Projection type display device for vehicle

Abstract

To provide a projection type display device for a vehicle that can detect existence of an object positioned on an emission surface with a simple structure and high accuracy.SOLUTION: A display device 1 includes a cover panel 52 having an emission surface 52a whose height varies in front and rear directions F, R and which emits display light, infrared light sources 20, 30 which emit infrared light R1, R2, and an infrared sensor 10 that can detect reflected infrared light obtained by reflecting the infrared light R1 emitted from the infrared light source 20 and the infrared light R2 emitted from the infrared light source 30 on an object on the emission surface 52a. The infrared light source 30 is disposed on a lateral side of the emission surface 52a in a vehicle width direction W so as to be aligned with the infrared sensor 10 in the front and rear directions F, R, and is provided corresponding to a position with a first height of the emission surface 52a in the front and rear directions F, R. The infrared light source 20 and the infrared sensor 10 are positioned to face each other across the emission surface 52a in the vehicle width direction W and are provided corresponding to a position with a second height lower than the first height of the emission surface 52a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a projection display device for a vehicle. [Background technology]

[0002] The head-up display device described in Patent Document 1 above includes a light source that emits light and a display unit that generates display light from the light, and reflects the display light off the windshield to display a virtual image to the viewer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-73536 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, if an object falls onto the emission surface of the head-up display device, the display light is blocked by the object, resulting in a deterioration in the display quality of the virtual image. Therefore, there has been a demand for a simple configuration and a high-accuracy method for detecting the presence of an object on the emission surface.

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and aims to provide a projection display device for a vehicle that can detect the presence of an object on the exit surface with a simple configuration and high accuracy. [Means for solving the problem]

[0006] In order to achieve the above object, the vehicle projection display device according to the present disclosure comprises: A projection display device for a vehicle that displays an image by projecting display light from an emission port onto a projection target member, a cover panel that has a height that changes in the longitudinal direction of the vehicle, has an emission surface that emits the display light toward the projection member, is formed in a plate shape that closes the emission port, and is translucent so that the display light passes through; first and second infrared light sources each emitting infrared light along the emission surface; an infrared sensor configured to detect infrared light that directly arrives from the first infrared light source and infrared light that is reflected by an object on the emission surface and is obtained by reflecting infrared light from the second infrared light source, the second infrared light source is arranged on a side of the exit surface in a width direction perpendicular to the front-rear direction so as to be aligned with the infrared sensor in the front-rear direction, and is provided at a height of the exit surface in the front-rear direction corresponding to a position of the first height, The first infrared light source and the infrared sensor are positioned so as to face each other in the width direction via the emission surface, and are arranged in the front-to-rear direction corresponding to a second height position on the emission surface that is lower than the first height. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to detect the presence of an object on the emission surface with a simple configuration and high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a display device according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic plan view of a display device according to an embodiment of the present disclosure. [Figure 3] 1 is a schematic plan view of a display device according to an embodiment of the present disclosure. [Figure 4] 1 is a schematic cross-sectional view of a display device according to an embodiment of the present disclosure, as viewed from the front. [Figure 5] 1 is a schematic cross-sectional side view of a display device according to an embodiment of the present disclosure. [Figure 6] 1 is a schematic plan view of a display device according to an embodiment of the present disclosure. [Figure 7]1 is a schematic cross-sectional view of a display device according to an embodiment of the present disclosure, as viewed from the front. [Figure 8] 1 is a schematic cross-sectional side view of a display device according to an embodiment of the present disclosure. [Figure 9] 10 is a flowchart illustrating a determination process procedure according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic diagram of a vehicle equipped with a head-up display device according to a modified example of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] A projection display device for a vehicle according to an embodiment of the present disclosure will be described with reference to the drawings. 1, a projection-type display device 1 for a vehicle is mounted in a dashboard 205 of a vehicle 200. The display device 1 projects display light L onto a windshield 201, which is a projection target, to display a projection image including vehicle information such as vehicle speed so that it can be viewed by a viewer Us. In other words, the display device 1 is a windshield display (WSD) in which display light L from a display panel 51 (described later) of the display device 1 is directly projected onto the windshield 201.

[0010] The windshield 201 has a light-transmitting portion 202 and a light-blocking portion 203. The light-transmitting portion 202 is a portion that allows a viewer Us inside the vehicle cabin to view the actual scenery outside the vehicle cabin. The light-blocking portion 203 is located at the lower end of the light-transmitting portion 202 and is formed in an area of ​​the windshield 201 that faces the dashboard 205. The light-blocking portion 203 is formed of a black ceramic print. The display device 1 projects display light L onto the light-blocking portion 203, thereby displaying a projection image with the light-blocking portion 203 as a background.

[0011] Specifically, an outlet 207 facing the windshield 201 is formed in the dashboard 205. The display device 1 is mounted in the dashboard 205 so that the display light L passes through the cylindrical outlet 207. There is a risk that objects S1 and S2 placed on dashboard 205 may fall into outlet 207 due to inertial forces, etc. (including inertial forces generated by acceleration accompanying the running of vehicle 200 (including collisions and vibrations due to accidents), and gravity, the direction of which changes with changes in vehicle attitude). Display device 1 is configured to be able to determine whether objects S1 and S2 are located on exit surface 52a that emits display light L. In the following description, the forward direction F, the rearward direction R, the upward direction U, the downward direction D, and the vehicle width direction W, which is the left-right direction, are defined based on the viewpoint of the viewer Us.

[0012] As shown in FIG. 2, the display device 1 includes an infrared sensor 10, a first infrared light source 20, a second infrared light source 30, a control unit 40, a display 50, a case 60, boards 71, 72, and 73, and cables 75 and .

[0013] 4, the display device 50 includes a display panel 51, a cover panel 52, and a backlight 53. The display panel 51, the cover panel 52, and the backlight 53 are shaped like rectangular plates that are long in the vehicle width direction W, and are stacked in the up-down directions U and D.

[0014] The display panel 51 is a TFT (Thin Film Transistor) type liquid crystal panel. The display panel 51 displays an image including vehicle information such as vehicle speed under the control of the control unit 40. When the display panel 51 displays an image, it receives illumination light from the backlight 53 and emits display light L that shows the image. The backlight 53 is located below the display panel 51 in the direction D, and illuminates the display panel 51 under the control of the control unit 40 .

[0015] The cover panel 52 is located on the upper surface (image display surface) of the display panel 51, and is made of a resin or glass material that is optically transparent. The upper surface of the cover panel 52 is an exit surface 52a through which display light L from the display panel 51 passes through the cover panel 52 and exits. As shown in FIG. 1, the exit surface 52a is the surface of the display device 1 that is exposed to the projection target member (windshield 201). An exit port 207 is located on the outer periphery of the exit surface 52a. The exit port 207 is formed as a cylindrical internal space that penetrates in the up-down directions U and D.

[0016] The emission surface 52a is a flat surface, in this example a rectangular flat surface that is long in the vehicle width direction W, and is uniformly inclined with respect to the front-rear directions F, R. Specifically, the emission surface 52a is inclined in a downward direction D as it approaches the front direction F of the emission surface 52a. In other words, the height above the surface of the emission surface 52a decreases as it approaches the front direction F. The emission surface 52a is formed along the vehicle width direction W. It should be noted that, without being limited to this embodiment, the emission surface 52a may be inclined with respect to the vehicle width direction W. In this case, for example, the emission surface 52a may be inclined in a downward direction D as it moves toward the outer side of the vehicle in the vehicle width direction W. Furthermore, the light exit surface 52a may be inclined in a downward direction D as it goes in a rear direction R of the light exit surface 52a.

[0017] The case 60 is made of a light-shielding resin or metal and has a frame shape (a rectangular frame shape in this example), and is formed so as to surround the outer peripheries of the display panel 51, the cover panel 52, and the backlight 53. 2, the case 60 includes a pair of short side walls 60a, 60b and a pair of long side walls 60c, 60d. The pair of short side walls 60a, 60b extend in the front-rear directions F, R, respectively, and are positioned so as to face each other in the vehicle width direction W. The pair of long side walls 60c, 60d are longer than the short side walls 60a, 60b, extend in the vehicle width direction W, and are positioned so as to face each other in the front-rear directions F, R.

[0018] The case 60 has infrared transmitting portions 62, 63, and 64 as windows that partially transmit infrared light. The infrared transmitting portions 62, 63, and 64 are fitted into holes that penetrate the thickness direction of each of the wall portions 60a to 60d of the case 60. The infrared transmitting portions 62, 63, and 64 transmit infrared light in the thickness direction of the infrared transmitting portions 62, 63, and 64 so that the infrared light can move between the internal space of the case 60 and the external space. The infrared transmitting portion 62 is located at the end of the short side wall portion 60a in the rear direction R. The infrared transmitting portion 63 is located at the end of the short side wall portion 60a in the forward direction F. The infrared transmitting portion 64 is located at the end of the short side wall portion 60b in the forward direction F. The infrared transmitting portions 63 and 64 are located opposite each other in the vehicle width direction W.

[0019] The first infrared light source 20 is a light emitter that emits infrared light toward the infrared sensor 10. The first infrared light source 20 is located outside the case 60, facing the infrared transmitting portion 64. The first infrared light source 20 is located facing the infrared sensor 10 in the vehicle width direction W. The first infrared light source 20 is mounted on a substrate 72. The substrate 72 is electrically connected to the substrate 71 via a cable 76.

[0020] The first infrared light source 20 and the infrared sensor 10 constitute an infrared transmission type object detection system. The infrared transmission type object detection system determines the presence or absence of an object based on whether the infrared light from the infrared light source is blocked by the object. The infrared transmission type object detection system has a long detection distance and high detection position accuracy. It can also detect opaque objects regardless of their shape, color, or material, even if they are thin or plate-like. Furthermore, it is characterized by its resistance to dirt and dust on the light-emitting part (infrared light source) and the light-receiving part (infrared sensor).

[0021] The second infrared light source 30 is a light emitter that emits infrared light. The second infrared light source 30 is located outside the case 60 and faces the infrared transmitting portion 62. The second infrared light source 30 is located in the rear direction R of the infrared sensor 10.

[0022] The second infrared light source 30 and the infrared sensor 10 constitute an infrared reflective object detection system. This infrared reflective object detection system determines the presence or absence of an object based on the presence or absence of infrared light from the infrared light source reflected by the object. The infrared reflective object detection system does not take up much space because it only requires the second infrared light source 30 and the infrared sensor 10 to be placed on one side of the display 50 in the vehicle width direction W. In addition, it has the characteristics that it does not require optical axis alignment and can detect transparent objects as long as they are reflective. Note that reflection here includes not only specular reflection but also diffuse reflection.

[0023] The directivity of the infrared light emitted by the first infrared light source 20 is set to be higher than the directivity of the infrared light emitted by the second infrared light source 30. In other words, the directivity angle of the infrared light emitted by the first infrared light source 20 is set to be smaller than the directivity angle of the infrared light emitted by the second infrared light source 30.

[0024] The infrared sensor 10 is a light receiver that receives infrared light. The infrared sensor 10 is located outside the case 60, facing the infrared transmitting portion 63. The infrared sensor 10 senses the light intensity of the received infrared light, and outputs the sensed sensing signal Se to the control unit 40.

[0025] 4, the infrared sensor 10 is located at the same height as the first infrared light source 20 in the up-down directions U and D, and is located lower in the direction D than the second infrared light source 30. The infrared sensor 10 and the first infrared light source 20 are located corresponding to the lower end (in the direction of gravity) of the emission surface 52a, which is inclined in the front-rear directions F and R. This lower end of the emission surface 52a is an area where objects on the emission surface 52a are likely to gather due to the inertial force of the vehicle 200, etc. The second infrared light source 30 is provided at a position corresponding to a first height H1 (see FIG. 5) on the emission surface 52a, whose height varies in the front-rear directions F and R. The infrared sensor 10 and the first infrared light source 20 are provided at a position corresponding to a second height H2 (see FIG. 5), which is lower than the first height H1, on the emission surface 52a, whose height varies in the front-rear directions F and R. The position of the first height H1 is near the highest position on the emission surface 52a. The position of the second height H2 is near the lowest position on the emission surface 52a.

[0026] When there is no object between the infrared sensor 10 and the first infrared light source 20, the infrared sensor 10 directly receives the infrared light R1 (see FIGS. 6 and 7) from the first infrared light source 20. The infrared sensor 10 indirectly receives reflected infrared light R2a (see FIGS. 3 and 4) that is infrared light R2 (see FIGS. 3 and 4) emitted from the second infrared light source 30 and reflected by the object S1. 2, the infrared sensor 10 and the second infrared light source 30 are mounted on a common substrate 71. The substrate 71 is electrically connected via a cable 75 to the substrate 71 on which the control unit 40 is mounted.

[0027] The control unit 40 includes a CPU (Central Processing Unit), a GDC (Graphics Display Controller), etc. The control unit 40 includes a display control unit 41 that controls the display device 50, and an object determination unit 42 that determines whether or not an object is present on the emission surface 52a. The object determination unit 42 controls the infrared light sources 20 and 30 to emit the infrared light beams R1 and R2 at different timings, and receives a sensing signal Se from the infrared sensor 10. The object determination unit 42 determines the presence or absence of an object based on the received sensing signal Se. This determination process will be described later.

[0028] When the object determining unit 42 determines that there is no object on the emission surface 52a, the display control unit 41 displays on the display panel 51 an image including vehicle information such as the vehicle speed. When the object determination unit 42 determines that an object is present on the emission surface 52a, the display control unit 41 displays a warning image on the display panel 51. This warning image includes information such as the presence of an object on the emission surface 52a or a request for inspection at a car dealership. This warning image may be displayed together with an image including vehicle information. This warning image may be displayed only when the ignition of the vehicle 200 is turned on.

[0029] Next, the determination process procedure of the object determination unit 42 will be described with reference to the flowchart of Fig. 9. This determination process procedure is repeatedly executed while an image is being displayed on the display panel 51. First, the object determining unit 42 causes the first infrared light source 20 to emit infrared light R1 (step S101). Then, the object determining unit 42 determines whether or not an object exists between the infrared sensor 10 on the emission surface 52a and the first infrared light source 20, based on the sensing signal Se from the infrared sensor 10 (step S102).

[0030] In this step S102, as shown in Figures 3 to 5, if the infrared light R1 from the first infrared light source 20 is blocked by the object S2 and the infrared light R1 cannot be received by the infrared sensor 10, the object determination unit 42 determines that the object S2 is present between the infrared sensor 10 on the emission surface 52a and the first infrared light source 20 (step S102; YES).

[0031] When the object determination unit 42 determines that the object S2 is present (step S102; YES), the display control unit 41 displays a warning image on the display panel 51 (step S103), and the determination process ends.

[0032] 2, when the object determination unit 42 receives the infrared light R1 from the first infrared light source 20 via the infrared sensor 10, it determines that no object is present between the infrared sensor 10 on the emission surface 52a and the first infrared light source 20 (step S102; NO). More specifically, the object determination unit 42 determines that no object is present when the light intensity of the infrared light indicated by the sensing signal Se is equal to or greater than a first threshold value Th1. The first threshold value Th1 is set to a signal strength between the received signal strength of the infrared light R1 directly from the first infrared light source 20 at the infrared sensor 10 and the received signal strength at the infrared sensor 10 when the infrared light R1 is blocked by an object. When the object determining unit 42 determines that the object S2 does not exist (step S102; NO), it causes the second infrared light source 30 to emit infrared light R2 (step S104).

[0033] Then, the object determining unit 42 determines whether or not an object exists on the emission surface 52a based on the sensing signal Se from the infrared sensor 10 (step S105). 3 to 5, when the object determination unit 42 receives reflected infrared light R2a, which is infrared light R2 from the second infrared light source 30 and reflected by the object S1, via the infrared sensor 10, the object determination unit 42 determines that the object S1 is present on the emission surface 52a (step S105; YES). More specifically, the object determination unit 42 determines that the object is present on the emission surface 52a when the light intensity of the infrared light indicated by the sensing signal Se is equal to or greater than the second threshold value Th2. As shown in Figures 3 and 4, when the infrared sensor 10 receives reflected infrared light R2a that is infrared light R2 from the second infrared light source 30 reflected by the object S1, the light intensity of the reflected infrared light R2a detected by the infrared sensor 10 is greater than or equal to the second threshold value Th2. The second threshold Th2 is set to a signal strength between the received signal strength at the infrared sensor 10 of reflected infrared light R2a, which is infrared light R2 from the second infrared light source 30 reflected by the object S1, and the received signal strength at the infrared sensor 10 of reflected infrared light from the second infrared light source 30 reflected by each side wall portion or infrared light incident through the windshield 201.

[0034] When the object determination unit 42 determines that the object S2 is present (step S105; YES), the display control unit 41 displays a warning image on the display panel 51 (step S103), and the determination process ends.

[0035] Meanwhile, returning to step S105, after emitting infrared light R2 from the second infrared light source 30, if the light intensity of the infrared light indicated by the sensing signal Se is less than the second threshold value Th2, the object determination unit 42 determines that no object is present on the emission surface 52a (step S105; NO), and terminates the determination process while maintaining the display of the image including the vehicle information.

[0036] When the objects S1 and S2 are positioned on the emission surface 52a, the objects S1 and S2 may move back and forth in the front-rear directions F and R on the emission surface 52a due to the inertial force of the vehicle 200 or the like. For example, as shown in FIGS. 6 to 8 , when the spherical object S1 is located at the end of the emission surface 52a in the forward direction F, the infrared light R1 from the first infrared light source 20 passes through a gap Sp (see FIG. 8 ) between the outer circumferential surface of the object S1, the short side wall portion 60b, and the emission surface 52a. Therefore, in this state, the combination of the first infrared light source 20 and the infrared sensor 10 does not determine that the object S1 is located on the emission surface 52a, while the combination of the infrared light source 30 and the infrared sensor 10 determines that the object S1 is located on the emission surface 52a. However, when the object S1 moves in the forward direction F on the emission surface 52a due to the inertial force of the vehicle 200 or the like, the spherical object S1 is located at the end of the emission surface 52a in the rearward direction R, as shown in FIGS. 3 to 5 . Even in this state, the combination of the second infrared light source 30 and the infrared sensor 10 determines that the object S1 is located on the emission surface 52a, as described above.

[0037] Furthermore, for example, as shown in FIGS. 6 to 8, if a small object S2 is located at the end of the emission surface 52a in the rear direction R and near the short side wall portion 60b, it may be difficult to determine that the object S2 is located on the emission surface 52a using the combination of the second infrared light source 30 and the infrared sensor 10. However, if the object S2 moves in the forward direction F on the emission surface 52a due to the inertial force of the vehicle 200 or the like, the object S2 is located at the end of the emission surface 52a in the forward direction F, as shown in FIGS. 3 to 5. In this state, as described above, the combination of the first infrared light source 20 and the infrared sensor 10 determines that the object S2 is located on the emission surface 52a. The combination of the first infrared light source 20 and the infrared sensor 10 can accurately detect the object S2 even if the object S2 is thin or if the object S2 is located near the short side wall portions 60a, 60b.

[0038] (effect) According to the embodiment described above, the following effects are achieved. (1) Display device 1, which is an example of a vehicle projection display device, displays an image by projecting display light L from emission port 207 onto windshield 201, which is an example of a projection target member. Display device 1 includes: a cover panel 52, which is formed in a plate shape that closes emission port 207 and has an emission surface 52a that changes in height in the longitudinal directions F and R of vehicle 200 and emits display light L toward windshield 201, and which is translucent so that display light L passes through; first and second infrared light sources 20 and 30 that emit infrared light R1 and R2, respectively, along emission surface 52a; and an infrared sensor 10 that is configured to detect infrared light R1 that arrives directly from first infrared light source 20 and reflected infrared light R2a that is infrared light R2 from second infrared light source 30 reflected by an object S1 on emission surface 52a. The second infrared light source 30 is disposed to the side of the emission surface 52a in the vehicle width direction W, which is perpendicular to the front-to-rear direction F, R, so as to be aligned with the infrared sensor 10 in the front-to-rear direction F, R, and is provided so that the height of the emission surface 52a in the front-to-rear direction F, R corresponds to a position of a first height H1. The first infrared light source 20 and the infrared sensor 10 are positioned so as to face each other across the emission surface 52a in the vehicle width direction W, and are provided so that the height of the emission surface 52a in the front-to-rear direction F, R corresponds to a position of a second height H2 that is lower than the first height H1. According to this configuration, the number of infrared sensors 10 required is smaller than the number of infrared light sources 20, 30, and therefore the configuration can be simplified. Furthermore, an object on the emission surface 52a is likely to be located between the first infrared light source 20, which is low in height, and the infrared sensor 10. Therefore, it is possible to effectively utilize an infrared transmission type object detection system with high detection accuracy that is formed by combining the first infrared light source 20 and the infrared sensor 10.

[0039] (2) The first infrared light source 20 emits infrared light that is more directional than the infrared light from the second infrared light source 30 . According to this configuration, by combining the infrared light sources 20 and 30 with different directivities, it is possible to combine the features of the infrared transmission type and the infrared reflection type described above while compensating for each other's shortcomings.

[0040] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure. An example of such a modification is described below.

[0041] (Variation) In the above embodiment, the display device 1 projects the display light L onto the light-shielding portion 203 of the windshield 201, but this is not limiting, and the display light L may be projected onto the light-transmitting portion 202 of the windshield 201. In this case, the projected image may be superimposed on the actual scenery. In the above embodiment, the light blocking portion 203 of the windshield 201 may be omitted. In the above embodiment, the display device 1 may project the display light L onto a dedicated combiner.

[0042] In the above embodiment, the object determination unit 42 may receive vehicle speed information from an external source and determine whether an object is present on the emission surface 52a by taking the vehicle speed into consideration. For example, the object determination unit 42 may add a change in vehicle speed, i.e., an inertial force or the like exceeding a predetermined value, as one of the conditions for determining whether an object is present on the emission surface 52a. This predetermined value may be set to an inertial force or the like that may cause an object on the dashboard 205 to fall into the emission port 207.

[0043] In the above embodiment, the infrared transmitting portions 62, 63, and 64 may be condensing lenses that condense the infrared light that passes through them. The substrates 71, 72, and 73 in the above embodiment can be omitted. In the above embodiment, the infrared light sources 20, 30 and the infrared sensor 10 may be mounted on a control board below the display 50. In this case, a light-guiding member may be provided between the infrared light sources 20, 30 and the infrared sensor 10 and the side of the emission surface 52a.

[0044] In the above embodiment, the first infrared light source 20 emits infrared light with higher directivity than the infrared light from the second infrared light source 30, but this is not limited thereto, and the first infrared light source 20 may emit infrared light with lower directivity than the infrared light from the second infrared light source 30, or with the same directivity as the infrared light from the second infrared light source 30.

[0045] In the above embodiment, the infrared reflective object detection system has one second infrared light source 30, but multiple second infrared light sources 30 may be provided. For example, multiple (e.g., two) second infrared light sources 30 may be arranged in the front-rear directions F and R along the outer surface of the short side wall portion 60. Furthermore, the directivity and wavelength characteristics of the respective infrared light sources may be the same or different. Furthermore, threshold values ​​used for determination may be set individually depending on the respective infrared light sources. Furthermore, the emission of multiple infrared light sources may be controlled within a single detection operation, or may be controlled in a time-division manner.

[0046] The infrared sensor 10, the second infrared light source 30, and the first infrared light source 20 are arranged on both sides of the exit surface 52a in the vehicle width direction W, but they may also be arranged on both sides of the exit surface 52a in the front-to-rear directions F and R.

[0047] The infrared transmitting portions 62, 63, and 64 in the above embodiment may be formed as light guiding members. Also, the infrared transmitting portions 62, 63, and 64 may be omitted. In this case, the case 60 is formed so that infrared light passes through the through holes.

[0048] In the above embodiment, the exit surface 52a of the display panel 51 is configured to directly face the projection target (windshield 201), but this is not limiting, and a plate-shaped cover material made of translucent resin or glass may be provided between the display panel 51 and the projection target. The infrared sensor 10 and the infrared light sources 20, 30 may be arranged so as to be able to determine the presence or absence of an object on the exit surface of the cover material that faces the projection target. As an example of this modification, as shown in FIG. 10 , a head-up display (HUD) device 100 as a projection-type display device for a vehicle includes an HUD case 160, a cover material 162, a display device 50, and mirrors 120 and 130. The mirrors 120 and 130 are optical relays that guide display light L from the display device 50 to a projection target. The HUD case 160 houses the display device 50 and other components, and has an opening formed in a position facing a windshield 201. A translucent cover material 162 through which the display light L passes is fitted into this opening. The cover material 162 is shaped like a concavely curved plate that is inclined in the front-rear directions F and R. The infrared sensor 10 and infrared light sources 20 and 30 are arranged so as to be able to determine the presence or absence of an object on the emission surface (top surface) of the cover material 162. The cover material 162 may be lowest near the center in the front-to-back directions F, R, in which case the infrared sensor 10 and the first infrared light source 20 may be placed near the center, and the second infrared light source 30 may be placed on either side of this center in the front-to-back directions F, R. Furthermore, although the emission surfaces are formed at the same height in the vehicle width direction W, they may be formed at different heights in the vehicle width direction W. In this case, the infrared sensor 10 and the first infrared light source 20 may be disposed at the lowest positions in the front-rear directions F, R and the vehicle width direction W.

[0049] In the above embodiment, the display device 1 is a type equipped with a liquid crystal panel, but it may be of any type as long as it has an emission surface that emits display light L, and may be a type that uses an organic EL panel, a MEMS (Micro Electro Mechanical Systems), or a DMD (Digital Micro mirror Device). In the determination process procedure of the above embodiment, the order of emitting the infrared light R1 and R2 may be reversed.

[0050] In the above embodiment, when the object determination unit 42 determines that there is no object on the emission surface 52a, the display control unit 41 displays an image including vehicle information such as vehicle speed on the display panel 51. However, even when the object determination unit 42 determines that there is no object on the emission surface 52a, if the display control unit 41 has previously displayed a warning image, the display control unit 41 may maintain that display. For example, an object located on the emission surface 52a may be displaced due to inertial forces, etc. caused by the running of the vehicle 200. Therefore, even if the object determination unit 42 determines that there is no object on the emission surface 52a, there is a possibility that the object is simply temporarily outside the detection range. Therefore, even if the object determination unit 42 determines that there is no object on the emission surface 52a, if the display control unit 41 has previously displayed a warning image, the display may be maintained. In particular, since this possibility increases when the vehicle 200 is moving, the control to maintain the most recent warning image display may be performed only when the vehicle 200 is moving (i.e., excluding when parked or stopped). In such a case, prior to step S103 of the flowchart shown in FIG. 9, a step may be executed in which the object determination unit 42 retains a determination result indicating the presence of object S2, and the display control unit 41 determines whether to display a warning image or whether to change whether or not the immediately preceding warning image is displayed.

[0051] In the above embodiment, the object determination unit 42 determines whether an object is present on the emission surface 52a, but the object determination unit 42 may determine whether an object is present based on the results of measuring the light intensity multiple times. Measuring the light intensity multiple times (i.e., increasing the number of sampling times) reduces the possibility of erroneous determination due to disturbances and improves the accuracy of the determination result. [Explanation of symbols]

[0052] 1...display device, 10...Infrared sensor 20...First infrared light source 30...Second infrared light source 40...control unit, 41...display control unit, 42...object determination unit 50...display unit, 51...display panel, 52...cover panel, 52a...emission surface 53...Backlight 60... case, 60a, 60b... short side wall portions, 60c, 60d... long side wall portions, 62, 63, 64... infrared transmitting portions 71, 72, 73... Circuit board, 75, 76... Cable 100...head-up display device, 120, 130...mirror, 160...HUD case, 162...covering material 200...vehicle, 201...windshield, 202...transparent portion, 203...light-shielding portion, 205...dashboard, 207...exit port U...upward, D...downward, F...forward, R...rearward, W...vehicle width direction, L...display light, R1, R2...infrared light, R2a...reflected infrared light, S1, S2...object, Se...sensing signal, Th1...first threshold, Th2...second threshold, Sp...gap, Us...viewer

Claims

1. A projection display device for a vehicle that displays an image by projecting display light from an emission port onto a projection target member, a cover panel that has a height that changes in the longitudinal direction of the vehicle, has an emission surface that emits the display light toward the projection member, is formed in a plate shape that closes the emission port, and is translucent so that the display light passes through; first and second infrared light sources each emitting infrared light along the emission surface; an infrared sensor configured to detect infrared light that directly arrives from the first infrared light source and infrared light that is reflected by an object on the emission surface and is infrared light from the second infrared light source; the second infrared light source is arranged on a side of the exit surface in a width direction perpendicular to the front-rear direction so as to be aligned with the infrared sensor in the front-rear direction, and is provided at a height of the exit surface in the front-rear direction corresponding to a position of a first height, the first infrared light source and the infrared sensor are positioned to face each other in the width direction with the emission surface interposed therebetween, and are provided corresponding to a position of the emission surface at a second height in the front-rear direction, the height of the emission surface being lower than the first height. Projection display device for vehicles.

2. The first infrared light source emits infrared light having higher directionality than the infrared light from the second infrared light source.

2. The projection display device for a vehicle according to claim 1.

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