JPH01214828A - Automatically focused projecting device - Google Patents

Abstract

PURPOSE:To correct distortion of a projected image by employing a part which generates signal along an optical axis of a projecting lens, a part which receives the signal, and an adjusting part which moves the projecting lens and a projecting object in relation to each other. CONSTITUTION:When a point P on an original 7 is projected onto a screen 14, a light emitting means 16 projects infrared ray to a point P2 on the screen by command of a processor 37; a position detecting means 21 receives reflected light; and then photoelectric currents I1 and I2 are obtained from electrodes 21d and 21e, respectively, based on the center of gravity of incident light LP. Information on the position of incident spot light LP is given to the processor 37 via amplifiers 32 and 33, an analog switch 35, and an A/D converter 36. The processor 37 calculates the degree of deviation from a focal point and rotates a motor 39 by a prescribed quantity so that the lens 10 moves along the optical axis, thereby adjusting the focal point. When a projection center is transferred to B, an expanding and contracting part 4c is extended by a prescribed length R. Thus, the point P is transferred to the projection center B, and the image, having the point B as its center, is free from a trapezoid distortion.

Description

[Detailed description of the invention] -1 The present invention relates to an autofocus projection device.

Referring to FIG. 8, a conventional t-focus projection apparatus has an autofocus lens system and a projection lens C attached to a mirror a and a head h. Manuscript d
The projected image passes through a projection lens C, is reflected by a mirror a, and is enlarged and projected onto a screen e. The distance of the optical axis from this stop mirror a to the screen e is i. In this state, measure the distance from the A-to-focus lens system to the screen e. A distance of 1lllli is estimated by this distance measurement.

However, when the image is rectangular at point A on screen e, when the inclination of mirror a is changed to raise the image to 8 points as shown by the broken line, the image becomes as shown in Figure 7. It becomes distorted and trapezoidal.

At this time, the distance g of the optical axis from mirror a to the screen
becomes 1=gcosα and becomes large. In other words, autofocus will not work correctly if the distance between the autofocus lens system and the screen e is directly measured.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an autofocus projection device that can reduce trapezoidal distortion of a projected image caused by a change in the projection position and can form an image correctly.

11 sad 11 The invention is summarized in the claims.

・To resolve Please refer to FIGS. 1 and 2.

An overhead projector 1 as an autofocus projection device includes a projection lens 11 and an adjustment section H. The projection lens 11 projects a projection object (original 7 in the embodiment) onto the screen 14 .

The adjustment section H forms an image of the projection object 7 on the screen 14.

The signal generator 12 emits a signal toward the screen 14 . The signal receiving section 13 receives the signal reflected from the screen 14 and outputs an output signal according to the distance to the screen 14.

In response to the output from the signal receiving section 13, the adjustment section H moves the projection lens 11 and the projection object 7 relatively in a direction perpendicular to the optical axis thereof, so that the image of the projection object 7 is adjusted to The screen is configured to be formed on the screen.

When it is desired to raise the position of the projected image on the 1-pan screen 14 as shown in FIG. 2, the projection lens 11 is shifted toward the screen 14. As a result, by relatively moving the projection lens 11 and the projection object 7, the distortion of the projected image is corrected.

i1 Please refer to FIGS. 1 and 2.

[Overhead Projector 1] The overhead O-projector 1 includes a main body 2, a support 3, and a head portion 4. A pillar 3 is provided vertically at the corner of the main body 2. A head portion 4 is set on this support 3 so as to be adjustable in vertical movement.

[Wooden body 2] The main body 2 is provided with a reset button 5 and a transparent document table 6. A normal original 7 is placed on this original table 6. Further, inside the main body 2, a light source 8 and a condensing Fresnel lens 9 are provided.

This light source 8 emits visible light, and preferably has a small amount of infrared light component. In addition, a filter can be installed to remove infrared light if necessary.

[Head Section 41 The base section 4a of the head section 4 supports a projection lens 10, a reflecting mirror 11, a signal generating section 12, a signal receiving section 13, and the like.

[Adjustment Unit H] The adjustment unit H includes a projection lens 10, a reflection mirror 11, a signal generation unit 12, a signal reception unit 13, an operating means 30, and the like.

The base portion 4a is connected to the fixed portion 4C via the expandable portion 4b.

The base portion 4a is movable in a direction perpendicular to the optical axis by a driving means 4d of the fixed portion 4C.

The stretchable part 4b is made of flexible rubber or the like.

Further, the driving means 4d is, for example, a combination of a motor and a ball screw.

The signal generating section 12 and the signal receiving section 13 are located on both sides of the projection lens 10. That is, the signal generating section 12, the projection lens 10, and the signal receiving section 13 are arranged parallel to the screen surface 14.

The light from the light source 8 passes through the Fresnel lens 9, the document table 6, and the document 7, and is focused onto the projection lens 10 by the Fresnel lens 9. The light containing the contents of the original 7 is enlarged and projected onto the screen surface 14 in a conjugate relationship by the projection lens 10 and the reflection mirror 11, so that the contents of the original 7 can be displayed on the screen surface 14. Optical axis 1 of this projection lens 10
As shown by 0a, a point P on the original 7 is projected on the screen surface 14 at a projection position Δ in a conjugate relationship.

As is well known, this adjusting section enables the projection lens section 10 to move in the direction of its optical axis by rotating a motor 39 in response to a signal from a signal receiving section, thereby correctly projecting the original 7 onto the screen surface.

Refer to FIG. 3 for the signal generating section 121. The signal generating section 12 has a light emitting means 16 and a light projecting means 17 for emitting light. The light emitting means 16 is preferably capable of emitting light in the infrared or near infrared wavelength region, and can be a light emitting diode (LED) or a laser diode (LD). The light projecting means 17 is a convex light projecting lens, and the light from the light emitting means 16 is directed to the screen surface 14.
It is designed to project light towards.

[Signal Receiving Section 13] On the other hand, the signal receiving section 13 includes a light collecting means 20 and a light receiving position detecting means 21.

The light condensing means 20 directs the light from the light projecting means 17 to the screen surface 1.
4 is focused on the light receiving position detection means 21. The light receiving position in the light receiving position detecting means 21 corresponds to the distance 1IIIL between the screen surface 14 and the condensing means 20.

[Light receiving position detection means 21] Here, the light receiving position detecting means 21 will be explained.

The light receiving position detecting means 21 in FIG. 4 is preferably a semiconductor device detector (position sensor).
Detector).

[Operation means 301 The operating means 30 shown in FIG. 3 will be explained.

The input terminals of the amplifiers 32 and 33 are connected to the light receiving position detection means 21.
are connected to electrodes 21d and 21c, respectively. The output terminals of amplifiers 32,33 are connected to analog switch 35. Analog switch 35 is connected to microprocessor 37 via A/D converter 36.

This microprocessor 37 has the reset button 5.
and a motor 39 as a step motor and a light emitting means 16
is connected.

This reset button 5 is also shown in FIG.

The motor 39 is capable of moving the projection lens 10 in the direction of its optical axis according to commands from the microprocessor 37. The movement position information of the projection lens 1o is stored in the microprocessor 37.
feedback is provided. Further, the light emitting means 16 emits light in response to a command from the microphone setter 37.

[Operation] First, turn on the power and press the reset button 5 in Figures 1 and 3.
Press to reset the microprocessor 37.

As shown in FIGS. 1 and 2, a document 7 containing desired content is placed on the document table 6. The light source 8 causes the projection lens 1 to
o. The contents of the original document 7 are projected onto the screen surface 14 via the reflecting mirror 11. Point P of the original 7 is projected onto the projection center.

At this time, the projection lens 10 is moved in the optical axis direction for focusing. See Figure 3.

That is, according to a command from the microprocessor 37, light in the near-infrared or infrared region is emitted from the light emitting means 16 onto the screen surface 1.
The light is projected through the light projecting means 17 toward the point P2 of No. 4. This light reflected by the screen surface 14 is received by the light receiving position detecting means 21 by the condensing means 20. Opposite the incident spot light LP, photocurrents It and I2 are input to amplifiers 32 and 33 from electrodes 21d and 21e, respectively.

These photocurrents ■1 and I2 are generated by amplifiers 32 and 33,
Current-to-voltage conversion is amplified. Then, the analog switch 35 switches the two voltage values corresponding to the photocurrents I+ and I2, and the A/D converter 36 sequentially converts the photocurrents I+ and I2 into A/D converter 36.
D-converted.

The signal thus converted into a digital value is sent to the microprocessor 37 as position data of the incident spot light LP. Based on this data, the microprocessor 37 determines the defocused suspension and motor 3.
9 to rotate by a predetermined number of steps.

As a result, the projection lens 10 is moved by a predetermined direction a along the optical axis direction, and focusing is completed.

By the way, as shown by the broken line, the position information of the projection lens 10 is fed back to the microprocessor 37 and stored in the memory. Thereby, the next time the reset button 5 is pressed, the projection lens 10 is moved from that position. In addition, when the reset button 5 is pressed again or the power is turned on again, the projection lens 10 is moved and focused, that is, the autofocus operation is performed. When the autofocus operation is completed, the following The positional state of the projection lens 10 during autofocus is maintained until a reset operation or the power is turned on again.

If autofocus is always activated, the light receiving position detection means 21 may detect the person explaining the projected image on the screen or the pointing stick, and the autofocus may operate to try to focus there, or other disturbance conditions may occur. The focus point constantly moves. This makes the screen very difficult to see. In order to eliminate this problem, after focusing by -degree, the focus is fixed until the next reset or power is turned on again, so that a stable image plane can be obtained and the screen surface can be easily distorted.

Next, when moving the projection center from A to B in FIG. 2, the driving means 4d is driven to extend the telescopic portion 4c by a predetermined shift ff1R. In other words, the projection lens 10 moves in the direction perpendicular to its optical axis by the amount of shift ff1R between the projection lens 10 and the original 6! Here and there.

As a result, the optical axis passing through point P of the original document 6 follows the path shown by the dotted line, and point P is moved to the projection center B and is enlarged and projected.

Even in this case, the image on the return 14 whose projection center is 8 does not suffer from trapezoidal distortion.

4 and 5 are principle diagrams showing the relationship between the projection lens 10, the original 6, and the screen 14. FIG. However, the reflection mirror is omitted. FIG. 4 corresponds to the position of the solid line in FIG.

FIG. 5 corresponds to the position of the broken line in FIG.

When moving the projected image on the screen 14 upward from the standard state shown in FIG. 4 as shown in FIG.
Although the projection image is moved by the shift ff1R in the direction perpendicular to 0a, the projected image does not suffer from trapezoidal distortion because the original 16 and screen 14 remain in the plane perpendicular to the optical axis 10a.

When the projection center shifts from A to B in this manner, the projection lens 10 is automatically focused in the same way as in the above case.

At this time, the projection lens 10, the signal generating section 12, the signal receiving section 13, etc. that constitute the autofocus optical system are moved together by a predetermined shift amount. and projection lens 10
The optical axes of the signal generator 12 and the signal receiver 13 are substantially parallel to each other. For this reason, the signal generating section 12. Even if the projection lens is moved, the distance determined by the signal receiving section 13 is measured along the optical axis from the projection lens 10 to the screen 14, so that accurate autofocus can always be performed.

The 6th time shows the slide projector side. A signal generating section 112 and a signal receiving section 113, which are arranged on both sides of the projection lens 110, are provided on the base section 104a. The base portion 104a is shiftable in a direction perpendicular to the optical axis of the projection lens 110. Base part 104
a moves as shown by the dotted line.

The image on film F moves from point A to point 8 on screen 114.

However, the present invention is not limited to overhead projectors and slide projectors.

It can also be applied to other formats.

In the embodiments, the signal is described as light, but any signal that is reflected and can be used to determine distance, such as an ultrasonic wave, can be applied to the present invention.

As explained above, even if the projection position is changed, the distortion of the projected image can be reduced, the operator's operation precision can be improved, and the handling can be made easier.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of an autofocus projection device of the present invention, FIG. 2 is a side view of this embodiment, FIG. 3 is a diagram showing an autofocus distance measuring control device, and FIGS. FIG. 5 is a diagram for explaining the principle of autofocus, FIG. 6 is a diagram showing another embodiment of the present invention, and FIGS. 7 and 8 are diagrams showing a conventional example. 1... Overhead projector 11...
...Reflection mirror 12...Signal generating section 13...Signal receiving section 14...Screen 1-First attorney Patent attorney 1) Toru Hebe Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A projection lens section (10) that projects a projection object (7) onto a screen (14), and an adjustment section (H) that forms an image of the projection object (7) on the screen (14). )
An autofocus projection device comprising: a signal generating section (14) that emits a signal toward the screen (14) substantially along the optical axis of the projection lens section;
12), and a signal receiving section (13) that receives a signal reflected from the screen (14) substantially along the optical axis of the projection lens section and outputs an output signal according to the distance to the screen (14). The adjustment section (H) forms an image of the projection object according to the output from the signal reception section, while the projection lens section (10) is arranged in a direction orthogonal to the optical axis thereof. An autofocus projection device characterized in that it is configured to relatively move the projection object (7) and the projection object (7) to form an image of the projection object (7) on the screen (14).