JP2010243758A - Head-up display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head-up display capable of suppressing luminance reduction of a display light projected to a projection member, as much as possible, thereby enabling an observer to view a proper display state. <P>SOLUTION: The head-up display includes a liquid crystal display element (display element) 23 for emitting the display light L; a concave mirror 41 for reflecting the display light L; and a housing 70, including a cavity part 73 for housing the liquid crystal display element 23 and the concave mirror 41, and a translucent part 74, through which the display light L reflected by the concave mirror 41 passes, wherein a hot mirror 63 for transmitting the display light L and reflecting the infrared light emitted to the cavity part 73 is provided on the optical path of the display light L. The hot mirror 63 includes a light-transmissive substrate 63a and a reflecting layer 63b; the display light L emitted from the translucent part 74 is projected to the projection member 13 so as to display for the observer 14; and the liquid crystal element 23 and the substrate 63a are jointed together with a translucent member 80, having a refractive index nearly equal to that of the substrate 63a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a head-up display device that projects display light emitted from a display (display element) onto a projection member such as a windshield of a vehicle and displays a virtual image to an observer.

  Conventionally, in this type of head-up display device, for example, as described in Patent Document 1 below, a device that projects a display light from a display on a windshield (projection member) of a vehicle to display a virtual image. Are known.

JP 2007-65011 A

  The head-up display device described in Patent Document 1 is mounted inside an instrument panel (hereinafter referred to as an instrument panel) of a vehicle, and reflects a display that emits display light and display light emitted from the display. A concave mirror (reflecting member), a housing having a space portion for housing (accommodating) the display and the concave mirror, and a translucent portion through which display light reflected by the concave mirror passes, and from the translucent portion via the concave mirror The emitted display light is projected onto a projection member to display a virtual image (display image) to an observer (driver).

  In this case, the display is positioned on the front side of the light source so as to form a display light by transmitting the illumination light from the light source composed of a wiring board, a light emitting diode mounted on the wiring board, and the light source. A liquid crystal display element (display element) to be mounted, a hot mirror (transmission / reflection member) disposed at a distance from the front side of the liquid crystal display element, a wiring board, a light source, a liquid crystal display element, and a hot mirror And a case body made of resin.

  The hot mirror is composed of a light-transmitting glass substrate (substrate) made of a substantially rectangular acrylic resin and a reflective layer made of a multilayer interference film provided on one surface of the glass substrate (that is, the surface facing the concave mirror). And disposed in the optical path of the display light from the liquid crystal display element to the concave mirror. The hot mirror efficiently transmits display light composed of visible light emitted from the liquid crystal display element to the concave mirror side and irradiates the space portion through the light transmitting portion of the housing (for example, the display device through the light transmitting portion and the concave mirror). It has a function (characteristic) to reflect infrared rays (heat rays) in sunlight (incident to the side).

  The case body has an opening formed so as to correspond to the shape of the hot mirror, and a front opening for facing the reflective layer to the outside and a rear side peripheral edge of the hot mirror (glass substrate) are placed (held). Therefore, the holding part which consists of a collar part protrudingly formed inward from the case body wall surface is formed. This means that the hot mirror is configured to be held by the holding portion so that the reflective layer side, which is the front side, faces the front opening.

  In the case of the above-described head-up display device, the hot mirror located in the optical path from the liquid crystal display element to the concave mirror is arranged with a space in front of the liquid crystal display element. That is, a clearance formed of a spatial region is provided between the liquid crystal display element and the hot mirror (glass substrate).

  Then, the refractive index of the glass substrate, which is an acrylic resin provided in the hot mirror, is about 1.5, whereas the refractive index of the clearance (that is, air) is 1. When the emitted display light is incident on the hot mirror (glass substrate) through the clearance, a part of the display light is on the boundary surface between the hot mirror and the clearance (that is, the back surface of the glass substrate located on the liquid crystal display element side). The phenomenon of being reflected.

With the occurrence of a phenomenon in which all of the display light emitted from the liquid crystal display element is not incident on the hot mirror (glass substrate) and a part of the display light is reflected as reflected light at the boundary surface, The brightness of the display light projected onto the projection member through the concave mirror is reduced by the amount of the reflected light, and this makes it difficult for the observer to visually recognize a good display form.
In view of the above-described problems, the present invention provides a head-up display device that suppresses a decrease in luminance of display light projected onto a projection member as much as possible and allows an observer to visually recognize a good display form. It is what.

  The present invention provides a display element that emits display light, a reflective member that reflects the display light, a space that houses the display element and the reflective member, and a light transmission through which the display light reflected by the reflective member passes. A display unit that transmits the display light and reflects infrared rays applied to the space portion through the light transmitting part in the optical path of the display light from the display element to the reflecting member. A transmission / reflection member is provided, and the transmission / reflection member includes a light-transmitting substrate and a reflection layer provided on one surface of the substrate to reflect the infrared rays, In the head-up display device for projecting the emitted display light onto a projection member to display to a viewer, the display element disposed on the other surface side opposite to the one surface And said substrate, characterized by comprising bonded via a transparent member having a refractive index approximately the same refractive index of the substrate.

  In the invention, it is preferable that the translucent member is made of a translucent resin material.

  ADVANTAGE OF THE INVENTION According to this invention, the initial objective can be achieved, the head-up display apparatus which can suppress the brightness | luminance fall of the display light projected on a projection member as much as possible, and an observer can visually recognize a favorable display form can be provided.

1 is a schematic view of a head-up display device according to an embodiment of the present invention. Sectional drawing of the display apparatus by the embodiment.

  Hereinafter, an embodiment in which the present invention is applied to a head-up display device for a vehicle will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the head-up display device is configured such that the display light L projected by the display device 12, which is a display unit disposed on the instrument panel 11 of the vehicle 10, is generated by the windshield 13 of the vehicle 10 that is a projection member. The virtual image V is displayed by reflecting in the direction of the driver (observer) 14. In other words, the head-up display device irradiates (projects) the display light L emitted from a liquid crystal display (described later) of the display device 12 onto the windshield 13 (the projection member), and displays a display image ( Virtual image) V is made visible to the driver 14. Thus, the driver 14 can observe the virtual image V superimposed on the landscape.

  As shown in FIG. 2, the display device 12 mainly includes a liquid crystal display 20, a first reflector 30, a second reflector 40, a circuit board 50, a cover member 60, and a housing 70. Yes.

  The liquid crystal display 20 has a light source 22 composed of a light emitting diode mounted on the wiring board 21 and a front side (directly above) the light source 22 so as to transmit the illumination light from the light source 22 and form the display light L. It is mainly composed of a TFT type liquid crystal display element (display element) 23 which is positioned. This means that the light source 22 is disposed behind (directly below) the liquid crystal display element 23, and the liquid crystal display element 23 displays predetermined information (information to be described later) by the light emitted from the light source 22. I mean.

  The liquid crystal display 20 configured as described above is provided in the housing 70 such that the surface on the emission side of the display light L faces a hot mirror (described later) provided in the cover member 60, and the optical axis of the display light L Is fixed and held at such a position and orientation as to cross the hot mirror.

  In addition, the liquid crystal display element 23 displays information (for example, vehicle speed) to be displayed by an element driving circuit (not shown) by light emission display with numerical values. The liquid crystal display 20 outputs display light L composed of light in the visible wavelength range, and for example, a light source 22 that emits red light (mainly emission wavelength range of 610 to 640 nm) can be applied. Needless to say, the information to be displayed is not limited to the vehicle speed, and any display form such as the engine speed can be adopted.

  The first reflector 30 has a cold mirror 31 located above (directly above) the hot mirror, and an attachment member 32 for attaching and fixing the cold mirror 31 using predetermined attachment means. ing.

  The cold mirror 31 includes a substantially rectangular glass substrate 31a and a first reflective film 31b formed on one surface of the glass substrate 31a (a surface facing a concave mirror described later of the second reflector 40). The first reflective film 31b is composed of multilayer interference films having different film thicknesses, and is formed by a method such as vapor deposition.

  The cold mirror 31 is a position that reflects the display light L emitted from the liquid crystal display 20 (liquid crystal display element 23) and transmitted through the hot mirror toward the second reflector 40 (the concave mirror). In an inclined state.

  The cold mirror 31 reflects light in the visible wavelength range (450 to 750 nm) including the emission wavelength range of the liquid crystal display 20 with a high reflectance (for example, 80% or more), and lowers light outside the visible wavelength range. It reflects with reflectivity. In this case, a cold mirror 31 that reflects light in the infrared wavelength region other than the visible wavelength region (sunlight heat rays) with a low reflectance (for example, 15% or less) is applied. The light that is not reflected by the first reflective film 31 b is configured to pass through the cold mirror 31. The attachment member 32 is made of, for example, a black synthetic resin material, and is fixed to the housing 70.

  The second reflector 40 includes a concave mirror (reflecting member) 41 that reflects the display light L from the cold mirror 31 (that is, the liquid crystal display element 23), and a mirror holder 42 that holds the concave mirror 41.

  The concave mirror 41 is formed by vapor-depositing a second reflective film 41a on a resin substrate made of polycarbonate having a concave surface. The concave mirror 41 is disposed in an inclined state at a position where the second reflective film 41a faces the cold mirror 31 and a translucent cover (to be described later) of the housing 70 and faces the translucent cover.

  The concave mirror 41 is for reflecting (projecting) the display light L from the cold mirror 31 toward the translucent cover (the windshield 13 of the vehicle 10). This means that the concave mirror 41 enlarges the display light L reflected by the cold mirror 31 and projects the enlarged display light L onto the windshield 13 through the translucent cover. The concave mirror 41 is bonded to the mirror holder 42 with a double-sided adhesive tape. The mirror holder 42 is made of synthetic resin (for example, ABS resin) and is fixed to the housing 70.

  The circuit board 50 is made of, for example, a hard circuit board on which a predetermined wiring pattern is applied, and is fixed in the housing 70 by appropriate fixing means. The circuit board 50 is mounted with a connector 51 to which one end of a flexible wiring board to be described later is attached, the element driving circuit for driving the liquid crystal display element 23, a light source driving circuit (not shown) for controlling light emission of the light source 22, and the like. .

  In FIG. 2, F is a flexible wiring board, and this flexible wiring board F is used for electrical connection between the liquid crystal display element 23 and the circuit board 50, and includes a power line, a signal line, and a ground. A signal transmission line (not shown) made up of lines is provided.

  In such a flexible wiring board F, one end side of the flexible wiring board F on the circuit board 50 side is mounted inside the connector 51, so that a signal transmission line located on one end side of the flexible wiring board F is inside the connector 51. Each of the plurality of electrode terminals (not shown) provided is electrically connected. Here, the electrode terminal is configured to be protected by a resin-made outer case provided in the connector 51.

  The covering member 60 is made of, for example, a black synthetic resin material, and is positioned above the circuit board 50 (the liquid crystal display 20) so as to cover the circuit board 50 and the like. By being fixed to the housing 70 by this.

  The covering member 60 has a substantially rectangular opening 61 having a dimension that is several millimeters larger than the external dimension of the liquid crystal display element 23 above the position where the liquid crystal display element 23 is disposed. The opening 61 includes an opening window that allows the display light L, which is emitted from the liquid crystal display element 23 and reaches from the liquid crystal display element 23 to the cold mirror 31 (concave mirror 41), to pass therethrough. In the present embodiment, a configuration is adopted in which a hot mirror (transmission / reflection member) 63 is disposed (fixed) on the back surface portion 62 of the covering member 60 on the liquid crystal display element 23 or the circuit board 50 side so as to close the opening 61. Yes.

  The hot mirror 63 includes a light-transmitting glass substrate (substrate) 63a made of a substantially rectangular acrylic resin and multilayer interference provided on one surface of the glass substrate 63a (that is, the front surface of the glass substrate 63a in FIG. 2). A reflective layer 63b made of a film and disposed in the optical path of the display light L from the liquid crystal display element 23 to the cold mirror 31 (concave mirror 41). In this example, the reflective layer 63b is formed on the cold mirror 31. The positional relationship is such that it faces the first reflective film 31b.

  The hot mirror 63 efficiently transmits the display light L, which is visible light emitted from the liquid crystal display element 23, toward the cold mirror 31, and enters the housing 70 through the translucent cover, the concave mirror 41, and the cold mirror 31. Irradiates the liquid crystal display 20 (or directly irradiates the liquid crystal display 20 inside the housing 70 through the translucent cover without passing through the concave mirror 41 and the cold mirror 31). It has a function (characteristic).

  That is, since the reflective layer 63b formed on the hot mirror 63 has a function of reflecting the heat rays, the heat rays do not reach the liquid crystal display 20 side. In addition, the hot mirror 63 is fixed to the back surface part 62 using fixing means, such as a double-sided tape. Moreover, it is desirable to apply black coating on the surface of the covering member 60 opposite to the back surface portion 62 in order to reduce reflection of external light due to sunlight.

  In the present embodiment, the liquid crystal display element 23 and the glass substrate 63a disposed on the other surface side (that is, the back surface side) of the glass substrate 63a opposite to the one surface on which the reflective layer 63b is formed. However, it is the structure joined through the translucent member 80. The translucent member 80 is made of a translucent resin material (translucent silicon resin in this example), is formed in a substantially flat plate shape, and its refractive index is approximately the same as the refractive index of the glass substrate 63a. Is set to In this example, the refractive index of the translucent member 80 is about 1.4, and the refractive index of the glass substrate 63a is about 1.5.

  As described above, the present invention employs a configuration in which the liquid crystal display element 23, the translucent member 80, and the hot mirror 63 (glass substrate 63a) are stacked in order from the bottom in FIG. Is arranged with a gap in front of the liquid crystal display element, the refractive index of the clearance (that is, air) formed between the hot mirror (glass substrate) and the liquid crystal display element is 1. The refractive index of the hot mirror (glass substrate) is about 1.5, and the display light at the boundary surface between the hot mirror and the clearance (that is, the back surface of the glass substrate located on the liquid crystal display element side) due to the difference in refractive index between the two. Is prevented as much as possible.

  In other words, in FIG. 2, when the liquid crystal display element 23, the translucent member 80, and the hot mirror 63 (glass substrate 63a) are laminated in order from the bottom, the display light L emitted from the liquid crystal display element 23 is translucent. When the refractive index of the transparent member 80 is approximately the same as the refractive index of the glass substrate 63a, the transparent member 80 and the glass substrate are transmitted through the transparent member 80 to the glass substrate 63. The amount of light reflected by the boundary surface P with 63a and returning into the translucent member 80 is very small.

  As a result, the display light L emitted from the liquid crystal display element 23 passes through the translucent member 80 and the hot mirror 63 with almost no attenuation of the amount of light, and then reaches the cold mirror 31 side.

  The housing 70 is formed of, for example, a black synthetic resin material, and includes an upper case body 71 and a lower case body 72 both having a substantially concave shape in cross section, and the upper case body 71 and the lower case body 72 include In the space 73 which is an internal space to be formed, the liquid crystal display 20 (the liquid crystal display element 23), the first reflector 30, the second reflector 40 (concave mirror 41), the circuit board 50, the covering member 60, and the like are accommodated. It becomes.

  The upper case body 71 is formed with an opening window portion 71a in which an upper portion (on the windshield 13 side of the vehicle 10) of the concave mirror 41 is opened, and the light transmission portion that is a light transmitting portion is formed in the opening window portion 71a. A protective cover 74 is provided. The translucent cover 74 is made of a translucent synthetic resin material (for example, acrylic resin) and has a function as a light transmissive member that transmits (passes) the display light L reflected by the concave mirror 41. . That is, the display light L reflected by the cold mirror 31 and the concave mirror 41 is emitted from the translucent cover 74 disposed in the opening window 71a, and the display light L emitted from the translucent cover 74 is front-fronted. By projecting on the glass 13, a virtual image display is performed for the driver 14.

  At this time, as described above, the display light emitted from the liquid crystal display element 23 has the refractive index of the translucent member 80 approximately the same as the refractive index of the glass substrate 63a. When the light passes through the mirror 63, the amount of light reaches the cold mirror 31 with almost no attenuation. As a result, the brightness of the display light L that is projected onto the windshield 13 through the cold mirror 31 and the concave mirror 41 decreases. Is suppressed as much as possible, so that the driver 14 can visually recognize a good display form (display image V).

  As described above, in this embodiment, the liquid crystal display element 23 that emits the display light L, the concave mirror 41 that reflects the display light L, the space 73 that houses the liquid crystal display element 23 and the concave mirror 41, and the concave mirror 41 are reflected. And a housing 70 having a translucent cover 74 through which the display light L passes. In the optical path of the display light L from the liquid crystal display element 23 to the concave mirror 41, the display light L is transmitted and the infrared light is reflected. In the head-up display device that displays the display light L emitted from the translucent cover 74 on the windshield 13 and displays it on the driver 14, the hot mirror 63 includes: A light transmissive glass substrate 63a, and a reflective layer 63b provided on the front surface of the glass substrate 63a to reflect the infrared rays, the glass substrate 63a A liquid crystal display element 23 and the glass substrate 63a which is disposed on the rear side, formed by joining through a translucent member 80 having a refractive index approximately the same refractive index of the glass substrate 63a.

  Accordingly, when the display light emitted from the liquid crystal display element 23 passes through the translucent member 80 and the hot mirror 63, the amount of light reaches the cold mirror 31 with almost no attenuation, and is projected onto the windshield 13. The decrease in the luminance of the display light L to be suppressed is suppressed as much as possible, and this makes it possible for the driver 14 to visually recognize a good display form (display image V).

  In the present embodiment, the example in which the translucent member 80 is formed of a translucent silicon resin material having the same refractive index as that of the glass substrate (substrate) 63 has been described. Instead of acrylic resin or urethane resin may be used.

  In this embodiment, the example in which the display light L emitted from the liquid crystal display element 23 is projected onto the windshield 13 has been described. However, for example, a combiner that reflects the display light L in the direction of the driver 14 on the windshield 13. A film may be provided, or the display light L may be projected onto a dedicated reflector different from the windshield 13.

13 Windshield (projection member)
14 Driver (observer)
23 Liquid crystal display elements (display elements)
41 Concave mirror (reflective member)
50 circuit board 60 covering member 61 opening 63 hot mirror (transmission reflection member)
63a Glass substrate (substrate)
63b Reflective layer 70 Housing 73 Space portion 74 Translucent cover (translucent portion)
80 Translucent member L Display light

Claims (2)

A display element that emits display light; a reflective member that reflects the display light; a space that houses the display element and the reflective member; and a translucent part through which the display light reflected by the reflective member passes. A housing,
In the optical path of the display light from the display element to the reflection member, a transmission / reflection member is provided that transmits the display light and reflects infrared rays applied to the space portion through the light transmission portion. ,
The transmissive reflecting member is composed of a light transmissive substrate and a reflective layer provided on one surface of the substrate to reflect the infrared rays,
In a head-up display device that projects the display light emitted from the translucent part onto a projection member and displays it to an observer,
The display element disposed on the other surface side opposite to the one surface is bonded to the substrate via a translucent member having a refractive index comparable to the refractive index of the substrate. A head-up display device. The head-up display device according to claim 1, wherein the translucent member is made of a translucent resin material.

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