JPH07318840A - Display device - Google Patents

Abstract

PURPOSE:To make a display device small in size and light in weight and to reduce assembly man-hour by providing a concave mirror with two functions such as a lens effect and a reflection mirror in the display device forming a two-dimensional picture by reflecting the point light train of a light emitting element array where light emitting elements are arrayed in a line by reflection mirror whose angle is oscillationally changed after enlarging it by a lens and causing an afterimage phenomenon. CONSTITUTION:This device is constituted of the light emitting element array 4 were the light emitting elements are plurally arrayed in a line, the concave mirror 1 changing an optical path by enlarging and reflecting the image outputted from the array 4, and an actuator 2 changing the reflection angle of the mirror 1 by oscillating the mirror 1.

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 displaying characters and images, and more particularly to a display device utilizing an afterimage phenomenon.

[0002]

2. Description of the Related Art Private Eye (manufactured by Reflection Technology in the United States) is available as a display device that utilizes the afterimage phenomenon. The patents related to this product are US Patent No. 4
902083 and U.S. Pat. No. 4,934,773.

A conventional display device will be described with reference to FIG. The conventional display device mainly includes a line-type LED array as the light emitting element 4, an optical lens 31, and a reflecting mirror 30 capable of oscillatingly changing the reflection angle, and the display is viewed from the viewpoint 5. When the one-dimensional data output from the light emitting element is projected onto the reflecting mirror 30, the reflecting mirror 30
The two-dimensional image is obtained by synchronizing the angle of 1 and the data transfer for one line given to the LED and utilizing the afterimage phenomenon caused by the one-dimensional LED light reflected from the reflecting mirror whose angle changes oscillatingly. To generate.

The reflecting mirror 30 scans one screen at a speed of about 50 times per second, and the bright spots of the LED projected on the reflecting mirror 30 are projected on the next same spot. LE is always used as an afterimage until (1/50 second in this case)
It is felt as if the light of D remains. Since the afterimage phenomenon occurs in all the point sequences in the scanning direction, the total 2
A three-dimensional image can be obtained. This product has high resolution as a small display (displays 280 dots vertically × 720 dots horizontally in a window of about 24 mm × 22 mm).

[0005]

In the method of changing the reflection angle of the reflecting mirror and enlarging by the lens as described in the prior art, both the reflecting mirror and the lens are required, which hinders space saving and weight reduction. Becomes In particular, when the device is mounted on the head by using a dedicated arm, or when the device is incorporated as a viewer of a portable facsimile, further downsizing and weight reduction of the device become an issue.

An object of the present invention is to provide a display device which can be reduced in size and weight, and which can reduce the number of assembling steps.

[0007]

The features of the present invention are that, in the display device described in the prior art, the function of the reflecting mirror that changes the angle in a vibrational manner for scanning and the image of the LED array are displayed. The point is to use a concave mirror as a component that also has the function of magnifying.

[0008]

A two-dimensional image is generated by enlarging and reflecting a point light train of a light emitting element array in which light emitting elements are arranged in a line by a concave mirror whose angle changes oscillatingly and causing an afterimage phenomenon. By providing the concave mirror with the two functions of the lens effect and the reflecting mirror, it is possible to reduce the size and weight of the device and reduce the number of assembling steps.

[0009]

EXAMPLES Examples according to the present invention will be described.

FIG. 1 is a perspective view showing a display device according to a first embodiment. This display device has a line-type red LED array as a light emitting element 4 and a rotation support mechanism 3 and can change the angle of reflection, and further has a concave mirror 1 having a magnifying function for making the LED array look larger than it actually is. And an actuator 2 for oscillating the reflection angle of the concave mirror 1 in the scanning direction 6. When the display device is used, the user's viewpoint 5 is placed at a position where the light of the LED array which is reflected by the concave mirror and expanded can be seen.

FIG. 2 shows the state of image data sent to the LED array. In FIG. 2, column data in either one of the vertical and horizontal directions of the two-dimensional image data 7 is sequentially sent from the end to the LED array which is the light emitting element 4 of FIG. In the figure, line units in the vertical direction at both ends of the two-dimensional image data are indicated by 8 and 9. At the same time, the concave mirror 1 vibratingly changes the reflection angle by the actuator 2, and the LED array vibrates in the direction 5 perpendicular to the direction of the LED array at the viewpoint 5 of the user who is looking at the concave mirror 1. looks like. At this time, the reflection angle of the concave mirror and the image for one line output from the LED array are synchronized, and the angle of the concave mirror 1 changes as the image for one line is updated. When the concave mirror rotates by the angle of one screen, this time it rotates in the opposite direction. Then, the swing in which the reflection angle of the concave mirror changes is oscillatingly repeated.

From the concave mirror 1 which changes the reflection angle in an oscillating manner, the LED light which is instantly updated line by line is reflected toward the line of sight of the user. The lens effect of the concave mirror 1 has a function of enlarging the line image output from the LED array 4 and giving an image larger than the actual LED light emitting portion to the viewpoint.

The concave mirror scans one screen at a speed of about 50 times per second, so that the user can see the bright spots of LEDs projected on the concave mirror on the next same spot. Until the image is projected (1/50 seconds in this case), it is felt that the LED is always lit as an afterimage. Then, since this afterimage phenomenon occurs in all point sequences in the scanning direction, a two-dimensional image can be obtained as a whole.

By the blinking of the LED array and the operation of the concave mirror described above, the one-dimensional LED light is magnified, causing an afterimage phenomenon to the user and generating a two-dimensional image.

Next, the state of scanning by swinging the concave mirror will be described using specific numerical values as an example. One screen is 30
Give a resolution of 0 dots x 700 dots, 5 per second
The screen will be updated 0 times. In this case, the frequency of rotational vibration of the concave mirror is 50/2 = 25 [Hz], assuming that different images are generated in the reciprocating scanning direction. Assuming that even the part where the rotation direction is reversed can be displayed ideally 1
When the display frequency per line is calculated, the vibration frequency of the concave mirror is doubled and the resolution in the scanning direction is multiplied by 25 × 2.
× 700 = 35 [kHz]. Actually, in the vicinity where the rotation direction is reversed, the display time per line greatly affects the distortion of the image, so the display is stopped. Therefore, it is necessary to switch and output the LED images line by line at a speed faster than this frequency. In this embodiment, as the light emitting element 4, a chip in which 300 red LEDs capable of blinking up to 70 kHz or more are integrated in an array having a length of 15 mm is used.

The reflection and refraction of the LED array light according to this embodiment will be described with reference to FIG. 3 and an example of the distance relationship between the respective elements with reference to FIG.

FIG. 3 is a plane that cuts the array direction of the LED array perpendicularly. The viewpoint 5, the concave mirror 1, the LED array 10,
And the arrangement of the virtual image 11 is shown. The light from the LED array hits the concave mirror 1 and is reflected by the reflection angle at that time to be magnified and delivered to the viewpoint 5.
The ED array 10 is captured as an image width A with an afterimage phenomenon. The image width B is obtained by removing the lens effect of the concave mirror 1 from the image width A. Also, considering the effects of the lens action of the concave mirror and the swing in the scanning direction 6, the actual LE
The user sees the LED array virtual image 11 with respect to the D array 10. The viewing angle 12 formed by the virtual image due to the afterimage phenomenon is an angle formed by the viewpoint 5 and the image width A.

FIG. 4 is for clarifying the positional relationship by eliminating the reflection effect of the concave mirror in order to capture the viewing angle 5 and by cutting along the plane parallel to the array direction of the LED array. Figure 4
In, the lens effect of the concave mirror is replaced with the virtual lens 15, but the focal length of this virtual lens 15 is 10 m.
m (13 and 14 indicate a focus), an LED as a light emitting element
8 mm from the array 10 to the concave mirror 1, user's viewpoint 5
If the distance from the position to the virtual lens 15 (actually a concave mirror) is 60 mm, the length of the LED array 10 is 15 mm.
Since the size is mm, the size of the virtual image 11 formed by the virtual lens 15 is 75 mm. The position of the LED array virtual image 11 is
Approximately by the paraxial imaging method of spherical reflection, 1 / (distance from concave mirror to image) + 1 / (distance from concave mirror to virtual image) = 2 / (spherical radius) (focal length) = (spherical radius) / When calculated using the relationship of 2, the distance from the virtual lens is about 40 mm. Next, consider the size of the virtual image in the scanning direction. When 700 dots in the scanning direction are developed with the same resolution for 300 dots in the LED array direction, the size of the virtual image in the scanning direction becomes 175 mm. Therefore, the viewing angle formed by the display range from the user's viewpoint is 36 degrees on the short side and 82.4 degrees on the long side (scanning direction).

The concave mirror 1 may be formed by polishing glass and applying a reflecting material as in the conventional case, but in this embodiment, in order to reduce the weight, a concave surface is formed of plastic and a reflecting material is vapor-deposited on the concave surface. There is.

As shown in FIGS. 5 (a), 5 (b) and 5 (c), the actuator 2 that gives the concave mirror 1 an oscillatory swing is an electromagnetic type including a voice coil motor 16 and a speed reducer 18. The rotary motor 17, the piezoelectric actuator 19, and the like can be used.

Further, as shown in FIG. 6 (a), the concave mirror 1
By adjusting the weight of the spring 20 and attaching the spring 20 to the concave mirror, a resonance system is formed by the spring 20 with the rotational movement (rotation center 21), the concave mirror model 23, and the external force 22 as shown in FIG. By stably performing the vibration of No. 1, it is possible to reduce the power consumption and improve the quality of the displayed image.

Further, the rocking of the concave mirror does not have to be a rotational motion, and the LE corresponding to the position corresponding to the viewing angle of the user is used.
It suffices that the blinking of the D array can be enlarged and reflected, and for example, an elliptic actuation that focuses on the position of the light emitting element and the viewpoint may be used as the locus.

[0023]

According to the present invention, by making a concave mirror have two functions of a lens effect and a reflecting mirror, it is possible to reduce the size and weight of the apparatus and reduce the number of assembling steps.

[Brief description of drawings]

FIG. 1 is a perspective view showing a display device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing line-by-line data of a two-dimensional image.

FIG. 3 is an explanatory diagram showing how an image width is formed according to the present invention.

FIG. 4 is a diagram illustrating generation of a virtual image using a virtual lens according to the present invention.

FIG. 5 is a perspective view showing an actuator that swings a concave mirror according to the present invention.

FIG. 6 is a diagram for explaining a resonance system of a concave mirror according to the present invention.

FIG. 7 is a perspective view showing a conventional display device.

[Explanation of symbols]

 1 Concave Mirror 2 Actuator 3 Rotation Supporting Mechanism 4 Light Emitting Element 5 Viewpoint 6 Scanning Direction 7 Two-dimensional Image 8, 9 Line Unit 10 LED Array 11 LED Array Virtual Image 12 Viewing Angle 13, 14 Focus 15 Virtual Lens 16 Voice Coil Motor 17 Motor 18 Deceleration Device 19 Piezoelectric actuator 20 Spring 21 Center of rotation 22 Force 23 Concave mirror model 30 Reflector 31 Lens A, B Image width

Claims (4)

[Claims] 1. A light emitting element array arranged in a plurality of lines,
A display device including a concave mirror that magnifies and reflects an image output from a light emitting element array to change an optical path, and an actuator that swings the concave mirror to change a reflection angle of the concave mirror. 2. The display device according to claim 1, wherein the user's viewpoint is placed at a position where the light of the light emitting element array reflected and expanded by the concave mirror can be seen. 3. The display according to claim 2, wherein the reflection angle of the concave mirror and the image for one line output from the light emitting element array are synchronized, and the reflection angle of the concave mirror is changed as the image for one line is updated. apparatus. 4. The display device according to claim 3, wherein the actuator is a voice coil motor, an electromagnetic rotary motor with a speed reducer, or a piezoelectric actuator.