JPS595231A - Projector - Google Patents

Abstract

PURPOSE:To obtain an easily visible projection image on a screen by controlling an illumination part in such a way as to minimize the difference in the quantity of light between the part near the optical axis of projection and the peripheral part. CONSTITUTION:A photoelectric transducer 15 is disposed on the optical axis behind the 1st reflecting mirror 12, and a photoelectric transducer 16 in the peripheral part thereof, respectively. The respective output voltages thereof are calculated in a subtractor 23. When the observer presses a start switch, a start signal 22 is generated to operate a motor driving circuit 26 which runs a motor 18; at the same time, a peak detection circuit 25 starts to operate. Then, the 1st condenser lens 7 starts to move, and when the difference between the outputs of the transducers 15, 16 is minimized, a peak is detected with the circuit 25, and a stop signal is emitted to the circuit 26, then the lens 7 stops movement. Thereupon, if the observer inserts a micro-film F into a fiche carrier 2, it is able to observe under the optimum condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a projection device for projecting an image of a document such as a microfilm, and particularly to a projection device for a reader or reader printer for observing the image.

In a microfilm reader or reader printer, the image recorded on the microfilm is enlarged and projected onto a screen using a projection lens, and the image projected on the screen is read or a reader printer is used to obtain a copy of the image. There is.

Since the reduction ratio of images recorded on microfilm generally varies, it is necessary to change the projection magnification depending on the microfilm used, and therefore, multiple projection lenses with different focal lengths are used interchangeably. to convert the projection magnification.

Make the most of this group of interchangeable lenses! To light the furnace, create a filament image of the illumination lamp in the pupil on the film side of the projection lens. It is necessary to perform so-called Kohler illumination. This l! If the brightness is not appropriate, the amount of light illuminating the projection lens may be extremely small, or the amount of light may be highly uneven.

For this reason, if the difference in projection magnification used is small, the position of the pupil on the film side from the film surface can be designed to be the same when designing a lens, but if the difference in projection magnification used becomes large, such a lens design becomes difficult. 1 normal because it becomes , and the cost also increases.

A method has been implemented in which a condenser lens is moved to match the projection lens so that a filament image of the illumination lamp is formed at the position of the pupil on the projection Lensnof film side.

However, this method relies on visual inspection to determine the position of the condenser lens, making it difficult to align the condenser lens with the projection lens. It was observed that in the case of a printer, there was a possibility that a certain V1 would make defective copies due to the unevenness of the projection opening, resulting in unnecessary copies being made.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks and to:1. It is an object of the present invention to provide a projection device capable of obtaining an easy-to-see projected image by controlling an illumination unit so that the difference in light amount between the vicinity of the projection optical axis and the peripheral area is minimized.

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention.
Microfilm F, 2 sheets of film holding glass 3. It is equipped with a fish carrier that is held in place by a microfiche, and each frame on the microfiche can be selectively projected. Elucidation lamp S installed at the bottom of the Fish Carrier Co.
The emitted light passes through the seventh condenser lens 7 and the fixed co-condenser lens, changes its direction by 90 degrees by the fixed reflection mirror 9, communicates with the fixed third condenser lens 10, and passes through the fixed third condenser lens 10. A filament image of the illumination lamp S is formed on the pupil of the film side of the projection lens l/ disposed in the projection lens L/. The projection lens 7 can be interchangeably used with various focal lengths depending on the applied magnification. Note that the reflective spherical mirror B placed at the rear of the lamp S is for condensing the light of the lamp S to use it effectively.

Microfilm F stored in fish carrier λ
is magnified by the projection lens 7 on the top, and is further reflected by the first reflection mirror fixed on the top surface inside the reader housing and the second reflection mirror fixed on the side, and then reflected by the reader housing. Projection on the projection screen pufferfish attached to the
An image is observed. Behind the first reflecting mirror /, 2 is a photoelectric conversion element AIk on the optical axis! Photoelectric conversion elements +3/B are arranged around the periphery.

To explain Fig. 1, the first condenser lens 7 is resting on a layered lens fixing block 17 with a female screw/7a, and a screw rod/9 is connected directly to the motor ig.
The threaded part/qa and the female threaded part/7a are engaged, and the lens fixing block is configured to move in parallel by rotation of the motor/g. A limit switch A0 and a limit switch B2/ are provided on both sides of the movement range of the lens fixing block Noah.
7. Prevent excessive movement.

Further, the effects of the present invention will be explained with reference to FIGS. 3 and 9. FIG. 3 is a control block diagram of the projection apparatus of the present invention, and FIG. 3 is a timing graph of this block diagram.

Now, when the observer turns on the illumination lamp by turning on the power switch (not shown) without putting the microfilm F into the fish carrier 2, the seventh condenser lens 7 is located at the position (X) (see Fig. 2). .

First reflecting mirror l,! The photoelectric conversion element AI and the photoelectric conversion element B17. generates output voltages (A') and (B') on (X) A in FIG. 9(a), respectively.

The subtraction circuit 23 shown in FIG.
/, 4 output voltage (IJ') ) - (photoelectric conversion element A
/The left output voltage (AI)'l is calculated, and the output voltage is represented by the point (X) in Figure (b). A certain bias is applied to the bias circuit 217 (Figure m3), and the negative output voltage is converted to positive as shown in Figure 9(C). This output is the peak detection circuit! 3
(Figure 3) and the peak is detected.

If this continues, the output will be 0 because the peak detection circuit 2 is inoperative.

Next, when the observer presses a start switch (not shown), a start signal 22 (Fig. 3) is generated, the motor drive circuit λB (Fig. 3) operates, and the motor /g rotates.
At the same time, the left peak detection circuit 2 (FIG. 3) starts operating.

As a result, the first condenser lens 7 is
Start moving in the direction shown in the figure). The outputs of the photoelectric conversion element A15 and the photoelectric conversion element 13, and the subtraction circuit Ω3. Bias circuit, 2 pieces, peak detection circuit 1ri each on the left, Figure qa.

Point (X) on the graphs shown in b, c, and d begins to move to the right.

The illumination position is correctly positioned when the difference in the output of the photoelectric conversion element between the center and the periphery is the smallest, so the first condenser lens 7 is positioned at point (Y) (see Figure 9). ), the peak detection circuit detects the peak at 2 o'clock 1-L (the output difference between each photoelectric conversion element /left and /B is the smallest).

Motor drive circuit (Figure 3) A stop signal is issued and the motor/g stops. This aligns the illumination system correctly and the observer can now insert the microfilm F into the fish carrier λ and observe the microfiche cmicrofilm F) under optimal conditions.

In the explanation of the above embodiment, the peak value could be detected immediately by motor movement, but if the position of the first condenser lens 7 and the direction of movement thereof are not appropriate.

Lens fixing block 17 to limit switch A or B
comes into contact. When the lens fixing block 17 comes into contact with the limit switch A or B, a signal is sent to the rotation direction switching circuit near (Fig. 3), a switching signal for the motor rotation direction is sent to the motor drive circuit 2. The direction of rotation is reversed. The above peak detection operation continues until the peak is detected.

The motor/g will stop when the skin hits it.

In the above embodiment, the motor initially rotates in one direction;
When the peak value was not captured, it was reversed using a limit switch, but the output of the subtraction circuit or bias circuit was used to calculate the current value and the previous value to determine the direction of rotation of the motor. It is also possible to set the FCL so that the peak value is always reached in the shortest possible time.

In the above embodiment, the film reader is described as an example, but it goes without saying that the present invention can also be applied to a film printer or a reader or printer that uses documents other than film.

1 shows another embodiment of the present invention, shown in FIG. 1.
A photoelectric conversion element is placed behind the seventh reflecting mirror 7.2.
Instead, a lens 3θ, 3.2. ->? Electrical conversion element, 3/, 3
3, and peak detection may be performed by photometry [7] using a combination of a lens system and a lightning exchange element to measure the red part of the center and peripheral parts of the screen.

In addition, any other place where fAl+light can be produced may be used.

In the above example, the condenser lens is moved,
Prepare multiple condenser lenses with different focal lengths,
Then, the most suitable one may be selected from among them. Also fix the condenser lens 1.2. Moving the lamp has the same effect.

Start confidence is performed using a start switch, but it may also be linked to the power switch.Also, when changing lenses, the lens change signal can be taken out with a micro switch, etc., and this signal can be used. 1l111 light 1 may be used.

As explained above, according to the present invention, in a reader etc. that uses a large number of interchangeable lenses, an optimal elucidation system can always be obtained for the projection lens used, with clear and high quality light without uneven illuminance. You can observe beautiful images.

Further, in the printer, high-quality copies can be obtained in the same manner as above.

[Brief explanation of the drawing]

FIG. 7 is a sectional view of an embodiment of the present invention, FIG. Ω is a detailed sectional view of the illumination section of FIG. 3 is a timing graph of the block diagram, and FIG. 3 is a sectional view of another embodiment of the present invention. l...Reader housing. Ω...Fish carrier. S...Lighting lamp. 7...First condenser lens. /l... Projection lens. Noko: First reflecting mirror. lLeft, /B...Photoelectric conversion element. (X) (Y) ---Konderesai Standing Ca> (Cn Fig. 5

Claims (1)

[Claims] L In a projection device that projects an image of a document illuminated by an illumination source, an illumination unit is controlled so that the difference between the amount of light near the projection optical axis and the amount of light at the peripheral area is minimized. Characteristic projection device. 2. The projection device according to claim 1, characterized in that the condenser lens is moved and controlled. 3. The projection apparatus according to claim 1, characterized in that a plurality of condenser lenses are prepared and controlled by exchanging or combining them.