JP2002281532A - Back projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an observer or the like from being directly irradiated with laser light when a transmission screen is damaged. SOLUTION: This device is provided with a plurality of transparent electrode films 8 provided for each of prescribed pitches on the outer surface of a renticular lens sheet 7 of a transmission screen 5, 5 V power source 9 for impressing a voltage while being connected to one terminal of each of transparent electrode films 8 and a voltage deciding block 11 for deciding whether the voltage is impressed from the 5 V power source 9 or not while being connected to the other terminal of each of transparent electrode films 8. When a breakpoint occurs on the transmission screen 5 occasionally or intensively, the voltage deciding block 11 decides that the transparent conductive film 8 at the breakpoint is not made conductive any more and turns off the output of a laser beam light source 1. Thus, laser light is not radiated through the breakpoint and the safety of the observer can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection display device for projecting image light formed by a liquid crystal panel or the like from the rear side of a transmission screen and displaying an image on the front side of the transmission screen. In particular, the present invention relates to a rear-projection display device that can prevent a laser beam from being directly irradiated to a viewer or the like when a laser beam is used as a light source.

[0002]

2. Description of the Related Art In recent years, a projection display device for projecting image light formed by liquid crystal projection or the like onto a large-screen screen or the like has become popular. As such a projection display device, a rear projection display device that projects image light from the rear side of a screen and displays an image on the front side of the screen is known.

FIG. 5 is a cross-sectional view schematically showing a schematic configuration of a conventional rear projection display device.

The rear projection display device has a transmission screen 25 provided on the front surface of a hollow housing 29. The light source 2 is provided inside the housing 29.
1, an image projection unit 22 that generates image light using light emitted from the light source 21, and a projection lens 23 that enlarges the image light generated by the image projection unit 22. The image light enlarged and projected from the projection lens 23 is applied to a reflector mirror 24 provided in an inclined state so as to face the transmission screen 25, and the image light reflected by the reflector mirror 24 is transmitted to the transmission screen 25. 25 is projected on the back. The transmissive screen 25 displays an image on the front surface by the image light that is enlarged and projected. The image displayed on the transmission screen 25 is viewed by a viewer located in front of the transmission screen 25.

FIG. 6 is a perspective view showing a schematic configuration of the transmission screen 25.

The transmissive screen 25 has a two-layer structure in which a Fresnel lens sheet 26 disposed on the back side and a lenticular lens sheet 27 disposed on the front side are laminated on each other. The Fresnel lens sheet 26 and the lenticular lens sheet 27 are each formed of methacrylic resin (acrylic resin) or the like.

The Fresnel lens sheet 26 has a number of lens portions formed in a ring shape having a predetermined width along a concentric circle centered on a substantially central portion of the transmission screen 25. The Fresnel lens sheet 26 having a large number of concentric ring-shaped lens portions as described above has:
Despite being thin, it has the same function as a large-diameter lens. The Fresnel lens sheet 26 prevents the image light from diverging around the transmissive screen 25 by concentrating the image light emitted from the projection lens 23 at the central portion on the front side.

The lenticular lens sheet 27 is composed of a plurality of lenticular lenses 2 each of which extends in the vertical direction.
7a, and the lenticular lenses 27a are arranged at a predetermined pitch in the horizontal direction. The lenticular lens 27a diffuses the image light transmitted through the Fresnel lens sheet 26 in the horizontal direction, so that the image displayed on the transmission screen 25 has a wide horizontal viewing angle.

On the front side of the lenticular lens sheet 27, a plurality of black stripes 28, each extending in the vertical direction, are formed at a predetermined pitch in the horizontal direction in order to reduce a decrease in contrast due to external light.

As the light source 21, a discharge lamp which emits light from an object having a predetermined size is usually used.

Recently, it has been proposed to use a laser beam as the light source 21 of the display device, which can increase the efficiency and reduce the size of the projection display device, instead of the structure of the conventional display device using a discharge lamp. Have been.

The laser light emitted from the laser beam light source is emitted with an extremely small beam diameter, which is a point light source, as compared with the light emitted from the discharge lamp. Therefore, the optical path width of the entire optical system is reduced. In addition, the optical path length can be shortened. Therefore, the configuration of the entire optical system can be reduced in size. In addition, since the laser beam is emitted from the point light source, the light collection efficiency when condensing the light on the image projection unit can be dramatically improved.

However, since the laser beam used in the projection type display apparatus and having effective radiation in the visible spectrum region has a high output of several watts or more, the laser beam is emitted in a space region where the laser beam can reach. Directly,
Irradiation to the human body, especially to the eyes, is harmful because of possible burns, loss of vision, blindness, and the like. Therefore, when laser light is used as a light source, it is necessary to sufficiently consider protection of the viewer.

In a rear projection display device using a laser light source, the safety of a viewer in a normal use state is secured by diffusing a laser beam emitted from a transmission screen.

However, if the transmissive screen of the rear projection display device is accidentally or intentionally damaged, the laser light is directly radiated to the outside without being diffused, and the eyes of the viewer or the like are disturbed. There is a risk of damaging the human body.

When a laser light source is used as a light source, a projection display device having a safety mechanism for avoiding the danger of irradiating a laser beam is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-5014.
19 and JP-A-2000-267621.

In the projection display apparatus described in Japanese Patent Application Laid-Open No. 11-501419, an image generating means for generating an image based on a laser light source has a first operation in a standard operation mode for projecting image light. It is possible to switch between two operation modes, a mode and a second operation mode, which is an operation mode in which the laser beam is rendered harmless to a person located in the laser reachable area. A safety circuit having at least one sensor is provided in a monitoring area between the image generating means and the projection screen, and the safety circuit monitors whether or not the object exists in the monitoring area, and determines whether the object exists in the monitoring area. Then, the mode is switched to the second operation mode, which is an operation mode in which the image generation unit is rendered harmless to humans. This prevents the laser light from being directly applied to the human body.

The transmissive display device described in Japanese Patent Application Laid-Open No. 2000-267621 is provided with a detecting means for detecting whether or not a light beam converting means for converting a laser beam into a thick beam and lowering an exit is operating normally. When the detection means detects that the light beam conversion means is not operating normally, the laser light irradiation means restricts the irradiation of the laser light, thereby preventing danger caused by the laser light. .

[0019]

[Problems to be Solved by the Invention]
In the projection display device described in Japanese Patent No. 19,
A safety circuit having at least one sensor is provided in a monitoring area between the projection screen and the presence of an object in the monitoring area by the safety circuit, and the presence of the object is detected by the sensor. Before switching to the second operation mode, the object in the monitoring area may be irradiated with laser light. In particular,
In the rear projection display device, since the eyes of the viewer face the irradiation side of the laser light, the laser light is directly irradiated to the eyes, and the eyes may be damaged.

In the projection type display device disclosed in Japanese Patent Application Laid-Open No. 2000-267621, since the detecting means detects that the light beam converting means is operating normally, the screen serving as an observer's observation surface is used. Even if the viewer is irradiated with laser light due to damage on the top, the state cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is an object of the present invention to prevent a laser beam from being directly irradiated to a viewer or the like when a transmission screen is damaged. It is an object of the present invention to provide a projection type display device which can be used.

[0022]

In order to solve the above-mentioned problems, a rear projection type display apparatus according to the present invention generates image light by laser light emitted from a laser light source, and transmits the image light to the rear side of a transmission screen. A rear projection display device that displays an image on the front side of the transmission screen by projecting from the laser screen, wherein the laser light is transmitted to the front surface of the transmission screen due to damage to the projection screen. A monitoring means is provided for detecting the fact and turning off the output of the laser light source.

In the above invention, the monitoring means includes a plurality of conductive parts provided at predetermined intervals on a front surface of the transmission screen, and voltage applying means for applying a predetermined voltage to each conductive part. And voltage determining means for determining whether each conductive portion is in a conductive state.

In the present invention, each of the conductive portions is preferably formed of a transparent conductive film.

In the present invention, each of the conductive portions is preferably a black stripe formed of a conductive material.

In the present invention, it is preferable that a black stripe is formed on the front surface of the conductive portion.

[0027]

(Embodiment 1) Hereinafter, a rear projection type display device of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a rear projection type display device according to the first embodiment.

This rear projection type display device has a transmission type screen 5 provided on a front surface of a hollow housing 10. Inside the housing 10, a laser beam light source 1, an image projection unit 2 that generates image light with laser light emitted from the laser beam light source 1,
A projection lens 3 for enlarging the image light generated by the image projection unit 2. The image light enlarged and projected from the projection lens 3 is applied to a reflector mirror 4 provided in an inclined state so as to face the transmission screen 5, and the image light reflected by the reflector mirror 4 is transmitted to the transmission screen 5. 5 is projected on the back. The transmissive screen 5 displays an image on the front surface by the image light that is enlarged and projected. The image displayed on the transmissive screen 5 is viewed by a viewer located in front of the transmissive screen 5.

FIG. 2 is a perspective view showing a schematic configuration of the transmission screen 5 used in the projection display device of the first embodiment.

The transmissive screen 5 has a two-layer structure in which a Fresnel lens sheet 6 disposed on the back side and a lenticular lens sheet 7 disposed on the front side are mutually laminated. This lenticular lens sheet 7
Further, a plurality of transparent conductive films 8 arranged in stripes along the vertical direction at a predetermined pitch in the horizontal direction are provided on the front surface. The Fresnel lens sheet 6 and the lenticular lens sheet 7 are each formed of methacrylic resin (for example, acrylic resin) or the like.

The Fresnel lens sheet 6 has a large number of lens portions each formed in a ring shape having a predetermined width along a concentric circle centered on a substantially central portion of the screen. The Fresnel lens sheet 6 having a large number of concentric ring-shaped lens portions has the same function as a large-diameter lens despite its thinness. The Fresnel lens sheet 6 prevents the image light from diverging around the transmission screen 5 by concentrating the image light emitted from the projection lens 3 at the central portion on the front side.

The lenticular lens sheet 7 has a plurality of lenticular lenses 7a each of which extends in the vertical direction.
And the lenticular lenses 7a are arranged at a predetermined pitch in the horizontal direction. The lenticular lens 7a diffuses the image light transmitted through the Fresnel lens sheet 6 in the horizontal direction, so that the image displayed on the transmission screen 5 has a wide horizontal viewing angle.

As described above, in the transmission screen 5, the image light reflected by the reflector mirror 4 is
Although it is converged forward by the Fresnel lens sheet 6,
The light is emitted to the periphery of the transmission screen 5 while being diffused in the horizontal direction by the lenticular lens sheet 7. As described above, in a normal use state, the high-power laser light is diffused around the transmission screen 5,
Light of a detoxified level is emitted to the viewer.

Each transparent conductive film 8 formed on the front surface of the lenticular lens sheet 7 is formed by printing a transparent conductive member such as ITO by a printing method or an etching method.
By patterning in a stripe shape extending in the vertical direction, they are arranged at a predetermined pitch in the horizontal direction.

The pitch of each transparent conductive film 8 can be set arbitrarily. For example, in the case of a 60-inch high-vision rear projector using a 2.6-inch high-vision liquid crystal panel (1280 horizontal pixels), each transparent conductive film 8 formed on the lenticular lens sheet 7
Is 0.14 mm, the pitch is 0.2 mm
Set to about.

Each transparent conductive film 8 is connected to a power supply substrate by being pressed against a flexible substrate via an anisotropic conductive film, for example. One end of each transparent conductive film 8
Each of them is connected to a 5V power supply 9 via a resistor of about several tens kΩ. The other end of each transparent conductive film 8 is connected to the voltage determination block 11, respectively.

The voltage determination block 11 is provided for each transparent conductive film 8
A state where a voltage of 5 V is applied or a state where a voltage is not applied (0 V) is monitored.
When a voltage of 5 V is applied to all of the transparent conductive films 8, it is determined that the transmission screen 5 is not damaged, and the power supply for driving the laser beam light source 1 is kept on. On the other hand, when the voltage of any of the transparent conductive films 8 is 0 V
In the case of, the lenticular lens sheet 7 in the portion where the transparent electrode film 8 is provided is determined to be damaged, and the power of the laser beam light source 1 is turned off.

Therefore, if the lenticular lens sheet 7 of the transmissive screen 5 is accidentally or intentionally damaged, the transparent conductive film 8 at the location where the damage occurs becomes non-conductive, so that the voltage is increased. The determination block 11 detects that the voltage of the transparent conductive film 8 is 0V. For this reason, the voltage determination block 11 that detects the voltage of 0 V of the transparent conductive film instantaneously determines the damage almost simultaneously with the occurrence of the damage on the lenticular lens sheet 8 and turns off the output of the laser beam light source 1. Therefore, on the front side of the transmissive screen 5, the laser light is not irradiated through the damaged portion. Thereby, there is no possibility that the laser light is irradiated to the eyes of the viewer or the like, and the safety of the viewer can be achieved.

In the transmissive screen 5 shown in FIG. 2, the transparent conductive films 8 are arranged in parallel, and the applied voltage is determined for each transparent conductive film 8. Damaged portions that have been damaged can be easily specified.

As described above, for each transparent conductive film 8,
Instead of a configuration for determining the application of a voltage, each transparent conductive film 8 is connected in series, and the transparent conductive films 8
Can be monitored for the occurrence of damage in the transmissive screen 5 by connecting the open ends of the screen to the 5V power supply 9 and the voltage determination block 11, respectively.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
FIG. 2 is a perspective view showing a schematic configuration of a transmission screen used for the rear projection display device of FIG.

In the transmission screen 5, black stripes 12 extending in the vertical direction are arranged at a predetermined pitch in the horizontal direction on the front surface of the lenticular lens sheet 7.

Each of the black stripes 12 is formed of a conductive material such as carbon. Therefore, unlike a normal black stripe formed by black ink or the like, the black stripe 12 has conductivity.

One end of each black stripe 12 is connected to a 5V power supply 9 via a resistance of about several tens kΩ. The other end of each black stripe 12 is connected to the voltage determination block 11, respectively.

Each of the black stripes 12 also has a function of reducing a decrease in contrast caused by light emitted to the front side of the lenticular lens sheet 7. In order to prevent this, when the image projection unit 2 generates an image using a liquid crystal panel, it is set to be equal to or less than the pixel pitch of the liquid crystal panel.

The other configuration is the same as that of the transmissive screen 5 of the rear projection display device of the first embodiment, and the detailed description is omitted.

In the transmissive screen 5 shown in FIG. 3, if the lenticular lens 7 is damaged accidentally or intentionally, the black stripe 1 at the place where the lenticular lens 7 is damaged becomes non-conductive, so The voltage of the black stripe 12 is set to 0 V by the decision block 11.
Is detected. The voltage determination block 11 that has detected the voltage 0 V of the black stripe 12 almost instantaneously determines the occurrence of damage on the lenticular lens sheet 7 and instantaneously determines the damage and turns off the output of the laser beam light source 1. On the front side of the mold screen 5, the laser beam is not irradiated through the damaged portion, and the safety of the viewer can be achieved.

(Embodiment 3) FIG. 4 shows Embodiment 3 of the present invention.
FIG. 2 is a perspective view showing a schematic configuration of a transmission screen 5 used in the rear projection display device of FIG.

The transmission screen 5 has a plurality of stripe-shaped conductive films 13 having a predetermined pitch in the vertical direction on the front surface of the lenticular lens sheet 7. On the outer surface side of the conductive film 13, a black stripe 14 made of black ink or the like is formed.

The conductive film 13 is formed of a material having good electric conductivity such as Cu and Al. Therefore, compared to the transmissive screen 5 used in the rear projection display device of the first embodiment, the degree of freedom in selecting a material used for the conductive film 13 is increased.

The other configuration is the same as that of the rear projection display device of the first embodiment, and the detailed description is omitted.

In the transmissive screen 5 shown in FIG. 4, if the lenticular lens 7 is accidentally or intentionally damaged, the conductive film 13 at the location where the damage has occurred
Is not conductive, the voltage determination block 11 detects that the voltage of the conductive film 13 is 0V. Therefore, the voltage determination block 11 that has detected the voltage 0V of the conductive film 13 instantaneously determines the damage almost simultaneously with the occurrence of the damage on the lenticular lens sheet 7,
Since the output of the laser beam light source 1 is turned off, laser light is not irradiated through the damaged portion on the front side of the transmission screen 5, and safety of the viewer can be achieved.

[0054]

According to the rear projection type display apparatus of the present invention, the outer surface of the transmission type screen is monitored for the damage of the external projection type screen, and when the damage occurs, the output of the laser light source is turned off. Due to the provision of means, even if the transmission screen is damaged accidentally or intentionally,
The output of the laser light source can be instantly turned off, and the safety of the viewer in front of the projection screen can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of a rear projection display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a projection screen of the rear projection display device according to the first embodiment.

FIG. 3 is a perspective view schematically showing a projection screen of a rear projection display device according to a second embodiment.

FIG. 4 is a perspective view schematically showing a projection screen of a rear projection display device according to a third embodiment.

FIG. 5 is a schematic view showing an outline of a conventional rear projection display device.

FIG. 6 is a perspective view schematically showing a transmission screen used in a conventional rear projection display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam light source 2 Image projection part 3 Projection lens 4 Reflector mirror 5 Transmissive screen 6 Fresnel lens sheet 7 Lenticular lens sheet 8 Transparent conductive film 9 5V power supply 10 Housing 11 Voltage judgment block 12 Black stripe 13 Conductive film 14 Black stripe

Claims (5)

[Claims] An image light is generated by a laser beam emitted from a laser light source, and the image light is projected from the rear side of the transmission screen to thereby display an image on the front side of the transmission screen. A display device, wherein a monitoring means for detecting that laser light is transmitted due to damage of the projection screen and turning off the output of the laser light source is provided on a front surface of the transmission screen. A rear projection display device. 2. The monitoring means comprises: a plurality of conductive parts provided at predetermined intervals on a front surface of the transmission screen; a voltage applying means for applying a predetermined voltage to each conductive part; The rear projection display device according to claim 1, further comprising voltage determination means for determining whether the unit is in a conductive state. 3. The rear projection display device according to claim 2, wherein each of the conductive portions is formed of a transparent conductive film. 4. The rear projection display device according to claim 2, wherein each of the conductive portions is a black stripe formed of a conductive material. 5. The rear projection display device according to claim 2, wherein a black stripe is formed on a front surface of the conductive portion.