JPH0223862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to an electrophotographic copying machine, and more particularly, to an electrophotographic copying machine that aligns an original placed on a platen so that the center of a specified copy area coincides with the center of a sheet of paper. death,
Furthermore, if necessary, you can erase unnecessary image parts outside the specified area, or automatically enlarge or reduce the size of the copy image in the specified area to fit the paper size. The present invention relates to an electrophotographic copying machine equipped with a control means that allows

(Prior Art) As is well known, in conventional electrophotographic copying machines, the paper tray is loaded in a fixed position on the premise that the document is correctly placed at a pre-specified position on the platen. (2) Paper feeding timing is also fixed for each copying machine.

For this reason, when attempting to copy only a portion of a specified area of a document, the operator must take the specified area into consideration and place the document correctly on the platen, otherwise the resulting copy image of the specified area will be tilt or
Not only does the center of the copy image deviate from the center of the paper, but in extreme cases, the copy image protrudes from the paper, making it unusable.

In addition, unnecessary parts other than the designated area are also copied at the same time, making the copied image difficult to see.Furthermore, if there is a large difference between the dimensions of the designated area and the paper size, a small portion of the paper may be copied. There are disadvantages such as the image of the designated area being copied onto the copy, or the designated area extending beyond the paper. For this reason, the original standard, which was conventionally fixed to the original placing surface, has been changed to
You can set it to move freely in the X and Y directions,
Some devices are designed to match the set document standard with the edge of the paper. However, when the desired copy area is aligned with the edge of the paper in this way, the image tends to be biased to one side of the paper. formed unevenly at the top,
The problem was that it was unsightly.

(Purpose) The present invention has been made to improve the above-mentioned drawbacks, and its purpose is to ensure that the center of the resulting copy image and the center of the paper are aligned no matter where in the document the designated area is. The objective is to provide an electrophotographic copying machine that can match the

(Summary) In order to achieve the above object, the present invention first determines the center of the copy designated area of the original placed on the platen when starting copying, and then adjusts the direction of copy paper conveyance accordingly. so that the center in the direction perpendicular to coincides with the center of the specified copy area,
The feature is that the position of the paper storage tray can be adjusted, and a further feature is that the paper feeding start timing is delayed depending on the shift in the center of the designated copy area on the document. be.

(Example) The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic plan view and block diagram showing the main configuration and control circuit of an embodiment of the present invention.

The platen 11 for placing the original 12 includes
According to a known method, the X-direction document guide 13
and a Y-direction document guide 14.
In this specification, an XY coordinate plane is assumed in which the origin (0, 0) is the intersection of the two guides.

Markers are provided along the X-direction document guide 13 and the Y-direction document guide 14 to designate a desired copy area within the document 12.

These markers include an X-direction upper limit marker 15 and an X-direction lower limit marker 1 that specify the upper and lower limits in the X direction.
6, and a Y-direction upper limit marker 17 and a Y-direction lower limit marker 18 that specify the upper and lower limits in the Y direction. As each of the above-mentioned markers, known appropriate ones can be used.

In the example of FIG. 1, linear slide resistors 15R to 18R are used, each having sliders 15A to 18A mechanically interlocked with each marker 15 to 18.

Each of the slide resistors is arranged substantially parallel to the X-direction document guide 13 or the Y-direction document guide 14.
They are arranged as shown in the figure, and each is connected to the power source E in parallel.

Therefore, the potential of each slider 15A-18A represents the coordinate position of each marker 15-18.

As is clear from Figure 1, the designated area to be copied is a rectangular area surrounded by two sides A and C parallel to the X axis and two sides B and D parallel to the Y axis. be.

Here, the Y coordinates of sides A and C are Ymin,
Expressed as Ymax, the X coordinates of sides B and D are Xmin,
When expressed as Xmax, the X and Y coordinates Xc and Yc of the center 10 of the designated area 19 are expressed by the following equations (1) and (2), respectively.

Xc=Xmin+Xmax/2...(1) Yc=Ymin+Ymax/2...(2) Therefore, the Y coordinate Ya of the center 20 of the paper 21 stored in the paper tray 22 is calculated using the above formula (2). If it is equal to the value Yc, the specified area 19
The center line in the Y direction should match the center line in the Y direction of the paper 21.

For this purpose, it is obvious that the paper tray 2
2 may be translated from the illustrated position to the right by dY so that the center 20 of the paper 21 comes to the position indicated by 20a.

Here, when the paper tray 22 is set to the reference position, the Y coordinate Ya of the center 20 is the selected paper size and loading direction (vertical or horizontal position).
is known if it is known.

Therefore, the distance in the Y direction of the paper 21 to be moved is
dY can be calculated as follows.

Ya+dY=Yc dY=Yc-Ya=Ymin+Ymax/2-Ya (3) Next, a means for moving the paper tray 22 in parallel in the Y direction will be described.

The rotation of the tray motor 23 is changed (reduced) in speed by a gear box 24, and the threaded rod 25 is rotated. When the threaded rod 25 rotates, the paper tray 22 is translated parallel to the Y-axis to the right or to the left depending on the direction.

The encoder 26 generates a signal proportional to the number of rotations or the rotation angle of the tray motor 23. Here, for convenience of explanation, it is assumed that one pulse is generated for each rotation of the tray motor 23.

The home position switch 27 is set so that the paper tray 22 is placed in the correct reference position - that is, the original 12 of the same size as the paper 21 is placed correctly so that it contacts both the X-direction original guide 13 and the Y-direction original guide 14. When the center 20 of the paper 21
It is installed so as to be activated when it is loaded in a position that coincides with the center 10 of the document 12.

Therefore, (1) When loading the paper tray 22 or starting a copy operation, first set the paper tray 22 at the reference position - that is, activate the home position switch 27, (2) In response, the up-down counter 28
(3) When the tray motor 23 rotates forward and the paper tray 22 moves to the right (direction in which the Y coordinate increases), the encoder 26 (4) When the tray motor 23 rotates in the opposite direction and the paper tray 22 moves to the left (in the direction in which the Y coordinate decreases), the output pulse of the encoder 26 is added to the up-down counter 28. By subtracting it from the count value of the up-down counter 28, the count value of the up-down counter 28 will always represent the current position (Ya+dY) of the center 20 of the paper tray 22.

As the encoder 26, it is possible to use other types of encoders (for example, those that can directly display the rotational position of the tray motor 23), as well as encoders of a type that can directly read the moving position of the paper tray 22. Of course, you can also use other materials.

On the other hand, the copy designated area calculator 31 calculates the coordinates of each side A to D of the designated area obtained as described above.
Ymin, Ymax, Xmin, Xmax (analog values) are supplied, and as well as converting them to digital values,
The result is transmitted to the specified area center coordinate calculator 32.

The specified area center coordinate calculator 32 calculates coordinates Xc and Yc representing the center 10 of the specified area 19 based on the conversion data. The obtained coordinate Yc is
It is supplied to the comparator 33, where it is compared with the center coordinate (Ya+dY) of the paper 21 supplied from the up-down counter 28.

When the two do not match, the difference is supplied to the polarity discrimination driver 34. Polarity discrimination bar 34
The tray motor 23 is rotated in the forward direction or the reverse direction depending on the polarity of the difference, and the paper tray 22 is rotated.
move to the right or left.

The difference between the coordinates Yc and (Ya + dY) is the tolerance δ
When the Y coordinate of the center 10 of the designated area 19 matches the Y coordinate of the center 20 of the paper 21, the output of the comparator 33 decreases. Along with this, the tray motor 23 also stops, and the paper tray 22 stops.

By the above operation, the center 2 of the paper 21 in the Y direction is
0 is made to coincide with the center 10 of the designated area 19 in the Y direction.

The deviation of the center 10 of the designated area 19 in the X direction is corrected by adjusting the paper feed timing with respect to the operation timing of the optical system.

If the X coordinate of the center 20 of the paper 21 is Xa, then
In order to match the center 10 of the specified area 19 and the center 20 of the paper 21, the timing of paper feeding must be adjusted as follows.
The time T calculated from the regular time using the following formula (4)
Just delay it.

T = 1/2 (Xmin + Xmax) - Xa/V ... (4) where V is the scanning speed The delay time T is calculated by the paper feed timing delay time calculator 35 in FIG. 1, and the obtained delay is The delay time of the delay circuit 36 is determined according to the time T.

Therefore, the paper feed timing signal obtained in the conventional apparatus is delayed by the time T in the delay circuit 36, and is supplied to the paper feed mechanism 37 to start it.

As described above, the center 20 of the paper 21 is perfectly aligned with the center 10 of the specified area 19, so no matter which position on the original 12 is selected as the specified area, the center of the resulting copy image is It is always located at the center 10 of the paper 21, and a well-balanced copy image can be obtained.

It is clear that the above control operations can also be performed by a computer or the like. FIG. 2 shows a flowchart in this case, and the processing at each step will be explained below.

Step S1...When a document to be copied is placed on the platen and the positions of the upper and lower limit markers in the X and Y directions for specifying the copy area are set, the device first determines the position of each of these markers. - That is, read the coordinates of each side A, B, C, D of the rectangular copy designated area on the platen (Ymin, Xmin, Ymax, Xmax shown in Figure 1),
Store in appropriate memory.

Step S2...Based on the data obtained in the above step, the coordinates of the center of the specified area are calculated.
The calculation formulas are the above-mentioned formulas (1) and (2). The calculated center coordinates Yc and Xc are similarly read into an appropriate memory.

Step S3... The currently selected paper size (for example, B5, A4, B4, etc.) is read,
Numerical values Xa and Ya corresponding to 1/2 of the paper size in the X-axis and Y-axis directions are set in the X counter and Y counter, respectively. At the same time, the paper tray is driven to the home position and initialization is executed.

Step S4: The absolute value of the difference between the Y coordinate Yc of the center of the document and the Y coordinate Ya of the center of the paper is compared with a reference value δ, and it is determined whether the absolute value is larger than δ. If it is larger than δ, proceed to step S5; if not, proceed to step S8.

Step S5...The Y coordinate Yc of the center of the specified area is
Determine whether it is larger than the Y coordinate Ya of the center of the center, and if it is larger, proceed to step S6,
If it is not large, proceed to step S7.

Step S6...The tray motor is rotated in the positive direction by a unit amount, and at the same time, 1 is added to the Y counter to set Ya to (Ya+1).

Step S7...The tray drive motor is rotated by a unit amount in the opposite direction, and -1 is added to the Y counter. As a result, the count value of Y counter is
Changes from Ya to (Ya−1).

After completing step S6 and step S7, the process returns to step S4, and it is again determined whether the absolute value of the difference between Ya and Yc is larger than the reference value.

While the absolute value of the difference is greater than the reference value, the loop from step S5 to step S6 or from step S5 to step S7 is repeated.

When the Y coordinate Ya of the center of the paper becomes sufficiently close to the Y coordinate Yc of the center of the specified area and the difference therebetween is no longer larger than the reference value, the process proceeds to step S8.

Step S8...In order to compensate for the misalignment of the copied image due to the specified area on the original placed on the platen being offset from the center of the original, the actual start of paper feeding is set to the regular paper feeding timing. Calculate the time T to be delayed from.

The calculation of the delay time T is performed according to the above-mentioned equation (4). The delay time T thus obtained is set in a delay timer.

Step S9...It is determined whether a regular paper feed timing signal, which is originally generated in a normal copying machine, has been generated. It waits here until this signal is generated.

Step S10...If a regular paper feed timing signal is generated, the process advances to step S10 and a delay timer is started.

Step S11... It is determined whether the count value of the delay timer has reached T, that is, whether the delay time calculated in step S8 has elapsed.
This loop continues until this time has elapsed.

Step S12...If the determination in the previous step is satisfied, the process advances to step S12, where a paper feed signal is generated to actually feed the paper.

The subsequent processing is the same as in a normal copying machine, so its explanation will be omitted.

According to the embodiment described above, the center of the specified area on the document can be made to coincide with the center of the paper. However, in this case, if the size of the specified area is smaller than the size of the paper, unnecessary portions of the document will be copied, making it difficult to see the copied image.

The second aspect of the present invention solves these difficulties.
This is an embodiment, and a block diagram of its main parts is shown in FIG. In this figure, the same reference numerals as in FIG. 1 represent the same or equivalent parts.

Also, as is clear from the explanation below, the third
The configuration other than that shown in the figure may be exactly the same as that in FIG. 1.

The drum rotation amount detector 41 detects the rotation amount of a photosensitive drum (not shown) or the moving distance of the photosensitive drum surface, and can be, for example, an encoder that rotates in synchronization with the photosensitive drum.

However, the output of the drum rotation amount detector 41
Xrun must be the sum of the rotation angle from the exposure position to the eraser 49 or the distance along the circumferential surface of the photosensitive drum to the actual amount of rotation of the photosensitive drum or the moving distance of the surface of the photosensitive drum.

The eraser 49 may be any known suitable eraser, but in this case, the eraser 49 has a size approximately equivalent to one pixel.
The following description assumes that an array of LEDs (light emitting diodes) are arranged facing each other in a line parallel to the axis of the photosensitive drum along the circumferential surface between the exposure position and the development position on the photosensitive drum.

Each LED can be independently controlled to blink, and as you can see, the lit LED
The electrostatic latent image on the circumferential surface of the photosensitive drum corresponding to is erased.

The lower limit comparator 42 is the output Xrun of the drum rotation amount detector 41 and the output of the specified area calculator 31.
It compares with Xmin and produces a "1" output while Xrun is smaller than Xmin. The output is the OR gate 4
4 to the all-column lighting controller 45.

As a result, the all-column lighting controller 45 controls the eraser drive section 48 to light all the LEDs included in the eraser 49. Therefore, in FIG. 1, all electrostatic latent images on the photosensitive drum whose X coordinates correspond to the range from 0 to Xmin are erased.

The upper limit comparator 43 is the output Xrun of the drum rotation amount detector 41 and the output of the specified area calculator 31.
Xmax and produces a "1" output as long as Xrun is greater than Xmax.

The output is supplied to an all-column lighting controller 45 via an OR gate 44. As a result, the all-column lighting controller 45 controls the eraser drive section 48 to light all the LEDs included in the eraser 49.

Therefore, in FIG. 1, all electrostatic latent images on the photosensitive drum corresponding to the range where the X coordinate is larger than Xmax are erased.

On the other hand, the output Ymin of the specified area calculator 31 is supplied to the left end lighting controller 46. The left-end lighting controller 46 controls the eraser drive unit 48 to erase the electrostatic latent image on the photosensitive drum in the range to the left of the Y coordinate Ymin shown in FIG.

On the other hand, the output Ymax of the specified area calculator 31
is supplied to the right end lighting controller 47. The right end lighting controller 47 controls the eraser drive section 48 to
The electrostatic latent image on the photosensitive drum facing the range to the right of the Y coordinate Ymax shown in FIG. 1 is erased.

As described above, according to this embodiment, the electrostatic latent image in areas other than the designated area is erased before development, so that an image of only the designated area excluding unnecessary parts can be obtained as a copy image. .

Note that as the left end lighting controller 46 and the right end lighting controller 47 described above, any known appropriate ones can be employed. As an example, a diode array 51 is shown as 52 and 53 in FIGS. 1 and 4.
Ground plates 52 and 53 that are in sliding contact with the ground side terminals of the respective LEDs that make up the
It can be configured to move in conjunction with the upper limit marker 17 in the direction and the lower limit marker 18 in the Y direction.

Moreover, in the above-mentioned first and second embodiments,
When calculating the delay time, the calculation formula used is as shown in (4) above.
The following equation (5) can be used instead of the equation.

T=Xmin/V...(5) In this case, the tip of the specified area 19 (i.e.
In the case of FIG. 1, since the upper side B) is aligned with the leading edge of the paper 21, the copy image will not protrude from the paper.

The above description has been about the case where the paper tray 22 is set to the home position and initialization is executed. However, even when placing a new document 12 on the platen 11 and starting copying, the paper tray 22 is It is easily understood that unless the paper 21 is replaced, the coordinates of the center 20 of the paper 21 are already known, so the above-mentioned initialization operation can be omitted.

The processing procedure in this case is shown in the flowchart of FIG. As is clear from the comparison with Figure 2,
The flowchart in Figure 5 follows the steps in Figure 2.
Step S3 is defined as steps 1 to 1 of S3 as explained below.
It corresponds to the one changed to 3 of S3.

Step S3 1...Read the selected paper size (Xa, Ya).

Step S3-2: The newly read paper size (Xa, Ya) is compared with the value read and stored immediately before, that is, the old paper size, and it is determined whether or not the two are equal. If they are equal, the above-mentioned initialization process is not necessary and the process directly advances to step S4.

Step S3-3...New paper size (Xa,
If Ya) is not equal to the old paper size, proceed to this step and perform the same initialization process as described above. That is, the paper tray is driven to the home position, a new Ya is preset in the Y counter, and new Xa and Ya are stored.

(Modifications) In addition to the above, the present invention can be modified as follows.

(1) The size of the specified area, i.e. (Ymax−
Compare (Ymin) and (Xmax − Xmin) with the currently selected paper sizes 2Ya and 2Xa, and (B) If the paper size is smaller than the specified area, (B-1) Load larger size paper in advance. Either select a new one from among the trays currently available, or (a-2) calculate the required reduction ratio and make a reduced copy, or (b) if the paper size is larger than the specified area, 1) Similarly, use a smaller size paper.
Select a new one from the tray, or (2) calculate the possible enlargement ratio and make an enlarged copy.

According to the above modification, the size of the specified area is compared with the currently selected paper size, the necessary reduction and enlargement ratios are calculated, and the specified area on the document is copied to fill as much of the paper as possible. A flowchart for computer control is shown in FIG. 6, and each step will be explained below.

Step S1...The positions of the upper and lower limit markers in the X and Y directions are read, and the coordinates of each side of the copy designated area are Xmax, Xmin, Ymax,
Determine Ymin.

Step S2……Difference Xw between Xmax and Xmin and
Calculate the difference Yw between Ymax and Ymin to find the dimensions of the designated copy area.

Step S3……Currently selected paper size
Read 2Xa, 2Ya.

Step S4...The paper size 2Xa obtained in the previous two steps is compared with the X-direction dimension Xw of the specified area. If the two are equal, proceed to step S6, and the paper size 2Xa is the X-direction dimension of the specified area.
If it is larger than Xw, proceed to step S5.
Also, paper size 2Xa is the X direction dimension of the specified area.
If it is smaller than Xw, proceed to step S8.

Step S5...Previous step in the Y direction
Perform the same comparison as S4. If the two are equal, proceed to step S6, and the paper size is 2Ya.
is larger than the Y-direction dimension Yw of the designated area, the process advances to step S7, and the paper size is
If 2Ya is smaller than the Y-direction dimension Yw of the specified area, the process advances to step S8.

Step S6...Select and set the copy magnification to 1.

Step S7...Expansion rate in X and Y directions (2Xa/
Xw) and (2Ya/Yw), and select the smaller of the calculation results. In reality, it may not be possible to set the magnification obtained by calculation as it is, but in that case, select a magnification that is as close as possible to the smaller of the calculated magnifications and smaller than that, and then operate the device. Set to that value.

Step S8... Reduction rate in X and Y directions (Xw/
2Xa) and (Yw/2Ya), and select the larger one as the actual reduction rate. In addition,
As in the previous step S7, if the selected reduction ratio cannot be directly set on the device,
A value that is close to and larger than the selected reduction ratio is selected as the actual reduction ratio, and the device is set.

In the case of this modified embodiment, it is clear that the required image area on the photosensitive drum changes depending on the reduction/enlargement ratio. Therefore, Xmin, Ymin, used for controlling the eraser 49 in FIGS.
When the reduction and enlargement ratios are M, Xmax and Ymax need to be modified and used as follows.

(1) Xmin is Xmin−Xmax−Xmin/2(M−1) shall be.

(2) Xmax is Xmax+Xmax−Xmin/2(M−1) shall be.

(3) Ymin is Ymin−Ymax−Ymin/2(M−1) shall be.

(4) Ymax is Ymax+Xmax−Xmin/2(M−1) shall be.

(Effects) As is clear from the above description, according to the present invention, no matter which part of the document on the platen is designated, the center of the obtained copy image is always located at the center of the paper. This prevents the images from shifting excessively on the paper, and by aligning the centers in the paper feed direction, the copy image will always be located at the center of the paper, resulting in well-balanced copies. .

Furthermore, by erasing the electrostatic latent image corresponding to a portion other than the designated area on the original, only the necessary portion is copied, resulting in an extremely legible copy. In addition, especially when the dimensions of the specified area on the document are small or large compared to the paper size, it can be automatically enlarged or reduced to a size close to the paper size to achieve a well-balanced copy. An image is obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view and block diagram showing the main configuration and control circuit of an embodiment of the present invention, and FIG.
The figure is a flowchart showing the processing procedure when the present invention is implemented on a computer, etc., Figure 3 is a block diagram showing the main structure of another embodiment of the present invention, and Figure 4 is the left end lighting in Figure 3. A fifth schematic diagram showing a specific configuration example of the controller 46 and the right end lighting controller 47.
6 and 6 are flowcharts showing processing procedures in still other embodiments of the present invention, respectively. 11...Platen, 12...Original, 13...X
Direction document guide, 14...Y direction document guide, 1
5... X direction upper limit marker, 16... X direction lower limit marker, 17... Y direction upper limit marker, 18... Y direction lower limit marker, 19... Copy designation area, 21...
Paper, 22... Paper tray, 23... Tray motor, 25... Threaded rod, 27... Home position switch, 28... Up/down counter, 29
...Preset value memory, 31...Specified area calculator, 32...Specified area center coordinate calculator, 33...
Comparator, 34... Polarity discrimination driver, 35... Paper feeding timing delay time calculator, 36... Delay circuit, 37... Paper feeding mechanism, 41... Drum rotation amount detector, 42... Lower limit comparator, 43... Upper limit comparator, 45... All column lighting controller, 46... Left end lighting controller, 47... Right end lighting controller, 48... Eraser drive unit, 49... Eraser.

Claims (1)

[Claims] 1. The scanning direction of the original placed on the platen (hereinafter referred to as the X direction) and the direction perpendicular to this (hereinafter referred to as the Y direction)
Upper and lower limit markers are arranged in pairs along each of the X- and Y-direction original guides provided in the X-direction and the Y-direction, respectively, and are used to designate a desired area to be copied in each of the X- and Y-directions. , each X direction and Y direction of the upper and lower limit markers
a position detecting means for detecting the position in the direction; a desired copy area center calculating means for calculating the center position of the specified area based on the detection output of the position detecting means; and a size of the paper stored in the paper tray. paper size detection means for detecting the paper size corresponding to the X direction and the Y direction; and paper center calculation means for calculating the center position of the paper stored in the paper tray based on the detection output of the paper size detection means. An electrophotographic copying machine, comprising: an image forming control means for controlling an image forming means so that the center position of the specified area and the center position of the sheet coincide.