Vehicle drawing device

Abstract

A vehicle drawing device (1) installed in a vehicle (100) comprises a light source unit that emits drawing light (L), a scanning unit that forms a drawing pattern (P) by scanning the drawing light (L) emitted from the light source unit, and a control unit that variably controls the drawing pattern (P) by performing drive control for the scanning unit. When the external light illuminance of an irradiation range (E) irradiated with the drawing light (L) exceeds a threshold value, the control unit performs drive control for scanning the drawing light (L) in a scanning range that is smaller than the irradiation range (E).

Description

Vehicle drawing device

[0001] This application claims priority to Japanese Patent Application No. 2023-187658, filed November 1, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, laser light sources such as laser diodes (LDs) that can produce high-brightness, high-power light have been used to perform drawing on road surfaces and the like by scanning the laser light emitted from the laser light source (see, for example, Patent Document 1 below).

[0003] Furthermore, among laser light sources, there is a laser light source 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] With such a laser light source, it is possible to arbitrarily change the color tone (emission color) of the laser light obtained by combining (mixing) these colored lights while controlling the ratio of red light, green light, and blue light emitted by each LD chip in the LD package.

[0005] Japanese Patent Application Publication No. 2020-122365

[0006] In order to improve the visibility of images in bright environments such as daytime, it is necessary to increase the output of the laser light when drawing.

[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 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 conventional drawing devices or drawing systems, even if the outputs of the three color laser beams of the red LD chip, green LD chip, and blue LD chip are increased simultaneously, the output of the red LD chip cannot keep up, resulting in insufficient brightness of the drawing, deviation from the intended chromaticity, and insufficient contrast, making it difficult to improve visibility. For this reason, drawing is generally performed in dark environments such as at night.

[0009] An aspect of the present invention provides a drawing device for a vehicle that can improve the visibility of drawings in bright environments.

[0010] The present invention provides the following aspects: [1] A vehicle-mounted drawing device comprising: a light source unit that emits drawing light; a scanning unit that forms a drawing pattern by scanning the drawing light emitted from the light source unit; and a control unit that variably controls the drawing pattern by driving and controlling the scanning unit, wherein the control unit drives and controls the scanning unit to scan the drawing light over a scanning range that is smaller than the irradiation range when the illuminance of external light in an irradiation range where the drawing light is irradiated exceeds a threshold. [2] The scanning unit includes a mirror unit that reflects the drawing light emitted from the light source unit, and scans the drawing light by variably controlling the reflection direction of the drawing light while swinging the mirror unit in two-dimensional directions within a plane, and the control unit drives and controls the scanning unit to reduce the swing range of the mirror unit when the illuminance of external light exceeds a threshold. [3] The vehicle-mounted drawing device described in [1], wherein the light source unit includes a laser light source. [4] The drawing device for a vehicle according to [1], wherein the control unit determines whether the illuminance of external light exceeds a threshold value based on the illuminance of external light detected by an illuminance sensor mounted on the vehicle. [5] The drawing device for a vehicle according to [2], wherein, when the illuminance of external light exceeds a threshold value, the control unit controls to reduce the swing range of the mirror unit so that the scanning range becomes smaller stepwise or continuously as the illuminance of external light increases. [6] The drawing device for a vehicle according to [1], wherein the light source unit includes a plurality of light sources that emit light of different wavelengths, and emits drawing light of a color tone corresponding to a proportion of light emitted from each light source, and the control unit variably controls the color tone of the drawing light by controlling the lighting of the plurality of light sources, and when the illuminance of external light in an irradiation range irradiated with the drawing light exceeds a threshold value, turns off one light source of the plurality of light sources that emits light of the longest wavelength and controls the lighting of the other light sources. [7] The vehicle imaging device according to [6], wherein when the illuminance of external light exceeds a threshold value, the control unit performs control to increase the output of the other light source compared to before the illuminance of external light exceeded the threshold value.[8] The vehicle drawing device according to [6], wherein 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, and 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. [9] The vehicle drawing device according to [1], wherein the control unit determines whether the external light illuminance in the illumination range irradiated with the drawing light exceeds a threshold based on external light illuminance information supplied via a communication unit mounted on the vehicle.

[10] The vehicle drawing device according to [1], wherein the drawing pattern is projected onto a road surface.

[11] The vehicle drawing device according to [1], wherein the drawing pattern is projected onto a vehicle body.

[0011] As described above, according to the aspects of the present invention, a drawing device for a vehicle is provided that can improve the visibility of drawings in bright environments.

[0012] 1 is a schematic diagram showing an example of road surface drawing by a vehicle drawing device according to an embodiment of the present invention; FIG. 1 is a block diagram showing the configuration of the vehicle drawing device; FIG. 2 is a schematic diagram showing the configuration of a light source unit and a scanning unit provided in the vehicle drawing device; FIG. 3 is a schematic diagram showing the configuration of the light source unit; FIG. 4 is a schematic diagram illustrating a drawing pattern by drive control of a MEMS mirror; FIG. 5 is a schematic diagram illustrating a drawing pattern by drive control of a MEMS mirror; FIG. 6 is a flowchart for explaining road surface drawing by drive control of a MEMS mirror; FIG. 7 is a flowchart for explaining road surface drawing by lighting control of a light source unit; FIG. 8 is a schematic diagram illustrating a drawing pattern by lighting control of a light source unit; FIG. 9 is a schematic diagram illustrating a drawing pattern by lighting control of a light source unit;

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

[0014] As an embodiment of the present invention, a vehicle drawing device 1 shown in, for example, FIGS. 1 to 10 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 included in the vehicle drawing device 1. FIG. 4 is a schematic diagram showing the configuration of the light source unit 2. FIG. 5A is a schematic diagram illustrating an example of a drawing pattern P produced by drive control of the MEMS mirror 3. FIG. 5B is a schematic diagram illustrating an example of a drawing pattern P produced by drive control of the MEMS mirror 3. FIG. 6 is a flowchart for explaining road surface drawing by drive control of the MEMS mirror 3. FIG. 7 is a flowchart for explaining an application example of road surface drawing by drive control of the MEMS mirror 3. FIG. 8 is a flowchart for explaining road surface drawing by lighting control of the light source unit 2. FIG. 9A is a schematic diagram illustrating an example of a drawing pattern P produced by lighting control of the light source unit 2. FIG. 9B is a schematic diagram illustrating an example of a drawing pattern P produced by lighting control of the light source unit 2. 9C is a schematic diagram illustrating a drawing pattern P obtained by controlling the lighting of the light source unit 2. FIG. 10 is a flowchart illustrating an application example of road surface drawing using lighting control of the light source unit 2.

[0016] The vehicle drawing device 1 of this embodiment is installed on the door mirror 101 of a vehicle 100, as shown in Figure 1, and performs road surface drawing by projecting a drawing pattern P, such as letters or images, using drawing light L that is 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 displays the word "welcome" to the passenger H.

[0018] Specifically, as shown in Figures 2 and 3, this 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.

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

[0020] The light source unit 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 the green light GL and transmits the red light RL, a first condenser lens 7R that collects the red light RL, a second condenser lens 7G that collects the green light GL, and a third condenser lens 7B that collects the blue light BL.

[0021] In FIG. 4, for the sake of convenience, the optical axes of the red light RL, green light GL, and blue light BL that are combined together are shown shifted from one another, but 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 blue light BL emitted from the blue light source 5B and reflected by the first dichroic mirror 6B coincides with the optical axis of green light GL emitted from the green light source 5G and reflected by the second dichroic mirror 6G. Furthermore, the optical axis of red light RL emitted from the red light source 5R and 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] Furthermore, in the light source unit 2, while controlling the ratio of red light RL, green light GL, and blue light BL, it is possible to arbitrarily change the color tone (emission color) of these colored lights RL, GL, and BL or the drawing light L obtained by combining (mixing) these colored 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 section 31 that reflects the drawing light L emitted from the light source section 2, two torsion bars (not shown) that twist due to the vibration of piezoelectric elements formed on both sides of the mirror section 31, a bellows-shaped meander section 32 that moves due to the vibration of the piezoelectric elements, and an outer frame 34 that supports the meander section 32.

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

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

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

[0030] Therefore, the MEMS mirror 3 two-dimensionally scans the drawing light L reflected by the mirror 31 while swinging the mirror 31 two-dimensionally within its plane. 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] The mirror part 31 swings in the AX direction at a first deflection angle ΔθX1 around the central axis AY, while the mirror part 31 swings in the AY direction at a first deflection angle ΔθY1 around the central axis AX.

[0032] Although the mirror portion 31 normally oscillates at approximately the maximum deflection angle, the first deflection angles ΔθX1 and ΔθY1 are not limited to the maximum deflection angle, and may be set to be several to several tens of percent smaller than the maximum deflection angle to allow for some leeway.

[0033] Therefore, as shown in Figure 5A, when the swing range of the mirror part 31 is set to the first deflection angles ΔθX1, ΔθY1, the first scanning range F1 of the drawing light L becomes approximately the same size as the irradiation range E, and a first drawing pattern P1 (P) of a size corresponding to this first scanning range F1 is formed.

[0034] On the other hand, when the drawing light L scans a second scanning range F2 that is smaller than the irradiation range E, the mirror unit 31 swings in the AX direction around the central axis AY by a second swing angle ΔθX2 that is smaller than the first swing angle ΔθX1. On the other hand, the mirror unit 31 swings in the AY direction around the central axis AX by a second swing angle ΔθY2 that is smaller than the first swing angle ΔθY1.

[0035] 5B , when the swing range of the mirror unit 31 is set to second deflection angles ΔθX2, ΔθY2 that are smaller than the first deflection angles ΔθX1, ΔθY1, the second scanning range F2 of the drawing light L is smaller in size than the first scanning range F1, and a second drawing pattern P2(P) having a size corresponding to this second scanning range F2 is formed. That is, the second drawing pattern P2(P) having a size smaller than the first drawing pattern P1(P) is formed.

[0036] In this embodiment, the swing range of the mirror part 31 is not limited to swinging in both the AX direction and the AY direction, but even if it swings in only one of the directions, it is possible to form a second drawing pattern P2 that is smaller in size than the first drawing pattern P1.

[0037] In addition, in this embodiment, the oscillation range of the mirror portion 31 described above is determined by the deflection angle of the mirror portion 31. However, since there is a correlation between the amplitude and deflection angle when the mirror portion 31 is oscillated at a predetermined resonant frequency or non-resonant frequency, it is also possible to determine the oscillation range of the mirror portion 31 by the amplitude of the resonant frequency or non-resonant frequency.

[0038] 2, the control unit 4 is formed of a microcomputer such as a CPU, and controls the lighting of the plurality of light sources 5R, 5G, and 5B (light source unit 2) to control the light intensity and color gradation of the drawing light L. The control unit 4 also controls the driving of the MEMS mirror 3 to variably control the drawing pattern P.

[0039] 1, in the vehicle drawing device 1 of this embodiment having the above-described 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, within the irradiation range E irradiated by the drawing light L.

[0040] In the vehicle drawing device 1 of this embodiment, when the illuminance of external light in the irradiation range E where the drawing light L is irradiated exceeds a threshold value, the MEMS mirror 3 is driven so that the swing range of the mirror part 31 of the MEMS mirror 3 becomes smaller, and drive control is performed to scan the drawing light L in a scanning range that is smaller than the irradiation range E.

[0041] Specifically, the drawing light L is scanned over a second scanning range F2 of the drawing light L, which is reduced from a first scanning range F1 of the drawing light L when the swing range of the mirror part 31 is set to a first deflection angle ΔθX1, ΔθY1 to a second deflection angle ΔθX2, ΔθY2.

[0042] For example, in this embodiment, compared to drawing a first drawing pattern P1 in a first scanning range F1 that is approximately the same as the irradiation range E as shown in Figure 5A, by drawing a second drawing pattern P2 in a second scanning range F2 that is smaller than the irradiation range E of the drawing light L as shown in Figure 5B, although the second drawing pattern P2 is smaller than the first drawing pattern P1, it is possible to increase the illuminance (brightness) of this second drawing pattern P2 more than that of the first drawing pattern P1.

[0043] This makes it possible to increase the illuminance of the drawing light L and improve the visibility of the second drawing pattern P2 even when drawing on a road surface in a bright environment.

[0044] In order to control the driving of the MEMS mirror 3 described above, the control unit 4 is electrically connected to an illuminance sensor 50 mounted on the vehicle 100, as shown in FIG.

[0045] A phototransistor or a photodiode, for example, 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.

[0046] The control unit 4 determines whether the illuminance of external light in the illumination range E irradiated with the drawing light L exceeds a threshold value based on the illuminance of external light detected by the illuminance sensor 50. The threshold value is set to the value of the illuminance of external light at which sufficient output cannot be obtained even when the drive current of the one light source (red light source 5R) described above is increased.

[0047] In this embodiment, based on the relationship between the light output of a light source and the illuminance of external light, the threshold value is set to the value of the illuminance of external light when the light output of the light source no longer contributes to the brightness of the road surface drawing. Alternatively, the threshold value may be set to the value of the illuminance of external light when the drive current or light output of the 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 light source is expected to occur, i.e., the value of the illuminance of external light under street lights or on cloudy or sunny days. (Under street lights: 3,000 lux, cloudy: 30,000 lux, sunny: 70,000 lux)

[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 vehicle drawing device 1, for example.

[0049] Furthermore, in the vehicle drawing device 1 of this embodiment, instead of the above-mentioned illuminance sensor 50, it may be configured to determine whether the external light illuminance of the illumination range E irradiated with the drawing light L exceeds a threshold value, for example, based on external light illuminance information supplied via a communication unit mounted on the vehicle 100.

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

[0051] In the vehicle imaging device 1 of this embodiment having the above-described configuration, when performing the road surface imaging described above, the driving control of the MEMS mirror 3 is performed according to the flowchart shown in FIG. 6, for example.

[0052] Specifically, first, as shown in step S101 of FIG. 6, it is detected that the owner of the key (passenger H) has unlocked the key lock of the vehicle 100 or that the passenger H has approached the vehicle 100.

[0053] Next, as shown in step S102 of FIG. 6, 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 begins.

[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 from the person 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 transmitting ultrasonic waves that hit a person and receive the reflected waves. The human presence sensor detects the occupant H by reacting within a detection range that surrounds the irradiation range E of the drawing light L, and outputs this detection signal to the control unit 4.

[0056] Furthermore, the human presence sensor can react not only to the passenger H but also to pedestrians, animals, bicycles, motorcycles, etc. When the human presence sensor reacts, the vehicular drawing device 1 can stop outputting the drawing light L and stop drawing on the road surface.

[0057] As another sensing function, 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.

[0058] The driver detection unit may be a combination of one or more 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 that the engine has started, and a sensor (heat detection type, pressure detection type, etc.) that detects that passenger H has sat in the driver's seat.

[0059] Next, as shown in step S103 of FIG. 6, the control unit 4 starts driving the MEMS mirror 3 (ON) and turns off each of the light sources 5R, 5G, and 5B (OFF), thereby enabling the MEMS mirror 3 to start scanning.

[0060] The MEMS mirror 3 is driven early because it takes time to prepare for irradiation. However, if it is to be started up instantly, it may be started up at the same time as the drawing starts in steps S106 and S108 in FIG. 6 described later, and step S103 in FIG. 6 may be omitted.

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

[0062] In this embodiment, the threshold value is set based on the illuminance of ambient light, but it may also 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 a portion of the red light RL from the red light source 5R. Then, the value of the illuminance of ambient 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 value, and the determination may be made based on whether the threshold value is exceeded.

[0063] If it is determined that the external light illuminance exceeds the threshold value (Yes), the process proceeds to step S105 in FIG. 6, and the control unit 4 performs drive control to scan the drawing light L in a first scanning range F1 that is smaller than the irradiation range E of the drawing light L.

[0064] Then, as shown in step S106 of Figure 6, while controlling (ON) the power supplies of the red light source 5R, green light source 5G, and blue light source 5B, drawing of the second drawing pattern P2 on the road surface is started in a second scanning range F2 that is smaller than the irradiation range E using drawing light L obtained from the red light RL, green light GL, and blue light BL.

[0065] On the other hand, if it is determined that the illuminance of external light does not exceed the threshold value (No), the process proceeds to step S107 in FIG. 6, and the control unit 4 performs drive control to scan the drawing light L in a first scanning range F1 that is approximately the same as the irradiation range E of the drawing light L.

[0066] Then, as shown in step S108 of Figure 6, while controlling (ON) the power supplies of the red light source 5R, green light source 5G, and blue light source 5B, drawing of the first drawing pattern P1 on the road surface is started in the first scanning range F1, which is approximately the same as the irradiation range E, using the drawing light L obtained from the red light RL, green light GL, and blue light BL.

[0067] 6, when the human presence sensor reacts, the human presence sensor outputs a detection signal to the control unit 4. Upon receiving the detection signal, the control unit 4 stops outputting the drawing light L and transmits a stop signal to the light source unit 2 to stop drawing on the road surface.

[0068] Next, as shown in step S110 of FIG. 6, the light source unit 2, having received the stop signal, turns off all of the light sources 5R, 5G, and 5B, and stops drawing the road surface.

[0069] Next, as shown in step S111 of Fig. 6, when the driver detection unit reacts and detects that a passenger H is present in the vehicle 100, the driving of the MEMS mirror 3 is stopped (turned off) as shown in step S112 of Fig. 6, and then the power of the illuminance sensor 50 and the human presence sensor is turned off as shown in step S113 of Fig. 6, thereby ending sensing. This ends the flow of this embodiment.

[0070] As described above, in the vehicle drawing device 1 of this embodiment, when the external light illuminance of the irradiation range E onto which the above-mentioned drawing light L is irradiated is below a threshold value, the first drawing pattern P1 is drawn on the road surface in the first scanning range F1, which is approximately the same as the irradiation range E.

[0071] On the other hand, if the external light illuminance of the irradiation range E where the above-mentioned drawing light L is irradiated exceeds the threshold value, the second drawing pattern P2 is drawn on the road surface in a second scanning range F2 which is smaller than the irradiation range E of the drawing light L.

[0072] In this case, the second drawing pattern P2 drawn in the second scanning range F2, which is smaller than the irradiation range E of the drawing light L, is smaller than the first drawing pattern P1 drawn in the first scanning range F1, which is approximately the same as the irradiation range E, but the illuminance (brightness) of this second drawing pattern P2 can be made higher than that of the first drawing pattern P1.

[0073] As a result, in the vehicle drawing device 1 of this embodiment, even when road surface drawing is performed in a bright environment, the illuminance of the drawing light L can be increased, thereby improving the visibility of the second drawing pattern P2.

[0074] As an application example of this embodiment, when the illuminance of the external light unit exceeds a threshold value, the control unit 4 may perform control to reduce the swing range of the mirror unit 31 so that the second scanning range F2 of the drawing light L becomes smaller in a stepwise or continuous manner as the illuminance of the external light unit increases.

[0075] In this case, the size of the second drawing pattern P2 can be reduced stepwise or continuously as the illuminance of external light increases, thereby increasing the illuminance of the drawing light L and improving the visibility of the second drawing pattern P2 even when drawing on a road surface in a bright environment.

[0076] Specifically, in an application example of this embodiment, when the above-described road surface drawing is performed, the drive control of the MEMS mirror 3 is performed according to the flowchart shown in FIG.

[0077] Specifically, if it is determined in step S104 of FIG. 6 that the illuminance of external light exceeds the threshold value (Yes), the process proceeds to step S151 of FIG. 7, and the control unit 4 reads the value of the illuminance of external light detected by the illuminance sensor 50.

[0078] Then, as shown in step S152 of FIG. 7, the control unit 4 calculates a second scanning range F2 of the drawing light L according to the value of the external light illuminance detected by the illuminance sensor 50, and performs control to reduce the swing range of the mirror unit 31 in accordance with the second scanning range F2.

[0079] For example, when the value of the external light illuminance is the illuminance under a street light (e.g., 3,000 Lux or more and less than 30,000 Lux), the control unit 4 controls the second scanning range F2 of the drawing light L to be reduced to the extent that the second drawing pattern P2 can be seen under the street light.

[0080] When the external light illuminance value is the illuminance of a cloudy day (for example, 30,000 lux or more and less than 70,000 lux), the second scanning range F2 of the drawing light L is controlled to be smaller than that in the case of illuminance under street lights.

[0081] Furthermore, when the value of the external light illuminance is the illuminance of a fine day (for example, 70,000 lux or more), the second scanning range F2 of the drawing light L is controlled to be smaller than in the case of cloudy day illuminance.

[0082] This makes it possible to form a second drawing pattern P2 of a size corresponding to the value of the external light illuminance while scanning the drawing light L in a second scanning range F2 of the drawing light L corresponding to the value of the external light illuminance detected by the illuminance sensor 50.

[0083] Then, as shown in step S153 of FIG. 7, while controlling (ON) the power supplies of the red light source 5R, the green light source 5G, and the blue light source 5B, drawing of the second drawing pattern P2 on the road surface is started in a second scanning range F2 that is smaller than the irradiation range E and that is also reduced to a size corresponding to the value of the external light illuminance, using drawing light L obtained from the red light RL, the green light GL, and the blue light BL.

[0084] Thereafter, the flow of the application example of this embodiment is completed through steps S109 to S111 in FIG.

[0085] As described above, in an application example of this embodiment, the size of the second drawing pattern P2 can be variably adjusted according to the value of the external light illuminance detected by the illuminance sensor 50, thereby optimizing the illuminance (brightness) of this second drawing pattern P2 according to the value of the external light illuminance.

[0086] As a result, in the application example of this embodiment, it is possible to optimize the illuminance of the drawing light L in accordance with the external environment, and further improve the visibility of the second drawing pattern P2.

[0087] The second scanning range F2 of the drawing light L according to the value of the external light illuminance may not only change stepwise with respect to the value of the external light illuminance as described above, but may also change continuously.

[0088] In this embodiment, the illuminance (brightness) of the second drawing pattern P2 can be increased by reducing the size of the second drawing pattern P2 as the illuminance of external light increases, but there is a natural limit (lower limit) to how much the second drawing pattern P2 can be reduced in size. For example, even under clear skies in the daytime, in summer the environment becomes brighter than expected.

[0089] On the other hand, in order to improve the visibility of the second drawing pattern P2 in such a bright environment, it is necessary to further increase the output of the drawing light L emitted from the light source unit 2.

[0090] 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 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 so sufficient output cannot be obtained even when the drive current is increased.

[0091] Therefore, in the vehicle drawing device 1 of this embodiment, when the external light illuminance in 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).

[0092] 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 also be used. Also, a GaAs-based light emitting element such as AlGaAs can be used as the red light source 5R.

[0093] On the other hand, unlike the red light source 5R, the other light sources, the green light source 5G and the blue light source 5B, are less likely to experience a decrease in light extraction efficiency from the LD chip even if the temperature of the LD chip increases with an increase in drive current, and therefore can increase light output with an increase in drive current.

[0094] 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. Alternatively, the green light source 5G may be, for example, a GaN-based or InGaN-based light emitting element.

[0095] In the case of a GaN-based or InGaN-based LD chip, even if the temperature of the LD chip rises due to an increase in the drive current, the decrease in light emission efficiency can be suppressed, and therefore the optical output can be increased.

[0096] 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. Alternatively, the blue light source 5B may be, for example, a GaN-based light emitting element.

[0097] With a GaN-based LD chip, even if the temperature of the LD chip rises due to an increase in drive current, the decrease in light emission efficiency can be suppressed, and therefore the optical output can be increased.

[0098] In the vehicle drawing device 1 of this embodiment, in the above-described bright environment, road surface drawing is performed using 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.

[0099] In addition, when the illuminance of external light in the irradiation range E onto which the drawing light L is irradiated exceeds a threshold value, the control unit 4 controls the output of the other light sources (green light source 5G and blue light source 5B) to be higher than before the threshold value was exceeded.

[0100] In the vehicle imaging device 1 of this embodiment having the above-described configuration, lighting control of the light source unit 2 is performed according to the flowchart shown in FIG. 8, for example.

[0101] Specifically, first, as shown in step S101 of FIG. 8, it is detected that the owner of the key (passenger H) has unlocked the key lock of the vehicle 100 or has approached the vehicle 100.

[0102] Next, as shown in step S102 of FIG. 8, 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 begins.

[0103] 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 from the person can be used.

[0104] The human presence sensor may be a type of sonic wave sensor such as a sonar sensor that detects human movement by transmitting ultrasonic waves that hit a person and receive the reflected waves. The human presence sensor detects the occupant H by reacting within a detection range that surrounds the irradiation range E of the drawing light L, and outputs this detection signal to the control unit 4.

[0105] Furthermore, the human presence sensor can react not only to the passenger H but also to pedestrians, animals, bicycles, motorcycles, etc. When the human presence sensor reacts, the vehicular drawing device 1 can stop outputting the drawing light L and stop drawing on the road surface.

[0106] As another sensing function, 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.

[0107] The driver detection unit may be a combination of one or more 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 that the engine has started, and a sensor (heat detection type, pressure detection type, etc.) that detects that passenger H has sat in the driver's seat.

[0108] Next, as shown in step S103 of FIG. 8, the control unit 4 starts driving the MEMS mirror 3 (ON) and turns off each of the light sources 5R, 5G, and 5B (OFF), thereby enabling the MEMS mirror 3 to start scanning.

[0109] The MEMS mirror 3 is driven early because it takes time to prepare for irradiation. However, if it is started up instantly, it may be started up at the same time as the drawing starts in steps S'106 and S'108 in FIG. 8, which will be described later, and step S103 in FIG. 8 may be omitted.

[0110] Next, the control unit 4 determines whether or not the illuminance of external light exceeds a threshold value, as shown in step S104 of FIG.

[0111] In this embodiment, the threshold value is set based on the illuminance of ambient light, but it may also 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 a portion of the red light RL from the red light source 5R. Then, the value of the illuminance of ambient 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 value, and the determination may be made based on whether the threshold value is exceeded.

[0112] If it is determined that the external light illuminance exceeds the threshold value (Yes), the process proceeds to step S'105 in Figure 8, where the control unit 4 reads the external illuminance, reduces the scanning range from the irradiation range according to the external illuminance, keeps the red light source 5R off (OFF), and controls the green light source 5G and blue light source 5B to be on (ON).

[0113] 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 compared to when the ambient light illuminance is equal to or less than the threshold value. Furthermore, the drive current may be controlled to be further increased according to the magnitude of the ambient light illuminance.

[0114] Then, as shown in step S'106 of FIG. 8, 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.

[0115] On the other hand, if it is determined that the external light illuminance does not exceed the threshold (No), the process proceeds to step S'107 in FIG. 8, 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.

[0116] Then, as shown in step S'108 of FIG. 8, the MEMS mirror 3 is driven using the drawing light L obtained from the red light RL, the green light GL, and the blue light BL to start drawing on the road surface.

[0117] Next, as shown in step S109 of Fig. 8, when the human presence sensor reacts, the human presence sensor outputs a detection signal to the control unit 4. Upon receiving the detection signal, the control unit 4 stops outputting the drawing light L and transmits a stop signal to the light source unit 2 to stop drawing on the road surface.

[0118] Next, as shown in step S110 of FIG. 8, the light source unit 2, having received the stop signal, turns off all of the light sources 5R, 5G, and 5B, and stops drawing the road surface.

[0119] Next, as shown in step S111 of Fig. 8, when the driver detection unit reacts and detects that a passenger H is present in the vehicle 100, the driving of the MEMS mirror 3 is stopped (turned off) as shown in step S112 of Fig. 8, and then the power of the illuminance sensor 50 and the human presence sensor is turned off as shown in step S113 of Fig. 8, thereby ending sensing. This ends the flow of this embodiment.

[0120] As described above, in the vehicle drawing device 1 of this embodiment, when the external light illuminance in 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 from red light RL, green light GL and blue light BL.

[0121] On the other hand, when the external light illuminance of the irradiation range E onto which the above-mentioned drawing light L is irradiated exceeds a threshold value, in addition to reducing the scanning range from the irradiation range in accordance with the external illuminance, road surface drawing is performed using drawing light L obtained from green light GL and blue light BL without using red light RL.

[0122] This makes it possible to increase the contrast of the drawing light L and improve the visibility of the drawing pattern P even when drawing on a road surface in a bright environment.

[0123] 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 9A, a bordered drawing pattern P obtained by green light GL and blue light BL as shown in Figure 9B, and a negative-positive drawing pattern P obtained by green light GL and blue light BL as shown in Figure 9C.

[0124] 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 when the illuminance of external light exceeds the first threshold, control the drawing light L to have a first color tone, and when the illuminance of external light exceeds the second threshold, control the drawing light L to have a second color tone having a contrast with a higher hue or saturation than the first color tone.

[0125] For example, road surface drawing is performed by changing the color tone of the drawing light L obtained by mixing green light GL and blue light BL according to the first and second threshold values ​​of the external light illuminance (for example, the value of the external light illuminance on a cloudy or sunny day), thereby gradually increasing the contrast.

[0126] 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. Examples of the drawing pattern P using drawing light L of the first color tone include a monochromatic drawing pattern P obtained using green light GL or blue light BL as shown in Fig. 9A above.

[0127] In this case, contrast due to saturation can be added to the drawing pattern P projected onto a dark road surface T such as asphalt, thereby improving the visibility of the drawing pattern P compared to when drawing on the road surface using white drawing light L obtained by mixing red light RL, green light GL, and blue light BL.

[0128] On the other hand, when the illuminance of external light, such as that on a clear day (e.g., 30,000 Lux or more), exceeds the first threshold, a second threshold is set as a second threshold, and road surface drawing is performed using drawing light L of a second color tone. Examples of drawing patterns P using drawing light L of the second color tone include an edge drawing pattern P obtained using green light GL and blue light BL as shown in Fig. 9B above, and a negative-positive drawing pattern P obtained using green light GL and blue light BL as shown in Fig. 9C above.

[0129] In this case, it is possible to provide contrast due to the contrast of hue in addition to the contrast due to the saturation described above to the drawing pattern P projected onto the road surface T. 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 improve the visibility of the drawing pattern P in a bright environment.

[0130] Although the drawing pattern P produced by the drawing light L of the second color tone described above is exemplified as a edging or negative-positive drawing pattern P obtained by combining green light GL and blue light BL, other drawing patterns P such as a edging or negative-positive drawing pattern P may also be formed by using colored light obtained by mixing green light GL and blue light BL (e.g., light blue light). Light blue light is a bright colored light, and therefore enhances the contrast of saturation as well as hue. This further enhances the visibility of the drawing pattern P.

[0131] Furthermore, 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 ambient 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 ambient light, and it is also possible to control the drive current to be increased in stages between the first threshold value and the second threshold value.

[0132] In an application example of this embodiment, lighting control of the light source unit 2 is performed according to the flowchart shown in FIG. 10, for example.

[0133] Specifically, as in steps S101 to S103 of FIG. 8, steps S101 to S103 of FIG. 10 are performed as follows: first, as shown in step S101 of FIG. 10, it is detected that the owner of the key (passenger H) has unlocked the key lock of the vehicle 100 or has approached the vehicle 100.

[0134] 10, 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 the driver detection unit (not shown), which can detect the presence of a passenger H inside the vehicle 100, is turned on.

[0135] Next, as shown in step S103 of FIG. 10, the control unit 4 starts driving the MEMS mirror 3 (ON) and turns off each of the light sources 5R, 5G, and 5B (OFF), thereby enabling the MEMS mirror 3 to start scanning.

[0136] Next, the control unit 4 determines whether or not the illuminance of external light exceeds a first threshold value (for example, 3,000 Lux), as shown in step S201 of FIG.

[0137] If it is determined that the external light illuminance does not exceed the first threshold (No), the process proceeds to step S107 in FIG. 10, similar to steps S107 and S108 in FIG. 8, 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.

[0138] Then, as shown in step S108 of FIG. 10, the MEMS mirror 3 is driven using the drawing light L obtained from the red light RL, the green light GL, and the blue light BL to start drawing on the road surface.

[0139] On the other hand, if it is determined that the ambient light illuminance has exceeded the first threshold (Yes), the process proceeds to step S202 in FIG. 10, where it is determined whether the ambient light illuminance has exceeded a second threshold (for example, 30,000 Lux).

[0140] If it is determined that the external light illuminance does not exceed the second threshold (NO), the process proceeds to step S203 in FIG. 10, where the control unit 4 reads the external illuminance, reduces the scanning range from the irradiation range in accordance with the external illuminance, keeps the red light source 5R turned off (OFF), and controls the green light source 5G and blue light source 5B to be turned on (ON).

[0141] Then, as shown in step S204 of FIG. 10, 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 combining the green light GL and the blue light BL.

[0142] 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 illuminance of the external light is equal to or lower than the first threshold value.

[0143] On the other hand, if it is determined that the external light illuminance exceeds the second threshold (YES), the process proceeds to step S205 in FIG. 10, where the control unit 4 reads the external illuminance, reduces the scanning range from the irradiation range in accordance with the external illuminance, keeps the red light source 5R turned off (OFF), and controls the green light source 5G and the blue light source 5B to be turned on (ON).

[0144] Then, as shown in step S206 of FIG. 10, 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 combining the green light GL and the blue light BL.

[0145] 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 illuminance of the external light is equal to or lower than the second threshold value.

[0146] 8, when the human presence sensor reacts, it outputs a detection signal to the control unit 4, as shown in step S109 of Fig. 10. The control unit 4 receives the detection signal and stops outputting the drawing light L, thereby transmitting a stop signal to the light source unit 2 to stop drawing on the road surface.

[0147] Next, as shown in step S110 of FIG. 10, the light source unit 2, having received the stop signal, turns off all of the light sources 5R, 5G, and 5B, and stops drawing the road surface.

[0148] Next, as shown in step S111 of Fig. 10, when the driver detection unit reacts and detects that a passenger H is present in the vehicle 100, the driving of the MEMS mirror 3 is stopped (turned off) as shown in step S112 of Fig. 10, and then, as shown in step S113 of Fig. 10, the power supply of the illuminance sensor 50 and the human presence sensor is turned off, thereby ending sensing. This ends the flow of this embodiment.

[0149] As described above, in the application example of this embodiment, when the illuminance of external light exceeds the first threshold, in addition to reducing the scanning range from the irradiation range in accordance with the external illuminance, road surface drawing is performed using drawing light L of the first color tone described above, and when the illuminance of external light exceeds the second threshold, in addition to reducing the scanning range from the irradiation range in accordance with the external illuminance, road surface drawing is performed using drawing light L of a second color tone that has a higher hue or saturation than the first color tone described above.

[0150] This makes it possible to further improve the visibility of the drawing pattern P in bright environments 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.

[0151] 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.

[0152] 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.

[0153] Furthermore, the vehicle drawing device 1 of this 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 .

[0154] Furthermore, the vehicle drawing device 1 of this embodiment is not limited to the case where road surface drawing is performed when the vehicle is stopped as described above, but can also perform road surface drawing while the vehicle is moving. In this case, the drawing pattern P can display, for example, an image corresponding to a turn signal or an "AUTOPILOT" display during autonomous driving.

[0155] Furthermore, 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.

[0156] Although the light source unit 2 is configured to include light sources corresponding to the three primary colors of red light RL, green light GL, and blue light BL, it may also be configured to include light sources that emit other colored light, such as orange light or white light. Furthermore, it is also possible to include multiple light sources of the same color.

[0157] 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 F1...first scanning range F2...second scanning range H...occupant T...road surface P...imaging pattern P1...first imaging pattern P2...second imaging pattern

Claims

1. A vehicle drawing device mounted on a vehicle, comprising: a light source unit that emits drawing light; a scanning unit that forms a drawing pattern by scanning the drawing light emitted from the light source unit; and a control unit that variably controls the drawing pattern by controlling the drive of the scanning unit, wherein the control unit performs drive control to scan the drawing light in a scanning range that is reduced compared to the irradiation range when the external light illuminance of the irradiation range where the drawing light is irradiated exceeds a threshold value.

2. The drawing device for a vehicle as described in claim 1, wherein the scanning unit includes a mirror unit that reflects the drawing light emitted from the light source unit, and scans the drawing light by variably controlling the reflection direction of the drawing light while swinging the mirror unit in two-dimensional directions within a plane, and the control unit controls the drive of the scanning unit so that the swing range of the mirror unit is reduced when the external light illuminance exceeds a threshold value.

3. The vehicle imaging device according to claim 1, wherein the light source unit includes a laser light source.

4. The drawing device for a vehicle according to claim 1, characterized in that 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.

5. The drawing device for a vehicle as described in claim 2, characterized in that when the external light illuminance exceeds a threshold value, the control unit performs control to reduce the swing range of the mirror unit so that the scanning range becomes smaller stepwise or continuously as the external light illuminance increases.

6. The drawing device for a vehicle as described in claim 1, wherein the light source unit includes a plurality of light sources that emit light of different wavelengths, and emits drawing light of a color tone corresponding to the proportion of light emitted from each light source, and the control unit variably controls the color tone of the drawing light by controlling the lighting of the plurality of light sources, and when the external light illuminance of the irradiation range onto which the drawing light is irradiated exceeds a threshold value, turns off one of the plurality of light sources that emits light of the longest wavelength, and controls the lighting of the other light sources.

7. The imaging device for a vehicle according to claim 6, wherein the control unit performs control so as to increase the output of the other light sources when the illuminance of external light exceeds a threshold value compared to before the illuminance of external light exceeded the threshold value.

8. The drawing device for a vehicle as described in claim 6, wherein 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, and the control unit is configured to turn off the red light source and perform lighting control for the green light source and the blue light source when the external light illuminance exceeds a threshold value.

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

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

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

Images