JP2000131642A - Head-up display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a head-up display device for vehicle in which the dispersion of light is less despite washout and the degree of freedom of display can be increased by arranging a screen for adjusting light behind a transmission type dot matrix liquid crystal display panel and arranging a backlight light source behind the screen for adjusting light. SOLUTION: A screen 26 for adjusting light for adjusting transmission light quantity of backlight is arranged behind a transmission type dot matrix liquid crystal display panel 24. Respective polarizing plates 27 are stuck to both of the surface and the back of the screen 26 for adjusting light. Visibility of display in which erroneous reading of display owing to washout can be reduced by using this transmission type dot matrix liquid crystal display panel 24 is enhanced. Also, illuminance adjustment of display light can be performed while holding luminance of backlight constant by arranging the screen 26 for adjusting light in the front of a backlight tube 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for a head-up type display device for a vehicle, which projects and displays a display image of the display device on a translucent reflector (combiner) disposed in a front view of a driver's seat. To prevent the washout phenomenon of
The present invention relates to a vehicular head-up display system capable of improving the durability of a backlight used for transmitting and illuminating the display.

[0002]

2. Description of the Related Art A conventional head-up display system of this type is, for example, as shown in FIG. Specifically, a main body case 3 having an opening 2 on an upper surface is embedded in an instrument panel 1 in front of a driver's seat, and a fluorescent display tube (VF) is provided inside the main body case 3.
T), a display 4 (projector), and the display 4
A flat mirror 5 for reflecting a display image from the camera 1 is disposed, and a transparent cover 6 for preventing dust from entering the main body case 3 is provided in the opening 2. A light-transmitting reflector 8 serving as a half mirror is provided on the inner surface of the windshield 7 located above the instrument panel 1 so that the display image of the display 4 can be displayed on the plane mirror 5 and the light-transmitting reflector. The light is reflected by the display 8 and the translucent reflection plate 8 can read the display image on the display 4 together with the scene in front of the vehicle. Reference numeral 9 denotes a main display of, for example, an analog type or a digital type provided at a lower portion of the instrument panel 1. Reference numeral 10 denotes a display controller for driving the main display 9 and the display 4. 2 shows a drive sensor for driving the devices 4 and 9.

[0003]

However, such a conventional display device for a head-up display system for a vehicle uses a self-luminous type fluorescent display tube, and further displays the fluorescent display. Since the light emitting pattern portion of the tube is coated with a phosphor for emitting light, when the sun (light) comes to a point A on an extension of the display light as shown in FIG. When the sunlight passes through the windshield 7 and the light bent by the reflector hits the light emission pattern in the fluorescent display tube, the light becomes scattered light on the pattern surface, and a part of the scattered light is reversed. Following the route, the light enters the combiner. Part of the incident light is transmitted to the outside world, but most of the remaining light reaches the eyes of the driver, so that it is difficult to distinguish between the originally lit display pattern and the unlit pattern. May misread the display. In addition, the display using the fluorescent display tube has a problem that the display pattern is limited and the degree of freedom of display is lacking.

The present invention has been made in view of such a conventional problem, and a display in a head-up display system uses a dot-matrix type light transmission type liquid crystal display panel, thereby washing out. SUMMARY OF THE INVENTION It is a first object of the present invention to provide a vehicle head-up display device capable of reducing light scattering and increasing display flexibility.

In the present invention, in order to improve the durability of the backlight, the brightness of the backlight is kept constant in order to increase the durability of the backlight for transmitting and illuminating the transmissive dot matrix liquid crystal display panel. A second object is to provide a head-up display device capable of adjusting the illuminance of display light.

[0006]

In order to achieve the first and second objects, according to the first aspect of the present invention, an information display such as characters and figures is provided on a windshield of a vehicle or in front of the windshield. A head-up display device that includes a display that reflects a light-transmitting reflection plate and projects a virtual image display image in front of the windshield, and displays the information in a manner superimposed on an external scene, wherein the display can be displayed graphically. A head-up display comprising a transparent dot matrix liquid crystal display panel, a dimming screen disposed behind the transmissive dot matrix liquid crystal display panel, and a backlight light source disposed behind the dimming screen It is characterized by being a device.

According to the head-up display device of the first aspect, erroneous reading of the display due to washout can be reduced, and the illuminance of the display light can be adjusted while controlling the brightness of the backlight by controlling the dimming screen. Therefore, the life of the backlight itself can be extended, that is, the durability of the backlight can be improved. Further, a wide light control range can be obtained by a synergistic effect of the change in the duty of the backlight and the change in the light transmission of the light control screen.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS. 1 to 3. The structure of this embodiment and the structure described in the conventional example are the same as those in the conventional example. The same reference numerals are used and the description of the same structural parts is omitted. 2
Reference numeral 0 denotes a display (projector) according to the present embodiment. The configuration of the display 20 will be described with reference to FIG. 2
Reference numeral 1 denotes a storage case having an opening 22. Inside the opening 22 provided in the storage case 21, a first cold filter 2 is provided so as to cover the opening 22.
3 are arranged. This first cold filter 23
Inside (rear side), a transmission dot matrix liquid crystal display panel 24 of a dot matrix display type is arranged. On both front and back surfaces of the transmission dot matrix liquid crystal display panel 24, respective polarizing plates 25 are integrally formed. They are pasted together.

On the back side (behind) of the transmission type dot matrix liquid crystal display panel 24, a dimming screen 26 for adjusting the amount of transmitted light of a backlight described later is arranged. Each polarizing plate 27 is attached to both front and back surfaces. Reference numeral 28 denotes a second cold filter disposed behind (behind) the dimming screen 26, and a light diffusion plate 29 is disposed behind (behind) the second cold filter 28. .

Reference numeral 30 denotes a backlight tube arranged on the back side of the light diffusing plate 29.
Behind 0, a light reflection plate 31 is arranged. Reference numeral 32 denotes an inverter, 33 denotes a liquid crystal display controller board, and 34 denotes a cooling fan for cooling heat generated by the backlight tube 30.

Reference numeral 35 denotes a driver IC for driving the liquid crystal, and the illustrated one is an IC on the common (COM) side. Similarly, an IC on the segment (SEG) side is also mounted (not shown). Reference numeral 36 denotes a reinforcing plate for mounting a driver on a flexible cable protruding from the COM and SEG sides of the transmission type dot matrix liquid crystal display panel 24. There is also a reinforcing plate on the SEG side (not shown). 3
Reference numerals 7 and 38 denote flexible cable connectors.

The structure of the transmissive dot matrix liquid crystal display panel 24 constitutes a dot screen capable of graphic display, and the backlight tube 30 uses a hot cathode fluorescent discharge lamp of ultra-high brightness. As a result, the actual display color is a backlight light color and a black display color because the part called white is actually transparent. That is, green / black (monochrome) display is possible because the backlight of green emission color is used.

The first and second cold filters 23
Reference numerals 28 denote filters formed by depositing metal-based magnesium oxide or the like on a glass base that reflects a heat ray segment of light emitted from the backlight tube 30. This prevents any heat from being transmitted to the transmission dot matrix liquid crystal display panel 24 and the polarizing plate 25 on the back side of the liquid crystal display panel, which are vulnerable to heat. The first cold filter 23 has an optical component on an extension of the display light of this unit, and collects and collects light and heat by the optical component when sunlight is incident back. Heat can be prevented from being applied to the liquid crystal panel 24 and the polarizing plate 25.

The above is the configuration of the present embodiment. Next, its operation will be described. In FIG. 2, light emitted from a backlight tube 30 passes through a light diffusion plate 29, and a substantially uniform surface light source is obtained on the surface thereof. This transmittance is defined as T1. Light diffusion plate 2
The light having passed through 9 enters the second cold filter 28 (transmittance T2). This transmitted light turns on the liquid crystal panel.
When the light enters a dot (transmissivity T3) (the case where the liquid crystal molecules are twisted so that light is transmitted is called an ON dot), a small amount of the light is transmitted. Further, when the light enters the first cold filter 23 (transmittance T4), only the transmittance of the light is transmitted, and eventually the display light emitted from the display unit becomes the luminance value (T1 * T2) of the backlight tube 30. × T3 × T4
) (Where T1 × T2 × T3 × T4
<1).

In FIG. 1, the display light having the brightness value (T1 × T2 × T3 × T4) of the backlight tube 30 passes through the representative optical path b, and the optical path is bent by the reflecting mirror and passes through the representative optical path a. Although this reflecting mirror depends on the incident angle .theta.1, the aluminum surface high reflecting mirror has a reflectance (R1) near a light ray, and at this time, the brightness value of the backlight tube 30 is (T1).
× T2 × T3 × T4 × R1). In the middle of the optical path a, an optical component 39 (for example, a convex lens) for enlarging the display and forming an image far away is provided. An image formed by the optical component 39 is an erect enlarged image (virtual image).
Further, the position of the image can be farther than the actual object.

In FIG. 1, when there is no optical component,
l = a + b holds, but due to optical components, l> a + b
Becomes It is possible to form an image farther away with the optical component than with the optical component.

Assuming that the light transmittance of the optical component 39 is T5, the luminance value of the backlight tube 30 is (T1 × T2 × T3).
× T4 × R1 × T5).

The display light passing through the representative optical path a enters one point P on the inner surface of the windshield 7, is reflected by the combiner 8 while maintaining the incident angle = reflection angle, and reaches the driver's eyes. The optical characteristics of the combiner 8 are such that the reflectance R2 of the specific wavelength at the incident angle .theta.2 is set to a certain value or more and the transmittance in the visible light region is set to a certain value or more. The display image 40 can be seen as a display brightness of (T3.times.T4.times.R1.times.T5.times.R2).

It is assumed that the vehicle is running on a highway at a certain speed. The speed indicator 9 in the meter system displays the vehicle speed. By recognizing the point from a specific point on the expressway by means of radio waves and inputting data in advance so as to be at the next interchange at that point, a display such as that shown in FIG. 3 is projected on the windshield. Therefore, even when driving on a high-risk expressway, the driver can display important information messages and the like different from those of the meter system while confirming the forward visibility.

The temperature sensor can of course be used to display the temperature. However, since heat is necessarily generated by the backlight light source, the temperature is detected, and if the temperature exceeds a certain temperature range, the head-up display is automatically suppressed. I can take it.

Therefore, according to the head-up display device according to the above-described embodiment, since the transmission type dot matrix liquid crystal display panel 24 is used as a display, a washout phenomenon is unlikely to occur, thereby effectively preventing erroneous recognition of the display. it can. Further, in the present embodiment, the dimming screen 26 is disposed in front of the backlight tube 30. By controlling the dimming screen 26, the illuminance of the display light is maintained while the luminance of the backlight 30 is kept constant. Since the adjustment can be performed, the life of the backlight tube 30 itself can be extended, that is, the durability of the backlight tube 30 can be improved. Further, a wide light control range can be obtained by the synergistic effect of the change in the duty of the backlight tube 30 and the change in the light transmission of the light control screen 26.

[0022]

As described above, according to the present invention, according to the head-up display device of the present invention, the use of the transmission type dot matrix liquid crystal display panel enhances the visibility of the display which can reduce the erroneous reading of the display due to the washout. Can be In addition, since the dimming screen 26 is disposed in front of the backlight tube 30, the dimming screen 2
Since the illuminance of the display light can be adjusted while maintaining the brightness of the backlight 30 constant by the control of 6, the life of the backlight tube 30 itself can be extended, that is, the durability of the backlight tube 30 can be improved. it can. Further, there is an effect that a wide light control range can be obtained by a synergistic effect of the change in the duty of the backlight tube 30 and the change in the light transmission of the light control screen 26.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a head-up display device according to the present invention.

FIG. 2 is an explanatory diagram of a configuration of only a display device of the present embodiment.

FIG. 3 is an explanatory diagram of a display mode according to the embodiment.

FIG. 4 is an explanatory diagram of a conventional head-up display device.

[Explanation of symbols]

 Reference Signs List 20 display 21 storage case 22 opening 23 first cold filter 24 transmissive dot matrix liquid crystal display panel 25 polarizing plate 26 dimming screen 27 polarizing plate 28 second cold filter 29 ... light diffusion plate 30 ... backlight tube 31 ... light reflection plate 32 ... inverter 33 ... liquid crystal display controller board 34 ... cooling fan 35 ... driver IC 36 ... reinforcement plates 37 and 38 ... connector 39 ... optical parts 40 ... display image

Claims (1)

[Claims] 1. A display device for reflecting an information display such as characters and figures on a windshield of a vehicle or a light-transmitting reflector provided in front of the windshield and projecting a virtual image display image in front of the windshield. A head-up display device for displaying the information in a superimposed manner with a scene, wherein the display is a graphic dot-display transmissive dot matrix liquid crystal display panel, and a dimming control disposed behind the transmissive dot matrix liquid crystal display panel. A head-up display device comprising a screen for light control and a backlight light source disposed behind the screen for light control.