JP2014010409A - Projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection display device whose optical detection means for correcting the deviation of an image projection position does not come into the view of a user watching an image projected on a screen.SOLUTION: A projection display device includes an optical sensor 210 detecting non-image light 211 scanned with a two-dimensional modulation element 202. A projection position of projection light 103 projected on a combiner 104 is corrected on the basis of a detection result of the optical sensor. The optical sensor is mounted on a folded mirror 205 which reflects image light scanned with the two-dimensional modulation element in such a manner that the light heads to the combiner or in the vicinity of the mirror.

Description

  The present invention relates to a projection display device that displays an image by projecting projection light onto a screen.

  2. Description of the Related Art Conventionally, in a projection type display device such as a projector that projects projection light (image light) based on image information onto a screen to display an image, a head-up display (HUD) that displays an image superimposed on a user's field of view There is a device. This HUD device uses a light-transmitting screen having a light-transmitting property to transmit light from the back side, and secures a field of view on the back side of the light-transmitting screen, while maintaining the front of the light-transmitting screen. An image is projected on the surface side. Such a HUD device is applied to a purpose of providing various information through vision to a driver (user) who drives a moving body such as a vehicle.

  2. Description of the Related Art As a projection display device, there is known a projector that employs an optical scanning method in which an image is displayed on a screen by scanning light emitted from a light source with respect to a screen by an optical scanning unit. Some optical scanning methods use a micro electro mechanical system (hereinafter referred to as “MEMS”) manufactured by a semiconductor process as the optical scanning means. The optical scanning means manufactured by the MEMS technology swings the direction of the light reflecting surface by a resonance operation, and deflects and scans the light incident on the light reflecting surface.

  When such an optical scanning means is used, optical scanning is performed using both the forward path and the backward path of the swinging operation, that is, using both from right to left and from left to right on the image. Thus, the number of scanning lines per unit time can be increased by projecting an image as compared with the case of projecting an image by performing optical scanning only in the forward path. However, the physical characteristics of various parts may change due to temperature and changes over time, which may cause the image portion projected during the forward pass and the image portion projected during the return pass to deviate during image drawing. . In this case, there arises a problem that the image becomes a double image (blurred image). Therefore, in the optical scanning method in which the light reflecting surface is swung, it is important to align the image projection position between the forward path and the backward path with high accuracy in order to suppress such a problem of the double image.

  Patent Document 1 discloses a scanning image display device (projection display device) having a configuration for suppressing a shift in image projection position between the forward path and the backward path. In this apparatus, light detection means for detecting scanning light is disposed at a position close to the outside of the effective area of the final optical surface of the scanning optical system (the surface of the screen on which an image visually recognized by the user is projected). Then, the deviation of the image projection position between the forward path and the backward path is corrected by controlling the light emission timing of the light source based on the signal from the light detection means.

  According to the projection display device described in Patent Document 1, the light detection means for detecting non-image light different from the image light irradiated to the effective region of the scanning light is outside the effective region of the final optical surface. Is arranged. For this reason, the image light applied to the effective area is not obstructed by the light detection means, so that it is possible to correct the deviation of the image projection position between the forward path and the backward path while projecting the image onto the final optical surface.

  However, in the projection display device described in Patent Document 1, since the light detection means is arranged at a position close to the effective area of the final optical surface, the light is detected in the field of view of the user who views the image displayed on the final optical surface. Means will get in. Therefore, there arises a problem that the aesthetic appearance of the projection display device viewed from the user is impaired by the light detection means. Further, when this projection type display device is used as a HUD device, there also arises a problem that the visual field part on the screen rear side is obstructed by the light detection means.

  These problems are not limited to the case where an image is projected by performing optical scanning using both the forward path and the backward path of the swinging operation. For example, even in the case where an image is projected by performing optical scanning only in the forward path of the swinging operation, the same is true in the configuration in which the light detection means for detecting the timing of the scanning light is disposed at a close position outside the effective area of the final optical surface This can be a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image displayed on a screen on which a light detection means for correcting a shift in the image projection position displays an image that is visually recognized by the user. It is an object of the present invention to provide a projection display device that does not enter the user's field of view.

  The present invention provides a light source that emits image light corresponding to image information and non-image light that is not the image light, an optical scanning unit that scans image light and non-image light emitted from the light source, and the optical scanning unit. In a projection display device having light detection means for detecting scanned non-image light and correction control means for correcting a projection position of image light projected on a screen based on a detection result of the light detection means, A light reflecting member that reflects the image light scanned by the light scanning unit toward the screen; and the light detecting unit is attached to or near the light reflecting member. .

  The light reflecting member reflects the image light toward the screen, and is disposed at a position that does not enter the field of view of the user who sees the image displayed on the screen. In the present invention, since the light detecting means is attached to or near the light reflecting member, the light detecting means is also arranged at a position that does not enter the field of view of the user who sees the image displayed on the screen.

  According to the present invention, it is possible to obtain an excellent effect that the light detection unit does not enter the field of view of the user who sees the image displayed on the screen that displays the image visually recognized by the user.

It is the schematic diagram which represented typically the structure of the motor vehicle carrying the HUD apparatus for motor vehicles in embodiment. It is the schematic diagram which represented typically the internal structure of the HUD apparatus for the vehicles. It is explanatory drawing which shows an example of the display image on a combiner. It is explanatory drawing when arrangement | positioning of the optical sensor of the HUD apparatus for motor vehicles is seen toward the reflective surface of a folding mirror. It is explanatory drawing for demonstrating the optical scanning system of the HUD apparatus for motor vehicles. It is explanatory drawing which shows the state in which the relative shift | offset | difference of an image projection position has not arisen between an outward path | route and a return path | route when a vertical line image is displayed. It is explanatory drawing which shows the state in which the relative shift | offset | difference of the image projection position has arisen between the outward path | route and a return path | route when a vertical line image is displayed. It is explanatory drawing when detecting non-image light with an optical sensor. (A) is explanatory drawing which shows the output signal of the optical sensor. (B) is explanatory drawing which shows the state in which position shift has not arisen between an outward path and a return path. (C) is explanatory drawing which shows the state which has produced position shift between an outward path and a return path. It is a block diagram which shows the flow of the position shift correction process in embodiment. It is explanatory drawing when the arrangement | positioning of the same optical sensor is seen from the direction parallel to the reflective surface of a folding mirror. It is explanatory drawing which shows one modification which has arrange | positioned the condensing lens 212 on the incident side of the same optical sensor.

Hereinafter, an embodiment in which a projection display device according to the present invention is applied to an automotive HUD device mounted on an automobile will be described.
FIG. 1 is a schematic diagram schematically showing the configuration of an automobile equipped with the automobile HUD device in the present embodiment.
FIG. 2 is a schematic diagram schematically showing the internal configuration of the automotive HUD device in the present embodiment.

  The automotive HUD device 100 according to the present embodiment is mainly composed of a light projection unit 102 installed in the dashboard of the automobile 101 and a combiner 104 as a screen disposed in proximity to the inner wall surface of the windshield 107. ing. The projection light 103, which is image light emitted from the light projection unit 102 in the dashboard, is reflected by the combiner 104 and travels to the driver 106 who is the user. The driver 106 can visually recognize an image displayed on the combiner 104 by the projection light 103. The combiner 104 of the present embodiment is a light-transmitting screen having a light-transmitting property that transmits about 70% of light from the back side (light entering from the windshield side). The driver 106 can view an image displayed on the combiner 104 while ensuring a view on the back side of the combiner 104 (a front view of the automobile 101).

  In this embodiment, the case where the combiner 104 installed on the inner wall surface side of the windshield 107 is used as the light transmissive screen will be described. However, a light transmissive screen may be attached to the inner wall surface of the windshield 107, or the windshield 107 itself may be used as the light transmissive screen.

  The light projection unit 102 includes red, green, and blue laser light sources 201R, 201G, and 201B, a two-dimensional modulation element 202, a projection lens 203, an intermediate screen 204, a folding mirror 205 as a light reflecting member, and various controls. And a controller unit 220 that performs the above-described operation and an input port 208.

  Laser light emitted from the laser light sources 201R, 201G, and 201B is two-dimensionally scanned by a two-dimensional modulation element 202 as an optical scanning unit, and projected and drawn on an intermediate screen 204 through a projection lens 203. Image data of an image to be displayed on the automotive HUD device 100 is input to the controller unit 220 via the input port 208. The controller unit 220 performs drive control of the laser light sources 201R, 201G, and 201B and drive control of the two-dimensional modulation element 202 based on the image data, and projects projection light for displaying an image according to the image data.

FIG. 3 is an explanatory diagram illustrating an example of a display image on the combiner 104.
In the present embodiment, on the combiner 104, the speed of the host vehicle (an image “60 km / h” in the illustrated example) is displayed by the automobile HUD device 100 in the first display area 104A. Speed information output from a speed measuring device (not shown) provided in the main body of the automobile 101 is input to the light projection unit 102 of the automotive HUD device 100 via the input port 208. The controller unit 220 of the light projection unit 102 controls the laser light sources 201R, 201G, 201B and the two-dimensional modulation element 202 according to the speed information, and displays an image indicating the speed according to the speed information on the combiner 104. .

  In the present embodiment, a navigation image based on car navigation control is displayed in the second display area 104B on the combiner 104. In the example shown in the figure, a right turn instruction image indicating the direction of turning at the next turn and an image “46 m” indicating the distance to the next turn are displayed as the navigation image. A map image based on car navigation control (a map image around the host vehicle) is displayed in the third display area 104C on the combiner 104.

FIG. 4 is an explanatory diagram when the arrangement of the photosensors 210 according to the present embodiment is viewed toward the reflection surface of the folding mirror 205.
In the present embodiment, in order to correct the projection position of the image light scanned by the two-dimensional modulation element 202 on the combiner 104, light for detecting the non-image light 211 from the two-dimensional modulation element 202 in the vicinity of the folding mirror 205. An optical sensor 210 is provided as detection means. The two-dimensional modulation element 202 and the optical sensor 210 are disposed in the apparatus case and are disposed at a position that cannot be visually recognized by the driver 106.

  As shown in FIG. 4, the image projected on the reflecting surface of the folding mirror 205 that reflects the projection light 103 from the two-dimensional modulation element 202 is displayed on the combiner 104 as shown in FIG. Become. A scannable area A by the two-dimensional modulation element 202 is a wider area than the display image drawing area B in which the image is displayed on the combiner 104 as the projection light 103.

FIG. 5 is an explanatory diagram for explaining an optical scanning method in the present embodiment.
The optical scanning of this embodiment employs a reciprocating scanning method in the main scanning direction (left-right direction) and a one-side scanning method in the sub-scanning direction (up-down direction). For the main scanning direction, for example, a resonant scanning device manufactured by MEMS technology can be used. Note that a one-side scanning method may be employed in the main scanning direction, and a reciprocating scanning method may be employed in the sub-scanning direction.

FIG. 6 is an explanatory diagram illustrating a state in which a relative shift of the image projection position does not occur between the forward path and the backward path when a vertical line image is displayed.
FIG. 7 is an explanatory diagram illustrating a state in which a relative shift of the image projection position occurs between the forward path and the backward path when a vertical line image is displayed.
When the reciprocating scanning method is adopted in the main scanning direction as in this embodiment, if the left-to-right scanning is the forward path and the right-to-left scanning is the backward path, the vertical position is slightly shifted between the forward path and the backward path. Each pixel is drawn. Therefore, as shown in the figure, when a vertical line image having a width of one pixel is drawn, a relative shift (hereinafter simply referred to as “position shift”) of the image projection position between the forward path and the return path. If it does not occur, as shown in FIG. 6, the pixels projected during the forward pass and the pixels projected during the return pass are alternately arranged to form a linear pixel line.

  However, the physical characteristics of the laser light sources 201R, 201G, 201B, the two-dimensional modulation element 202, the electronic circuit, and the like may change due to temperature and changes with time, and the response time (delay) may change. In such a case, the relative positions of the pixels projected on the forward path and the pixels projected on the backward path are shifted, and as shown in FIG. 7, even if an attempt is made to draw a vertical line, the pixels projected on the forward path and the pixels projected on the backward path The projected pixels are not linear, and the vertical lines appear double, making it impossible to draw properly.

  In the present embodiment, even if such a positional deviation occurs between the forward path and the backward path, this can be corrected based on the detection result of the optical sensor 210. In this embodiment, the optical sensor 210 is attached to the lower end of the folding mirror 205, and non-image light is scanned through the optical sensor 210. However, the arrangement of the optical sensor 210 is not limited to this. The optical sensor 210 may be disposed anywhere as long as it is within the scannable area A and can receive non-image light passing outside the display image drawing area B. However, the arrangement of the photosensors 210 in the main scanning direction (left-right direction) is preferably closer to the center than to positions near the left and right ends. This is because the scanning speed of the non-image light is slow at positions close to the left and right ends, and as a result of the short scanning distance in units of time, it is difficult to produce a difference in light detection timing according to the amount of positional deviation between the forward path and the backward path.

FIG. 8 is an explanatory diagram when non-image light is detected by the optical sensor 210.
FIG. 9A is an explanatory diagram showing an output signal of the optical sensor 210. FIG. 9B is an explanatory diagram illustrating a state in which no positional deviation occurs between the forward path and the return path. FIG. 9C is an explanatory diagram showing a state in which a positional deviation occurs between the forward path and the backward path.
When performing the process of correcting the positional deviation between the forward path and the backward path, the non-image light is scanned in the scannable area A outside the display image drawing area B, and as shown in FIG. Light is detected by the optical sensor 210 once for each return path.

  Here, as shown in FIG. 9A, the output signal of the optical sensor 210 is detected by the optical sensor 210 when the signal falls when detected by the optical sensor 210 during the forward scan and during the backward scan. The intermediate point in time of the signal rise at this time is the return timing of the forward path and the return path in the current detection result. In the present embodiment, how much the return timing is deviated from the target return timing is detected, and the positional deviation is corrected from the detection result.

  Specifically, the value of the main scanning counter is acquired at the time of signal fall when detected by the optical sensor 210 during forward scanning and at the time of signal rise when detected by the optical sensor 210 during backward scanning. . The value of this main scanning counter indicates the drawing order of each pixel constituting one image. Therefore, the value (target value) of the main scanning counter that should be detected when the signal of the optical sensor 210 falls during the forward scan, and the value of the main scanning counter that should be detected when the signal of the optical sensor 210 rises during the backward scan ( Target value) is grasped in advance. Therefore, by calculating the amount of deviation between the value of the main scanning counter acquired in each of the forward path and the backward path and the target value grasped in advance, the absolute positional deviation amount for each of the forward path and the backward path can be grasped. And the relative displacement between the return path and the return path.

FIG. 10 is a block diagram showing the flow of misalignment correction processing in the present embodiment.
In the present embodiment, the main scanning drawing control unit 221 realized by the controller unit 220 controls the light emission timings of the laser light sources 201R, 201G, and 201B. The main scanning drawing control unit 221 counts up the main scanning direction counter in synchronization with the light emission timings of the laser light sources 201R, 201G, and 201B for each image. Then, the value of the main scanning direction counter at the fall of the signal first detected from the optical sensor 210 (the detection signal of the non-image light in the forward path) is held in the counter Neg-time counter holding unit 222. Further, the value of the main scanning direction counter at the time of rising of the signal detected next from the optical sensor 210 (the detection signal of the non-image light during the return path) is held by the counter holding unit 223 during the return path Pos.

Thereafter, the turn-back point calculation unit 224 calculates the turn-back point C from the value A held by the forward-path Neg counter holding unit 222 and the value B held by the return-path Pos counter holding unit 223 by the following calculation. Obtained from equation (1). The turning point C calculated in this way is input to the correction value calculation unit 225.
C = A + (BA) / 2 (1)

  The correction value calculation unit 225 is also input with an assumed turning point D. The correction value calculation unit 225 calculates a difference value between the actual folding point C input from the folding point calculation unit 224 and the predicted folding point D, and uses this as a correction value E to perform main scanning drawing control. To the unit 221. Based on the input correction value E, the main scanning drawing control unit 221 corrects the light emission timings of the laser light sources 201R, 201G, and 201B so that the above-described difference value becomes small.

FIG. 11 is an explanatory diagram when the arrangement of the photosensors 210 in this embodiment is viewed from a direction parallel to the reflection surface of the folding mirror 205.
As described above, the optical sensor 210 of the present embodiment is disposed at the lower end of the folding mirror 205. When the irradiated surface of the optical sensor 210 irradiated with the non-image light 211 is in the same direction as the reflecting surface of the folding mirror 205, the non-image light 211 reflected by the irradiated surface of the optical sensor is reflected on the reflecting surface of the folding mirror 205. As with the projection light 103 reflected at, the light travels toward the combiner 104. In this case, an image by the non-image light 211 is displayed on the combiner 104 and may be visually recognized by the driver 106. When the driver 106 visually recognizes such an image by the non-image light 211, the quality of the image displayed on the combiner 104 may be deteriorated, or the driver 106 may be caused some misrecognition.

  Therefore, in this embodiment, the optical sensor 210 is provided so that the irradiated surface of the optical sensor 210 faces in a direction different from the reflection surface of the folding mirror 205. Preferably, as shown in FIG. 11, on the incident surface of the image light reflected by the reflecting surface of the folding mirror 205, to the side opposite to the side where the reflected light of the image light is emitted across the normal line of the reflecting surface, The optical sensor 210 is provided so that the non-image light reflected by the irradiated surface of the optical sensor 210 is directed. Thereby, the non-image light reflected by the irradiated surface of the optical sensor 210 is not projected on the combiner 104, and the image is not visually recognized by the driver 106.

  The non-image light 211 irradiated to the optical sensor 210 when performing the process of correcting the positional deviation between the forward path and the backward path may be light emitted from all the laser light sources 201R, 201G, and 201B. It is preferable to use light emitted from two laser light sources. If the light is emitted from only one laser light source, the non-image light 211 can be prevented from being defocused due to chromatic aberration. This is because when the focus of the non-image light 211 is defocused, the rise and fall of the output signal of the optical sensor 210 become slow, and the detection accuracy falls.

  In order to prevent the non-image light 211 from being defocused, an optical system such as a condensing lens 212 may be disposed as a condensing unit on the incident side of the optical sensor 210 as shown in FIG. Good. According to this, it is possible to stably avoid that the output accuracy of the optical sensor 210 slows down and the detection accuracy decreases.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
Scanning light sources such as laser light sources 201R, 201G, and 201B that emit image light such as projection light 103 according to image information and non-image light 211 that is not the image light, and image light and non-image light emitted from the light source An optical scanning unit such as a two-dimensional modulation element 202, a photodetection unit such as a photosensor 210 that detects non-image light 211 scanned by the optical scanning unit, and a combiner 104 based on the detection result of the photodetection unit. In a projection display apparatus having correction control means such as a controller unit 220 for correcting the projection position of image light projected on a screen such as the image light, the image light scanned by the light scanning means is directed toward the screen. A light reflecting member such as a folding mirror 205 to be reflected, and the light detecting means is attached to or near the light reflecting member; It is characterized in.
According to this, since the light detection means is arranged at a position that does not enter the field of view of the user (driver 106) who sees the image displayed on the screen, the beauty of the projection display device is impaired by the light detection means, The problem that the field of view on the back side of the screen is obstructed by the light detection means is solved.

(Aspect B)
In the aspect A, the light detection means is configured so that the reflected light of the non-image light reflected by the light detection means does not go to the screen.
According to this, the image by the non-image light 211 is not displayed on the screen, and the possibility of degrading the quality of the image displayed on the screen or causing some misrecognition to the user (driver 106) is avoided. it can.

(Aspect C)
In the aspect B, the irradiated surface of the light detecting unit irradiated with the non-image light is directed in a direction different from the reflecting surface of the light reflecting member that reflects the image light.
Thereby, even when the irradiated surface of the light detection means and the reflection surface of the light reflecting member are arranged side by side, an image by the non-image light 211 is not displayed on the screen.

(Aspect D)
In any one of the above aspects A to C, the light source has a condensing unit such as a condensing lens 212 that condenses the non-image light on the light detecting unit.
According to this, it is possible to stably avoid that the output accuracy of the optical sensor 210 slows down and the detection accuracy decreases.

(Aspect E)
In any one of the aspects A to D, the light source includes a plurality of light source units such as laser light sources 201R, 201G, and 201B that emit light of different colors, and the non-image light includes: The light is emitted from only one of the plurality of light source units.
According to this, it is possible to avoid the detection accuracy from deteriorating due to the focus of the non-image light 211 being blurred due to chromatic aberration and the rise and fall of the output signal of the optical sensor 210 being slow.

(Aspect F)
In any one of the above aspects A to E, the screen is a light-transmitting screen such as a combiner 104 having a light-transmitting property that transmits light from the back side.
According to this, the problem that the beauty of the HUD device is impaired by the light detection means, or the field of view on the back side of the screen is obstructed by the light detection means, is solved.

DESCRIPTION OF SYMBOLS 100 Automobile HUD apparatus 101 Automobile 102 Light projection part 103 Projection light 104 Combiner 106 Driver 107 Windshield 201R, 201G, 201B Laser light source 202 Two-dimensional modulation element 203 Projection lens 204 Intermediate screen 205 Folding mirror 210 Optical sensor 211 Non-image light 212 Condensing lens 220 Controller

JP 2006-235274 A

Claims (6)

A light source that emits image light according to image information and non-image light that is not the image light, an optical scanning unit that scans the image light and non-image light emitted from the light source, and a non-scan that is scanned by the optical scanning unit In a projection display device having light detection means for detecting image light and correction control means for correcting the projection position of the image light projected on the screen based on the detection result of the light detection means,
A light reflecting member that reflects the image light scanned by the light scanning unit toward the screen;
The projection display device, wherein the light detection means is attached to or near the light reflecting member. The projection display device according to claim 1,
The projection display device according to claim 1, wherein the light detection means is configured such that the reflected light of the non-image light reflected by the light detection means does not face the screen. The projection display device according to claim 2,
The projection display device according to claim 1, wherein an irradiated surface of the light detection unit irradiated with the non-image light is directed in a direction different from a reflection surface of the light reflecting member that reflects the image light. The projection display device according to any one of claims 1 to 3,
A projection-type display device comprising a light condensing means for condensing the non-image light on the light detecting means. In the projection type display device according to any one of claims 1 to 4,
The light source is composed of a plurality of light source sections that respectively emit light of different colors,
The non-image light is emitted from only one light source unit among the plurality of light source units. In the projection type display device according to any one of claims 1 to 5,
The projection display device, wherein the screen is a light-transmitting screen having a light-transmitting property that transmits light from the back side.

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