JPH10239767A - Projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service lives of the lamp itself of a projector and the parts of a power source for a lamp, and to reduce the using cost. SOLUTION: When the path of light for projecting picture is cut off by a cap 35, electric power supplied to the lamp 22 is lowered. Then, the light emitted from the lamp 22 is weakened according as the supply electric power is lowered. However, since the path of the light is already cut off by the cap 35 at this time, the dark picture is prevented from being projected. Therefore, the electric power supplied to the lamp 22 can be lowered without obstructing a using state and heat generated by the power source for a lamp can be also lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for projecting an image with light from a lamp.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a portion related to a lamp power supply in a conventional example of a DC lighting type liquid crystal projector. In this conventional example, a switch 13 is connected to an AC power supply 11 via a fuse 12, and a line filter 14, a rectifier 15, and a power factor correction circuit 16 are sequentially connected to the switch 13.

[0003] A DC-DC converter 17 and an igniter 18 for generating a high voltage are sequentially connected to a power factor improving circuit 16, and the DC-DC converter 17 and the igniter 18 constitute a lamp power supply 21. . A lamp 22 is connected to a lamp power supply 21, and a light transmissive liquid crystal panel 23 is disposed in front of the lamp 22. Further, a lens 24 is arranged in front of the liquid crystal panel 23, and a projection surface 25 is arranged further in front of the lens 24.

FIG. 4 schematically shows an entire conventional example including the portion shown in FIG. In this conventional example, a plug 32 is attached to a main body 31, and a power supply circuit 33 including a lamp power supply 21 is connected to the plug 32. The lamp 22 is connected to the power supply circuit 33, and an optical unit 34 including the liquid crystal panel 23 is arranged near the lamp 22.

[0005] The lens 24 is arranged close to the optical unit 34, and a cap 35 capable of covering the lens 24 is prepared. In one conventional example as described above, the liquid crystal panel 23 and the lens 24
Is transmitted to the projection surface 25, the image formed on the liquid crystal panel 23 is displayed on the projection surface 25.
Projected above.

In this conventional liquid crystal projector or the like,
In order to project a bright image on the projection surface 25, the lamp 2
Discharge lamps such as metal halide lamps are mainly used as No. 2, and this metal halide lamp is lit as brightly as possible and with a constant power.

However, during the operation of the metal halide lamp, the temperature of the lamp is raised to about 900 ° C., and the pressure inside the lamp is considerably increased. For this reason, once the metal halide lamp is turned off, in order to turn it on again, wait until the pressure in the lamp decreases to a dischargeable pressure, or apply a high discharge voltage corresponding to the high pressure in the lamp to the lamp. Must be applied.

That is, it is difficult to freely turn on and off the metal halide lamp. For this reason, when projecting an image immediately after stopping it once, etc.,
Instead of turning off the metal halide lamp once, the path of the light 36 is blocked by covering the lens 24 with a cap 35.

[0009]

However, the image is not projected simply by blocking the path of the light 36 by covering the lens 24 with the cap 35 as in the conventional example shown in FIGS. Nevertheless, lamp 2 uses the same power as the projection
2 is lit. For this reason, the life of the lamp 22 was shorter than the actual use time.

Also, when an image is not projected, the lamp power supply 21 supplies the same power to the lamp 22 as at the time of projection.
-The life of components of the lamp power supply 21, such as the DC converter 17 and the igniter 18, was short. Therefore, in the conventional example shown in FIGS. 3 and 4, the use cost was high.

[0011]

A projector according to the present invention includes a lamp for emitting light for projecting an image, a blocking member for blocking a path of the light, and detecting the blocking. And a power control means for reducing the power supplied to the lamp when the detection signal is being input.

[0012] In the projector according to the present invention, the power may be DC power, and the power control means may control the current to control the DC power.

In the projector according to the present invention, the power may be AC power, and the power control unit may control the AC power by controlling a frequency.

[0014] The projector according to the invention of the present application may include a lens for projecting the image, and a cap covering the lens may be the blocking member.

[0015] The projector according to the present invention may include a lens for projecting the image, and a light shielding plate inserted between the lamp and the lens may be the blocking member.

In the projector according to the present invention, the cutoff detecting means may include a switch for detecting the cutoff by contacting the cutoff member in the cutoff state.

In the projector according to the invention of the present application, the cut-off detecting means may include a photosensitive element for detecting the cut-off by being blocked from entering the light by the cut-off member in the cut-off state.

In the projector according to the present invention, the range in which the power control means reduces the power when the detection signal is input is within 50% of the power when the detection signal is not input. Is preferred.

In the projector according to the present invention, the power supplied to the lamp is reduced when the light path for projecting an image is blocked by the blocking member. The light that is emitted is also weaker.
However, at this time, since the light path is already blocked by the blocking member, a dark image is not projected. Therefore, the power supplied to the lamp can be reduced and the heat generated by the lamp power supply can be reduced without any trouble in use.

Further, when the path of the light for projecting the image is blocked by the blocking member, the range in which the power control means reduces the power supplied to the lamp is 5% of the non-blocked power supply.
If it is within 0%, it is possible to reliably prevent the lamp from being turned off even if the power supplied to the lamp is reduced. Therefore, the intensity of the light emitted from the lamp is restored stably and in a short time due to the restoration of the supply power after the interruption is released, and a high-quality image can be promptly projected again.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a DC lighting type liquid crystal projector will be described below with reference to FIGS.
This will be described with reference to FIG. 1 and 2, FIG.
The same components as those of the conventional example shown in FIG. 4 are denoted by the same reference numerals. FIG. 1 schematically shows a portion related to a lamp power supply in the present embodiment.

In this embodiment, the DC-DC converter 1
A current detection circuit 41 is connected between the igniter 7 and the igniter 18, and the current supplied to the lamp 22 always detects the current. As the current detection circuit 41, DC
A circuit in which a resistance element is inserted in series with the DC converter 17 and the igniter 18 to detect a potential difference between both ends of the resistance element, a general current detection circuit such as a current transformer, and the like are used.

A current control circuit 42 is connected to the current detection circuit 41, and the current control circuit 42 outputs a current control signal for reducing the current value detected by the current detection circuit 41 to a predetermined value.

In the vicinity of the lens 24 and the cap 35,
A cap detecting element 43 for detecting that the cap 35 covers the lens 24 and blocks the path of the light 36 is provided. As the cap detecting element 43, FIG.
The micro switch 44 shown in FIG. 2A and the photosensitive element 45 shown in FIG. 2B are used.

The microswitch 44 contacts the cap 35 covering the lens 24 and detects the interruption of the light path. When the incident light 36 from the lens 24 is blocked by the cap 35 covering the lens 24, the resistance of the photosensitive element 45 changes to detect the interruption of the path of the light 36. As the photosensitive element 47, a CdS element, a photodiode, or the like is used.

A cap detecting circuit 46 is connected to the cap detecting element 43. When the cap detecting element 43 detects that the cap 35 covers the lens 24 and blocks the path of the light 36, the cap detecting circuit 46 detects the cap. Circuit 46 outputs a cap detection signal.

Current control circuit 42 and cap detection circuit 4
6 are both connected to a switch circuit 47. The switch circuit 47 conducts when a cap detection signal is input from the cap detection circuit 46, and converts the current control signal input from the current control circuit 42 into a DC-DC signal. Converter 17
Tell As a result, the current supplied to the lamp 22 is changed to DC
-The DC converter 17 drops.

In the present embodiment as described above, when the lens 24 is covered with the cap 35, the current supplied to the lamp 22 decreases, and the power supplied to the lamp 22 also decreases. When the power is reduced by 10%, the brightness of the lamp 22 is reduced by 20% or more, so that the life of the lamp 22 is extended.

The electric power supplied to the lamp 22 is 10
If the percentage decreases, the heat generation due to power loss in the components of the lamp power supply 21 such as the DC-DC converter 17 and the igniter 18 also decreases by about 20%, so that the life of these components is prolonged.

In this embodiment, a current detection circuit 41, a current control circuit 42, a cap detection element 43, a cap detection circuit 46, a switch circuit 47, and the like are newly required as compared with the above-described conventional example. It is cheaper than the lamp 22 and the lamp power supply 21. Therefore, the present embodiment, in which the number of replacements of the lamp 22 and the lamp power supply 21 may be smaller than that of the above-described conventional example, is low in overall use cost.

If the power supplied to the lamp 22 is too low, the lamp 22 is turned off. As a result, even if the power supplied to the lamp 22 when the cap 35 is removed from the lens 24 is restored, the intensity of the light 36 emitted from the lamp 22 cannot be restored stably and in a short time. And difficult to use. Therefore, when the lens 24 is covered with the cap 35, the range in which the power is reduced is preferably within 50% of the case where the lens 24 is not covered with the cap 35.

The power supplied to the lamp 22 can be controlled by both the voltage and the current.
At the time of lighting of 2, the discharge voltage is constant. For this reason, in the present embodiment in which the power supplied to the lamp 22 is controlled while the lamp 22 is turned on, it is necessary to control the current supplied to the lamp 22 as described above.

Although the path of the light 36 is blocked by covering the lens 24 with the cap 35 in the above embodiment, the path of the light 36 is inserted by inserting a light shielding plate between the lamp 22 and the lens 24. , And a microswitch 44, a photosensitive element 45, or the like may be used for the light shielding plate.

In the above embodiment, the present invention is applied to a DC lighting type liquid crystal projector.
The invention of the present application can also be applied to an AC lighting type liquid crystal projector, in which case the power supplied to the lamp is controlled by controlling the frequency. Further, the invention of the present application can be applied to projectors other than the liquid crystal projector.

[0035]

In the projector according to the present invention, the power supplied to the lamp can be reduced and the heat generated by the lamp power supply can be reduced without any trouble in use. Long life of power supply components and low usage cost.

If the range in which the power control means reduces the supply power to the lamp is within 50% of the supply power when the lamp is not shut off, the intensity of light emitted from the lamp is restored by restoring the supply power after the shutdown is released. Moreover, since the image can be stably restored in a short time and a high-quality image can be promptly projected again, it is easy to use.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a portion related to a lamp power supply in an embodiment of the present invention.

FIG. 2 is a schematic side view of a cap detection element that may be used in one embodiment.

FIG. 3 is a block diagram schematically showing a portion related to a lamp power supply in a conventional example of the present invention.

FIG. 4 is an overall schematic block diagram of one conventional example.

[Explanation of symbols]

22 lamp 24 lens 35 cap (blocking member) 36 light 41 current detection circuit (power control unit) 42 current control circuit (power control unit) 43 cap detection element (blocking detection unit) 44 micro switch (blocking detection unit) 45 photosensitive element (Cutoff detecting means) 46 cap detecting circuit (cutoff detecting means) 47 switch circuit (power control means)

Claims (8)

[Claims] A lamp that emits light for projecting an image, a blocking member for blocking a path of the light, a blocking detection unit that outputs a detection signal when the blocking is detected, A power control unit configured to reduce power supplied to the lamp when the detection signal is being input. 2. The projector according to claim 1, wherein the power is DC power, and the power control unit controls the DC power by controlling a current. 3. The projector according to claim 1, wherein the power is AC power, and the power control unit controls the AC power by controlling a frequency. 4. The projector according to claim 1, further comprising a lens for projecting the image, wherein a cap covering the lens is the blocking member. 5. The projector according to claim 1, further comprising a lens for projecting the image, wherein a light blocking plate inserted between the lamp and the lens is the blocking member. . 6. The projector according to claim 1, wherein the cut-off detecting means includes a switch for detecting the cut-off by contacting the cut-off member in the cut-off state. 7. The cut-off detecting means according to claim 1, wherein said cut-off detecting means comprises a photosensitive element for detecting said cut-off by being prevented from entering said light by said cut-off member in said cut-off state. projector. 8. The range in which the power control means reduces the power when the detection signal is input is within 50% of the power when the detection signal is not input. Item 1. The projector according to Item 1.