JPH0470823A - Light quantity controller for projection equipment - Google Patents

Abstract

PURPOSE:To control the quantity of light matching projection area on a screen, to stability the illuminance of a projection image, and to prolong the life of a light source lamp by converting the movement quantity of a focus ring into a DC level and adjusting an output to the light source according to the converted value. CONSTITUTION:When the focus ring 21 is rotated, a projection lens varies in the division ratio between variable resistor connection terminals (a) and (b), and (b) and (c) associatively with the rotation. At this time, the rotation quantity of the projection lens and the focal length and projection area of the projection lens are proportional, so the rotation quantity of the focus ring 21 is detected and converted into a certain quantitative value, which is used to control the electric power of a lamp stabilizer, thereby controlling the quantity of light. For the detection, a voltage is applied between the variable resistor connection terminals (a) and (c) from a DC power source and a DC voltage which is associated with the rotation quantity of the focus ring 21 is led out of the variable resistor connection terminal (b) and detected. The electric power outputted from the lamp stabilizer to the light source is controlled according to the detected voltage to control the brightness of a light source according to both- surface size.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to liquid crystal projectors and OHP (overhead projectors) that project images on a screen.
), etc., relates to a light amount control device for a projection device that adjusts the light amount of the projection device.

[Prior Art] For example, as shown in FIG. 2, a liquid crystal projector-P includes a light J2 with a reflector 1, a cold mirror 3, a dichroic mirror 45 for color separation, and a total reflection mirror 6. 7 and ff1J crystal panel 8 for the three primary colors R, G, and B
It is composed of R, 8G, 8B, a dichroic mirror 9.10 for color synthesis, and a retrofocus type lens 11 as a projection lens.

Then, light is emitted from the light source 2 by power supplied from the power source 12 via the lamp ballast 13.

Of the light emitted from the light a2 and the light reflected by the reflector 1, only the visible light is optically converted by the cold mirror 3.
Transmits infrared and ultraviolet rays.

The visible light reflected by the cold mirror 3 is sent from the dichroic mirror 4.5 for color separation to the liquid crystal panel 8R18G,
8B, the transmitted light is color-combined by a dichroic mirror 9.10 for color combination, and the image light is sent to a screen 14 by a light amount control lens 11 for a projection device that can extend the life of a retrofocus type projector. The image is enlarged and projected.

The retrofocus lens 11 of the liquid crystal globjector described above does not have a means for controlling the amount of light from the light source 2 in accordance with the size of projection onto the screen 14.

[Intelligence M to be Solved by the Invention] In the conventional liquid crystal projector-P, there was no control of the light amount of the light source depending on the projection screen size, so the illuminance of the drawing could change depending on the projection screen size. Also,
When the projection screen is small, the temperature of the liquid crystal module increases, deteriorating the liquid crystal module, and there is a loss of lamp output, making it impossible to extend the life of the lamp.

This invention was made based on the above points, and it stabilizes the illuminance of the projected image by controlling the electrical output for the light source according to the focus and controlling the amount of light according to the projection area on the screen. In addition, the purpose is to provide a liquid crystal module and a light source run page.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, in a projection device such as a liquid crystal projector that enlarges and projects an image on a screen, the amount of movement of the focus ring is reduced. The present invention is characterized by comprising: a movement amount detecting means for electrically detecting the detected amount; a converting means for converting the detected amount into a DC level; and an output adjusting means for adjusting the output to the light source based on the converted value.

[Function] In FIGS. 1 and 2 showing the embodiment, when the focus ring is turned to focus the screen in a liquid crystal projector that uses a retrofocus lens, the amount of rotation changes. It is electrically detected by a resistive volume built into the focus ring.

The detected value is then converted to a DC level, and the power output to the light source is controlled accordingly.

[Embodiment] Next, an embodiment of the light amount control device for a projection device according to the present invention will be described in detail with reference to FIG. 1 and FIG. 2.

The present invention provides a moving amount detecting means for electrically detecting the moving amount of a focus ring in a projection device such as a liquid crystal projector for projecting an enlarged image on a screen, and a moving amount detecting means for electrically detecting the moving amount of a focus ring, and a moving amount detecting means for electrically detecting the moving amount of a focus ring. The present invention is characterized in that it comprises a converting means for converting into a value, and an output adjusting means for adjusting the output to the light source according to the converted value.

FIG. 1 is a schematic diagram showing an example of the actual rope of a light amount control device for a projection device according to the present invention.

In FIG. 1, a light amount control device for a projection device is attached to, for example, a retrofocus type lens 11 (hereinafter simply referred to as a projection lens).

Further, in FIG. 1, the projection device light amount control device includes a focus ring 21, a flute holder 22, a mounting screw 23, a focus ring interlocking volume 24, a DCt source 25, and volume connection terminals a, b, It consists of c.

When the focus ring 21 is rotated, the above-mentioned projection lens 11 interlocks between the volume connection terminals a and b of the focus ring interlocking volume 24, and c.
The division ratio between the two changes.

At this time, in the projection lens 11, the focus ring 21
Since the amount of rotation of the focus ring 21 is proportional to the focal length and projection area, the amount of rotation of the focus ring 21 is detected and converted to a quantitative value, and the converted value is used to control the power of the lamp ballast 13 (see Figure 2). By controlling the amount of light, the amount of light can be controlled.

Then, the detection is performed using the volume connection terminal a-crWJ.
To DC! A voltage is applied from 211, and a DC voltage linked to the amount of rotation of the focus ring 21 is taken out and detected from the volume connection terminal.

Therefore, the power output from the lamp ballast 13 to the light j12 (see FIG. 2) is controlled based on the detected voltage, and the brightness of the light a12 is controlled according to the screen size.

212th! 5. Outline of a liquid crystal projector incorporating a light amount control device for a projection device according to the present invention
II composition.

In FIG. 2, the liquid crystal projector-P includes a light source 2 with a reflector 1, a cold mirror 3, a dichroic mirror 4.5 for color separation, a total reflection mirror 67, and a light source 2 for the three primary colors R, G, and B. LCD panel 8R, 8G, 8
B, a dichroic mirror 9.10 for color synthesis, and a projection lens 11.

Then, light is emitted from l[2 by the power supplied from til12 via the lamp ballast 13.

For example, a metal halide lamp containing a metal halide is used as the light fi2.

Of the light emitted from the light source 2 and the light reflected by the reflector 1, only visible light is reflected by the cold mirror 3, and infrared rays and ultraviolet rays are removed.

Of the light reflected by the cold mirror 3, only the red color is reflected by the dichroic mirror 4, and the remaining light passes through.

The light reflected by the dichroic mirror 4 is reflected again by the total reflection mirror 6, and then passes through the liquid crystal panel 8R.
The light passes through a dichroic mirror 910 for color synthesis and is output to the projection lens 11 .

Further, of the light transmitted through the dichroic mirror 4, only the blue light is reflected by the dichroic mirror 5, and the remaining light is transmitted.

The light reflected by the dichroic mirror 5 passes through the liquid crystal panel 8B and then passes through the dichroic ink mirror 9 for color synthesis.
The light is reflected by the red light, combined with the red light, transmitted through the dichroic mirror 10 and output to the projection lens 11.

The green light that has passed through the dichroic mirror 5 passes through the liquid crystal panel 8G, is reflected by the total reflection mirror 7, and the dichroic mirror 10 for color synthesis, where it is combined with a composite light of red light and blue light, and then projected. It is emitted to Shins 11.

The light incident on the projection lens 11 is emitted onto the screen 14.

[Effects of the Invention] As described above, the light amount control device for a projection device according to the present invention detects the change in resistance value as the amount of change in the DC level by rotating the focus ring, and uses the DC level signal to detect the change in the resistance value as the amount of change in the DC level. Controls the output power of the source lamp ballast.

Therefore, even if the area of the projection image on the screen changes, the image can be projected with the set illuminance.

Further, when the projection area on the screen is small, the temperature rise of the liquid crystal module can be suppressed and the driving power of the light source can be reduced, so that the durability of the liquid crystal module and the light source can be improved.

Figure 1 shows the light amount control device for projection equipment according to the invention! FIG. 2 is a schematic configuration diagram showing an example of implementation of the light amount control device for a projection device according to the present invention! 1 is a schematic configuration diagram of a liquid crystal projector in which a liquid crystal projector is incorporated.

a, b, c Volume connection terminal LCD projector light source Trofocus type lens lamp ballast focus ring Focus ring interlocking volume DC power supply

Claims (1)

[Claims] (1) In projection devices such as liquid crystal projectors and overhead projectors that enlarge and project images on a screen, there is a movement amount detection means that electrically detects the amount of movement of the focus ring and converts the detected amount to a DC level. 1. A light amount control device for a projection device, comprising a conversion means and an output adjustment means for adjusting output to a light source based on the conversion value.