JP2008070782A - Headup display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a headup display which suppresses the irradiation of a display device with outside light without causing deterioration due to the outside light. <P>SOLUTION: The headup display device 10 for displaying a predetermined display image overlapping on a user's view comprises a liquid crystal display device 20 that serves as a light emitting part for emitting light based on the display signal related to the display image. A reflection type polarizing plate 26 which is irradiated with the light, and reflects the predetermined polarized light contained in the light. It further comprises a combiner 28 which is irradiated with the predetermined polarized light reflected by the reflection type polarizing plate, reflects the polarized light to a user's side, and makes visible the display image by the polarized light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a head-up display for displaying information in a normal view of a user.

  The head-up display is used, for example, to display information on the windshield of the vehicle, so that the driver can view desired information with little movement of the line of sight and adjustment of the focus. In such an apparatus, a display image can be visually recognized by projecting signal light onto a windshield, which is a combiner, and reflecting the signal light toward the user. In such a head-up display, external light entering in the direction opposite to the signal light may be applied to a display device that emits signal light such as a liquid crystal display device. When the display device is irradiated with external light in this way, the display device may be deteriorated or the performance may be deteriorated by heat, infrared rays, or ultraviolet rays. Therefore, it is desirable to suppress the display device from being irradiated with external light. As a configuration for suppressing irradiation of the display device by external light, a configuration in which a polarizing plate is disposed in an optical path through which external light is guided to the display device and a part of the external light is absorbed by the polarizing plate has been proposed. (For example, refer to Patent Document 1).

JP-A-10-138794 JP-A-5-131866 Japanese Patent Laid-Open No. 7-230059

  However, in the case of suppressing the irradiation of external light to the display using the absorption type polarizing plate in this way, the absorption type polarizing plate is relatively weak against heat and has a limited incident power. When strong external light accompanied with water is absorbed, there is a problem that the polarizing plate deteriorates.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to suppress irradiation of external light to a display device without causing deterioration due to external light in a head-up display. And

In order to achieve the above object, the present invention provides a head-up display that displays a predetermined display image superimposed on a user's field of view,
A light emitting unit for emitting light based on a display signal related to the display image;
A reflective polarizing plate that is irradiated with the light and reflects predetermined polarized light included in the light;
A combiner that irradiates the predetermined polarized light reflected by the reflective polarizing plate, reflects the polarized light toward the user, and makes a display image by the polarized light visible. The gist.

  According to the head-up display of the present invention configured as described above, the reflection type polarizing plate is arranged in the middle of the optical path in which the light emitted from the light emitting unit is irradiated to the combiner. Even when the light is reflected to the light emitting portion, the amount of light reflected can be reduced. For this reason, it is possible to suppress deterioration of the light emitting portion and performance degradation due to external light irradiation. In this way, to reduce the amount of external light radiated to the light emitting part, a reflective polarizing plate with excellent strength and high durability is used, so heads up due to suppressing the entry of external light A decrease in durability of the entire display can be suppressed.

In the head-up display of the present invention,
The light emitted from the light emitting section may be linearly polarized light reflected by the reflective polarizing plate.

  With such a configuration, the light emitted from the light emitting unit can be efficiently used for displaying a display image.

In the head-up display of the present invention,
The reflection-type polarizing plate is arranged at an angle where specular reflection light obtained by regular reflection of external light irradiated on the reflection-type polarizing plate from the outside of the head-up display is directed to a position different from the position of the user. It is also good to have.

  With such a configuration, even when external light is reflected by the reflective polarizing plate, it is possible to prevent a decrease in visibility due to reflected light by the user.

In the head-up display of the present invention,
Prior to reflection by the reflective polarizing plate, a divergence angle adjusting unit that reduces the divergence angle of the diffused light may be provided.

  According to such a configuration, since the position (virtual image position) where the display image is displayed by forming the virtual image can be further distant, in the user who is focusing relatively far away, The burden of focus adjustment when viewing the display image can be reduced.

  In such a head-up display of the present invention, the divergence angle adjusting unit may be a convex lens disposed between the light emitting unit and the reflective polarizing plate. Alternatively, the divergence angle adjusting unit may be a concave mirror that reflects the light emitted from the light emitting unit to the reflective polarizing plate. By setting it as such a structure, the divergence angle of the light which is a diffused light can be made small easily.

In the head-up display of the present invention,
It is good also as providing the light-absorbing plate arrange | positioned in the position which can absorb the external light which was irradiated to the said reflective polarizing plate from the exterior of the said head-up display, and permeate | transmitted the said reflective polarizing plate.

  With such a configuration, it is possible to secure the absorption of the external light transmitted through the reflective polarizing plate and suppress inconvenience due to the transmitted external light.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in a form such as a method for suppressing deterioration due to heat caused by external light in a display that is provided in a head-up display and emits light. Is possible.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a head-up display device 10 as a preferred embodiment of the present invention. The head-up display device 10 includes a liquid crystal display device 20, a lens 24, a reflective polarizing plate 26, a combiner 28, and a housing 30. Such a head-up display device 10 according to the present embodiment is a device that is mounted on a vehicle and displays information related to the vehicle in a superimposed manner on the field of view of the driver who is the user. Here, the combiner 28 may be formed on a part of the windshield of the vehicle, or the entire windshield may be formed as the combiner 28. The components other than the combiner 28 in the head-up display device 10 are housed in the housing 30 and are arranged in the vicinity of the driver's seat, such as the dashboard or the inside of the instrument panel.

  The liquid crystal display device 20 is a light emitting unit that emits light 15, and includes a liquid crystal light valve 21 and a light source 22. As the light source 22, various light sources such as a fluorescent tube, a light emitting diode (LED), a halogen lamp, and a high-pressure mercury lamp can be used, and may be appropriately selected in consideration of the amount of light obtained, power consumption, and the like. The liquid crystal light valve 21 is a TN liquid crystal light valve having a structure in which a layer made of liquid crystal is sandwiched between two polarizing filters whose polarization directions of transmitted light are orthogonal to each other. The light emitted from the light source 22 is modulated according to the video signal (display signal) in the liquid crystal light valve 21, and linearly polarized light is emitted as the light 15 from the liquid crystal display device 20.

  The light 15 emitted from the liquid crystal display device 20 passes through a lens 24 that is a convex lens. At this time, the divergence angle of the light 15 which is diffused light is changed by passing through the lens 24, and the divergence angle becomes smaller. As described above, the lens 24 functions as a divergence angle adjusting unit that adjusts the divergence angle of the light 15, and a virtual image position of a display image to be described later becomes farther as the divergence angle of the light 15 becomes smaller.

  The light 15 transmitted through the lens 24 is reflected by the reflective polarizing plate 26. The reflective polarizing plate 26 is a polarizer that reflects polarized light in a specific direction included in the irradiated light, and can be constituted by, for example, a wire grid polarizer. Here, in this embodiment, the optical axis of the reflective polarizing plate 26 is adjusted so that the light 15 that is linearly polarized light emitted from the liquid crystal display device 20 is reflected, and the light 15 is reflected by the reflective polarizing plate. At 26, almost 100% is reflected.

  The light 15 reflected by the reflective polarizing plate 26 is further reflected to the driver side by the combiner 28, and the display image by the light 15 is visually recognized by the driver. When the combiner 28 is formed so as to overlap a part of the windshield, the combiner 28 can be formed by, for example, a half mirror deposited with a metal film or a dielectric multilayer film. Here, the display information included in the light 15 is visually recognized by the driver by forming a virtual image at the virtual image position shown in FIG. As described above, the light has a smaller divergence angle by passing through the lens 24 prior to reflection by the reflective polarizing plate 26, and therefore the virtual image position of the display image is not provided with the lens 24. It will be farther than. FIG. 2 shows that light that is diffused light emitted from the liquid crystal display device 20 passes through the lens 24 and has a small divergence angle, and then is reflected by the reflective polarizing plate 26 and the combiner 28, at a farther position. It shows how a virtual image is formed. 2 shows the state of the light 15 when the distance between the liquid crystal display device 20 that is the light source of the light 15 and the lens 24 is shorter than the focal length of the lens 24. FIG.

  In a vehicle equipped with such a head-up display device 10, when external light enters the vehicle, a part of the light enters the reflective polarizing plate 26 and can be reflected by the reflective polarizing plate 26. Of the external light incident on the reflective polarizing plate 26, the external light incident in the reverse direction on the optical path when the light 15 reflected by the reflective polarizing plate 26 is applied to the combiner 28 is reflected in the reflective polarizing plate 26. Reflected toward the liquid crystal display device 20 side. External light at other angles incident on the reflective polarizing plate 26 is reflected by the reflective polarizing plate 26, and most of it is absorbed by the inner wall surface of the housing 30 that houses the head-up display device 10. As described above, when external light is reflected by the reflective polarizing plate 26, 50% of the external light is reflected, and the remaining 50% of the external light is transmitted through the reflective polarizing plate 26. Here, most of the external light transmitted through the reflective polarizing plate 26 is absorbed by the inner wall surface of the housing 30. When absorption of transmitted light by the inner wall surface of the housing 30 is insufficient, a black plate is provided on the back side of the reflective polarizing plate 26 (the side opposite to the side where light is reflected) in the housing 30. A light absorption plate 32 such as the above may be disposed (see FIG. 1) to ensure absorption of transmitted light.

  According to the head-up display device 10 of the present embodiment configured as described above, the reflection-type polarization is provided in the middle of the optical path in which the light emitted from the liquid crystal display device 20 that is the light emitting unit is irradiated to the combiner 28. Since the plate 26 is disposed, the amount of reflected light can be reduced even when external light is reflected to the light emitting portion. For this reason, it is possible to suppress the deterioration and performance deterioration of the light emitting portion due to the irradiation of external light, specifically the deterioration and performance deterioration of the liquid crystal light valve 21.

  Furthermore, according to the head-up display device 10 of the present embodiment, a reflective polarizing plate having excellent strength and high durability is used in order to reduce the external light irradiated to the light emitting portion. Therefore, unlike the case where, for example, an absorption type polarizing plate is used to suppress the entry of external light, the durability of the entire head-up display device 10 is not lowered.

  Further, according to this embodiment, since the optical axis of the polarizing plate of the liquid crystal light valve 21 is aligned so that substantially 100% of the light 15 is reflected by the reflective polarizing plate 26, the light is emitted from the liquid crystal display device 20. The emitted light 15 can contribute to display efficiently.

  Furthermore, according to the present embodiment, since the reflection type polarizing plate 26 is used as a reflection plate for changing the direction of the optical path of the light 15 irradiated from the light emitting portion to the combiner 28, the reflection plate Even when external light is reflected toward the driver, the amount of reflected external light can be reduced to 50%. Thereby, even if it is a case where reflection of external light occurs, the fall of the visibility resulting from reflected light in a driver | operator can be suppressed.

  In addition, in order to suppress a decrease in visibility due to reflection of external light by the reflective polarizing plate 26, external light from any direction in the vehicle is taken into consideration in consideration of the position of a window provided in the vehicle. Even when the light enters the reflective polarizing plate 26, the direction of the reflective polarizing plate 26 may be set so that the regular reflected light of the external light incident on the reflective polarizing plate 26 is directed to a position different from the position of the driver. good. Thereby, a driver | operator's visibility can be ensured more fully. Alternatively, in the case housing the reflective polarizing plate 26 and the liquid crystal display device 20, the shape near the opening through which the light 15 irradiated from the reflective polarizing plate 26 to the combiner 28 passes is set to a predetermined shape. The reflection of external light incident on the reflective polarizing plate 26 to the driver may be prevented.

  In addition, according to the present embodiment, the light 15 emitted from the liquid crystal display device 20 is transmitted through the lens 24 which is a divergence angle adjusting unit before being reflected by the reflective polarizing plate 26, and the divergence of the light 15 is performed. The corners are made smaller, thereby making the formation position of the virtual image as the display image farther. Therefore, it is possible to reduce the burden of adjusting the focus when the driver who is driving with the focus relatively far away looks at the display image. However, a configuration in which the lens 24 that is a divergence angle adjusting unit is not provided is also possible. In such a case, although the virtual image position is closer, a similar effect of suppressing reflection of external light can be obtained.

  Strictly speaking, in order to use the lens 24 as a divergence angle adjusting unit that reduces the divergence angle of the light 15, the distance between the lens 24 and the liquid crystal display device 20 is made closer to the focal length of the lens 24. The lens 24 and the liquid crystal display device 20 may be disposed. When the lens 24 and the liquid crystal display device 20 are arranged at such positions, especially when the distance between the lens 24 and the liquid crystal display device 20 is the focal length of the lens 24, the virtual image position of the display image is infinite. . Thus, the virtual image position of the display image changes depending on the arrangement of the lens 24 and the liquid crystal display device 20. Therefore, when the lens 24 is used, the arrangement of the lens 24 and the liquid crystal display device 20 should be appropriately set in consideration of the driver's normal focus position so as to further reduce the burden of focus adjustment on the driver. That's fine.

  The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

Modification 1:
In the embodiment, the light emitting unit is the liquid crystal display device 20 that directly emits linearly polarized light, but may have a different configuration. For example, an LED display device, a fluorescent display tube, or an electroluminescence (EL) display can be used. However, when the light emitted from the light emitting portion is not polarized light, half of the light is transmitted through the reflective polarizing plate 26. Therefore, in order to ensure the efficiency with which light contributes to display, it is desirable to use a light emitting unit that emits linearly polarized light corresponding to the reflective polarizing plate.

Modification 2:
In the embodiment, the convex lens is provided as the divergence angle adjusting unit for adjusting the divergence angle of the light 15 in order to make the virtual image position of the display image farther, but a different configuration may be used. For example, the divergence angle adjusting unit can be formed by a concave mirror. A head-up display device 110 having such a configuration is shown in FIG. 2 as a modification. Since the head-up display device 110 has the same configuration as that of the head-up display device 10 of the embodiment except that the head-up display device 110 includes a concave mirror 124 instead of the lens 24, the same reference numerals are assigned to the components common to the embodiment. Detailed description will be omitted.

  In the head-up display device 110, the light 15 emitted from the liquid crystal display device 20 is reflected by the concave mirror 124, enters the reflective polarizing plate 26, is reflected by the reflective polarizing plate 26, and further passes to the combiner 28. It is irradiated. By using such a concave mirror 124, it becomes possible to change the divergence angle of the light 15 which is diffused light, and to make the light 15 into diffused light having a smaller divergence angle. Accordingly, the virtual image position of the display image can be further distant as in the embodiment in which the lens 24 is disposed. In such a head-up display device 110 as well, the use of the reflective polarizing plate 26 reduces the amount of external light reflected by the reflective polarizing plate 26 and the concave mirror 124 and applied to the light emitting portion. An effect is obtained.

Modification 3:
Although not described in the head-up display device 10 of the embodiment shown in FIG. 1, the light irradiated from the reflective polarizing plate 26 to the combiner 28 in the housing that houses the reflective polarizing plate 26 and the light emitting portion. You may provide protective glass in the opening part through which 15 passes. With such a configuration, the device in the housing can be protected from dust and the reliability of the device can be improved. At this time, a part of the external light entering the vehicle is reflected by the protective glass, but half of the external light that passes through the protective glass and enters the reflective polarizing plate 26 is reflected by the reflective polarizing plate 26. By transmitting the light, it is possible to obtain the same effect of suppressing the external light irradiation to the light emitting portion or the reflection to the driver.

2 is an explanatory diagram illustrating a schematic configuration of a head-up display device 10. FIG. It is explanatory drawing showing a mode that the emitted light forms a virtual image. 3 is an explanatory diagram illustrating a schematic configuration of a head-up display device 110. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 ... Head-up display device 15 ... Light 20 ... Liquid crystal display device 21 ... Liquid crystal light valve 22 ... Light source 24 ... Lens 26 ... Reflective polarizing plate 28 ... Combiner 30 ... Housing 32 ... Absorbing plate 124 ... Concave mirror

Claims (7)

A head-up display that displays a predetermined display image superimposed on the user's field of view,
A light emitting unit for emitting light based on a display signal related to the display image;
A reflective polarizing plate that is irradiated with the light and reflects predetermined polarized light included in the light;
A head-up comprising: a combiner that is irradiated with the predetermined polarized light reflected by the reflective polarizing plate, reflects the polarized light toward the user side, and makes a display image by the polarized light visible. display. The head-up display according to claim 1,
The light emitted from the light emitting unit is linearly polarized light reflected by the reflective polarizing plate. The head-up display according to claim 1 or 2,
The reflection-type polarizing plate is arranged at an angle where specular reflection light obtained by regular reflection of external light irradiated on the reflection-type polarizing plate from the outside of the head-up display is directed to a position different from the position of the user. Head up display. The head-up display according to any one of claims 1 to 3, further comprising:
A head-up display including a divergence angle adjusting unit that reduces the divergence angle of the diffused light prior to reflection by the reflective polarizing plate. The head-up display according to claim 4,
The divergence angle adjusting unit is a convex lens disposed between the light emitting unit and the reflective polarizing plate. The head-up display according to claim 4,
The divergence angle adjusting unit is a concave mirror that reflects the light emitted by the light emitting unit to the reflective polarizing plate. The head-up display according to any one of claims 1 to 6, further comprising:
A head-up display comprising a light-absorbing plate disposed at a position capable of absorbing external light that has been applied to the reflective polarizing plate from the outside of the head-up display and transmitted through the reflective polarizing plate.

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