Three dimensional color display and system

Abstract: The disclosure relates to a three dimensional color display wherein controlled modulated laser light (3,7,11) of predetermined different frequencies (1,5,9) is transmitted via fiber optics (13,15,17) and combined in a fiber optic coupler (19) to provide a combined light beam. This light beam is transmitted along a fiber optic path (21) wherefrom it is collimated and a three dimensional color display is formed therefrom. The three dimensional display is provided by an x-y scanner (25) for forming a two dimensional image (27) from the light on the single fiber optic path, a rotating display screen (29) for causing each point on the two dimensional image to move along a path making an acute angle with the two dimensional image wherein operation of one of the scanner and the rotating display screen is controlled relative to the other.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to a color display system as defined in the precharacterizing part of claim 1. BRIEF DESCRIPTION OF THE PRIOR ART It has been known in the prior art to modulate or scan a beam, such as a laser beam and then to project the scanned beam onto a screen. Examples of such systems are set forth in Baker US-Patent Nos. 3,471,641 and 3,549,800. It has also been long desired to provide a three dimensional display. Prior art systems for creating such a display have involved moving a flat plate mirror or flexing a plastic mirror to reflect a CRT image to create a volume display. Similar techniques have employed a Mylar membrane stretched over a metal ring and silvered on the surface, such mirror being vibrated to reflect the information displayed on the CRT in synchronism with the mirror motion. Such techniques and techniques for converting a cathode ray tube two dimensional display into a three dimensional image are discussed in the article "Terminal Puts 3-Dimensional Graphics on Solid Ground", by Harry S. Stover, Electronics , July 28, 1961. Prior art three dimensional display techniques were limited because of their use with CRT screens in that the produced image may be viewed only from selected angles. Moreover, such prior art systems have generally not been able to produce real time images and have been limited in the possible vibration frequencies of the screens. Furthermore, the use of vibrating mirrors has created difficulties due to the relatively large mass of the mirrors which prevent substantial deflections. For example, such prior art systems have generally been capable of providing a mirror displacement of about 0.4 millimeters. A need thus arose for a simple and economical three dimensional display system that could produce substantial displacement at a variety of frequencies in order to provide three dimensional images which can be viewed from all angles. A system which solved this problem is known wherein the three dimensional display includes a laser which directs a beam of light toward a mirror, the mirror being moved in an X-Y plane by piezoelectric transducers. The reflected light beam is directed to a vibrating screen which is moved by a piezoelectric transducer to form a three dimensional image. This system, while providing the desired result, is limited as to the size of the image displayed since the screen and image size are determined by the size of the piezoelectric transducer. Also, this system is affected by G forces, thereby presenting problems where such forces exist, such as in aircraft. The above problems have been minimized in accordance with a prior system wherein a single laser and modulator system provide a light beam which is directed onto an x-y scanner, the latter providing a two dimensional image on a rotating screen. The rotating screen is positioned so that points on the image are constantly moving along an axis normal to the image plane to provide a three dimensional image. In addition, US-Patents 1,794,103, 3,682,553 and 3,970,361 set forth typical prior art displays of the above noted type. The above noted prior art still is unable to adequately provide three dimensional color images wherein the colors can be continually varied on-line. SUMMARY OF THE INVENTION In accordance with the present invention, the above noted problem of the prior art is overcome by color display having the features of the characterizing part of claim 1. Briefly, the above is accomplished by providing a plurality of different color producing lasers, the colors being predetermined so that in preferred embodiments all colors including white can be provided by properly combining the colors as is well known in the color television art, for example. In the preferred embodiment, the lasers produce red (633 nm), blue (476 nm) and green (514 nm) light. The light emanating from each laser is separately modulated by an externally controlled acousto-optic modulator to determine the intensity of the beam exiting the modulator. This intensity can include zero light transmission. The outputs of the modulators are each transmitted along a fiber optic path, to a fiber optic coupler, where they are combined as is well known in the art. The output of the fiber optic coupler can be any preselected color including white, this depending upon the particular mix of colors and intensity thereof entering the coupler for combination therein. The particular mix and intensity of the colors is controlled by the operation of the modulators in combination. The combined light signal exiting the optic coupler is transmitted along a fiber optic path and is transmitted to a standard x-y scanner, preferably via a collimating lens and focusing facility. The x-y scanner provides a two dimensional color image which is focused upon a rotatable, generally planar viewing surface or screen which makes an acute angle with the two dimensional image and is rotatable on an axis which is oblique to its plane. The rotatability and angular orientation may be achieved by attaching the screen to the shaft of a motor making a 45 degree angle with the plane of the screen, though this angle can be varied to provide a larger or smaller height or z-axis dimension, so that, as the screen rotates, a displacement of any given point thereon along the z-axis takes place. The screen can be made of a translucent material, such as lucite, so that images can be projected thereon onto the front and/or rear surfaces thereof. The modulation or strobing of the scan is then synchronized with the rotating screen by control of the motor speed and/or the scanning rate of the scanner so that a three dimensional color pattern appears on the screen. It can be seen that any point on the x-y scan from the scanner which impinges upon the screen will move along a z-axis direction since the screen at that point produces such z-axis movement. This movement of the points of the displayed image provides the three dimensional effect. The adjustment of the angle between the screen surface and the x-y plane of the scanned x-y image will determine the z dimension or height of the three dimensional image, the screen angle being adjustable on-line, if so desired. In addition, US-Patents 1,223,459, 2,589,569, 3,757,106, 3,825,335, 3,825,336, and 4,535,394 set forth typical prior art displays of generally the above noted type. BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a schematic diagram of a circuit embodiment in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with the present invention, the above noted problems of the prior art are minimized and there is provided a system capable of providing a three dimensional display in color with on-line control of the color, using relatively simple and inexpensive circuitry as set forth in the FIGURE. The system includes a red laser 1 providing red light of frequency 633 nm with an externally controlled modulator 3 which controls the intensity as well as the duty cycle of the output from its associated laser. The modulator 3 can be controlled to provide light pulses therefrom whereby, at predetermined times, the light intensity becomes zero. Also provided are a laser 5 providing blue light of frequency 476 nm with its associated modulator 7 and a laser 9 providing green light of frequency 514 nm with its associated modulator 11. The modulators 7 and 11 are the same as, and operate in identical manner to, modulator 3. The modulated light outputs of each of the modulators 3, 7 and 11 are transmitted along fiber optic legs 13, 15 and 17 respectively to a fiber optic coupler 19 wherein the modulated light is combined in well known and standard manner. The output of the coupler 19 is a color which is determined by the particular mix and intensity of the modulated light which entered therein, this output being transmitted along fiber optic line 21 and through a collimating lens 23 to an x-y scanner 25. The scanner receives the collimated light passing through the lens 23 and provides a two dimensional image therefrom. This two dimensional image 27 is reflected onto a rotating screen 29 which makes an acute angle with the two dimensional image, the screen 29 and its operation corresponding to the above noted prior art system. The screen 29 is rotated by a motor 31, the rotational speed of the motor being synchronized with the scanning rate of the scanner 25 as in the above prior art system. Any point of light in the x-y or two dimensional image plane impinging upon the screen 29 will display a harmonic type motion in the z-plane due to the similar movement of points on the screen. Accordingly, if the scanning rate of the scanner and the rotation rate of the screen are sufficiently high, light impinging upon the screen at any point on the screen will move along the z-axis sufficiently rapidly to appear as a complete line, as is well known. The result is a three dimensional color display with height determined by the angle of the screen.

Claims: A color display system of the type which includes a first subsystem (1, 3) having a light source (1) for emitting light of a predetermined frequency and a facility (3) for modulating the emitted light (13) to vary, with respect to time, the intensity and duty cycle of the emitted light and a second subsystem (25, 29) having a scanner (25) for deflecting in two dimensions the modulated light (13) to produce a two dimensional pattern (27) which is displayable on a planar image surface coincident with an x-y image plane perpendicular to the axis of projection of the pattern, characterized by: additional first subsystems (5, 7; 9, 11) each comprising a light source, each of the light sources of the first subsystems emitting light of a different, predetermined frequency and each of the first subsystems independently modulating the light (13, 15, 17) emitted by the respective light source, fiber optic means (19) for combining the modulated light (13, 15, 17) and for transmitting the combined light along a single fiber optic path (21) to the second subsystem (25, 29), a display screen (29) making an acute angle with the axis of projection of the two dimensional pattern (27) of the transmitted combined light (13, 15, 17), means (31) for rotating the display screen (29) about an axis which is oblique to said x-y image plane, each point of the pattern moving along a path which is perpendicular to said x-y image plane and which makes the acute angle with the axis of projection of the pattern (27), so that each point of the pattern is displayed as a line, and means for synchronizing the scanner (25) and the rotation of the display screen (29) to produce a three dimensional color image. A display system as set forth in Claim 1 wherein each light source is a laser. A display system as set forth in Claim 1 or 2 which includes three first subsystems. A display system as set forth in Claim 1, 2 or 3 wherein the predetermined frequencies of each light source are such that they can be combined to produce white light.

Inventors: GARCIA FELIX JR, GARCIA, FELIX JR.
Applicants: TEXAS INSTRUMENTS INC, TEXAS INSTRUMENTS INCORPORATED
Application year: 1988
Main classification: G02B26
IPC codes: G02B27, G09F9, G09F19, G09G3, H04N13