JPH0553193A - Projection type display device - Google Patents

Abstract

PURPOSE:To always obtain stably an image being in focus by detecting a temperature variation of a projection lens or a light source, and correcting being out-of-focus caused by a temperature variation of the projection lens by executing an auto focus. CONSTITUTION:When a switch is turned on, a focus is adjusted by an auto focus, a photographing object 2 is projected to a screen 9, and a temperature of a projection lens 6 is detected by a temperature sensor 7 and stored in a memory. Subsequently, the temperature of the projection lens 6 being in the course of projection is detected by the temperature sensor 7, stored in the memory, compared with a temperature after the auto focus is executed and in the case the temperature variation of the projection lens exceeds a prescribed value, a focus is adjusted by the auto focus. In order to execute the auto focus, a light team projected from a projecting/photodetecting part 8 is reflected by a half mirror 3, and projected to a screen 9 by the projection lens 6. Also, this light beam is reflected by the screen 9 and subjected to photometry by the projecting/photodetecting part, 8, and a correction of a focus is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device having a temperature compensation function.

[0002]

2. Description of the Related Art A conventional projector, which is a typical example of a projection type display device, is constructed as shown in FIG. In the figure, 1 is a light source, 2 is a projection object, and 4 is a screen. Reference numeral 5 is a drive system for driving the projection lens 6, and 4 is a motor for driving the drive system 5. To adjust the focus,
The light projected from the light projecting / receiving unit 8 is reflected by the half mirror 3 and is projected on the screen 9 through the projection lens. Further, the projected light is reflected by the screen 9 and is metered by the light projecting / receiving unit 8 through the same path.

Focus adjustment is carried out when the power is turned on or by operating an automatic focus switch or the like in order to stabilize the projected image.

[0004]

However, in the above-mentioned conventional example, when the projection lens is changed in temperature during projection and is out of focus, it is necessary to operate the autofocus switch or the like, which is troublesome to handle. There was a flaw.

Therefore, an object of the present invention is to provide a projection type display device having a temperature change compensating function which can prevent the influence of the change even if the change occurs in the projection optical system or the light source due to the temperature change. It is to be.

[0006]

In a projection type display device according to the present invention, a detecting means for detecting a change in a projection lens and a temperature compensating function for driving a lens to adjust a focus according to an output of the detecting means. By providing the attached focusing means, a temperature compensation function is provided to detect a change in the light source, the projection lens, and the like during projection and automatically focus to correct a focus shift.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 to 3 show a first embodiment of the present invention.
An example of is shown.

FIG. 1 shows an application of the present invention to a slide projector. In the figure, 9 is a screen and 1 is a light source. 2 is a projection object projected on the screen 9, 6 is a projection lens for projecting the projection object 2 on the screen 9, 5 is a drive system for driving the projection lens 6 to adjust the focus, and 4 is a motor for moving the drive system 5. , 7 is a temperature sensor for detecting the temperature of the projection lens 6, 8 is a light projecting / receiving unit for performing autofocusing, 3 is a half mirror for reflecting the light from the projecting / receiving unit, and 10 is a slide projector. The casing. FIG. 2 is a block diagram showing the configuration of the control system of this embodiment. FIG. 3 is a flowchart showing the operation of the control system of this embodiment.

First, when the switch is turned on, the focus is adjusted by auto focus, and the object 2 is projected on the screen 9. Next, the temperature of the projection lens 6 is detected by the temperature sensor 7 and stored in the memory. Further, the temperature of the projection lens 6 during projection is detected by the temperature sensor 7, stored in a memory, and compared with the temperature after autofocusing, the temperature change of the projection lens is a predetermined value or more (for example, 10 ° C. or more). If, the focus is adjusted by auto focus. Emitting / receiving unit 8 for auto focus
The light rays projected by the half mirror 3 are reflected by the half mirror 3 and projected onto the screen 9 by the projection lens 6. Further, the projected light ray is reflected by the screen 9, passes through the same path, and is measured by the light projecting / light receiving portion 8 to correct the focus.

As described above, the focus shift due to the temperature change of the projection lens 6 is automatically corrected, and when the temperature change is small and the focus shift is small and correction is unnecessary, autofocus is not performed. A stable image can be obtained.

(Embodiment 2) FIGS. 4 and 5 are a schematic diagram of the configuration of a control system of a second embodiment of the present invention and a flow chart of the operation of the control system. In this embodiment, a timer is added to the first embodiment, and the temperature of the projection lens 6 is detected at regular time intervals determined by the timer. By using the timer to detect the temperature of the projection lens 6 at regular time intervals, unnecessary autofocus can be prevented.

(Embodiment 3) FIG. 6 is a flow chart showing the operation of the control system of the third embodiment of the present invention. In the present embodiment, autofocusing is performed when the detected temperature of the projection lens 6 is a predetermined temperature (for example, when the value is every 10 ° C. from 0 ° C. to 100 ° C.). However, if the temperature is the same as the temperature when the autofocus was performed last time, the autofocus is not performed.

(Embodiment 4) FIG. 7 shows the configuration of a control system according to a fourth embodiment of the present invention. In the figure, the parts designated by the same reference numerals as those in FIG. 1 are the same as the parts described in the first embodiment. Reference numeral 7a is a temperature sensor that detects the temperature of the light source 1. In this embodiment, the temperature sensor 7a detects a temperature change of the light source 1, and auto-focusing is performed when the temperature change exceeds a predetermined value.

(Embodiment 5) FIGS. 8 to 10 show a fifth embodiment of the present invention, in which the present invention is applied to an LCD projector. In the figure, the parts designated by the same reference numerals as those in FIG. 1 are the same as the parts described in the first embodiment.
11a is an LCD corresponding to green light, 11b is an LCD corresponding to blue light, 11c is an LCD corresponding to red light, 12
a is a dichroic mirror that reflects only green rays of light projected from the light source 1, 12b is a dichroic mirror that reflects only blue rays, and 13a is LCD 11
A half mirror for combining the light passing through a and the light passing through the LCD 11b, 13c a half mirror for reflecting the light passing through the LCD 11c, and 13b a half mirror for combining the light from the half mirror 13a and the light from the half mirror 13c. , 14 are mirrors that reflect the light rays reflected by the dichroic mirror 12a. The light beam projected from the light source 1 is reflected by the dichroic mirror 12a only as a green light beam. The reflected green light ray is reflected by the mirror 14 and passes through the LCD 11a. The rays that have passed through the dichroic mirror 12a are dichroic mirror 1
Only the blue ray is reflected by 2b. The reflected blue ray passes through the LCD 11b. The green light ray that has passed through the LCD 11a and the blue light ray that has passed through the LCD 11b are combined by the half mirror 13a. The light beam that has passed through the dichroic mirror 12b passes through the LCD 11c and is reflected by the half mirror 13c.
Are combined with the light rays combined by the half mirror 13a, and are projected onto the screen 9 through the projection lens 6.

As in the second embodiment, the temperature of the projection lens 6 is detected by the temperature sensor 7, and when the temperature change exceeds a predetermined value, autofocus is performed to correct the focus.

[0017]

As described above, in the apparatus of the present invention, the change in the temperature of the projection lens or the light source is detected, and the focus shift due to the change in the temperature of the projection lens is corrected by performing the autofocus. An in-focus image can be stably obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a slide projector that is a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing the configuration of a control system of the apparatus shown in FIG.

FIG. 3 is a flowchart showing the operation of the control system of FIG.

FIG. 4 is a flowchart showing the operation and function of the control system of the second embodiment of the present invention.

FIG. 5 is a flowchart showing the functions of the control system of the third embodiment of the present invention.

FIG. 6 is a flowchart showing the functions of the control system of the fourth embodiment of the present invention.

FIG. 7 is a schematic view of a slight projector according to a fifth embodiment of the present invention.

FIG. 8 is a schematic diagram of an LCD projector to which the present invention is applied.

9 is a schematic diagram of the configuration of the control system of FIG.

10 is a flowchart showing the functions of the control system shown in FIG.

FIG. 11 is a schematic view of a conventional slide projector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Projection object 3 ... Half mirror 4 ... Motor 5 ... Drive system 6 ... Projection lens 7 ... Temperature sensor 7a ... Temperature sensor 8 ... Projector / receiver 9 ... Screen 10 ... Casing 11a ... LCD 11b ... LCD 11c ... LCD 12a ... dichroic mirror 12b ... dichroic mirror 13a ... half mirror 13b ... half mirror 13c ... half mirror 14 ... mirror

Claims (3)

[Claims] 1. A projection type display device comprising: a photographing surface such as a screen; a projection optical system for projecting an image of a projection target on the shooting surface; and a light source for projecting light onto the projection target. A temperature-induced change detection means for detecting a change due to a temperature change of at least one of the projection optical system and the light source, and a temperature change compensation function for automatically focusing the projection optical system according to the output of the detection means. A projection-type display device, comprising: 2. The temperature-induced change detection means detects a change in the projection optical system.
Projection display device. 3. The projection type display device according to claim 1, wherein the temperature-induced change detecting means detects a change in the light source.