JPH0627431A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To provide a liquid crystal projector which is provided with an automatic focusing function and which can execute such automatic zooming that a picture is projected by full screen size when an interchangeable lens is used for the projection lens of the liquid crystal projector and to enable lens information such as the focal distance or the F-number of the projection lens to be easily and safely confirmed. CONSTITUTION:In the liquid crystal projector which irradiates a liquid crystal panel with a lamp and enlarges and projects the picture by the projection lens 2, a range-finding mechanism is provided and a contact part for transmitting distance information between a liquid crystal projector main body 1 and a screen 12 or a signal decided based on the distance information is provided between the main body 1 and the lens 2. Besides, a signal generation device for driving a focusing mechanism based on the lens information obtained from the lens 2 and the distance information obtained from the range-finding mechanism is provided. Then, the optical axis of the range-finding mechanism can be changed and the information of the lens 2 can be displayed. Besides, a screen size measurement mechanism is attached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This patent relates to the structure of liquid crystal projectors.

[0002]

2. Description of the Related Art The conventional autofocus mechanism of a liquid crystal projector is one in which a projection lens and a distance measuring mechanism using infrared rays are integrated. In other words, the distance measurement mechanism that measures the distance to the screen by emitting an infrared image and receiving it, and the focus mechanism of the projection lens are linked by gears, cams, etc. to automatically focus and generate by the liquid crystal panel. The image was beautifully magnified and projected on the screen. Moreover, since the projection lens of the conventional liquid crystal projector cannot be replaced, it is not necessary to display the focal length of the projection lens or the relationship between the projection distance and the screen size, and there is no mechanism. There was no mechanism to measure the size of the projected screen.

[0003]

It is conceivable to make the projection lens replaceable in order to expand the range of use of the liquid crystal projector, in contrast to the above-mentioned conventional techniques. For example, if projection lenses with different focal lengths are prepared, the screen size can be adjusted by attaching a lens suitable for the projection distance. In this case, in the mechanism in which the distance measuring mechanism is attached to the projection lens like the conventional auto-focus structure, the size of the projection lens becomes large, and the distance measuring mechanism is touched by a hand and the accuracy is deteriorated. was there. Also, as an interchangeable lens, the interchangeable lens of a single-lens reflex camera is the most popular lens if performance is allowed, but this lens has a focus adjusting mechanism but does not have a distance measuring mechanism for autofocus. Therefore,
I couldn't actually use it.

Further, even if the lens exchange mechanism is provided, there is a problem that the information about the lens and the screen size is not present in the screen or the display panel, which is inconvenient. For example, when the image is projected and the screen is small, the focal length of the lens currently in use is not displayed, so there is a problem that it is not clear which lens should be used next.
In addition, when deciding the screen size using the zoom lens, I was looking at the screen, so it took time to set and I missed the desired scene.

[0005]

To solve the above problems, in the projector of the present invention, the distance between the projection lens and the liquid crystal projector main body is determined by the distance information obtained from the distance measuring mechanism or the distance information. A contact part for transmitting a signal is attached. A projection lens having a focus adjusting mechanism, a distance measuring mechanism, and lens information transmitted from the projection lens to the main body side and distance information obtained from the distance measuring mechanism for generating a signal for driving the focus adjusting mechanism. A focus adjustment mechanism drive signal generator is provided. Also, an optical axis adjusting mechanism for changing the optical axis of the distance measuring mechanism is provided. Also, a display mechanism for displaying the information of the projection lens is attached. In addition, a screen size measuring mechanism was attached.

[0006]

【Example】

(Embodiment 1) FIG. 1 is a perspective view of an embodiment of a liquid crystal projector of the present invention, FIG. 2 is a perspective view of an embodiment of a projection lens of the liquid crystal projector of the present invention, and FIG. It is a block diagram of an Example.

1 is a main body, 2 is a projection lens, 3 is a light emitting element, 4 is a lens, 5 is a prism, 6 is a light emitting window, 7 is a light receiving element, 8 is a lens, 9 is a prism, 10 is a light receiving window, 11
Is a lens information display panel, and 13 is a screen. In the projection lens of FIG. 2, 21 is an engaging portion, 22 is a focal length information contact, 23 is a lens position information contact, 24 is a focus adjustment mechanism drive signal contact, 25 is an AF information contact,
Reference numeral 26 is a zoom mechanism drive signal contact. Inside the main body 1 is a liquid crystal panel driven by a video signal or the like. The back surface of the liquid crystal panel is illuminated by a metal halide lamp or the like, and enlarged and projected on the screen 13 by the projection lens 2. The projection screen is generally projected below or above the body 1. This is to prevent the main body 1 and the viewer from forming a shadow on the screen. The projection lens 2 has a mechanism that can be easily attached to and detached from the main body 1 by the engaging portion 21 as shown in FIG.

Inside the main body 1, there is a distance measuring mechanism capable of measuring the distance to the screen 13. The function of this distance measuring mechanism is as follows. After the infrared rays emitted from the light emitting element 3 are condensed by the lens 4 and the optical axis is changed to the central direction of the screen by the prism 5, the light emitting window 6 having the infrared transmitting characteristic is formed.
To project on the screen 13. The image is received by the light receiving window 10
The light is collected by the lens 8 and received by the light receiving element 7. In the light receiving element 7, generally two elements having the same characteristics are arranged side by side, and the distance to the screen 13 can be known by comparing the respective light receiving intensities. Here, the prism 9 is for aligning the optical axis of the light receiving system with the optical axis of the light emitting system to measure the distance at the center of the screen. Further, the projection lens 2 has a contact point for information regarding the projection lens 2 at an engaging portion with the main body 1.

In FIG. 2, there are a focal length information contact 22, a lens position information contact 23, and an AF information contact 25. Through these contacts, the focal length of the projection lens 2, the position of the lens for focus adjustment, and the projection lens are autofocused. The main body 1 side can know whether it is in the operable state or the manual operation state. From the distance and lens information obtained as described above, the liquid crystal panel can be focused on the screen 13 and projected. An example of a control mechanism for this purpose is shown in the block diagram of FIG.

According to this block diagram, from the distance information 34 obtained from the distance measuring mechanism 33 and the focal length information in the lens information 32 obtained from the projection lens 31, the position of the lens for focus adjustment of the projection lens is determined. It is calculated whether you should bring it. Further, since the current position of the focus adjusting lens can be known from the lens position information from the projection lens, the moving direction and moving distance of the focus adjusting lens are determined from the difference between the two. Accordingly, the focus mechanism drive signal 36 may be sent to the focus adjustment mechanism 37. The above-described work is performed by the focus adjustment mechanism drive signal generator 35 including a microprocessor or the like. In the focus mechanism 37, the focus adjustment lens of the projection lens 31 is moved based on the received signal to focus the image.

If the lens position information is not known from the projection lens 31, the focus may be moved to the closest point or the farthest point side once and then moved to the position where the focus is achieved. Further, when the projection lens 31 is set to the manual operation state by the lens information 32 from the projection lens 31, the auto focus mechanism is not operated and the lens information display section 11 displays that the manual focus state is set. Or if you display it on-screen on the screen,
The user does not make a mistake. In the embodiment shown in FIG. 3, the focus adjustment mechanism drive signal generator 35 is set in the main body 1, but if this is incorporated in the projection lens 31, the number of contact points between the main body 1 and the projection lens 2 is reduced, and the reliability is improved. Will be high.

(Embodiment 2) FIG. 4 shows a sectional view of an embodiment when the light emitting portion of the distance measuring mechanism of the liquid crystal projector of the present invention is tilted downward. 41 is a light emitting element, 42 is a lens, 43 is a variable apex angle prism, 44 is a bellows portion, and 45 is a bellows portion. The variable apex angle prism 43 can swing the optical axis up and down by opening and closing the bellows portions 44 and 45. Generally, the control of the variable apex angle prism 43 can be electrically controlled by a voltage or displacement conversion element such as a piezoelectric element.

With the above mechanism, the optical axis of the distance measuring mechanism can be vertically changed. Although only the light emitting portion of the distance measuring mechanism is shown in FIG. 4, the light receiving portion has a similar mechanism. When the liquid crystal projector is arranged near the ceiling, it is necessary to project the projection screen downward on the main body 1. In this case, when the main body 1 is tilted with respect to the screen 13, the upper part is projected smaller and the lower part is projected larger, resulting in a trapezoidal screen as a whole. Therefore, the projection screen can be projected below the main body 1 by moving the projection lens 2 downward with respect to the liquid crystal panel and disposing it. Here, adjustment is necessary so that infrared rays for distance measurement can also be emitted to the center of the projection screen. The amount of adjustment depends on the focal length of the projection lens 2 when the projection lens 2 is a replaceable lens. That is, if only the projection lens 2 is exchanged without changing the positional relationship between the mount portion of the projection lens 2 and the liquid crystal panel, the screen is enlarged as the lens having a shorter focal length, so that the center of the screen is projected at a shorter distance. Therefore, the optical axis of the distance measuring mechanism also needs to be oriented downward. When the screen is projected vertically on the main body 1 as described above, it is necessary to change the optical axis of the distance measuring mechanism depending on the focal length of the projection lens 2. According to the present embodiment, the focal length of the projection lens 2 is read from the focal length information contact point 22 on the main body 1 side, and the apex angle of the apex angle variable prism 43 is changed based on it, and the optical axis of the distance measuring mechanism is set to the center of the projection screen. Can be set. Therefore, a liquid crystal projector using an interchangeable lens can be realized.

The optical axis of the distance measuring mechanism may be changed not only by the variable apex angle prism but also by a mechanism for moving the light emitting element 41 up and down with respect to the lens 42. A mechanism for inclining the light emitting element 41 and the lens 42 integrally may be provided.

(Embodiment 3) In Embodiment 2, the distance measuring mechanism is used for focusing. However, the distance measuring mechanism of this embodiment can also be used to measure the screen size. The optical axis of the distance measuring mechanism is moved up and down, and the change in the signal input level of the light receiving element is examined. The reflectivity of the screen does not change drastically depending on the location, but the reflectivity changes greatly between the screen and the outside of the screen. That is, when the infrared rays emitted from the light emitting element are received by the light receiving element, it can be seen that the distance measuring light has come to the edge of the screen if the input level changes greatly. If this is placed at the top, bottom, left, and right of the screen, the size of the screen can be known from the adjustment amount of the optical axis of the distance measuring mechanism at this time. If the projection lens 2 has a zoom mechanism capable of changing the focal length with an electric signal, the screen size is determined so as to fit the screen based on the obtained screen size and the focal length information of the projection lens 2. The focal length of the projection lens 2 can be calculated by the microprocessor. FIG. 5 is a block diagram showing the above system. 5
1 is a projection lens, 52 is lens information, 53 is a screen size measuring mechanism, 54 is screen size information, 55 is a drive signal, 56 is a zoom mechanism drive signal generator, 57 is a zoom mechanism drive signal, and 58 is a zoom mechanism. . The screen size measuring mechanism 53 measures the size of the screen. The screen size measuring mechanism 53 may be a dedicated image sensor or a distance measuring mechanism as shown in FIG. On the other hand, from the projection lens 51, lens information 52 regarding the focal length is sent to the main body side, such as at the joint between the projection lens and the main body. Based on the above information, a zoom mechanism drive signal generator composed of a microprocessor, etc.
It calculates the focal length of the projection lens when the screen is projected on the full screen and drives the zoom mechanism. With the above system, a screen suitable for the screen can be automatically projected.

(Embodiment 4) FIG. 6 shows a plan view of an embodiment of the lens information display panel installed on the main body of the liquid crystal projector of the present invention. Reference numeral 61 is a focal length display unit, 62 is an F number display unit, and 63 is a focus state display unit. When the projection lens is an interchangeable lens, what kind of lens is attached to the main body and whether the autofocus mechanism is activated can be easily changed even if the lens is already attached. In the case of a liquid crystal projector, strong light is emitted from the projection lens. Therefore, it is dangerous to look into the lens to check the focal length, F number, etc., because it may worsen the eyes. According to this embodiment, the projection lens can be confirmed safely, and if an inappropriate projection lens is attached, it can be replaced with an appropriate projection lens. Note that these pieces of information may be inserted and displayed on the screen. Further, the size of the screen can be calculated and displayed by the microprocessor from the distance information and the lens information obtained from the distance measuring mechanism that measures the distance between the main body and the screen. Further, if a mechanism for measuring the screen size is provided, the focal length of the projection lens for making the screen fill the screen can be calculated from the screen size and the distance measurement result to the screen. Displaying this makes it easy to select a projection lens with an appropriate focal length.

[0017]

According to the present invention, a distance measuring mechanism for measuring the distance between the screen and the liquid crystal projector main body is provided, and distance information or a signal determined by the distance information is transmitted between the projection lens and the main body. Since the contact part is provided, autofocus with an interchangeable lens is possible. Further, since the signal generator for driving the focus adjusting mechanism is provided based on the distance information and the lens information of the projection lens, the automatic focusing by the interchangeable lens becomes possible. Also, because an optical axis adjustment mechanism for changing the optical axis of the distance measuring mechanism is provided,
Even if the screen is shifted vertically with respect to the main body, it is possible to use by exchanging lenses having different focal lengths and to perform autofocus. Further, since the display mechanism for displaying the information of the projection lens is mounted, the mounted projection lens can be confirmed safely and easily. Also, since a screen size measuring mechanism is provided, when the zoom lens is attached, the screen can be displayed in full screen.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a liquid crystal projector of the present invention.

FIG. 2 is a perspective view of an embodiment of a projection lens of the liquid crystal projector of the present invention.

FIG. 3 is a block diagram of an embodiment of the liquid crystal projector of the present invention.

FIG. 4 is a sectional view of an embodiment when the light emitting unit of the distance measuring mechanism of the liquid crystal projector of the present invention is tilted downward.

FIG. 5 is a block diagram of an embodiment of the liquid crystal projector of the present invention.

FIG. 6 is a plan view of an embodiment of the lens information display panel of the liquid crystal projector of the present invention.

[Explanation of symbols]

 1 Main body 2 Projection lens 3 Light emitting element 4 Lens 5 Prism 6 Light emitting window 7 Light receiving element 8 Lens 9 Prism 10 Light receiving window 11 Lens information display panel 13 Screen 21 Engagement portion 22 Focal distance information contact 23 Lens position information contact 24 Focus adjustment mechanism Drive signal contact 25 AF information contact 26 Zoom mechanism signal drive contact 31 Projection lens 32 Lens information 33 Distance measuring mechanism 34 Distance information 35 Focus adjustment mechanism drive signal generator 36 Focus mechanism drive signal 37 Focus mechanism 41 Light emitting element 42 Lens 43 Vertical angle Variable prism 44 Bellows portion 45 Bellows portion 51 Projection lens 52 Lens information 53 Screen size measurement mechanism 54 Screen size information 55 Drive signal 56 Zoom mechanism drive signal generator 57 Zoom mechanism drive signal 58 Zoom mechanism 61 Focal length display 62 F number display 63 Focus status display

Claims (5)

[Claims] 1. A liquid crystal projector equipped with a projection lens having at least a liquid crystal panel, a lamp, a drive mechanism for focus adjustment, and a distance measuring mechanism, wherein the distance measuring mechanism is provided between the projection lens and the liquid crystal projector main body. A liquid crystal projector having a contact portion for transmitting the obtained distance information or a signal determined by the distance information. 2. A focus is determined from a liquid crystal panel, a lamp, a projection lens having a drive mechanism for focus adjustment, a distance measuring mechanism, lens information transmitted from the projection lens to the main body side, and distance information obtained from the distance measuring mechanism. A liquid crystal projector comprising a focus adjustment mechanism drive signal generator that calculates and generates a signal for driving an adjustment mechanism. 3. A liquid crystal projector comprising a liquid crystal panel, a lamp, a projection lens having a focus adjusting mechanism, a distance measuring mechanism, and an optical axis adjusting mechanism for changing an optical axis of the distance measuring mechanism. 4. A liquid crystal panel, a lamp, a projection lens, and
A liquid crystal projector equipped with a display mechanism for displaying information of the projection lens. 5. A liquid crystal projector equipped with a liquid crystal panel, a lamp, a projection lens, a distance measuring mechanism, and a screen size measuring mechanism.