JPS63294517A - Head-up display - Google Patents

Abstract

PURPOSE:To maintain always the good contrast of an outside world image and symbol image superposed on a combiner independently of the brightness of the outside world by providing an outside world light shutter which changes the transmittance of the outside world light in accordance with a luminance detection signal. CONSTITUTION:This device has a display device 10 which emits the symbol light A corresponding to the symbol image 70 superposed on the outside world image and the combiner which is disposed in front of an observer's position and superposes the outside world light B corresponding to the outside world image 50 transmitted from the rear face on the symbol light A. The device has a luminance detector 30 which detects the luminance around the image 50 and outputs the same as the luminance detection signal and the outside world light shutter 40 which changes the transmittance of the light B in accordance with the luminance detection signal. The transmittance of the light B transmitted through the combiner 20, therefore, changes according to the luminance around the image 50. The contrast of the outside world image 50 and symbol image 70 superposed by the combiner 20 is thereby maintained always in the desired state independently of the brightness of the outside world.

Description

[Detailed Description of the Invention] The present invention relates to a hand-held display mounted on, for example, an aircraft, and in particular, the present invention relates to a hand-held display mounted on an aircraft, etc., and in particular, the present invention relates to a hand-held display mounted on an aircraft, etc. In particular, the contrast between an external image and a symbol image superimposed by a combiner is always good. This invention relates to a head-up display that has the following functions.

A head-up display installed in conventional aircraft is a device that projects information necessary for navigation as a symbolic image onto a combiner installed on the windshield of the cockpit. CRT that processes commands and displays corresponding symbol images
In order to make the symbol image projected on the combiner easier to see, the unit lacks a function that adjusts the brightness of the symbol image according to the brightness of the outside world.

It's raining. However, in the conventional method described above, due to the functional limitations of CRT, it is not possible to adjust the brightness within a wide range of increase/decrease. There is a problem in that the symbol image cannot be recognized.This also leads to unnecessary burden on the pilot loft who performs various and complex tasks.

The present invention was created in view of the above circumstances, and includes:
To provide a handheld display improved so that the contrast between an external world image and a symbol image superimposed on a combiner is always good regardless of the brightness of the external world.

Such a head-up display for divination includes a display device that emits symbol light corresponding to a symbol image superimposed on an external image;
This device is placed in front of the observer and has a combiner that superimposes external light corresponding to the external image transmitted from the back onto the symbol light, and detects the brightness around the external image and It consists of a brightness detector that outputs a brightness detection signal, and two polarizing plates sandwiched between a PLZT electro-optic body.
and an external light shank that changes the transmittance of external light based on the brightness detection signal.

When starving, the transmittance of external light passing through the combiner changes depending on the brightness around the external image.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a head-up display according to the present invention will be described below with reference to the drawings. Figure 1 is a configuration diagram of the belly button up display, Figure 2 is a sectional view of a combiner explaining the configuration of the external light shutter, Figure 3 is a diagram of the operating principle of the external light shutter, and Figure 4 is the application of the external light shutter. It is a voltage-transmittance characteristic graph.

In the figure, 20 is a combiner that is a curved flat half mirror, and is provided inside the windshield (not shown) of an aircraft. Outside world light B corresponding to the outside world image 50 in front of the striking aircraft enters the combiner 20 from the back side (in the figure, outside world light B transmitted through the combiner 20 is referred to as outside world light C).

Further, symbol light A emitted from the CRT unit 10 (the display screen is a symbol image 70) provided below is irradiated onto the front of the combiner 20 via a mirror 11 and a relay lens 12. It has become.

Note that the mounting position and angle of the combiner 20 are adjusted appropriately in advance so that the symbol light A described above is reflected in the direction of the pilot 60. In other words, the symbol light A reflected from the front of the combiner 20 is superimposed on the above-mentioned external light C, and as a result, the pilot 60
A superimposed image of the external world image 50 and the symbol image 70 is recognized in a state of looking forward.

To explain in more detail, inside the combiner 20, there is a P
An external light shutter 40 having an LZT electro-optic body 43 is attached (see FIG. 2), and is used to control the transmittance of external light B in accordance with the brightness of the external world. The external light shutter 40 will be described later, but first the brightness detector 30 that detects the brightness of the outside world will be described.

The brightness detector 30 is an optical sensor made of, for example, a photodiode, and in order to receive external light B, its light receiving surface is attached to a predetermined part of a windshield (not shown), and the brightness of the external light B is converted to a predetermined value. The brightness detection signal 31 thus obtained is outputted to the external light shutter 40 via the voltage control circuit 32. In this embodiment, the voltage control circuit 32
is a voltage buffer circuit for the voltage-driven PLZT electro-optical body 43, and the drive signal 321 output from this is the same as the luminance detection signal 31, differing only in voltage level. The external light shutter 40 will be explained below with reference to FIG.

The external light shutter 40 is integrated with the combiner 20, and has a structure in which a PLZT electro-optical body 43 is sandwiched between polarizing filters 41 and 42 having the same polarization direction a (see FIG. 3) using an adhesive or the like. It becomes.

However, a PLZT electro-optical body is a P
It is a device that is an LZT (ferroelectric ceramic) substrate and produces a Kerr effect when a predetermined voltage is applied to its electrodes. On the other hand, inside the PLZT electro-optical body 43,
A comb-shaped electrode 431 is provided, and the drive signal 321 is connected to this.

To explain in more detail, an antireflection film 411 is provided on the outer surface of the polarizing filter 41, which is the incident surface of the external light B, and an antireflection film 411 is provided on the outer surface of the polarizing filter 42, which is the superimposed surface of the external light C and the symbol light A. A predetermined amount of reflective film 421 is applied to the external light shutter 40 so that the external light shutter 40 constitutes a half mirror.

The operating principle of this external light shutter 40 will be explained below with reference to FIG.

First, a process in which external light B having a random polarization plane passes through the external light shutter 40 and becomes external light C will be described. The external light B that has entered the external light shutter 40 is polarized by a polarizing filter 41, and the phase of the processed external light B is changed by the next PLZT electro-optical body 43. The external light B2 that has passed through the PLZT electro-optic body 43 is subjected to polarization processing by the next polarizing filter 42.

This is external light C.

To explain in more detail, when the applied voltage is zero, the external light B passes through the PLZT electro-optical body 43 and the polarizing filter 42 without being affected by anything. At this time, the transmittance of the external light B to the external light shutter 40 becomes maximum.

However, when the applied voltage is no longer zero, rotation occurs in the polarization plane of the external light B2 that passes through the PLZT electro-optic body 43.
Some components are blocked by the polarizing filter 42. Further, when the applied voltage E reaches such a level that the polarization plane of the external light B2 becomes perpendicular to the polarization direction a, the external light B2 is completely blocked. That is, the transmittance of external light B at this time becomes zero. FIG. 4 is a graph showing the relationship between the transmittance of external light B and the applied voltage.

Such a head-up display controls the external light shutter 40 described above based on the brightness detection signal 31, so that when the brightness of the external light B increases, the transmittance of the external light B is adjusted accordingly. Since the contrast between the external world image 50 and the symbol image 70 is reduced, the contrast between the external world image 50 and the symbol image 70 can be set to a desired state.

Note that the head-up display according to the present invention is not limited to the above-described embodiment, and the voltage control circuit 32 may be a pulse width modulation circuit.

That is, the brightness detection signal 31 (switching period T (#1/
The pulse width control is performed by varying the time width between tl and t2 of 60 (s))) according to the luminance detection signal 31. FIG. 5(a) shows the state of this drive signal 321. Moreover, FIG. 5(b) shows the state of the drive signal 321 when the brightness of the external light B becomes higher than in the state of FIG. 5(a). In other words, the transmittance of the external light B is reduced by increasing the proportion of the time T occupied by the external light shutter 40 to block the external light.

It goes without saying that the external light shutter 40 does not necessarily have to be integrated with the combiner 20, and its mounting position is not limited. In addition, the polarizing filter 41.
42, it is not necessarily necessary to use those having the same polarization direction; this is done in consideration of a failure of the voltage control circuit 32 or the like. Furthermore, it goes without saying that a head-up display may be installed on the windshield of an automobile or the like.

According to this head-up display, the transmittance of external light passing through the combiner changes depending on the brightness around the external image, so the combiner can be used regardless of the brightness of the external world. The contrast between the external world image and the symbol image which are folded into M can always be kept in a desired state. Furthermore, when such a head-up display is mounted on an aircraft, various effects are achieved in that it does not impose unnecessary burdens on pilots who perform various complex operations.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a head-up display according to the present invention, FIG. 2 is a sectional view of a combiner explaining the configuration of an external light shutter, FIG. 3 is a diagram of the operating principle of the external light shutter, and FIG. In the applied voltage-transmittance characteristic graph of the external light shutter in the figure, the fifth yI is a timing chart of a drive signal for explaining a modification of the voltage control circuit. "10... CRT unit 20... Combiner 30... Brightness detector 31... Brightness detection signal 40... External light shutter 41.42... Polarizing plate 43... PLZT electro-optical body 50 ...External world image 60...Observer A...Symbol light B, C...External world light

Claims (1)

[Claims] (1) A CRT unit that emits symbol light corresponding to a symbol image to be superimposed on an external world image, and a CRT unit that is disposed in front of the observer's position and emits external world light corresponding to the external world image transmitted from the back side of the symbol light. In a head-up display having a combiner that is superimposed on the outside image, a brightness detector that detects the brightness around the external image and outputs it as a brightness detection signal, and a PLZT electro-optic body are sandwiched between two polarizing plates. and an external light shutter that changes the transmittance of the external light based on the luminance detection signal.