JPH09185010A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of securing sufficiently enough display luminance even when a light source having a small calorific value is used as a back light device, reducing its cost because it is unnecessary to prepare switching elements for driving liquid crystal correspondingly to respective pixels and instantaneously displaying a clear information picture because pictures can be quickly switched. SOLUTION: This display device is provided with a combiner 4 for changing the optical path of picture display light rays L1 projected from a projecting device so as to lead the light rays L1 to the visual field of an observer A and transmitting light rays radiated from an observer's front visual field. The projecting device has a transmission type monochromatic simple matrix liquid crystal display 11 of which liquid crystal operation mode is a bistable twist nematic(BTN) mode, a back light device 12 capable of changing the light emitting wavelength peak of irradiating light from the display 11 and a means 13 capable of synchronizing the picture display timing of the display 11 with light emission timing based upon the light emitting wavelength peak outputted from the device 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device suitable for a head-up display device used for vehicles such as automobiles for land traveling, ships such as ships and aircrafts.

[0002]

2. Description of the Related Art For example, a head-up display device (HUD) for an automobile is used as a terminal for displaying car navigation information, so that route information can be obtained while looking ahead while driving.

Such a head-up display device emits an image display light beam, changes an optical path for guiding the image display light beam to the observer's visual field, and transmits the light beam from the observer's front visual field. It has a combiner.

Conventionally, as a device for emitting the image display light beam, a device for emitting the image display light beam having a fixed pattern by using a VFD (fluorescent display tube) capable of obtaining a sufficient display brightness has been mainly used. It has been proposed that a transmissive dot matrix liquid crystal display and a backlight are used to emit image display light beams of various patterns.

[0005]

As the dot matrix liquid crystal display, there are a simple matrix type which directly drives the liquid crystal of each pixel from the scanning electrodes and an active matrix type which has a switching element such as a TFT corresponding to each pixel. is there.

In the simple matrix type liquid crystal display, the STN mode is generally used as the liquid crystal operation mode. However, when performing color display in the STN mode, it is necessary to use a D-STN (Double Layered-STN) mode in which reverse twisted STNs for optical phase compensation and the like are stacked, which causes a problem that the structure becomes complicated. In addition, since the simple matrix type liquid crystal display has a slow response speed when switching display images, it is not possible to immediately display a clear information image.

The active matrix type liquid crystal display has a low aperture ratio because it is necessary to provide a switching element such as a TFT on the display panel. Therefore, when a color filter is stacked on a display panel for performing color display, the light transmittance as a whole is about 5%, which is extremely low, together with the low transmittance of the color filter. Therefore, in order to secure sufficient display brightness as a head-up display device, an LED light source or the like having a small heat generation amount cannot be used due to insufficient light amount, and a high-power light source is required, and the heat generation amount becomes enormous. Practicality is poor. Further, since a switching element such as a TFT is provided corresponding to each pixel, the cost will increase.

An object of the present invention is to provide a display device which can solve the above problems.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a device for emitting an image display light beam, and changing the optical path of the image display light beam to guide it to the observer's visual field, while transmitting the light beam from the observer's forward visual field. In a display device including a combiner for
The emission device of the image display light beam has a liquid crystal operation mode of BT.
Transmission type monochrome simple matrix liquid crystal display of N (bistable twisted nematic) mode, backlight device capable of changing emission wavelength peak of irradiation light of the liquid crystal display, image display timing of the liquid crystal display and backlight device And a means capable of synchronizing the light emission timing according to the desired light emission wavelength peak.

According to the structure of the present invention, a plurality of images forming one piece of information are repeatedly displayed on a liquid crystal display in a time division manner, and the display timing of the display image and the light emission timing according to a desired light emission wavelength peak of the backlight device. By synchronizing with, it is possible for an observer to recognize the one piece of information as a multicolor image without using a color filter. Further, the liquid crystal operation mode of the liquid crystal display is the BTN mode which utilizes the fact that the liquid crystal molecules maintain a constant arrangement for two seconds at two twist angles, so that the image switching can be performed without using a switching element such as a TFT. High-speed operation enables time-divisional display of multiple images, which is not possible in the D-STN mode.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a display device 1 which constitutes a head-up display device for a vehicle, and a device 3 for emitting an image display light beam L1 which is built in a casing 2 such as a dashboard of a vehicle, and an upper portion of the casing 2. And a combiner 4 provided in the vehicle navigation system and used as a terminal for displaying car navigation information.

The combiner 4 receives the image display light beam L.
The optical path of No. 1 is changed so as to be guided to the visual field of the observer A, and the light ray L2 from the front visual field of the observer A that passes through the windshield 5 of the vehicle is transmitted. As a result, the observer A can visually recognize the virtual image and the actual scene formed by the image display light beam L1 in the front distance. As the combiner 4, it is sufficient that the optical path of the image display light beam L1 is not coaxial before and after the change, and the light beam L2 from the front visual field of the observer A can be transmitted. It can be configured by a half mirror that reflects the light ray L1 or a hologram element that diffracts. It should be noted that another optical system such as a mirror may be interposed between the emitting device 3 and the combiner 4.

As shown in FIG. 2, the emitting device 3 is a transmission type monochrome simple matrix liquid crystal display 11.
The backlight device 12 capable of changing the wavelength of the irradiation light of the liquid crystal display 11, and the liquid crystal display 1
1 and the control device 13 of the backlight device 12.

The liquid crystal operation mode of the liquid crystal display 11 is a BTN mode which utilizes the fact that liquid crystal molecules maintain a constant alignment at two twist angles for several seconds, and directly drives the liquid crystal of each pixel from each scan electrode. Thus, each pixel can be switched between a light transmitting state and a non-light transmitting state.

The backlight device 12 includes an LED array 22 formed on a substrate 21 as a light source and an LE for the LED array 22.
Scattering plate 23 that scatters the light rays emitted from the D array 22 so that the entire display surface of the liquid crystal display 11 can be uniformly illuminated.
And The LED array 22 includes three types of LEDs 22r, 22g, 22b having different emission wavelength peaks.
Are formed so as to be uniformly distributed on the substrate 21. In the present embodiment, each type of LED 22
The colors corresponding to the emission wavelength peaks of r, 22g, and 22b are the three primary colors of red, green, and blue.

The control device 13 is capable of synchronizing the image display timing of the liquid crystal display 11 and the light emission timing of the backlight device 12 according to a desired light emission wavelength peak, and a liquid crystal driver 31 and a backlight driver 32. , A computer 33 for controlling both drivers 31, 32, a memory 34 connected to the driver control computer 33, a navigation information determination computer 35 connected to the computer 22 and the memory 34, and a computer 35. Connected GPS
And a sensor 36.

The GPS sensor 36 is a GPS (Global
A signal from an artificial satellite that constitutes the Positioning System) is sent to the navigation information determination computer 35.

The navigation information determination computer 35 uses the signals from the artificial satellite and the stored program to construct the navigation information in red, green, and
The specific data of each blue image is determined and stored in the memory 34, and a display instruction signal is generated based on the display order, display time, etc. of each data, and the driver control computer 3 is generated.
Send to 3.

The memory 34 has a storage area 34r for red image data, a storage area 34g for green image data, and a storage area 34b for blue image data.

The driver control computer 33 is
By the display instruction signal, each storage area 34 of the memory 34
The image specifying data is read from r, 34g, and 34b, a control signal corresponding to the shape of the image specified by the image specifying data is sent to the liquid crystal driver 31, and the image specifying data is sent to the backlight driver 32 in synchronization with the control signal. A control signal corresponding to the color of the image specified by is transmitted.

The liquid crystal driver 31 sends a liquid crystal drive signal for each pixel of the liquid crystal display 11.

The backlight driver 32 sends a light emission drive signal for the LEDs 22r, 22g, 22b to the backlight device 12.

(1), (2), (3) of FIG. 3 and FIG.
Shows an example of a right turn display by the display device 1.

First, the navigation information determination computer 35 determines to perform the right turn display based on the signal from the GPS sensor 36, and stores the image data corresponding to the circular area in the red image data storage area 34r of the memory 34. Then, the image data corresponding to the right turn instruction arrow is stored in the green image data storage area 34g and the blue image data storage area 34b. In addition, first, the red image data is displayed for a predetermined fixed unit time, then the right turn instruction arrow is displayed for twice as long as the red image data, and it is determined that the display is repeated, and a display corresponding to the determination is made. An instruction signal is generated and sent to the driver control computer 33.

As a result, the driver control computer 33 first receives the display instruction signal from the memory 34.
The image specifying data is read from the red image data storage area 34r, the control signal corresponding to the shape of the circular image is sent to the liquid crystal driver 31, and the control signal corresponding to red is sent to the backlight driver 32 in synchronization with the control signal. To send.

The liquid crystal driver 31 sends a drive signal so that the liquid crystal display 11 can have a pixel in a light transmitting state and a pixel in a non-transmissive state so that a circular image can be displayed on the liquid crystal display 11. As a result, as shown in (1) of FIG. 3, the pixels forming the circular image 11a in the liquid crystal display 11 are set in the light transmitting state, and the pixels in the other portions are set in the non-light transmitting state. Further, the backlight driver 32 sends a driving signal to the backlight device 12 to cause the LED 22r of the emission wavelength peak corresponding to red to emit light.
As a result, in synchronization with the display timing of the circular image on the liquid crystal display 11, the LED 22r of the emission wavelength peak corresponding to the red color of the backlight device 12 is turned on, and the LED 2 of the emission wavelength peak corresponding to the green color and the blue color is emitted.
2g and 22b are turned off.

Next, the driver control computer 33
The image reading data is read from the blue image data storage area 34b of the memory 34 by the display instruction signal, the control signal corresponding to the shape of the right turn arrow image is sent to the liquid crystal driver 31, and the back signal is synchronized with the control signal. A control signal corresponding to blue is sent to the write driver 32. The liquid crystal driver 31 sends a drive signal so that the liquid crystal display 11 has pixels that are in a light transmissive state and pixels that are in a non-transmissive state so that a right turn arrow image can be displayed. Thereby, as shown in (2) of FIG.
In 1, the pixels forming the right turn instruction arrow image 11b are set to the light transmission state, and the pixels of the other portions are set to the light non-transmission state. In synchronization with the display timing of the right turn instruction arrow image of the liquid crystal display 11, the LED 22b of the emission wavelength peak corresponding to blue of the backlight device 12 is turned on, and the LEDs 22r and 22g of the emission wavelength peak corresponding to red and green. Is turned off.

Next, the driver control computer 33
The image reading data is read from the green image data storage area 34g of the memory 34 by the display instruction signal, a control signal corresponding to the shape of the right turn arrow image is sent to the liquid crystal driver 31, and the back signal is synchronized with the control signal. A control signal corresponding to green is sent to the write driver 32. The liquid crystal driver 31 sends a drive signal so that the liquid crystal display 11 has pixels that are in a light transmissive state and pixels that are in a non-transmissive state so that a right turn arrow image can be displayed. Accordingly, as shown in (3) of FIG. 3, the liquid crystal display 1
In 1, the pixels forming the right turn instruction arrow image 11b are continuously set to the light transmission state, and the other pixels are set to the light non-transmission state. The LE of the emission wavelength peak corresponding to the green color of the backlight device 12 is synchronized with the display timing of the right turn instruction arrow image of the liquid crystal display 11.
D22g is turned on, and LEDs 22r and 22b having emission wavelength peaks corresponding to red and blue are turned off.

The images shown in (1) to (3) of FIG. 3 are repeatedly displayed in a time division manner, and at the display timing, the emission wavelength of a desired color in the LEDs 22r, 22g, 22b of the backlight unit 12 is displayed. The light emission timing of the peak is synchronized. As a result, as shown in FIG. 4, the observer A visually recognizes the white right turn instruction arrow image W in the red circular image R.

According to the above configuration, a plurality of images 11a and 11b constituting one information are repeatedly displayed on the liquid crystal display 11 in a time division manner, and the display images 11a and 11b are displayed.
By synchronizing the display timing of b with the emission timing of the desired emission wavelength peak of the backlight device 12, the observer A recognizes one piece of the information as the multicolor images R and W without using a color filter. You can Further, the liquid crystal operation mode of the liquid crystal display 11 is the BTN mode which utilizes the fact that the liquid crystal molecules maintain a constant arrangement at two twist angles for several seconds, so that the switching of images is not performed without using a switching element such as a TFT. Is performed at high speed, and time-divisional display of a plurality of images, which is impossible in the D-STN mode, becomes possible.

The present invention is not limited to the above embodiment. For example, the emission wavelength peak of the irradiation light of the liquid crystal display by the backlight device is not limited to those corresponding to the three primary colors, and may correspond to other colors, and may correspond to two colors or four or more colors. However, it is only necessary that at least two types of wavelength peaks can be emitted. Further, the content of the display image is not limited to that corresponding to the navigation information, and can be any content. Further, the use of the display device of the present invention is not limited to a head-up display device for mounting on an automobile, and for example, a head-up mounted on another vehicle, motorcycle, ship, aircraft or the like that requires clear information outdoors. It can also be used as a display device. Further, instead of the driver controlling computer 33, a programmable logic erasable PLD (Programmable Logic Dev) can be used.
ice) may be used. In addition, the plurality of types of LEDs serving as the light source of the backlight device are not limited to being uniformly distributed and arrayed, and are arrayed in a certain pattern according to the display image, and the LEDs of each pattern are controlled by independent circuits. May be. The light source is not limited to the LED, and any light source having a relatively small heat generation amount can be used.

[0033]

According to the display device of the present invention, since color display can be performed without using a color filter and it is not necessary to provide a switching element for driving a liquid crystal, the transmittance of backlight light in a liquid crystal display is improved, Sufficient display brightness can be ensured even if an LED light source or the like that generates a small amount of heat is used as the backlight device. Further, since it is not necessary to provide a switching element for driving the liquid crystal corresponding to each pixel, the cost can be reduced. Further, since the images can be switched at high speed, the information image can be displayed clearly and the eyestrain of the observer can be prevented.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The backlight device in the display device of the present invention comprises three types of light emitting elements having different emission wavelength peaks, and the colors corresponding to the emission wavelength peaks of the respective types of light emitting elements are the three primary colors. Is preferred. As a result, an image of any color can be displayed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a display device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a main part of the display device according to the embodiment of the present invention.

FIG. 3 is an operation explanatory view of the display device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a display example by a display device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Display Device 3 Emitting Device 4 Combiner 11 Liquid Crystal Display 12 Backlight Device 13 Control Device A Observer L1 Image Display Light

Claims (1)

[Claims] 1. A display device comprising: a device for emitting an image display light beam; and a combiner for changing the optical path for guiding the image display light beam to the observer's visual field and transmitting the light beam from the observer's forward visual field. The device for emitting the image display light beam is a transmission type monochrome simple matrix liquid crystal display in which the liquid crystal operation mode is the BTN mode, a backlight device capable of changing the emission wavelength peak of the irradiation light of the liquid crystal display, and the liquid crystal display And a means capable of synchronizing the image display timing with the emission timing according to a desired emission wavelength peak of the backlight device.