JPH03239085A - Projection type image display device - Google Patents

Abstract

PURPOSE:To automatically obtain the best focus by providing a distance measuring sensor on an optical axis of a projection lens, and providing two pieces of mirrors between the projection lens and the distance measuring sensor so that an image display body comes on the optical axis. CONSTITUTION:In the case of usually looking at an image, an image of a full color can be obtained by dividing a light beam emitted from a light source 1 into R, G and B and superposing images display bodies 7, 13 and 16. On the other hand, at the time of setting a projection distance, a total reflection mirror 14 is drawn back from on an optical axis 19, therefore, in a distance measuring sensor 32 on the optical axis 19, an image of a screen is formed from a projection lens 10. An output obtained in such a way is sent to a control circuit 34, a motor 29 is turned, and a lens fixing member 24 is turned. In such a way, an output of the distance measuring sensor 32 is varied. Subsequently, when this output becomes an output value set in advance, the control circuit 34 stops a motor 30, by which a projection distance of the projection lens 10 is set automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention is directed to i! i! displayed on the imitation display body! The present invention relates to a projection type image display device that enlarges and projects a false image onto a screen using a projection lens, and particularly relates to a configuration that includes a projection lens with a variable projection distance and that allows easy focus adjustment.

2. Description of the Related Art In conventional projection type image display devices, when the projected image position and the main body are configured to be distant from each other, it is difficult to determine the best focus position l because the projected image is far away during focus adjustment. Therefore, focus adjustment required time and effort.

PROBLEMS TO BE SOLVED BY THE INVENTION In recent years, two-body projection type image copying display devices equipped with a projection lens whose projection distance is variable have become popular in the market.

- The projection image projected by this two-body projection type image display device equipped with a projection lens whose projection distance is variable is formed at a distance from the main body. Therefore, when adjusting the focus,
As it becomes difficult to grasp the delicate focus, it becomes a two-person task where one person looks at the projected image and then adjusts the focus, and every time the focus position is slightly shifted, the projected image changes. I had to go up close and check the focus.

Therefore, the present invention provides a two-body projection type N copying display device equipped with a projection lens with a variable projection distance.When the projected image is formed at a distance from the main body, when performing focus adjustment, it is difficult to maintain a delicate focus. This solves the problem that it is difficult to understand.

Means for Solving the Problems In order to solve the above problems, the present invention provides a projection lens whose projection distance is variable by a motor, an image display body, and two mirrors, at least one of which is a dichroic mirror. , comprising a distance measurement sensor and a circuit that controls the motor by the output of the distance measurement sensor, the distance measurement sensor is provided on the optical axis of the projection lens, and the two mirrors are arranged on the optical axis of the projection lens. The light is reflected at a certain angle to the original optical axis and is provided between the projection lens and the distance measuring sensor so that the image display body is on the optical axis. Furthermore, at least one of the two mirrors is provided so as to be avoidable from above the optical axis. However, if one of the two mirrors is not a dichroic mirror, the mirror that can be avoided from the optical axis is a mirror that is not a dichroic mirror, which simplifies best focus.

Furthermore, by providing an auxiliary light irradiation device that is configured to irradiate a portion of the projection range of the projection lens whose projection distance is variable, the performance of the distance measurement sensor can be improved more reliably without being influenced by the environment. allows you to easily get the best focus.

Function The present invention provides a projection lens whose projection distance is variable by a motor;
an image display body, two mirrors, at least one of which is a dichroic mirror, a distance measuring sensor, and a circuit for controlling the motor based on the output of the distance measuring sensor; A distance measuring sensor is provided, and the two mirrors reflect the optical axis of the projection lens at a certain angle with the original optical axis, and the projection lens and the distance measuring sensor are arranged so that the image display body is on the optical axis. It is set in between. This makes it possible to project the image of the IN pattern display body through the projection lens.

Furthermore, at least one of the two mirrors is provided so as to be avoidable from above the optical axis.

However, if one of the two mirrors is not a dichroic mirror, the only mirror that can be avoided from the optical axis is a non-dichroic mirror, so that a light beam with a certain wavelength is guided to the distance measurement sensor. A circuit that controls the motor based on the output of the distance sensor at this time drives a motor that changes the projection distance of the projection lens, and stops the motor when a predetermined output is obtained. Therefore, it is possible to automatically obtain the best focus.

Furthermore, by providing an auxiliary light irradiation device that is set to irradiate a portion of the projection range of the projection lens whose projection distance is variable, it is possible to supply light of a stable wavelength or an image pattern suitable for the distance measurement sensor. This makes it possible to automatically obtain the best focus more reliably by making the performance of the ranging sensor less affected by the environment.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the structure of a two-body projection type image display device, in which symbol 2 is a light source, and light emitted from this is sent to a total reflection mirror 3 by a reflecting umbrella 2. In FIG. Reference numeral 4 denotes a blue-transmitting dichroic mirror, in which blue light is sent to a total reflection mirror 5 provided in front of it, and an image is displayed via a field lens 6 on an image display device 7 consisting of a liquid crystal panel or the like. is sent to the projection lens group 1O via a green-reflecting dichroic mirror 8 and a red-transmitting dichroic mirror 9. Further, the light transmitted through the blue-transmitting dichroic mirror 4 is reflected by the green-reflecting dichroic mirror 11 through the field lens 12, and the image displayed on the image display device ff113 is reflected by the green-reflecting dichroic mirror 7 and the red-transmitting dichroic mirror 11. It is sent to the projection lens 10 via the mirror 9. Similarly, for red light, the light that has passed through the green-reflecting dichroic mirror 11 passes through the field lens 15, and the image displayed on the image display device 16 is reflected by the total reflection mirror 14, and then is reflected by the red-transmitting dichroic mirror 9. It is reflected and sent to the projection lens group 10.

A fixing member 18 is attached to the housing 17 that houses the above-mentioned members.
A female helicoid screw is screwed into a male helicoid screw 22 formed on the outside of a lens support member 21 that has the optical axis 19 at the center and supports the projection lens 20 on the side opposite to the housing 17 and has the optical axis 19 at the center. A lens fixing member 24 having a rear end portion 23 is provided.

A projection lens 25 is supported inside this lens fixing member 24. Further, the lens fixing member 24 is provided with a gear 26 having the optical axis 22 as the center on the outside.

A gear 28 is engaged with this gear 26 and is rotatably attached to a guide shaft 27 that extends from the housing 17 in the direction of the optical axis 19 and is fixed. A gear 29 is fixed to the gear 28, and a gear 31 fixed to the rotating shaft of a motor 30 is engaged with the gear 29.

Further, a support member 33 is fixed to the housing 17 for fixedly supporting the distance measuring sensor 32 behind the total reflection mirror 14. A control circuit 33 is attached to this support member 33 for stopping the operation of the motor 30 based on the output of the distance measuring sensor 32. However, the distance measuring sensor 3
2 is the image display body 7.13.16 from the projection lens 10.
is set at the same distance.

Further, as shown in FIG. 2, the total reflection mirror 14 is retractably placed at the bottom of the tank from above the optical axis 19.

When viewing a normal image using the bottom of these tanks, a full-color image can be obtained by superimposing the R, G, and B portions of the light emitted from the light source 1 on the images on the image display unit 7.13.16. .

On the other hand, when setting the projection distance, the total reflection mirror 14 is retracted from above the optical axis 19 as shown in FIG.
An image of a screen, which is not shown in the picture, is formed by the projection lens 10 on the distance measuring sensor 32 located above. The output obtained by this is sent to the control circuit 34, and the motor 29 is rotated so that the output value is set in advance, and the gears 31, 29.
By rotating the lens fixing member 24 through 28 and 26, the projection lens 25 fixed to the lens fixing member 24 is rotated in the optical axis 19 direction by the male helicoid screw 22 and the female helicoid screw 23 screwed thereto. be forced to move.

As a result, the output of the ranging sensor 32 changes.

When this output reaches a preset output value, the control circuit 34 stops the motor 30, thereby automatically setting the projection distance of the projection lens 100.

Further, by providing an auxiliary light irradiation device 35 as shown in FIG. 3, the output of the distance measuring sensor 32 can be made stable at all times and not easily influenced by the environment. Further, by adding a distance measurement pattern to this auxiliary light irradiation device 35, it is possible to further improve accuracy.

Effects of the Invention According to the present invention, even if the projection distance of the projection lens of a projection type image display device with variable projection distance is set at an arbitrary position,
The projection distance can be set automatically, reducing labor and stably obtaining in-focus images. In addition, mechanically, it can be achieved by adding a distance measurement sensor and control circuit to the motor-driven focus mechanism currently on the market, and by simply moving one mirror, and it can be provided at a low cost. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the projection type image display device according to the present invention, and FIG. 2 is a cross section of the projection type image display device of FIG. 1 in a state where the mirror is avoided from the optical axis and distance measurement is performed. 3 are cross-sectional views when the projection type image display device of FIG. 2 is equipped with an auxiliary light irradiation device. l...Light source, 2...Reflector, 3,5.
14... Total reflection mirror, 4... Blue transmission dichroic mirror 7, 13.16... Image display device f, 8... Green reflection dichroic mirror, 9.11・・・Red transparent dichroic mirror,
10...Projection lens group, 20.25...
・Projection lens, 17... Housing, 30...
・Motor, 32... Distance sensor, 34...
...Control circuit, 35...Auxiliary light irradiation device.

Claims (2)

[Claims] (1) a projection lens whose projection distance is variable by a motor; an image display; two mirrors, at least one of which is a dichroic mirror; a distance measurement sensor provided on the optical axis of the projection lens; and a circuit that controls the motor based on the output of the ranging sensor, the two mirrors reflect the optical axis of the projection lens at a certain angle with the original optical axis, and the image display body is aligned with the optical axis. The projection type is provided between the projection lens and the distance measuring sensor so as to be located above, and at least one of the two mirrors is provided so as to be avoidable from above the optical axis. Image display device. (2) The projection type image display device according to claim 1, further comprising an auxiliary light irradiation device configured to irradiate a portion of the projection range of the projection lens.