JPH04288515A - Overhead display device - Google Patents

Abstract

PURPOSE:To enhance the display performance of a display unit in an overhead display device for vehicles by which a displayed image on the displayer is projected and displayed on a transparent reflecting plate set in a field of view before a driver's seat. CONSTITUTION:In a display unit 20 in an overhead display panel 23 is used. Light is hardly scattered even in case of washout and the degree of freedom of display can be increased.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a display device in a head-up display device for a vehicle that projects and displays a display image on a translucent reflector (combiner) disposed within the front field of view of the driver's seat. The present invention relates to a head-up display system for a vehicle that can improve display performance.

0002

2. Description of the Related Art As a conventional head-up display system of this type, there is one shown in FIG. 1, for example. A main body case 3 having an opening 2 on the top surface is embedded in the instrument panel 1 in front of the driver's seat, and a fluorescent display tube (VF) is installed inside the main body case 3.
A display device 4 according to T) and a plane mirror 5 that reflects the displayed image from the display device 4 are arranged, and further in the opening 2,
A transparent cover 6 is provided to prevent dust from entering the main body case 3. Furthermore, a translucent reflector plate 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 displayed image on the display 4 can be reflected by the plane mirror 5 and the translucent reflector plate. The light is reflected by the translucent reflector plate 8 so that the scene in front of the vehicle as well as the image displayed on the display 4 can be read. Reference numeral 9 denotes an analog or digital main display installed at the bottom of the instrument panel 1, 10 a display controller for driving the main display 9 and the display 4, and 11 the above-mentioned display. The sensors that drive the devices 4 and 9 are shown.

0003

[Problems to be Solved by the Invention] However, the display device in such a conventional vehicle head-up display system uses a self-luminous type fluorescent display tube, and furthermore, the fluorescent display The light emitting pattern part of the tube is coated with phosphor to make it emit light, so when the sun (light) comes to point A on the extension line of the indicator light shown in Figure 1, When sunlight passes through the windshield 7 and is bent by the reflecting mirror and hits the light emitting pattern inside the fluorescent display tube, the light on the pattern surface is
A portion of the scattered light rays follows the opposite route and enters the combiner. Although some of the incident light is transmitted to the outside world, most of the remaining light reaches the driver's eyes, making it difficult to distinguish between the original lighting display pattern and the non-lighting pattern, making it difficult for the driver to may cause the display to be read incorrectly. (Hereinafter referred to as "washout") Furthermore, display using a fluorescent display tube has a problem in that the display pattern is limited and the degree of freedom in display is lacking.

0004

[Means for Solving the Problems] The present invention has been made in view of these conventional problems, and it is an object of the present invention to utilize a dot matrix type light-transmissive liquid crystal display panel as a display device in a head-up display system. Therefore, it is an object of the present invention to provide a head-up display system for a vehicle, which causes less scattering of light even after washout and can provide a rich degree of display freedom.

[0005]

[Embodiment] The invention will be explained in detail below based on the embodiment shown in FIGS. 2 and 3. The same parts between the structure of this embodiment and the structure explained in the conventional example will be denoted by the reference numerals used in the conventional example. , and the explanation of the same structural parts will be omitted. Reference numeral 20 denotes a display device according to this embodiment, and the configuration of this display device 20 will be explained based on FIG. 3. Reference numeral 21 denotes a storage case having an opening 22, and a dot matrix display type transmissive liquid crystal panel 23 is arranged in the vicinity of the opening 22 inside the storage case 21. Cold filters 24 and 25 are arranged on the front and back sides of this liquid crystal panel 23, respectively. 23-1 indicates a polarizing plate of the liquid crystal panel 23. 26 is a light diffusing plate placed on the back side of the back side cold filter 25, 27 is a backlight tube placed on the back side of the light diffusing plate 26, and behind this backlight tube 27 is a light reflecting plate. 28 are arranged. 29 is an inverter, 30 is a liquid crystal display controller board, and 31 is a cooling fan for cooling the heat generated by the backlight tube 27.

The liquid crystal panel 23, which is important in this embodiment, is
The screen is made up of individual dots so that it can be displayed graphically. The backlight tube 27 is a super-high-intensity hot cathode fluorescent discharge lamp, and the figure shows an axial cross section of the tube.

[0007] As a result, the actual display color is the backlight light color and black, since the portion called white is actually transparent. That is, since a green backlight is used, a green/black (monochrome) display is obtained.

The cold filters 24 and 25 are filters in which metallic magnesium oxide or the like is deposited on a glass base that reflects the heat rays of the light emitted from the backlight tube 27. This makes the liquid crystal display panel 23 vulnerable to heat.
This also prevents even the slightest amount of heat from being transmitted to the lower surface side of the liquid crystal display panel polarizing plate 23-1. In addition, the cold filter 24 located at the front has an optical component on the extension line of the display light of this unit, and when sunlight is incident in the opposite direction, the optical component condenses and collects light and heat. This prevents heat from hitting the panel 23 and the polarizing plate 23-1. 32
is a driver IC for driving a liquid crystal, and the one shown is a common (COM) side IC. Similarly, an IC on the segment (SEG) side is also mounted (not shown). 3
3 is a reinforcing plate for mounting a driver on the flexible cable coming out from the COM and SEG sides of the liquid crystal display panel 23, and FIG. 3 shows the reinforcing plate on the COM side. There is a reinforcing plate on the SEG side as well (not shown). 34 is a flexible cable connector.

The structure of this embodiment has been described above, and its operation will now be explained.

In FIG. 3, after light emitted from a backlight tube 27 passes through a light diffusing plate 26, a substantially uniform surface light source is obtained on its surface. Let this transmittance be T1. Light diffuser plate 2
The light after passing through the cold filter 25 (transmittance T2
). When this transmitted light enters an ON dot (transmittance T3) of the liquid crystal panel (a case where liquid crystal molecules are twisted so that light is transmitted is called an ON dot), a small amount of the light is transmitted. Furthermore, the light is filtered through the cold filter 24 (
When the light enters the transmittance T4 ), only the transmittance of the light is transmitted, and in the end, the display light emitted from the display unit is equal to the luminance value of the backlight tube 27 (T1 × T2 × T3 × T4
) (however, T1 ×T2 ×T3
×T4 <1).

In FIG. 2, the display light whose luminance value of the backlight tube 27 is (T1×T2×T3×T4) passes through a representative optical path b, is bent by a reflecting mirror, and passes through a representative optical path a. This reflecting mirror depends on the incident angle θ1,
According to the aluminum surface high reflection mirror, the reflectance near the light beam (R1
), the brightness value of the backlight tube 27 at this point is (T1×T2×T3×T4×R1). In the middle of the optical path a, an optical component 36 (for example, a convex lens) is inserted to magnify the display and focus the image to a distant place. The image formed by the optical component 36 is an erect enlarged image (virtual image), and the position of the image is further away than the actual object.

In FIG. 4, if there are no optical components, l
=a+b holds, but due to optical components, l>a+b. An image can be focused at a slightly farther distance with an optical component than without an optical component.

If the light transmittance of this optical component is T5, then the luminance value of the backlight tube is (T1 × T2 × T3
×T4 ×R1 ×T5).

The display light that has passed through the representative optical path a is incident on a point P on the inner surface of the windshield 7, and is reflected by the combiner 8 while maintaining the angle of incidence = angle of reflection, and reaches the driver's eyes. The optical characteristics of this combiner 8 are such that the reflectance R2 of a specific wavelength at an incident angle θ2 is set to be above a certain level, and the transmittance in the visible light range is set above a certain level. ×T3 ×T4 ×R1 ×T5
The display image 37 can be seen as a display luminance of ×R2).

[0015] Suppose that you are now traveling on an expressway at a certain speed. A speed indicator 9 in the meter system displays the vehicle speed. If you input data in advance to recognize a specific point on the expressway using radio waves or other means and get off at the next interchange after that point, a display like the one shown in Figure 5 will be displayed on the windshield. Therefore, even when driving on a highly dangerous highway, it is possible to display important information messages that are different from the meter system to the driver while checking the forward visibility.

It is of course possible to display the temperature using a temperature sensor, but since the backlight source inevitably generates heat, it is necessary to detect the temperature and refrain from displaying it on the head-up display if the temperature exceeds a certain temperature range. It can be removed.

FIG. 6 is a diagram showing another embodiment of the present invention.

That is, 20 is a display device according to this embodiment, and the structure of this display device 20 will be explained based on FIG. 6. Reference numeral 21 denotes a storage case having an opening 22, and a dot matrix display type transmissive liquid crystal panel 23 is arranged in the vicinity of the opening 22 inside the storage case 21. Cold filters 24 and 25 are arranged on the front and back sides of this liquid crystal panel 23, respectively. 23
-1 indicates a polarizing plate of the liquid crystal panel 23. Reference numeral 26 denotes a light diffusing plate for converting backlight light into surface light, and is located directly above the lamp. Reference numeral 27 indicates a backlight tube disposed directly above the light diffusing plate 26, and this backlight tube 2
A light reflecting plate 28 is placed behind the lens 7 . 29 is an inverter, 30 is a liquid crystal display controller board, and 31 is a cooling fan for cooling the heat generated by the backlight tube 27.

Reference numeral 23' is a dimming screen that adjusts the amount of transmitted light from the backlight. This light control screen 23'
This is a liquid crystal panel in which the degree of light transmission is uniformly changed within a region covering the display area of the liquid crystal panel 23. 23'-a and 23'-b are polarizing plates of the dimming screen 23'. In addition, if the light transmittance of the polarizing plate itself is low, the panel side polarizing plate 23'- of the dimming screen 23'
You may delete a.

As shown in this embodiment, the backlight tube 2
By arranging the dimming screen 23' in front of 7, it is possible to adjust the illuminance of the display light while keeping the brightness of the backlight constant by controlling the dimming screen. In other words, the durability of the backlight can be improved. Furthermore, a wide dimming range can be obtained due to the synergistic effect of the change in duty of the backlight and the change in light transmission of the dimming screen.

[0021]

As described above, the present invention reflects information displays such as characters and figures on the windshield of a vehicle or the translucent combiner 8 provided in front of the windshield to project a virtual display image in front of the windshield. projector 20
In the head-up display device that displays the information superimposed on the scenery of the outside world, the projector 20 is provided with a transmissive dot matrix liquid crystal display panel 23 capable of displaying graphics, and arranged behind the liquid crystal display panel 23. Since it is a head-up display device composed of a backlight light source 27, according to this,
By using a transmissive dot matrix liquid crystal display panel, it is possible to reduce misreading of the display due to washout, and not only can specific instruments 9 in the meter system be displayed reflectively by the combiner 8, but also information unrelated to the meter system can be displayed. This has the effect of making it possible to display information that is extremely important to the driver.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional example.

FIG. 2 is an explanatory diagram showing an embodiment of a head-up display device according to the present invention.

FIG. 3 is an explanatory diagram of the configuration of only the display device of this embodiment.

FIG. 4 is an explanatory diagram of the operation of this embodiment.

FIG. 5 is an explanatory diagram of the display mode of this embodiment.

FIG. 6 is a configuration explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

20...Indicator
21...Storage case 22...Opening part
23...Liquid crystal panel 23'...Dimmer screen 24...Cold filter 25...Cold filter 26...Light diffusion plate 27...Backlight tube
28...Light reflecting plate 29...Inverter
30...Controller board

Claims (1)

[Claims] 1. A projector that reflects information displays such as characters and figures on a windshield (7) of a vehicle or a translucent reflector (8) provided in front of the windshield and projects a virtual display image in front of the windshield. (20), and displays the information superimposed on the scenery of the outside world, the head-up display device comprising: the projector (20);
), a transmissive dot matrix liquid crystal display panel (23) capable of displaying graphics;
A head-up display device comprising a backlight source (27) placed behind the head-up display device.