 5B.

[0020] The light source section 2 of this embodiment is composed of an LD package including a red LD chip (red light source) 5R that emits red light RL, a green LD chip (green light source) 5G that emits green light GL, a blue LD chip (blue light source) 5B that emits blue light BL, a first dichroic mirror 6B that reflects the blue light BL, a second dichroic mirror 6G that reflects the green light GL and transmits the blue light BL, a third dichroic mirror 6R that reflects the blue light BL and green light GL and transmits the red light RL, a first focusing lens 7R that collects the red light RL, a second focusing lens 7G that collects the green light GL, and a third focusing lens 7B that collects the blue light BL.

[0021] In FIG. 4, for the sake of convenience, the red light RL, green light GL, and blue light BL are shown with their optical axes shifted from one another to be combined; however, in reality, the optical axes of the combined colored lights are designed to be aligned and ultimately enter the MEMS mirror 3.

[0022] That is, in the light source unit 2 of this embodiment, the optical axis of the blue light BL emitted from the blue light source 5B and then reflected by the first dichroic mirror 6B coincides with the optical axis of the green light GL emitted from the green light source 5G and then reflected by the second dichroic mirror 6G. Furthermore, the optical axis of the red light RL emitted from the red light source 5R and then transmitted through the third dichroic mirror 6R coincides with the optical axes of the blue light BL and green light GL reflected by the third dichroic mirror 6R.

[0023] As a result, the three color lights RL, BL, and GL are combined with their optical axes aligned, so that they enter the MEMS mirror 3 at the same angle of incidence, are reflected by the MEMS mirror 3 at the same angle of reflection, and are scanned as a single drawing light L.

[0024] In addition, in the light source unit 2, it is possible to control the ratio of red light RL, green light GL, and blue light BL, and to arbitrarily change the color tone (emission color) of the drawing light L obtained by these color lights RL, GL, and BL, or by combining (mixing) these color lights RL, GL, and BL.

[0025] As shown in FIG. 3, the scanning unit 3 is configured by a MEMS (Micro-Electro-Mechanical Systems) mirror (hereinafter, referred to as the "MEMS mirror 3").

[0026] Specifically, this MEMS mirror 3 has at least a mirror portion 31 that reflects the drawing light L emitted from the light source portion 2, two torsion bars (not shown) that twist due to the vibration of piezoelectric elements formed on both sides of the mirror portion 31, a bellows-shaped meander portion 32 that moves due to the vibration of the piezoelectric elements, and an outer frame 34 that supports the meander portion 32.

[0027] In FIG. 3, central axes AX and AY that are perpendicular to each other are set within the plane of the MEMS mirror 3, and the direction of oscillation around one central axis AX is defined as the AY direction, and the direction of oscillation around the other central axis AY is defined as the AX direction.

[0028] The mirror section 31 is oscillated in the AY direction via a torsion bar that connects the mirror section 31 and the inner frame 33 in the AX direction. As a result, the drawing light L reflected by the mirror section 31 is scanned in a direction substantially parallel to the AX direction.

[0029] On the other hand, the mirror portion 31 is swung in the AX direction via the meander portion 32. As a result, the drawing light L reflected by the mirror portion 31 is scanned in a direction substantially parallel to the AY direction.

[0030] Therefore, in the MEMS mirror 3, the mirror portion 31 is swung in two-dimensional directions within its plane, and the drawing light L reflected by this mirror portion 31 is scanned two-dimensionally. This makes it possible to perform road surface drawing by projecting the drawing pattern P in an irradiation range E where the drawing light L is irradiated on the road surface T.

[0031] 2, the control unit 4 is composed of a microcomputer such as a CPU, and controls the lighting of the multiple light sources 5R, 5G, and 5B (light source unit 2) to control the light amount and color gradation of the drawing light L. In addition, the control unit 4 controls the driving of the MEMS mirror 3 to variably control the drawing pattern P.

[0032] 1, in the vehicle drawing device 1 of the present embodiment having the above-mentioned configuration, the drawing light L emitted from the light source unit 2 is scanned by the MEMS mirror 3, and the drawing light L is irradiated from the door mirror 101 toward the road surface T on the side of the vehicle. As a result, it is possible to perform road surface drawing by projecting a drawing pattern P, such as characters or an image, in the irradiation range E irradiated by the drawing light L.

[0033] Incidentally, in order to improve the visibility of the drawing pattern P in a bright environment such as daytime, it is necessary to increase the output of the drawing light L emitted from the light source section 2.

[0034] Here, we investigated the effect of the drive current on the output of the laser light, and found that when the output of the drawing light L is increased, the output of the red light source 5R is more susceptible to the effects of temperature than the outputs of the green light source 5G and blue light source 5B described above, and that as the drive current increases, the temperature of the LD chip (junction temperature: Tj) also increases, reducing the light extraction efficiency from the LD chip, and sufficient output cannot be obtained even when the drive current is increased.

[0035] Therefore, in the vehicle drawing device 1 of this embodiment, when the external light illuminance of the irradiation range E where the drawing light L is irradiated exceeds a threshold value, one of the multiple light sources 5R, 5G, 5B that emits light with the longest wavelength (in this embodiment, the red light source 5R) is turned off, and lighting control is performed for the other light sources (in this embodiment, the green light source 5G and the blue light source 5B).

[0036] In this embodiment, one light source is a red light source 5R that emits red light RL having a wavelength of 620 nm or more and 780 nm or less, but a light emitting element such as an LD or LED that emits light having a wavelength of 620 nm or more can be used. Also, as the red light source 5R, a GaAs-based light emitting element such as AlGaAs can be used.

[0037] On the other hand, the other light sources, the green light source 5G and the blue light source 5B, unlike the red light source 5R, are less likely to experience a decrease in the light extraction efficiency from the LD chip even if the temperature of the LD chip increases with an increase in the drive current, and therefore can increase the light output with an increase in the drive current.

[0038] The green light source 5G may be a light emitting element such as an LD or an LED that emits green light GL having a wavelength of 500 nm or more and 565 nm or less. Also, the green light source 5G may be, for example, a GaN-based or InGaN-based light emitting element.

[0039] In the case of a GaN-based or InGaN-based LD chip, even if the driving current is increased and the temperature of the LD chip rises, the decrease in light emission efficiency can be suppressed, and therefore the light output can be increased.

[0040] The blue light source 5B may be a light emitting element such as an LD or an LED that emits blue light BL having a wavelength of 450 nm or more and less than 500 nm. Also, the blue light source 5B may be, for example, a GaN-based light emitting element.

[0041] With a GaN-based LD chip, even if the drive current is increased and the temperature of the LD chip rises, the decrease in light emission efficiency can be suppressed, making it possible to increase the light output.

[0042] In the vehicle drawing device 1 of this embodiment, in the above-mentioned bright environment, road surface drawing is performed by drawing light L obtained by green light GL and blue light BL, without using red light RL. This makes it possible to increase the contrast of the drawing light L in a bright environment, and improve the visibility of the drawing pattern P.

[0043] Specifically, in order to perform the above-mentioned lighting control, the control unit 4 is electrically connected to an illuminance sensor 50 mounted on the vehicle 100, as shown in FIG.

[0044] For example, a phototransistor or a photodiode can be used as the illuminance sensor 50. The illuminance sensor 50 detects the illuminance (brightness) of external light outside the vehicle, and supplies the detected signal to the control unit 4. Since the illuminance sensor 50 handles the value of illuminance, it is possible to freely set a threshold value, and it is also possible to set multiple threshold values.

[0045] The control unit 4 determines whether the external light illuminance of the illumination range E irradiated with the drawing light L exceeds a threshold value based on the external light illuminance detected by the illuminance sensor 50. The threshold value is set to a value of the external light illuminance at which sufficient output cannot be obtained even if the drive current of the one light source (red light source 5R) described above is increased.

[0046] In this embodiment, based on the relationship between the light output of the one light source and the illuminance of external light, the value of the illuminance of external light at which the light output of the one light source no longer contributes to the brightness of the road surface drawing is set as the threshold value. The threshold value may also be set to the value of the illuminance of external light at which the drive current or light output of the one light source becomes difficult to increase (saturates) due to the influence of heat, for example. Furthermore, the threshold value may be set to the brightness of the surrounding environment where the problem of insufficient output of the one light source is expected to occur, that is, the value of the illuminance of external light under street lights or on a cloudy or sunny day. (Under street lights: 3,000 Lux, cloudy: 30,000 Lux, sunny day: 70,000 lux)

[0047] In addition, when the external light illuminance of the irradiation range E irradiated with the drawing light L exceeds a threshold, the control unit 4 performs control to increase the output of the other light sources (green light source 5G and blue light source 5B) compared to before the threshold was exceeded.

[0048] The illuminance sensor 50 is not necessarily limited to a configuration in which it is mounted on the vehicle 100, but may be a configuration in which it is mounted on the imaging device 1 for a vehicle, for example.

[0049] In addition, in the vehicle drawing device 1 of this embodiment, instead of the above-mentioned illuminance sensor 50, a configuration may be used to determine whether or not the external light illuminance of the irradiation range E where the drawing light L is irradiated exceeds a threshold value, based on external light illuminance information supplied via a communication unit mounted on the vehicle 100, for example.

[0050] With regard to the external light illuminance information, it is possible to determine that the external light illuminance has exceeded a threshold value, for example, based on the position information of the vehicle 100 and the weather information at that position.

[0051] The vehicle drawing device 1 of this embodiment having the above-mentioned configuration performs the above-mentioned road surface drawing, for example, in accordance with the flowchart shown in FIG.

[0052] Specifically, first, as shown in step S101 of FIG. 5, it is detected that the owner of the key (passenger H) has released the key lock of the vehicle 100 or has approached the vehicle 100.

[0053] Next, as shown in step S102 of FIG. 5, the power supply of the illuminance sensor 50 and the power supply of the human presence sensor (not shown), which correspond to sensing, are turned ON, and sensing is started.

[0054] As a human presence sensor, a type of optical sensor such as an infrared sensor (e.g., a pyroelectric IR sensor, an infrared reflective sensor that combines an infrared LED and a photodiode, etc.) that uses infrared (IR) to detect human movement from the heat and reflected light emitted by people can be used.

[0055] The human presence sensor may be a type of sonic wave sensor such as a sonar sensor that detects human movement by emitting ultrasonic waves that hit a person and receive the reflected waves. The human presence sensor detects the passenger H by reacting within a detection range surrounding the irradiation range E of the drawing light L, and outputs a detection signal to the control unit 4.

[0056] In addition, the human presence sensor can react not only to the passenger H but also to pedestrians, animals, bicycles, motorcycles, etc. In the vehicle drawing device 1, when the human presence sensor reacts, it is possible to stop outputting the drawing light L and stop drawing on the road surface.

[0057] As another sensing operation, the power supply of a driver detection unit (not shown) capable of detecting the presence of a passenger H inside the vehicle 100 is turned ON.

[0058] The driver detection unit may detect any one or a combination of the following: a door contact sensor that detects the opening and closing of the driver's seat door, an engine start sensor that detects when the engine is started, and a sensor (heat detection type, pressure detection type, etc.) that detects when passenger H sits in the driver's seat.

[0059] Next, as shown in step S103 of FIG. 5, the control unit 4 starts driving the MEMS mirror 3 (ON) and makes the MEMS mirror 3 ready to start scanning with the light sources 5R, 5G, and 5B turned off (OFF).

[0060] The MEMS mirror 3 is driven early because it takes time to prepare for irradiation. However, if it is started up instantaneously, it may be started up together with the start of drawing in steps S106 and S108 in FIG. 5 described later, and step S103 in FIG. 5 may be omitted.

[0061] Next, as shown in step S104 of FIG. 5, the control unit 4 determines whether or not the illuminance of external light exceeds a threshold value.

[0062] In this embodiment, the threshold is set based on the illuminance of external light, but the threshold may be set based on the drive current or optical output of the red light source 5R. In this case, the drive current may be read from the drive circuit of the red light source 5R. The optical output may be read from the voltage value of a photodiode receiving part of the red light RL from the red light source 5R. The value of the illuminance of external light when the drive current or optical output of the red light source 5R becomes difficult to increase (saturates) may be set as a threshold, and the determination may be made based on whether the threshold is exceeded.

[0063] If it is determined that the external light illuminance has exceeded the threshold (Yes), the process proceeds to step S105 in FIG. 5, where the control unit 4 keeps the red light source 5R off (OFF) and controls the green light source 5G and blue light source 5B to be on (ON).

[0064] At this time, the optical output of the green light source 5G and the blue light source 5B is increased by increasing the drive current more than when the external light illuminance is equal to or lower than the threshold value. Furthermore, the drive current may be controlled so as to be further increased according to the magnitude of the external light illuminance.

[0065] Then, as shown in step S106 of FIG. 5, the MEMS mirror 3 is driven using the drawing light L obtained from the green light GL and the blue light BL to start drawing on the road surface.

[0066] On the other hand, if it is determined that the external light illuminance does not exceed the threshold (No), the process proceeds to step S107 in FIG. 5, where the control unit 4 performs lighting control (ON) for the red LD light source 5R, the green light source 5G, and the blue light source 5B.

[0067] Then, as shown in step S108 of FIG. 5, the MEMS mirror 3 is driven to start drawing on the road surface using drawing light L obtained by the red light RL, the green light GL, and the blue light BL.

[0068] 5, when the human presence sensor reacts, the human presence sensor outputs a detection signal to the control unit 4. The control unit 4 that has received the detection signal stops output of the drawing light L and transmits a stop signal to the light source unit 2 to stop drawing on the road surface.

[0069] Next, as shown in step S110 of FIG. 5, upon receiving the stop signal, the light source unit 2 turns off all of the light sources 5R, 5G, and 5B, and stops drawing the road surface.

[0070] Next, as shown in step S111 of Fig. 5, when the driver detection unit reacts and detects that a passenger H is inside the vehicle 100, the driving of the MEMS mirror 3 is stopped (OFF) as shown in step S112 of Fig. 5, and then, as shown in step S113 of Fig. 5, the power supply of the illuminance sensor 50 and the human presence sensor is turned OFF, and sensing is terminated. This ends the flow of this embodiment.

[0071] As described above, in the vehicle drawing device 1 of this embodiment, when the external light illuminance of the irradiation range E where the above-mentioned drawing light L is irradiated is below a threshold value, road surface drawing is performed using the drawing light L obtained by the red light RL, green light GL and blue light BL.

[0072] On the other hand, when the illuminance of external light in the illumination range E illuminated by the above-mentioned drawing light L exceeds the threshold value, the red light RL is not used, and road surface drawing is performed using the drawing light L obtained by the green light GL and blue light BL.

[0073] As a result, even when road surface drawing is performed in a bright environment, the contrast of the drawing light L can be increased, and the visibility of the drawing pattern P can be improved.

[0074] For example, in this embodiment, it is possible to form a monochrome drawing pattern P obtained by green light GL or blue light BL, as shown in Figure 6(A), a bordered drawing pattern P obtained by green light GL and blue light BL, as shown in Figure 6(B), and a negative-positive drawing pattern P obtained by green light GL and blue light BL, as shown in Figure 6(C).

[0075] As an application example of this embodiment, the control unit 4 may set a first threshold and a second threshold higher than the first threshold, and perform control so that when the illuminance of external light exceeds the first threshold, the drawing light L is set to a first color tone, and when the illuminance of external light exceeds the second threshold, the drawing light L is set to a second color tone having a contrast with a higher hue or saturation than the first color tone.

[0076] For example, road surface drawing is performed while gradually increasing the contrast by changing the color tone of the drawing light L obtained by mixing green light GL and blue light BL according to a first threshold value and a second threshold value of the external light illuminance (for example, the value of the external light illuminance on a cloudy or sunny day).

[0077] Specifically, the illuminance of external light on a cloudy day (e.g., 3,000 Lux or more) is set as a first threshold, and when the illuminance of external light exceeds the first threshold, road surface drawing is performed using drawing light L of a first color tone. An example of the drawing pattern P using drawing light L of a first color tone is a monochrome drawing pattern P obtained using green light GL or blue light BL as shown in Fig. 6(A) above.

[0078] In this case, contrast due to saturation can be added to the drawing pattern P projected onto a dark-colored road surface T such as asphalt. This makes it possible to improve the visibility of the drawing pattern P compared to the case where road surface drawing is performed using white drawing light L obtained by mixing red light RL, green light GL, and blue light BL.

[0079] On the other hand, the illuminance of external light such as that on a clear day (e.g., 30,000 Lux or more) is set as a second threshold, and when the illuminance of external light exceeds the first threshold, road surface drawing is performed using drawing light L of a second color tone. Examples of drawing patterns P using drawing light L of a second color tone include a border drawing pattern P obtained using green light GL and blue light BL as shown in Fig. 6(B) above, and a negative-positive drawing pattern P obtained using green light GL and blue light BL as shown in Fig. 6(C) above.

[0080] In this case, in addition to the above-mentioned contrast due to saturation, a contrast due to hue can be applied to the drawing pattern P projected onto the road surface T. This makes it possible to improve the visibility of the drawing pattern P in a bright environment by drawing on the road surface with the drawing light L of a second color tone that has a higher hue and saturation than the first color tone.

[0081] Incidentally, with regard to the drawing pattern P by the drawing light L of the second color tone described above, a bordered or negative-positive drawing pattern P obtained by green light GL and blue light BL is exemplified, but other than that, for example, a colored light obtained by mixing green light GL and blue light BL (e.g. light blue light) may be used to form a bordered or negative-positive drawing pattern P. Since light blue light is a bright colored light, the contrast of saturation as well as hue is enhanced. This makes it possible to further improve the visibility of the drawing pattern P.

[0082] The optical output of the green light source 5G and the blue light source 5B is increased by increasing the drive current more than when the illuminance of the external light is equal to or lower than the first threshold value. Furthermore, the drive current may be controlled to be further increased according to the magnitude of the illuminance of the external light, and it is possible to control the drive current to be increased stepwise between the first threshold value and the second threshold value.

[0083] In an application example of this embodiment, road surface drawing is performed according to the flowchart shown in FIG.

[0084] Specifically, as for steps S101 to S103 in FIG. 7, similarly to steps S101 to S103 in FIG. 5 above, first, as shown in step S101 in FIG. 7, it is detected that the owner of the key (passenger H) has released the key lock of the vehicle 100 or has approached the vehicle 100.

[0085] 7, the power supply of the illuminance sensor 50 and the power supply of the human presence sensor (not shown), which correspond to sensing, are turned on to start sensing. In addition, as another sensing, the power supply of a driver detection unit (not shown) that can detect the presence of a passenger H inside the vehicle 100 is turned on.

[0086] Next, as shown in step S103 of FIG. 7, the control unit 4 starts driving the MEMS mirror 3 (ON) and makes the MEMS mirror 3 ready to start scanning with the light sources 5R, 5G, and 5B turned off (OFF).

[0087] Next, as shown in step S201 of FIG. 7, the control unit 4 determines whether or not the illuminance of external light exceeds a first threshold value (for example, 3,000 Lux).

[0088] If it is determined that the external light illuminance does not exceed the first threshold (No), the process proceeds to step S107 in FIG. 7, similar to steps S107 and S108 in FIG. 5 above, and the control unit 4 performs lighting control (ON) for the red LD light source 5R, the green light source 5G, and the blue light source 5B.

[0089] Then, as shown in step S108 of FIG. 7, the MEMS mirror 3 is driven to start drawing on the road surface using the drawing light L obtained by the red light RL, the green light GL, and the blue light BL.

[0090] On the other hand, if it is determined that the external light illuminance has exceeded the first threshold (Yes), the process proceeds to step S202 in FIG. 7, where it is determined whether the external light illuminance has exceeded a second threshold (for example, 30,000 Lux).

[0091] If it is determined that the external light illuminance does not exceed the second threshold (NO), the process proceeds to step S203 in FIG. 7, where the control unit 4 keeps the red light source 5R off (OFF) and controls the green light source 5G and blue light source 5B to be turned on (ON).

[0092] Then, as shown in step S204 of FIG. 7, the MEMS mirror 3 is driven to start drawing on the road surface using the drawing light L of the first color tone obtained by the green light GL and the blue light BL.

[0093] At this time, the optical output of green light source 5G and blue light source 5B is increased higher than the optical output by increasing the drive current more than when the illuminance of external light is equal to or lower than the first threshold value.

[0094] On the other hand, if it is determined that the external light illuminance has exceeded the second threshold (YES), the process proceeds to step S205 in FIG. 7, where the control unit 4 keeps the red light source 5R off (OFF) and controls the green light source 5G and blue light source 5B to be turned on (ON).

[0095] Then, as shown in step S206 of FIG. 7, the MEMS mirror 3 is driven to start drawing on the road surface using the drawing light L of the second color tone obtained by the green light GL and the blue light BL.

[0096] At this time, the optical output of green light source 5G and blue light source 5B is increased higher than the optical output by increasing the drive current compared to when the illuminance of external light is equal to or lower than the second threshold value.

[0097] Next, as for steps S109 to S113 in Fig. 7, similarly to steps S109 to S113 in Fig. 5 above, when the human presence sensor reacts, as shown in step S109 in Fig. 7, the human presence sensor outputs a detection signal to the control unit 4. The control unit 4 that has received the detection signal stops outputting the drawing light L and transmits a stop signal to the light source unit 2 to stop drawing on the road surface.

[0098] Next, as shown in step S110 of FIG. 7, upon receiving the stop signal, the light source unit 2 turns off all of the light sources 5R, 5G, and 5B, and stops drawing the road surface.

[0099] Next, as shown in step S111 of Fig. 7, when the driver detection unit reacts and detects that a passenger H is in the vehicle 100, the driving of the MEMS mirror 3 is stopped (OFF) as shown in step S112 of Fig. 7, and then, as shown in step S113 of Fig. 7, the power supply of the illuminance sensor 50 and the human presence sensor is turned OFF, and sensing is ended. This ends the flow of this embodiment.

[0100] As described above, in an application example of this embodiment, when the illuminance of external light exceeds a first threshold, road surface drawing is performed using drawing light L of the above-mentioned first color tone, and when the illuminance of external light exceeds a second threshold, road surface drawing is performed using drawing light L of a second color tone having a higher hue or saturation than the above-mentioned first color tone.

[0101] As a result, by drawing on the road surface using drawing light L of a second color tone that has a higher hue and saturation than the first color tone, it is possible to further improve the visibility of the drawing pattern P in a bright environment.

[0102] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0103] Specifically, in the above embodiment, a configuration is exemplified in which the vehicle drawing device 1 is installed on the door mirror 101 of the vehicle 100, but it is also possible to configure the vehicle drawing device 1 to be installed, for example, around the door, on the side, on the top or bottom of the vehicle 100.

[0104] Further, the vehicle drawing device 1 of the present embodiment is not limited to a configuration in which drawing is performed on the road surface T described above, and may be a configuration in which drawing is performed on the body of the vehicle 100.

[0105] Furthermore, the vehicle drawing device 1 of this embodiment is not limited to the above-mentioned case of drawing the road surface when the vehicle is stopped, but can also draw the road surface while the vehicle is traveling. In this case, the drawing pattern P can display, for example, an image corresponding to a turn signal or an "AUTOPILOT" display during automatic driving.

[0106] In addition, in the vehicle imaging device 1 of this embodiment, the light source unit 2 is configured to use laser light sources such as a red LD chip 5R, a green LD chip 5G, and a blue LD chip 5B, but it is also possible to use LED light sources such as a red LED chip 5R, a green LED chip 5G, and a blue LED chip 5B. When an LED light source is used, at least one lens that adjusts the light emitted from the LED light source into coherent light may be disposed between the LED light source and the dichroic mirror.

[0107] Although the light source unit 2 includes light sources corresponding to the three primary colors of red light RL, green light GL, and blue light BL, it may include light sources emitting other colors of light, such as orange light or white light. Furthermore, it is also possible to include a plurality of light sources of the same color. [Explanation of symbols]

[0108] REFERENCE SIGNS LIST 1...vehicle imaging device 2...light source unit 3...scanning unit (MEMS mirror) 4...control unit 5R...red LD chip (red light source) 5G...green LD chip (green light source) 5B...blue LD chip (blue light source) 6B...first dichroic mirror 6G...second dichroic mirror 6R...third dichroic mirror 7R...first condenser lens 7G...second condenser lens 7B...third condenser lens 50...illuminance sensor 100...vehicle 101...door mirror L...imaging light RL...red light GL...green light BL...blue light E...irradiation range H...occupant T...road surface P...imaging pattern

Claims

1. A vehicle drawing device mounted on a vehicle, a light source unit including a plurality of light sources emitting light of different wavelengths, the light source unit emitting drawing light of a color tone corresponding to a ratio of light emitted from each light source; a scanning unit that forms a drawing pattern by scanning the drawing light emitted from the light source unit; a control unit that variably controls a color tone of the drawing light and the drawing pattern by controlling lighting of the plurality of light sources, The control unit is characterized in that, when the external light illuminance in the irradiation range where the drawing light is irradiated exceeds a threshold value, it turns off one of the multiple light sources that emits light with the longest wavelength, and controls the lighting of the other light sources.

2. The imaging device for a vehicle according to claim 1 , wherein the control unit performs control such that, when the illuminance of the external light exceeds a threshold value, an output of the other light source is increased compared to an output before the illuminance of the external light exceeds the threshold value.

3. the light source unit includes a red light source that emits red light, a green light source that emits green light, and a blue light source that emits blue light, 2. The imaging device for a vehicle according to claim 1, wherein the control unit turns off the red light source and controls the green light source and the blue light source to be turned on when the external light illuminance exceeds a threshold value.

4. 2. The imaging device for a vehicle according to claim 1, wherein the wavelength of the light emitted from the one light source is 620 nm or more.

5. 2. The imaging device for a vehicle according to claim 1, wherein the wavelength of the light emitted by the other light source is 565 nm or less.

6. 6. The imaging device for a vehicle according to claim 5, wherein the other light source includes at least a GaN-based light-emitting element.

7. the other light sources include a green light source that emits green light and a blue light source that emits blue light, the green light source includes a GaN-based or InGaN-based light-emitting element; 7. The imaging device for a vehicle according to claim 6, wherein the blue light source includes a GaN-based light-emitting element.

8. 2. The vehicle drawing device according to claim 1, wherein the drawing pattern is formed by a border drawing pattern obtained by using lights of different colors or a negative-positive drawing pattern.

9. 2. The imaging device for a vehicle according to claim 1, wherein the plurality of light sources are laser light sources.

10. The vehicle imaging device according to claim 1 , wherein the control unit determines whether or not the external light illuminance exceeds a threshold value based on the external light illuminance detected by an illuminance sensor mounted on the vehicle.

11. The vehicle drawing device according to claim 1, characterized in that the control unit determines whether the external light illuminance exceeds a threshold value based on external light illuminance information supplied via a communication unit mounted on the vehicle.

12. The control unit sets a first threshold and a second threshold higher than the first threshold, When the external light illuminance exceeds the first threshold, the drawing light is set to a first color tone; The vehicle drawing device according to claim 1, characterized in that, when the external light illuminance exceeds the second threshold, the drawing light is controlled to be a second color tone having a contrast with a higher hue or saturation than the first color tone.

13. the drawing light of the first color tone is a monochromatic light obtained by mixing green light, blue light, or green light and blue light, The drawing light of the second color tone is green light, blue light, or a monochromatic light obtained by mixing green light and blue light, having a contrast with a higher hue or saturation than the drawing light of the first color tone.

14. 2. The drawing device for a vehicle according to claim 1, wherein the drawing pattern is projected onto a road surface.

15. 2. The drawing device for a vehicle according to claim 1, wherein the drawing pattern is projected onto a vehicle body.

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