JP2001117165A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect temperature rise in a cabinet even when the cabinet is installed upside down. SOLUTION: The cabinet 1 is provided with a light source 2 and a liquid crystal panel 7 irradiated by the light source 2 inside. At least two temperature sensors SE1 and SE2 outputting a signal showing that energizing the light source 2 should be cut off at the time of detecting that the temperature in the cabinet 1 reaches limit temperature at which optical parts in the cabinet 1 are damaged are respectively arranged up and down with respect to the light source 2. The respective sensors SE1 and SE2 output a signal for stopping power feeding to the light source 2 at the limit temperature at which the optical parts in the cabinet 1 are damaged in the normal posture or the reverse posture of the cabinet 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector for projecting an image on a liquid crystal panel by irradiating it with strong light.

[0002]

2. Description of the Related Art FIG. 4 is a sectional side view of a conventional liquid crystal projector. This is a so-called single-panel type liquid crystal projector, which irradiates an image displayed on one liquid crystal panel (7) provided in a cabinet (1) with strong light from a light source (2), and projects a projection lens. At (6), the image is transferred to a screen (not shown). Since the light source (2) is connected to the power supply circuit (40) and emits strong light and tends to become hot, a cooling intake fan (3) is provided behind the light source (2). The air in the cabinet (1) is discharged outside by the intake fan (3). Since the liquid crystal panel (7) is easily damaged by heat, a cooling fan (30) is provided above the liquid crystal panel (7). The blower fan (30) sends air outside the cabinet (1) into the cabinet (1). If both the fans (3) and (30) fail, or if the temperature outside the cabinet (1) is high, the temperature inside the cabinet (1) may reach a temperature that damages the liquid crystal panel (7). . In order to prevent the liquid crystal panel (7) from being damaged, a temperature sensor (S) is installed in the cabinet (1).
E1), and when the temperature inside the cabinet (1) becomes higher than a predetermined temperature due to the heat of the light source (2), the temperature sensor (SE1)
Projectors that emit a signal to that effect are known
(See Japanese Utility Model Application Laid-Open No. Hei 7-26886). Since the hot air from the light source (2) rises, the temperature sensor (SE1) is provided above the light source (2). A control circuit (4) is provided between the temperature sensor (SE1) and the power supply circuit (40), and based on a signal from the temperature sensor (SE1), the control circuit (4) Stop supplying power to (2).

[0003]

The cabinet (1) is
Generally, it is used in a normal posture placed on the desk (10) as shown in FIG. However, as shown in FIG. 2, the cabinet (1) is suspended from the ceiling in an upside down posture,
May illuminate the image. In this case, the temperature sensor (S
E1) is located below the light source (2), and the temperature rise due to the light source (2) cannot be accurately detected. An object of the present invention is to accurately detect a temperature rise in a cabinet even when the cabinet is installed upside down.

[0004]

[Means for solving the problem] In the cabinet (1),
At least two temperature sensors (SE1) (SE2)
Temperature sensors (SE1), which are arranged above and below (2) respectively
(SE2) is a normal posture or a reversed posture of the cabinet (1), respectively, when the temperature inside the cabinet (1) reaches a limit temperature,
A signal for stopping power supply to the light source (2) is issued.

[0005]

[Operation and effect] Each of the temperature sensors (SE1) and (SE2) is a light source
(2) are installed above and below, and each temperature sensor (SE1) (SE
2) issues a signal to cut off the power to the light source (2) at the limit temperature at which the optical components in the cabinet (1) are damaged.
In either the normal posture or the inverted posture of the cabinet (1), the hot air from the light source (2) is supplied to any of the temperature sensors (S
Touch E1) (SE2). That is, even if the cabinet (1) is turned upside down, it is reliably detected that the inside of the cabinet (1) has reached the limit temperature, and the power supply to the light source (2) is cut off.
Optical components can be prevented from being damaged.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional side view of the cabinet (1), showing a normal posture in which the cabinet (1) is placed on a desk (10). As before, in the cabinet (1), one liquid crystal panel (7), a light source (2) for irradiating an image of the liquid crystal panel (7) with strong light, and the light source (2) are provided. An intake fan (3) that cools and releases the air inside the cabinet (1) to the outside
And a blower fan (30) for cooling the liquid crystal panel (7) and taking in the air outside the cabinet (1). Screw holes (11) and (11) are formed in the bottom surface of the cabinet (1), and adjustment screws (12) and (12) in contact with the desk surface (10) are screwed into the screw holes (11) and (11). ing. If the adjusting screws (12) and (12) are rotated, the height of the cabinet (1) from the desk (10) changes. In the cabinet (1), a first temperature sensor (SE1) and a second temperature sensor (SE2) are provided above and below the light source (2), respectively. The light source (2) is connected to the power supply circuit (40), and the power supply circuit (40)
Is connected to the control circuit (4). Both temperature sensors (SE1) and (SE2) are connected in series to the control circuit (4). Normally, the temperature sensors (SE1) and (SE2) are turned on to allow the control circuit (4) to energize. In this example, the light source (2) is interposed
Even if two temperature sensors (SE1) and (SE2) are provided up and down and the cabinet (1) is turned upside down, the temperature rise in the cabinet (1) is accurately detected.

FIG. 2 is a cross-sectional side view showing an inverted posture in which the cabinet (1) is suspended from the ceiling (9). The ceiling (9) is provided with a mounting bracket (8), and the mounting bracket (8) is provided with a support plate at a lower end of a hanging rod (80) whose upper end is fixed to the ceiling (9).
(81) is stretched horizontally. At the support plate (81),
Through holes (82) (82) are formed in the cabinet (1) at locations facing the screw holes (11) (11). cabinet
To suspend (1) from the ceiling (9), remove the adjustment screws (12) and (12), turn the cabinet (1) upside down and place it under the support plate (81). ) (11) is opposed to the through holes (82) (82). The setscrew (83) (83) is inserted from above the through hole (82) (82) and screwed into the screw hole (11) (11).

Normal posture As shown in FIG. 1, when the cabinet (1) is placed on the desk (10), the air heated by the light source (2) rises and the first temperature sensor (SE1) is turned on. This hot air is detected. The first temperature sensor (SE1) is turned off when the temperature of the hot air is equal to or higher than a predetermined temperature, and cuts off the power supply from the control circuit (4). As shown in FIG. 2, when the cabinet (1) is turned upside down to irradiate an image by hanging it from the ceiling (9), the air heated by the light source (2) rises and the second temperature sensor (SE2). ) Detects this hot air. The second temperature sensor (SE2) is turned off when the temperature of the hot air is higher than a predetermined temperature, and the control circuit (4)
Cut off the power supply from. The control circuit (4) is a cabinet
It detects that the temperature in (1) is abnormally high, and stops power supply to the light source (2). Since the first and second temperature sensors (SE1) and (SE2) are connected in series to the control circuit (4), if any one of the temperature sensors (SE1) and (SE2) is turned off, the control circuit ( The energization from 4) is cut off.

There are various first and second temperature sensors (SE1) and (SE2) having different temperatures at which the first and second temperature sensors are turned off. . In the experiment of the applicant, the cabinet (1) was placed on the desk (1).
0) (see FIG. 1), the light source (2) is continuously irradiated, and when the temperature near the first temperature sensor (SE1) reaches about 60 ° C., the operation of the liquid crystal panel (7) and the like is stopped. It turned out to be a guarantee limit. At this time, the temperature outside the cabinet (1) was about 35 ° C., and the temperature near the second temperature sensor (SE2) was about 45 ° C. When the cabinet (1) is turned upside down (see FIG. 2) and the measurement is performed in the same manner, the second temperature sensor is obtained.
When the vicinity of (SE2) reaches about 55 ° C., the liquid crystal panel (7)
It has been found that the above operation is the limit that can be guaranteed. At this time, the temperature near the second temperature sensor (SE2) was about 50 ° C. LCD panel in both forward and reverse positions of cabinet (1)
The difference in the critical temperature at which the operation of (7) is guaranteed is different in the first case.
Temperature sensor (SE1) consists of blower fan (30) and intake fan (3)
It is located near the flow path between and is easy to touch the flow of air,
The reason may be that the second temperature sensor (SE2) is difficult to touch the flow of air.

In this embodiment, temperature sensors (SE1) and (SE2) are provided above and below the light source (2), respectively, and each temperature sensor (S
E1) and (SE2) are light sources (2) at the limit temperature at which the optical components in the cabinet (1), specifically, the liquid crystal panel (7) are damaged.
In any of the normal posture and the inverted posture of the cabinet (1), the hot air from the light source (2) is supplied to any of the temperature sensors in any of the normal posture and the inverted posture of the cabinet (1). Touch (SE1) and (SE2). The fact that the temperature inside the cabinet (1) has reached the limit temperature that damages the liquid crystal panel (7) is reliably detected, the power supply to the light source (2) is cut off, and the liquid crystal panel (7) can be prevented from being damaged. .

The temperature sensors (SE1) and (SE2) are light sources.
Although it is said that it is deployed above and below (2), it is not limited to this,
As shown by a dashed line in FIG. 1, a new third temperature sensor (S
E3) is provided near the blower fan (30), and the third temperature sensor
(SE3) and the first and second temperature sensors (SE1) and (SE2) may be connected in series. In the experiment of the applicant, if the blower fan (30) failed, the third temperature sensor (SE
When the temperature in the vicinity of 3) reached about 65 ° C., it was found that the operation of the liquid crystal panel (7) and the like reached a limit at which operation could be guaranteed. Further, although both temperature sensors (SE1) and (SE2) are connected in series to the control circuit (4), instead of the temperature sensors (SE1) and (SE2), as shown in FIG. AND circuit between (4)
(41) is installed, and one of the temperature sensors (SE1) and (SE2)
When the signal becomes F, that is, L, the L signal from the AND circuit (41) may be input to the control circuit (4). Further, although the liquid crystal projector is provided with one liquid crystal panel (7), instead of this, as shown in FIG. 5, three liquid crystals corresponding to the three primary colors of light, R, G, and B, are used. Panel (7) (70) (71), dichroic mirror (5) (50) (51) (52) and total reflection mirror
A well-known liquid crystal projector provided with (53) and (54) may be used. The light from the light source (2) is split into R, G, and B light and then combined by a combining dichroic mirror (52). The temperature sensors (SE1) (SE2) are provided at the upper and lower ends of the cabinet (1).

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of a cabinet, showing a normal posture.

FIG. 2 is a cross-sectional side view showing an inverted posture of the cabinet.

FIG. 3 is a diagram showing an example in which an AND circuit is provided between a control circuit and a temperature sensor.

FIG. 4 is a sectional side view of a conventional cabinet.

FIG. 5 is a sectional side view of a cabinet of another liquid crystal projector.

[Explanation of symbols]

 (1) Cabinet (2) Light source (7) Liquid crystal panel (SE1) Temperature sensor (SE2) Temperature sensor

Claims (1)

[Claims] A light source (2) in a cabinet (1) and a light source
Liquid crystal panel (7) illuminated by (2) and cabinet
When it detects that the temperature in (1) has reached the limit temperature that damages the optical components in the cabinet (1), the light source (2)
And a temperature sensor that emits a signal indicating that power to the power supply should be cut off. At least two temperature sensors (SE1) and (SE2)
The temperature sensors (SE1) and (SE2) are disposed above and below the cabinet (1), respectively, when the cabinet (1) reaches the limit temperature in the normal posture or the inverted posture of the cabinet (1). A liquid crystal projector which emits a signal for stopping power supply to a light source (2).