JPH02221995A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a stable color index signal even a screen is at a black level by mixing an UV laser beam and an infrared laser beam, irradiating/ scanning a screen with the mixed beam, and converting the infrared beam reflected by a reflector to an electric signal by a photodetector. CONSTITUTION:The UV laser beam generated from a light source 1 is made incident on a light modulator 12 and is modulated by a color image signal; moreover, the UV laser beam is made incident on a polarizing beam splitter PBS 19 through an expander 13 constituted of such as a concave lens and a focal lens. An IR laser beam and the UV laser beam which are made incident on the PBS 19 are polarized linearly. If the UV laser has P polarizing component and the IR laser beam S polarizing component, 100% of the P polarizing component of the UV laser beam passes through the PBS 19. S polarizing component of the IR laser beam is reflected by the boundary surface of the PBS 19 and becomes a mixed laser beam 16. The screen 4 is irradiated with the mixed laser beam 16. In this normal beam, the visible light phospher normally emits, and excitation corresponding to the black level is transmitted without affecting the visible light phospher at the black level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image display device suitable for use in a projector that scans a screen provided with a visible light phosphor with an ultraviolet laser beam.

[Summary of the invention]

The present invention relates to an image display device suitable for use in a projector in which a screen provided with a visible light phosphor is scanned with an ultraviolet laser beam. A laser beam that is a combination of an ultraviolet laser beam and an infrared laser beam is produced in an image display device in which a visible light phosphor that emits light and a light reflecting means that returns the ultraviolet laser beam substantially in the incident direction are arranged in a predetermined pattern. By scanning the screen with the infrared laser beam and using the return light of the infrared laser beam from the reflecting means as the index signal, a stable index signal can be obtained even when the display screen is completely dark and there is no ultraviolet laser beam to excite the visible light phosphor. It was designed so that it could be done.

[Conventional technology]

For example, red (R) in stripes on the screen.

An image display device that can display an image by exciting a plurality of visible light phosphors that emit visible light of green (G) and blue (B) with an ultraviolet laser beam to cause a screen to emit light at a predetermined brightness and hue. The applicant is the Japanese Patent Publication No. 61-22
It was proposed earlier as No. 518.

The outline described in this publication will be explained with reference to FIGS. 3 and 4. FIG. 3 shows a schematic diagram of a conventional ultraviolet laser scanning type image display device, in which a coherent ultraviolet laser beam (hereinafter referred to as U
V laser beam) is emitted. , this light source (1
) contains an optical modulator that modulates brightness and darkness with the television video signal. The modulated UV laser beam is passed horizontally on a screen (4) at a predetermined speed by a polygon mirror (2) for scanning in the Y-axis direction and a polygon mirror (3) for scanning in the X-axis direction, which constitute deflection means. It is designed to move sequentially in the vertical direction while scanning.

On the screen (2), there is a striped retroreflector similar to striped visible light phosphors (5R) (5G) (5B) that emit light in each hue of R, G, and B when excited by a UV laser beam. The bodies (6) are arranged in a predetermined repeating pattern on the birch, each with the longitudinal direction of its stripes coinciding with the vertical direction on the screen (4).

The retroreflector (6) is a UV laser beam screen (2
) It is provided for the purpose of obtaining an index signal for detecting the scanning position on the top surface, and it uses cube mirrors arranged in many rows or glass beads arranged in many rows. This retroreflector (6) is designed so that the incident light hits the retroreflector (6) and most of it is reflected in the direction of the incident light.

Fig. 4 is a schematic diagram of the optical system showing the state of reception of the index signal. Most of the incident UV laser beam (8) that is scanned in the X- and Y-axis directions and hits the retroreflector (6) is reflected to become a reflected UV laser beam (9), which is focused by a lens (10). It is converted into an electrical signal by a light receiving element (11) such as a photodiode, and a color index signal is obtained.

[Problem to be solved by the invention]

In the conventional configuration shown in FIGS. 3 and 4, the light emitting source (1
) When passing a UV laser beam emitted from a laser beam through an optical modulator and modulating it with a color video signal, etc., if the UV laser beam is completely focused when the screen in the color video signal is at a black level, a color index signal will be generated. Also the light receiving element (11
) on the light-receiving surface, so even if the screen has a black level, it is scanned with a weak UV laser beam to obtain a color index signal, which makes it impossible to completely express black on the screen. was there.

The present invention was made to solve the problem of ridges, and its object is to provide an image display device that can obtain stable color index signals.

[Means to solve the problem]

An example of the image display device of the present invention is as shown in FIG.
A visible light phosphor (5R) (5G) (5B) that emits multiple colors of visible light when irradiated with the ultraviolet laser beam (8) and a light reflecting means (6) that returns this ultraviolet laser beam (8) approximately in the direction of incidence are arranged in a predetermined pattern. In the image display device arranged in , a laser beam (16) which is a combination of an ultraviolet laser beam and an infrared laser beam is scanned over a screen (4), and an infrared laser beam (17) from a reflecting means (6) is scanned. The returned light is used as an index signal.

[Effect]

The image display device of the present invention irradiates and scans a laser beam (16), which is a mixture of a UV laser beam and an infrared laser beam, onto a screen (4), and reflects the laser beam by hitting a reflecting means (6) provided on the screen (4). infrared laser beam (
17) is received by a light-receiving element and converted into an electrical signal to produce a color index signal, so a stable color index signal can be obtained even if the screen is at a black level.

[Example] Hereinafter, an image display device of the present invention will be explained with reference to FIGS. 1 and 2.

In FIG. 1, parts corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, and redundant explanation will be omitted.

The image display device of this example has a configuration suitable for use as a projector, and can be used as a front projector or a rear projector. FIG. 1 shows the screen (4) when constructed as a beam abjector.

The screen (4) is made of transparent glass or transparent acrylic resin that blocks violet and external rays that are harmful to human eyes, and is made of visible light phosphor (S) that is excited by a UV laser beam.
R) (5G) (5B) is applied in stripes,
Retroreflector (
A screen (
4) A black stripe (18) is formed on the viewer's side, a retroreflector (6) such as glass beads or a cube mirror is coated or pasted on the black stripe (18), and a UV laser beam ( 1) is projected from behind the screen (4). A UV laser beam is generated from a light emitting source (1). This UV laser beam is incident on the optical modulator (12),
The light is modulated by a color video signal and is made incident on a polarizing beam splitter (hereinafter referred to as PBS) (19) through an expander (13) through a concave lens, a focusing lens, etc. −
A light emitting source (1) that generates an infrared laser beam (hereinafter referred to as IR laser beam) for color index signal detection.
4) The IR laser beam emitted from the expander (
15) and enters P B S (19). P
The IR laser beam and UV laser beam incident on the BS (19) are linearly polarized, and the UV laser beam is P
Assuming that the IR laser beam has an S-polarized component, 100% of the P-polarized component of the UV laser beam passes through P B S (19), and! The S-polarized component of the R laser beam is reflected at the interface of P B S (19),
Y-axis and X-axis polygon mirrors (2) (3) and mirrors (7
) incident tJV, IR mixed laser beam (16)
and is irradiated onto the screen (4).

That is, the UV laser beam is optically modulated with a color video signal by an optical modulator (12), and is then optically modulated with a color video signal by an optical modulator (12), and is then optically modulated with a color video signal by an optical modulator (12).
) (5G) (5B) is excited, but when the level corresponds to the color video signal, the modulated UV corresponding to that level is excited.
A laser beam is irradiated, and excitation corresponding to the level of the laser beam is applied. At this normal level, the RGB visible light phosphors (5R) (5G) (5B) emit light normally, and when it reaches the black level, it is excited corresponding to the black level, but at that time, the IR laser beam The intensity of wavelength 1 is selected so as not to have any effect on the photophosphor. On the other hand, the IR laser beam, which is aligned with the same optical axis as the U laser beam, is reflected by the retroreflector (6) and enters the light-receiving surface of the light-receiving element (11) such as a photodiode via the focusing lens (7). Therefore, a stable color index signal can be obtained even with a UV laser beam with almost no phosphor excitation.

In this example, a beam projector has been described, but when a front projector type structure is used, the screen structure shown in FIG. 3 or 4 may be used so that the image can be viewed from the irradiation direction.

Note that the present invention is not limited to the embodiments on the ridges, and various modifications can be made without departing from the gist of the present invention.

According to the image display device of the present invention, even when the phosphor is hardly excited by the UV laser beam in a completely dark scene such as when the screen is at a black level, the I
Since the reflected light of the R laser beam can be detected, a stable color index signal can be obtained at all times, and black level display will not be difficult.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the color index signal reception state of the image display device of the present invention, FIG. 2 is an explanatory diagram of laser beam synthesis, and FIG. 3 is a schematic diagram of a conventional ultraviolet laser scanning type image display device. FIG. 4 is a schematic diagram of an optical system showing a conventional color index signal reception state. (1) (14) is a light emitting source, (4) is a screen, (5R
) (5G) (5B) is a visible light phosphor, (6) is a retroreflector, (12) is a light modulator, and (19) is a PBS.

Claims (1)

[Claims] A visible light phosphor that emits visible light of multiple colors by irradiating an ultraviolet laser beam onto a screen and a light reflecting means that returns the ultraviolet laser beam substantially in the direction of incidence are formed in a predetermined pattern. In the installed image display device, the screen is scanned with a laser beam that is a combination of the ultraviolet laser beam and the infrared laser beam, and the return light of the infrared laser beam from the reflection means is used as an index signal. Characteristic image display device.