JPS59232331A - Automatic exposure adjusting mechanism of reader printer - Google Patents

Abstract

PURPOSE:To obtain an inexpensive mechanism by utilizing turning of a mirror to scan a light quantity detecting sensor provided in a position across the optical path of the turning mirror. CONSTITUTION:If data to be copied exists on a microfilm 1, a changeover switch 7 is switched, and a turning mirror 3 starts turning in the direction of an arrow N1. At this time, a timing control circuit 12 releases a reset signal RS, and the output of a light quantity detecting sensor 8 is inputted to an integrator 9. The timing control circuit 12 outputs a mode signal MD to an exposure adjusting circuit 11, and the exposure adjusting circuit 11 gives a certain voltage to a light source 2. While the turning mirror 3 is turned, the light quantity detecting sensor 8 continues measuring a light LT, and it is integrated by the integrator 9. The timing control circuit 12 turns off an on/off switch 10 again; and at this time, the integrator 9 keeps a certain output S, and it becomes a measured value of the light LT transmitted through the microfilm 1. When the light LT reaches a copy system 6, the exposure adjusting circuit 11 adjusts the voltage of the light source 2 to a proper value on a basis of the output S and a correct exposure target value REF. Thus, the quantity of light in a wide range is measured to attain inexpensively a copy corresponding to the density of the microfilm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic exposure adjustment mechanism for a microfilm league printer for obtaining copies according to the density of the microfilm.

Generally, a league printer has a light source 2 that irradiates the microfilm 1 and a rotating shaft 3, as shown in Fig. 1.
A rotating mirror 3 that rotates around the light source 2 to change the optical path from the light source 2 to a copy system or a screen system;
A mirror drive system 4 that switches by rotating, a screen system 5 that projects an enlarged image of the microfilm l onto a screen, a copy system 6 that makes a copy of the microfilm l, and a screen system 5 that operates the mirror drive system 4. Alternatively, the copy system 6 is configured with a changeover switch 7 for switching the copy system 6.

In such a configuration, in the screen mode for viewing an enlarged image of the microfilm 1, the rotating mirror 3 is in the position shown by the solid line in FIG. The optical path is changed through the moving mirror 3 and reaches the screen system 5. Therefore, microfilm l
Enlarged images of each frame are successively projected onto the screen each time the microfilm 1 moves in the M direction. If some of these frames require copying, the switch 7 operates the mirror drive system 4 to switch to the copy mode, and the rotating mirror 3 is moved to the position shown by the broken line in FIG. Rotate it in the N1 direction until it reaches . At this time,
The light from the light source 2 passes through a predetermined frame of the microfilm 1 and reaches the copying system 6 as it is without changing the optical path by the rotating mirror 3. Therefore, a copy of a predetermined frame of the microfilm l can be obtained by the copying system 6. When copying with this copy system 6, for example, when copying black or other characters written on white paper, there is almost no need to adjust the exposure from the initial setting, but when the pack is not white, such as gray, If you copy it as is, the entire image will be black and difficult to see, so you will need to adjust the exposure. Furthermore, when copying microfilm as a document as in a league printer, the density of the microfilm, which is the background of characters, differs for each development, and there is considerable variation, so exposure adjustment is required.

The automatic exposure adjustment mechanism of conventional league printers uses several light detection sensors to determine the exposure amount,
It is necessary to separately provide a mechanism for scanning the sensor, which has the drawback of increasing costs. Therefore, an object of the present invention is to provide an automatic exposure adjustment mechanism for a league printer that is inexpensive and does not require a special scanning mechanism by attaching a sensor to a rotating mirror and utilizing the movement of the rotating mirror. It is in.

This invention will be explained below.

This invention provides a light amount detection sensor (for example, a photodiode) 8 with a small light-receiving area at a position across the optical path of the rotating mirror 3 of the league printer shown in Fig. NS1, for example, at the tip position B on the opposite side of the rotating shaft 31, and The light amount of the light source 2 is adjusted according to the output detected by the light amount sensor 8 when the mode is switched from the copy mode to the copy mode.

FIG. 3 is a block diagram showing an embodiment of the present invention, in which the microfilm l shown in FIG. 1, the light source 21, the rotating mirror 3. Mirror drive system 4. Screen system 5. In addition to the copy system 6 and the changeover switch 7, a scene detection sensor 8 and a light amount detection sensor 8 provided at the tip B of the rotating mirror 3
an integrator 9 that integrates the output of the light intensity sensor 8, an on/off switch 10 that controls input of the output of the light amount detection sensor 8 to the integrator 9, and an on/off switch 10 that controls the output of the integrator 9 and the appropriate exposure target value REF to adjust the voltage of the light source 2 appropriately. and an exposure adjustment circuit 11 that adjusts the exposure.

Copying system 6, a depending on the rotation state 9 position of the rotation mirror 3
Separator 9. On-off switch 10. :Jl light adjustment circuit 1
1 and a timing control circuit 12 that controls the timing of each operation.

In such a configuration, in the screen mode, the on/off switch lO is turned off, and the rotating mirror 3 is turned off.
is switched to the screen system 5 (solid line M in Figure 1), and the light LT emitted from the light source 2 and passed through the microfilm l reaches the screen system 5, and the enlarged image of the microfilm l is displayed on the screen system 5. be projected. At this time, since the reset signal R8 is output from the timing control circuit 12 to the integrator 9, the integrator 9 does not operate, and at the same time, the mode signal MU is output to the exposure adjustment circuit 11 to indicate that it is in the screen mode. Therefore, the exposure adjustment circuit 11
provides a constant voltage to the light source 2 for screen projection.

Next, if there is one that requires copying among the frames of the microfilm l that are being projected one after another on the screen system 5, the changeover switch 7 is turned over to switch to the copy mode. As a result, the mirror drive system 4 is activated, and the rotating mirror 3 begins to rotate in the N1 direction. At this time, the timing control circuit 12 cancels the reset signal R9 that has been output to the integrator 9, and in order to turn on the on-off switch 10, the output of the light amount detection sensor 8 is input to the integrator 9 and integrated. . In addition, the timing control circuit 12 outputs a mode signal NO to the exposure adjustment circuit 11 to notify that the screen mode or copy mode has been switched, so the exposure adjustment circuit 11 applies a constant voltage to the light source 2 for light amount detection. give. While the rotating mirror 3 is rotating, the light amount detection sensor 8 provided at the tip B of the rotating mirror 3 detects the light L.
The amount of light continues to be measured across the optical path of T, and the output is integrated by an integrator 9. The timing control circuit 12 returns the on/off switch 10 to the OFF state at an appropriate timing based on the size of the document on microfilm L, the rotating position of the rotating mirror 3, etc. At this time, the integrator 9 outputs a constant output S. This is the measured value of the light LT emitted from the light source 2 and passed through the microfilm 1. When the rotating mirror 3 has finished rotating (the position indicated by the broken line in FIG. 1) and the light LT reaches the copy system 6, the timing control circuit 12 outputs a mode signal ND to the exposure adjustment circuit 11 to enter copy mode. In order to convey this, the exposure adjustment circuit 11 appropriately adjusts the voltage of the light source 2 based on the output S of the integrator 9 and the appropriate exposure target value REF. When the light LT whose exposure has been adjusted in this way reaches the copy system 6, the timing control circuit 12 outputs a copy start signal ST to the copy system 6. You can obtain a copy of the exposure amount. When such a properly exposed copy is obtained by the copy system 6, the timing control circuit 12 notifies the mirror drive system 4 of the completion of the operation, and the mirror drive system 4 rotates the rotary mirror 3 in the N2 direction to transmit the light LT. is switched from the copy system 6 to the screen system 5 to obtain the screen system C. That is, the timing control circuit 12 outputs the reset signal R8 again to the integrator 9 to reset the integrator 9, and sends the screen mode mode signal N to the exposure adjustment circuit +1.
By outputting O, a constant voltage for screen projection is applied to the light source 2.

As described above, the present invention uses a single light intensity detection sensor with a small light receiving area and measures the light intensity over a wide range by utilizing the movement of a rotating mirror without adding a separate mechanism for scanning the light intensity detection sensor. , it becomes possible to obtain copies at low cost according to the density of the microfilm.

In the above embodiment, the light amount detection sensor was positioned at the tip of the rotating mirror shown in FIG. It may also be provided at a position across the optical path, such as a position such as C in FIG. Furthermore, if an in-sensor parallel to the rotation axis 31 is attached to the rotary mirror to detect the amount of light, even more accurate measured values can be obtained. Furthermore, in the above embodiment, a method of adjusting the exposure amount by changing the voltage of the light source was used as an exposure adjustment method, but by keeping the voltage of the light source constant and providing a shutter in the copying system, an appropriate exposure can be achieved. A method may be used in which the exposure amount is adjusted by changing the value REF and the output S of the integrator 9 or by changing the appropriate exposure time.

Further, in the above embodiment, switching from the copy mode to the screen mode is automatically performed, but it may also be performed by inputting an instruction to a changeover switch.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a league printer, FIG. 2 is a diagram showing an example of the mounting position of a light amount detection sensor, and FIG. 3 is a block diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Microfilm, 2...Light source, 3...Rotating mirror, 4...Mirror drive system, 5...Screen system, 6...Copy system, 7...Selector switch, 8...
- Light amount detection sensor, 9... Integrator, 10... On/off switch, 11... Exposure adjustment circuit, 12... Timing control circuit. Applicant's agent Yuzo Yasugata

Claims (1)

[Claims] A light source for imaging each frame of the microfilm, a screen system for projecting an enlarged image of each frame, a copying system for obtaining a copy of each frame, and light emitted from the light source and passing through the microfilm. A printer comprising a rotating mirror that switches and guides the image to the screen system or the copy system, a mirror drive system that rotates and switches the rotating mirror, and a changeover switch for the mirror drive system, A light amount detection sensor is provided at a position across the optical path of the rotating mirror, and the amount of light passing through the microfilm is measured by scanning the light amount detection sensor using the rotation of the rotating mirror. Liegplink's automatic exposure adjustment mechanism is characterized by automatically adjusting the exposure amount of the copying system depending on the amount of light.