JP2550827B2 - Helmet mounted display - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to helmet mounted displays.

[0002]

2. Description of the Related Art A helmet mounted display (HMD) device has been developed for displaying various images and information by superimposing it on a landscape in front of the eyes for an aircraft pilot and a trainer of a flight simulator for training the aircraft. There is. As shown in FIG. 3, the HMD 31 is a helmet 30.
Combiner 3 attached to both sides of the
The mounting position is adjusted so that the projection screen called 2 comes. The combiner 32 is semi-transparent, and the wearer sees an image projected on the combiner 32 and an image in which information such as the flight speed is superimposed on the external scenery seen through the combiner 32.

[0003]

As described above, the HMD3
The angle of the HMD 31 can be adjusted according to the wearer so that the combiner 32 comes to the front of the wearer's eye when the wearer 1 is worn. However, when such an angle adjustment is performed, the symbols and images are projected on the combiner 32 with an inclination.

Therefore, conventionally, the CRT 33 displaying the original image of the image projected on the combiner 32 is rotated so that the projected image on the combiner 32 is oriented in the correct direction. However, this angle adjustment is delicate and accurate adjustment is difficult. Further, a mechanism for mechanically rotating the HMD 31 is required, which hinders the weight reduction of the HMD 31. The present invention has been made to solve such a problem, and an object of the present invention is to provide a helmet mounted display capable of electrically correcting the inclination of such a projected image. It is in.

[0005]

MEANS FOR SOLVING THE PROBLEMS A helmet mounted display according to the present invention, which has been made to solve the above problems, comprises a) a display for displaying an image by raster scanning, and b) a display for displaying the image. An optical system for projecting an image on a combiner, c) an angle input means for inputting a rotation angle of a display image, and d) an image displayed on the screen of the display so as to rotate by the input rotation angle. Image rotation means for converting the coordinate of the x-deflection signal and the y-deflection signal of the container.

[0006]

When the wearer wears a helmet with a helmet mounted display, and the image projected on the combiner in front of the eye is tilted, the angle input means is adjusted so that the correct angle can be obtained while watching the image. Input the rotation angle with c. The image rotation means d is used in the raster scan of the display a according to the input rotation angle value x.
Coordinate conversion is performed on the deflection signal and the y deflection signal. Since the display a displays an image using the coordinate-converted x and y deflection signals, the display image is tilted by the input rotation angle.
When this image is projected onto the combiner via the optical system b, the image is visually recognized by the wearer without inclination.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A helmet mounted display (HMD) which is an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 3, the HMD 31 of this embodiment is mounted on both sides of the helmet 30 as in the conventional one. HM
A small CRT 33 is built in the D31, and various images and information are displayed on this screen. The image displayed on the screen of the CRT 33 is projected on the combiner 32 by the optical system provided inside the arm 34 of the HMD 31.

A mounting portion of the HMD 31 to the helmet 30,
Also, the main body of the HMD 31 and the arm 34 are rotatable, so that the combiner 32 of the HMD 31 can be adjusted so as to come to the front of the eye correctly according to the position of the eyes of the person wearing the helmet 30. But like this, HM
When the D31 main body and the arm 34 are rotated, the image projected on the combiner 32 also rotates accordingly, so that the image originally supposed to be seen by the wearer as shown in FIG. 4A is inclined as shown in FIG. 4B. To be seen.

The HMD 31 of this embodiment is provided with a tilt correction circuit as shown in FIG. 1 in order to correct the tilt of the projected image on the combiner 32. In the inclination correction circuit of the HMD 31 of this embodiment, the variable resistor 10,
A / D converter 12, sin θ ROM 14, cos θ
ROM15, 4 integrated D / A converters (MD /
A) 16, 17, 18, 19 and an adder / subtractor circuit 20 are provided. The operation of the tilt correction circuit of FIG. 1 will be described below.

The variable resistor 10 is a means for inputting a correction tilt angle, and an analog signal generated by the power source VB and the variable resistor 10 is input to the A / D converter 12 as a correction angle signal. The resistance value of the variable resistor 10 is changed by a "knob" or the like provided on the HMD 31. The A / D converter 12 outputs the angle value θ corresponding to the input signal to the sin θROM 14 and the cos θROM 15. The sin θROM 14 and the cos θROM 15 are ROMs (read-only memories) that store the values of sin θ and cos θ for various angles θ, and sin θ and the sin θ stored at the address corresponding to the angle value θ given from the A / D converter 12. The value of cos θ is output. The output values of the ROMs 14 and 15 are given to the two MD / A. On the other hand, the horizontal deflection signal x and the vertical deflection signal y of the CRT 33 built in the HMD 31 are also input to the two MDs / A. As a result, the four MD / A 16, 17, 18, and 19 are eventually (x and sin θ), (y and sin θ), and (x
And cos θ), and (y and cos θ), four types of combinations of analog signals and digital signals are input.

Each MD / A 16, 17, 18, 19 is
The input analog signals (x, y) are converted into digital signal values (si
An analog signal multiplied by nθ, cosθ) is output.
Output signals (x · sin θ, y · sin θ, x · cos θ, y · c of the four MD / A 16, 17, 18, 19
osθ) is input to the adder / subtractor circuit 20, where two types of analog signals X = x · cos θ + y · sin θ and Y = −x · sin θ + y · cos θ are generated.

These equations are nothing but conversion equations for converting the coordinate values of the (x, y) rectangular coordinate system into the coordinate values of the (X, Y) rectangular coordinate system rotated by the angle θ. Therefore, by using the analog signals X and Y as the horizontal deflection signal and the vertical deflection signal of the CRT 33, the image is rotated on the CRT screen by the angle θ and displayed. Graphs of the original horizontal deflection signal x, the vertical deflection signal y, and the horizontal deflection signal X and the vertical deflection signal Y output from the adder / subtractor circuit 20 are shown in FIGS. 2 (a) and 2 (b). This allows
The image projected on the combiner 32 is in the correct direction as seen from the wearer (state without inclination, FIG. 4A).

In the above embodiment, sin θ and cos
The value of θ is obtained by using the ROMs 14 and 15, but may be calculated, of course.

[0014]

In the helmet mounted display according to the present invention, the inclination of the image is electrically corrected, so that the relationship (gain) between the angle input and the image inclination angle can be set arbitrarily, and the angle of the subtle angle can be adjusted. Adjustment can also be easily performed. In addition, since it does not have a mechanical rotation mechanism, the structure is simple and the weight of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an example of a tilt correction circuit of a CRT of a helmet mounted display that is an embodiment of the present invention.

2 is a graph (a) of an original horizontal deflection signal x and a vertical deflection signal y, and a graph (b) of a horizontal deflection signal X and a vertical deflection signal Y for tilt correction generated by the circuit of FIG.

FIG. 3 is a side view (a) and a front view (b) of the helmet mounted display.

FIG. 4 is an explanatory view showing an image (a) projected on a combiner and an image (b) when it is tilted.

[Explanation of symbols]

10 ... Variable resistance 12 ... A / D converter 14 ... sin θ ROM 15 ... cos θ
ROM 16, 17, 18, 19 ... Accumulation D / A converter (M-
D / A) 20 ... Addition / subtraction circuit 30 ... Helmet 31 ... HMD 32 ... Combiner 33 ... CRT 34 ... Arm x, X ... Horizontal deflection signal y, Y ... Vertical deflection signal

Claims (1)

(57) [Claims] 1. A display device for displaying an image by raster scanning, b) an optical system for projecting the image displayed on the display device on a combiner, and c) an angle input means for inputting a rotation angle of the display image. D) Image rotation means for coordinate-converting the x-deflection signal and y-deflection signal of the display so that the image displayed on the screen of the display is rotated by the input angle. Helmet mounted display.