JPH0572572B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a printer that uses electrophotography to obtain a copy of a positive image from a negative original image recorded on a microfilm or the like.

[Conventional technology]

Conventionally, this type of apparatus illuminates a wider area than the frames of an image on a film, and forms the image on a photosensitive drum using a projection lens to obtain a hard copy.

Therefore, on the hard copy, toner adheres to the through-exposed portion corresponding to the outer edge position of the frame, resulting in a significant deterioration in aesthetic appearance. Furthermore, the amount of toner consumed is more than necessary, which is uneconomical.

Therefore, there is known a method of detecting an image area using an image sensor such as a CCD and shielding a photosensitive surface corresponding to the outside of the image area.

[Problem that the invention seeks to solve]

However, this method requires a complicated image sensor and image area discrimination circuit, and is very expensive.

The present invention provides an inexpensive alternative to the prior art devices described above.

B. Structure of the Invention [Means for Solving Problems] The present invention provides a printer that obtains a copy of a positive image from a negative film in which the outside area of the image frame on which the negative image is recorded is substantially transparent. a light detection means for detecting transmitted light of the entire image frame and an outer edge area on four sides of the image frame; and a light detection means for blocking light directed toward the light detection means from the image frame area and the edge outer area; and a light shielding means that can be changed in the X direction and the Y direction, and the output signal of the light detecting means is changed by changing the blocking area by the light shielding means in the X direction or the Y direction while keeping the position of the light detecting means constant. The printer is characterized in that it detects a bending point of the light beam and sets a shielding area by the light shielding means based on the detected bending point.

[Operation] The entire light amount from the original image is detected and the output is used to shield the photoreceptor surface corresponding to the area outside the edge position of the original image, so the image area excluding the area outside the edge position can be correctly identified. It is possible to do this, and the number of operations required is small.

〔Example〕

FIG. 1 shows the arrangement of the main components of an example of a reader printer to which the present invention is applied.
It passes through a projection section consisting of a field lens 3, a projection lens 5, etc., and then a screen 8 via mirrors 7, 7'.
It is projected onto and observed.

When copying, mirrors 10 and 11 located at home positions 10H and 11H are moved onto the optical path from the projection section to perform a scanning motion and guide image light to the copying section.

The copying section is equipped with process equipment for electrophotographic image formation. 13 is a cartridge,
Some of the process equipment, such as a photosensitive drum 15, a developing device 17, and one or more of a primary charger and cleaning means (not shown) are incorporated.
19 is a pre-static discharge exposure lamp, 20 is a transfer charger, 2
1 is a copy paper cassette, 22 is a synchronous paper feed roller, 2
3 ₁ and 23 ₂ are paper feed rollers, and 25 is a fixing device. Since the structure and operation of the copying section are well known, the details thereof will be omitted.

In the present invention, the projection unit is provided with a light shielding means 4 for blocking light in an arbitrary region of the image light from the original image F, and a light amount detection means 6 for measuring the total light amount of the image light.
Sequence control is performed as follows.
Note that the light shielding member ₄₁ of the light shielding means 4 is placed at a position out of the optical path when observing the film image on the screen.

When performing a copying operation, the light shielding member 4 ₁ is moved over the negative image on the film F by the driving device 4 ₂ while the light amount detection means 6 detects the total amount of light from the original image prior to scanning by the mirrors 10 and 11. Let it scan. In the example of FIG. 2, when the light shielding plate 4 ₁ is moved to the left direction of the arrow a by a drive device such as a motor 4 ₂ and a friction pulley 4 ₂₁ to scan the image F1 to be printed, the right end 4 of the light shielding plate 4 _{1 11} deviates from the left edge f ₁₁ of the image F1, the change in the light amount suddenly changes greatly as shown at the bending point n of the image light amount curve in FIG.

The light amount change detection circuit ₄₃ receiving the signal from the light amount detection means 6 in the block diagram of FIG. 5 detects the above-mentioned bending point n.

The above optical path change detection circuit ₄₃ includes, for example, a differentiating circuit ₄₃₁ and a comparator ₄₃₂ as shown in FIG.
When the rate of change in the amount of light corresponding to the movement of the light shielding plate ₄₁ becomes less than a certain amount, the output of the comparator is inverted, and as shown in FIG.
Detect points.

If the light shielding plate 4 ₁ is moved in the direction opposite to the arrow a, the change in the amount of light suddenly becomes smaller, so that point n can be detected in the same way.

Based on the detection signal, the control circuit ₄₄ controls the light shielding plate drive circuit ₄₅ , and controls the light shielding plate driving device (motor).
4 Stop ₂ . The light-shielding plate 4 ₁ stops at the edge f ₁₁ that corresponds to the bending point n of the change in image light amount of the image F 1 and blocks light on the outer side of the edge f ₁₁ .

In the above manner, the other three edges f ₁₂ of image F1 ~
The outside portions of _f14 are also successively shielded from light by respective light shielding plates, thereby shielding the edges corresponding to the outside of the image area of the original image F1.

Next, when the scanning mirrors 10 and 11 are driven by a drive source (not shown) to scan the image light of the image projected by the projection lens 5, the image is projected onto the rotating photoreceptor 15, and the copying section The original painting is copied according to the electrophotographic process. In that case, image F
Since the outer portions of the four edges of No. 1 are shielded from light, the aforementioned edge stains will not occur during negative to positive reversal development.

In other embodiments, a liquid crystal light shutter, a PLZT light shutter, or the like may be used in place of the light shielding plate ₄₁ .

FIGS. 7 and 8 show other examples of an apparatus for detecting the edge position of an image on film F, in which a light-shielding plate ₄₁ is moved by a knob 25, and the amount of light is appropriately amplified and read by a meter 26. By rotating the knob 25, the boundary between the area where the meter changes greatly and the area where it hardly changes is found, and the knob is stopped there. Thereby, the edge of the image and the edge of the light shielding plate coincide.

FIGS. 9 and 10 show still another light amount detection device 6.
shows. A member 29 holding the silicon photocell 27 and photodiode 28 is rotated onto the projection optical path of the lens 5 by the sensor rotation solenoid 30 and shaft 31, and stopped at the chain line position when the curved point n is detected. It should also be placed at the chain line position when printing. FIG. 11 shows an example in which the amount of light is detected using a scattering plate 32, an imaging lens 33, and a photodiode 34.

In the embodiment shown in FIG. 12, the image light is guided from the projection optical path of the lens 5 to the imaging lens 38 via the half mirror 37, and is imaged onto the silicon photocell 39.
A dot matrix liquid crystal shutter 40 is provided on the silicon photocell 39, and each cell is sequentially turned ON (or OFF) in the x direction and the y direction. 1st
FIG. 3 shows a block diagram of the system, in which the amount of light is detected by a silicon photocell 39, and the edges of the image are detected and controlled based on the relationship between the liquid crystal shutter control signal and the change in the amount of light.

Next, FIG. 14 shows an example of a light shielding means for shielding the outside of the image area during exposure.
The light shielding plates 18 ₁ and 18 ₂ on the exposure optical path are moved by motors 18 ₁₁ and 18 ₁₂ , and the image is vertically corrected based on the above-mentioned detection results. After that, scanning of the image is started, and the light shielding plate 18 ₃ is opened and closed by the exposure device drive circuit 4 ₆ (for example, a solenoid) in accordance with the scanning timing based on the above-mentioned detection results, and the horizontal direction of the image is adjusted. Obtain a copy.

C. Effects of the invention (1) Since the image area is detected by measuring the light amount of the entire original image, the image area can be correctly determined and malfunctions are reduced.

(2) Furthermore, since it is not necessary to provide a sensor corresponding to each edge of the document, the number of sensors can be reduced, and the device can be made inexpensive.

Furthermore, there is no need to move the sensor, which simplifies the structure of the device.

Conventionally, the image area has been detected using an image sensor such as a CCD, which has made the image sensor and image area discrimination circuit complicated and expensive.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a reader printer embodying the present invention, Fig. 2 is an enlarged view of main parts of a light shielding device, and Fig. 3 is a schematic diagram of a reader printer embodying the present invention.
The figure is an explanatory diagram of the operation of the light shielding member, Fig. 4 is an explanatory diagram of the change in the light quantity of the film image, Fig. 5 is a block diagram of the control system, Fig. 6 is an example of the light quantity detection circuit, and Fig. 7 is an explanatory diagram of the change in the light quantity of the film image.
8 is an embodiment of a manual edge detection device, FIGS. 9 to 12 are other embodiments of the light amount detection means, FIG. 13 is a block diagram of the control system of FIG. 12, and FIG. 14 is a block diagram of the control system of FIG. An example of a light shielding means for a light shielding body. 1 is a light source for film illumination, F is a film, 4,
18 is a light shielding means, 6 is a light amount detection means, 15 is a photoreceptor, F1 is a film image, and f ₁₁ to f ₁₄ are edges of the image.

Claims (1)

[Claims] 1. In a printer that obtains a copy of a positive image from a negative film in which the outside area of the image frame on which the negative image is recorded is substantially transparent, the transmitted light of the entire image frame and the outside area of the four sides of the image frame is a light detecting means for detecting; and a light shielding means for blocking light directed toward the light detecting means from the image frame area and the outer edge area, the blocking area being changeable in the X direction and the Y direction; The bending point of the output signal of the light detecting means is detected by changing the blocking area by the light blocking means in the X direction or the Y direction while keeping the position of the light detecting means constant, and based on the detected bending point. A printer characterized in that a shielding area is set by the light shielding means.