Patent Application
20180120686
This application is based on Japanese Patent Application No. 2015-89407 filed on Apr. 24, 2015, the disclosure of which is incorporated herein by reference.
The present disclosure relates to a road surface displaying device.
It has been known to place an optical material reflecting visible light of specific frequency on a road and project the visible light of the specific frequency from a track predicting device mounted to a vehicle, and thereby to perform a display (see patent literature 1).
Patent literature 1: JP-2005-139772A
In an art disclosed in the patent literature 1, a quantity of light reaching to a pedestrian or the like, which exists out of the vehicle, from the optical material is not sufficient and it is difficult for the pedestrian or the like to visually recognize the display.
In view of the foregoing issues, it is an object of the present disclosure to provide a road surface displaying device capable of performing a display having high visibility.
According to an aspect of the present disclosure, a road surface displaying device includes a light projecting unit and a polarization controlling unit. The light projecting unit projects light toward a road surface and performs a display by the light on the road surface. The polarization controlling unit sets a ratio of P-polarized light and S-polarized light in the light. The road surface displaying device sets the ratio of the P-polarized light and the S-polarized light in the light. As such, visibility of the display for pedestrian or the like is improved.
The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings, in which:
Embodiments will be described with reference to the drawings.
1. Structure of Road Surface Displaying Device 1.
An electrical structure of a road surface displaying device 1 will be described with reference to
The calculating portion 3 is a well-known computer having a CPU, a RAM, a ROM and the like. The calculating portion 3 executes processing described later by a program stored in the ROM. The calculating portion 3 controls each unit of the road surface displaying device 1. The calculating portion 3 functionally includes a polarization controlling unit 11, a target position detecting unit 13, a display image acquiring unit 15 and a light source controlling unit 17. The function of each unit will be described later.
The camera 5 is attached near a front edge of the own vehicle. The camera 5 takes pictures of scenery in front of the own vehicle and prepares image data. The prepared image data is transmitted to the calculating portion 3.
The light projecting unit 7 projects a light toward a road surface in front of the own vehicle and performs a display by the light on the road surface. The light projecting unit 7 includes a light emitting diode (i.e., LED) 19, a rotating unit 21 and a spatial modulator 23, as an electrical structure. The LED 19 emits visible light.
The rotating unit 21 sets a ratio of P-polarized light and S-polarized light (which is hereinafter referred to as a P/S ratio) in the light emitted by the LED 19 with a polarization plate 25, which will be described later. The details will be described later.
The LED 19 is one example of a circularly polarized light source. Other circularly polarized light source may be employed instead of the LED 19. For example, as the other circularly polarized light source, a halogen lamp, a high-intensity discharge (HID) lamp and the like may be employed.
For example, the polarization plate 25 is a film having minute slits and allows only polarized light parallel to the slits to pass through the film. The polarization plate 25 converts a non-linearly polarized light (e.g., a circularly polarized light such as laser) into linearly polarized light. An angle of a polarization plane (i.e., the P/S ratio) depends on an angle of the polarization plate 25. As the polarization plate 25, a ¼λ plate and the like may be employed. The ¼λ plate is made of a material causing birefringence such as crystal, isinglass and the like. A thickness of the ¼λ plate is adjusted so that ¼λ of phase lag occurs in the birefringence light. When the ¼λ plate is employed, it is preferable to employ the ¼λ plate together with the light source such as LED, HID and the like.
The spatial modulator 23 is a well-known digital mirror device (DMD). The spatial modulator 23 spatially modulates the light emitted by the LED 19 into a light expressing an image such as letters, figures and the like.
The input unit 9 is placed inside of the own vehicle and receives driver's input operation. For example, the driver's input operation includes settings by manual input of start and finish of the road surface display, selection of the image to be displayed on the road and the P/S ratio.
Next, the light projecting unit 7 will be described more precisely with reference to
As shown in
The P/S ratio of the light 24 passing through the polarization plate 25 varies depending on the angle of the polarization plate 25. That is, depending on the angle of the polarization plate 25, the P/S ratio of the light 24 passing through the polarization plate 25 is changed to a ratio substantially including only P-polarized light, and is changed to a ratio substantially including only S-polarized light.
The above described P-polarized light corresponds to a light having a polarization plane orthogonal to a road surface 27 (which is shown in
The rotating unit 21 is controlled by a polarization controlling unit 11 of the calculating portion 3. By controlling the rotating unit 21, the polarization controlling unit 11 can set the P/S ratio of the light 24 passing through the polarization plane 25 (i.e., the light 24 entering the road surface 27) into the ratio substantially including only P-polarized light and the ratio substantially including only S-polarized light.
2. Processing Executed by Road Surface Displaying Device 1
Processing executed by the road surface displaying device 1 (especially by the calculating portion 3) will be described with reference to
At step 1, the target position detecting unit 13 acquires an image of an area in front of the own vehicle shot by the camera 5.
At step 2, the target position detecting unit 13 executes a processing to recognize the target in the image acquired at the step 1, by using well-known image recognition techniques. The target that is to be recognized is, for example, a pedestrian, a bicycle and other vehicle.
At step 3, target position detecting unit 13 detects a position of the target recognized at the step 2. Then, the target position detecting unit 13 determines whether the position of the target is within a first region 29. As shown in
In a case where the position of the target is within the first region 29, the processing proceeds to a step 4. In the other cases (e.g., a case where the position of the target is out of the first region 29 or a case where the target is not recognized), the processing proceeds to a step 7.
At step 4, the polarization controlling unit 11 sets the P/S ratio of the light 24 entering the road surface 27 into the ratio substantially including only P-polarized light.
At step 5, the display image acquiring unit 15 outputs the information of the image to be displayed by the light 24 to the spatial modulator 23.
At step 6, the light source controlling unit 17 turns on the LED 19 to project the light from the light projecting unit 7 toward the road surface. The light to be projected toward the road surface displays the image outputted to the spatial modulator 23 at the step 5. In a case where the processing at the step 4 is executed, the P/S ratio of the light to be projected is the ratio substantially including P-polarized light. In a case where a processing at a step 8 is executed, which will be described later, the P/S ratio of the light to be projected is the ratio substantially including S-polarized light.
On the other hand, in a case where a negative determination is made at the step 3, the processing proceeds to the step 7. At the step 7, the target position detecting unit 13 detects the position of the target recognized at the step 2. Then, the target position detecting unit 13 determines whether the position of the target is within a second region 33.
As shown in
At the step 8, the polarization controlling unit 11 sets the P/S ratio of the light 24 entering the road surface 27 into the ratio substantially including S-polarized light.
3. Manual Setting of P/S Ratio
The input unit 9 has a function of receiving an input of the P/S ratio by the user. When the P/S ratio is inputted into the input unit 9, the polarization controlling unit 11 sets the P/S ratio of the light 24 to be consistent with the inputted P/S ratio.
4. Effects of the Road Surface Displaying Device 1
(1A) The road surface displaying device 1 sets the P/S ratio of the light 24. When the P/S ratio of the light 24 is set to the ratio substantially including the P-polarized light, as shown in
When the P/S ratio of the light 24 is set to the ratio substantially including the S-polarized light, as shown in
(1B) The road surface displaying device 1 detects the position of the target and sets the P/S ratio according to the position of the target. As such, the road surface displaying device 1 performs easily viewable display according to the position of the target.
(1C) The road surface displaying device 1 includes the LED 19 as the light source and sets the P/S ratio by using the polarization plate 25. As such, the road surface displaying device 1 sets the P/S ratio by simple structures.
(1D) The road surface displaying device 1 sets the P/S ratio by rotating the polarization plate 25. As such, the road surface displaying device 1 sets the P/S ratio by simple structures.
(1E) The road surface displaying device 1 projects the light expressing the image (e.g., letters or figures) on the road surface to display the image on the road surface.
1. Differences from First Embodiment
Basic structures of the second embodiment are similar to the first embodiment. Therefore, descriptions of common structures will be omitted and different structures will be mainly described.
As shown in
The switching unit 39 slides the polarization plate holder 40 in C direction or D direction shown in
On the other hand, when the switching unit 39 slides the polarization plate holder 40 in the D direction, the polarization plate 41 is located on the optical axis of the light 24 and the polarization plate 43 is located out of the optical axis of the light 24. In this case, the P/S ratio of the light 24 passing through the polarization plate 41 is the ratio substantially including the P-polarized light. That is, the switching unit 39 selects the polarization plate to be located on the optical axis of the light 24 from the polarization plates 41 and 43.
The switching unit 39 is controlled by the polarization controlling unit 11 of the calculating portion 3. By controlling the switching unit 39 to slide the polarization plate holder 40 in the C direction or the D direction, the polarization controlling unit 11 can set the P/S ratio of the light 24 entering the road surface 27 into the ratio substantially including only P-polarized light and the ratio substantially including only S-polarized light.
2. Effects of Road Surface Displaying Device 1
According to the above described second embodiment, the following effects are achieved in addition to the effects (1A) to (1C) and (1E) of the previously described first embodiment.
(2A) The road surface displaying device 1 sets the P/S ratio by selecting the polarization plate to be located on the optical axis of the light 24 from the polarization plates 41 and 43 whose directions of optical axes are different from each other. As such, the P/S ratio is set by simple structures.
1. Differences from First Embodiment
Basic structures of the third embodiment are similar to the first embodiment. Therefore, descriptions of common structures will be omitted and different structures will be mainly described.
As shown in
The ½λ plate 53 is made of a material causing birefringence such as crystal, isinglass and the like. A thickness of the ½λ plate is adjusted so that the constituent of the birefringence causes a phase lag corresponding to just half of a wavelength of the light emitted by the LD 1. The ½λ plate 53 changes the polarization angle of the linearly polarized light.
As shown in
The P/S ratio of the light 24 passing through the ½λ plate 53 varies depending on the angle of the ½λ plate 53. That is, depending on the angle of the ½λ plate 53, the P/S ratio of the light 24 passing through the ½λ plate 53 is changed to a ratio substantially including only P-polarized light and is changed to a ratio substantially including only S-polarized light.
The rotating unit 21 is controlled by the polarization controlling unit 11 of the calculating portion 3. By controlling the rotating unit 21, the polarization controlling unit 11 can set the P/S ratio of the light 24 passing through the ½λ plate 53 (i.e., the light 24 entering the road surface 27) into the ratio substantially including only P-polarized light and the ratio substantially including only S-polarized light.
2. Effects of Road Surface Displaying Device 1
According to the above described third embodiment, the following effects are achieved in addition to the effects (1A) (1B), (1E) of the previously described first embodiment.
(3A) The road surface displaying device 1 includes the LD 51 as the light source and sets the P/S ratio by using the ½λ plate 53. As such, the P/S ratio is set by simple structures.
(3B) The road surface displaying device 1 sets the P/S ratio by rotating the ½λ plate 53. As such, the P/S ratio is set by simple structures.
1. Differences from First Embodiment
Basic structures of the fourth embodiment are similar to the first embodiment. Therefore, descriptions of common structures will be omitted and different structures will be mainly described.
As shown in
The light projecting unit 307 includes the ½λ plate holder 61 shown in
The switching unit 39 slides the ½λ plate holder 61 in C direction or D direction shown in
On the other hand, when the switching unit 39 slides the ½λ plate holder 61 in the D direction, the ½λ plate 57 is located on the optical axis of the light 24 and the ½λ plate 59 is located out of the optical axis of the light 24. In this case, the P/S ratio of the light 24 passing through the ½λ plate 57 is the ratio substantially including only P-polarized light. That is, the switching unit 39 selects the polarization plate to be located on the optical axis of the light 24 from the ½λ plates 57 and 59.
The switching unit 39 is controlled by the polarization controlling unit 11 of the calculating portion 3. By controlling the switching unit 39 to slide the ½λ plate holder 61 in the C direction or the D direction, the polarization controlling unit 11 can set the P/S ratio of the light 24 entering the road surface 27 into the ratio substantially including only P-polarized light and the ratio substantially including only S-polarized light.
2. Effects of Road Surface Displaying Device 1
According to the above described fourth embodiment, the following effects are achieved in addition to the effects (1A), (1B) and (1E) of the previously described first embodiment.
(4A) The road surface displaying device 1 includes the LD 51 as the light source and sets the P/S ratio by using the ½λ plates 57 and 59. As such, the P/S ratio is set by simple structures.
(4B) The road surface displaying device 1 sets the P/S ratio by selecting the ½λ plate located on the optical axis of the light 24 from the ½λ plates 57 and 59 having the direction of the optical axis different from each other. As such, the P/S ratio is set by simple structures.
Although the embodiments are described hereinabove, the present disclosure is not limited to the above embodiments and may include several modifications.
(1) In the above first to fourth embodiments, the P/S ratio set by the polarization controlling unit 11 may include both of the P-polarized light and the S-polarized light. For example, at the step 4, the P/S ratio may be set to a ratio including 80% of P-polarized light and 20% of S-polarized light, and at the step 8, the P/S ratio may be set to a ratio including 20% of P-polarized light and 80% of S-polarized light.
(2) In the above first to fourth embodiments, the light to be projected on the road surface may be a light that does not express the image such as letters and figures. For example, the light may be a light having uniform illuminance and color regardless of the position.
(3) In the above second embodiment, the polarization plate holder 40 may hold three or more polarization plates. In this case, by sliding the polarization plate holder 40, one polarization plate to be located on the optical axis of the light 24 is selected from a group of three or more polarization plates.
In the above fourth embodiment, the ½λ plate holder 61 may hold three or more ½λ plates. In this case, by sliding the ½λ plate holder 61, one plate located on the optical axis of the light 24 is selected from a group of three or more ½λ plates.
(4) In the above first to fourth embodiments, as the spatial modulator 23, a liquid crystal panel, a galvanoscanner and the like may be employed instead of the DMD.
(5) In the above second embodiment, the switching unit 39 may select one polarization plate to be located on the optical axis of the light 24 by rotating the polarization plate holder 40. In the above fourth embodiment, the switching unit 39 may select one ½λ plate to be located on the optical axis of the light 24 by rotating the ½λ plate holder 61.
(6) In the above first to fourth embodiment, method for setting the first region 29 and the second region 33 may be suitably selected. For example, the method may be employed in which the first region 29 is set as described in the first embodiment and the other region is set as the second region 33. The method may be employed in which the second region 33 is set as described in the first embodiment the other region is set as the first region 29.
(7) In the above first to fourth embodiments, the processing when the negative determination is made at the step 7 may be changed. For example, the display may be performed even when the negative determination is made at the step 7. In this case, the P/S ratio of the light 24 may be suitably set. For example, the P/S ratio may be the ratio substantially including only P-polarized light, the ratio substantially including only S-polarized light, or intermediate ratio thereof.
(8) For example, a function of one of elements of the above embodiments may be dispersed in multiple elements, or functions of multiple elements may be combined in one of the elements. At least a part of the elements of the above embodiments may be replaced by an element having similar function. A part of the elements of the above embodiments may be omitted. At least a part of the elements of the above embodiments may be added to the other embodiments, or at least a part of the elements of the above embodiments may be replaced in the other embodiments.
(9) The present disclosure may be implemented in various ways, other than the above described road surface displaying device, such as a system including the road surface displaying device as an element, a program allowing a computer to function as the calculating portion of the road surface displaying device, a media storing the program, a method for the road surface display and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-89407 | Apr 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/001786 | 3/28/2016 | WO | 00 |
