GB2281055A - Mimeograph with editing stencil cutter. - Google Patents

Abstract

A printer in which a stencil is prepared from an original before printing has a function of printing the image at a selected position of a printing medium or sheet even when the image formed in a stencil is in a reduced or enlarged scale. <IMAGE>

Description

"PRINTER USING A STENCIL The present invention relates to a printer using a stencil which has a function of printing out a document image in a desired position of a printing medium even when the image formed in a stencil is in a reduced or enlarged scale.

A stencil cutting device capable of forming image information read from a plurality of documents in a single stencil is conventional and used with a printer operable with a thermosensitive stencil. Such a stencil cutting device may be implemented with a stationary platen to be loaded with a document. In this kind of device, so long as a plurality of documents to be read have sizes lying in an allowable range, their images can be formed in a single stencil in combination. Alternatively, the stencil cutting machine may be used in combination with a work station or a personal computer so as to edit the images of a plurality of documents or plurality of data on a display. Then, a single block copy will be produced and used to cut a stencil.A block copy for cutting a stencil may be prepared by a traditional scissors-and-paste job, i.e. combining the images of a plurality of documents by paste and scissors. Apart from the editing scheme, a system is known in which a plurality of documents of relatively small size are arranged side by side and formed in a single stencil continuously, as disclosed in Japanese Patent Laid-Open Publication No 21940/1990.

While the above-stated stationary platen scheme is capable of forming the images of a plurality of documents in a single stencil if their sizes are smaller than the maximum readable size, it cannot form images repetitively in a single stencil. The display scheme is not practicable unless the operator is expert in the manipulation of a work station or a personal computer.

The scissors-and-paste scheme has a problem that when some document images have been accidentally omitted from the block copy, a new block copy has to be produced to repeat a stencil cutting operation. Further, the last-mentioned continuous cutting scheme is disadvantageous in that the maximum readable size is limited to the maximum stencil cutting size.

A printer capable of printing an image formed in a stencil in any desired position of a printing medium has also been proposed, as disclosed in, for example, Japanese Patent Laid-Open Publication No 247164/1989. This type of printer reads an image of a document while transporting the document by document moving means to thereby cut a stencil, and prints out the image on a printing medium by using the cut stencil. The operating timing of the document moving means is automatically shifted to reduce the margin at the leading edge of a document, thereby shifting the image upward. As a result, the image position is maintained constant throughout all the printings. This kind of approach, however, causes the image of a document to be located in an unexpected position on a stencil and, therefore, on a printing when the image formed in the stencil is in a reduced or enlarged scale.

It is, therefore, an object of the present invention to provide a printer using a stencil which prints a document image in any desired positions of a printing medium even when the image is changed in magnification.

According to the present invention, there is provided a printer for reading image information from a document, writing said image information in a stencil by cutting said stencil, and printing out said image information in a predetermined position of a recording medium by said stencil having been cut, said printer comprising: marking means for marking a desired point on a document as a first observed point, and a position where said first observed point should be reproduced on a printing as a second observed point; and image moving means for moving an image carried on said document such that a pel of said first observed point on said documents coincides with a pel of said second observed point on said printing.

The invention will be further described by way of non-limitative example, with reference to the accompanying drawings, in which: Figures 1A to 1C are views for explaining a problem with a conventional printer; Figure 2 is a section showing an embodiment of the invention; Figures 3A, 3B and 4 show the movement of an image occurring in the second embodiment; Figure 5 is a block diagram schematically showing a control system for a printer using a stencil; Figure 6 is a block diagram schematically showing a specific construction of a main scanning direction magnification changing section included in the system of Figure 5; Figures 7A and 7B are timing charts demonstrating the operation of the magnification changing section shown in Figure 6; Figures 8 and 9 show the movement of an image in the main scanning direction;; Figures 10A and lOB show the movement of an image in the subscanning direction; Figures llA to llC are timing charts representative of the operation of a document feed motor and that of a stencil feed motor; Figure 12 is a flowchart demonstrating a specific operation of a CPU included in the system shown in Figure 5; and Figure 13 is a block diagram schematically showing the principle of the present invention.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

This pertains to a printer using a stencil which achieves the previously stated object of the present invention i.e., a printer capable of printing out a document image in a desired position of a recording medium even when the document image formed in a stencil is different in scale from the original document image.

A conventional printer of the type described, e.g. a printer described in Japanese Patent Laid-Open Publication 247164/1989 reads the image of a document while transporting the document by document moving means to thereby cut a stencil, and then prints out the image on a recording medium or sheet by using the cut stencil or master. The operating timing of the document moving means is automatically shifted to reduce the margin at the leading edge of the document. As a result, the image of the document is shifted upward to maintain the same image position throughout all the printings. The problem with this kind of implementation is that when the document image is changed in magnification in the event of cutting a stencil, it will assume an unexpected position on a stencil and, therefore, on a printing.Specifically, assume that a document 90 carrying an image 92 as shown in Figure 1A is twice enlarged. Then, as shown in Figure 1B, the image 96 will not be printed in the central area of a sheet 94, i.e. only upper part of the image 96 will be reproduced in a lower position of the sheet 94, as shown in Figure 1C. While the image 90 may be rearranged by a copier or similar equipment, then formed in a stencil, and then printed out to prevent the image 96 from being partly lost on the sheet 94, such a procedure is not practicable without degrading the image. The invention which will be described is free from the above-discussed problems.

Referring to Figure 2, an embodiment of the present invention is shown and implemented as a printer 100. As shown, the printer 100 has a scanner 104 for scanning a document 102 which is inserted therein. In the scanner 104, when a document feed motor implemented as a pulse motor 106 is energised, feed rollers 108 and 110 are rotated to drive the document at a predetermined speed to a transparent platen 122. As the document moves along the platen 112 past a reading line, a light source 114 illuminates it. The resulting reflection from the document is incident to a CCD image sensor 120 via a mirror 116 and a lens 118 and thereby transformed to an electric image signal. A stencil cutting section has a plotter 122 including a thermal head 124, and the scanner 104.As a stencil feed motor 126 included in the plotter 122 is energized, a platen roller 128 is rotated to pay out a stencil 130 from a roll. At the same time, the thermal head 124 writes an image in the stencil 130 in response to the image signal fed thereto from the image sensor 120 via an analog-to-digital converter (ADC) and an image processing section. The stencil 130 having been cut by the thermal head 124 is cut in a predetermined length by a cutter, not shown. Transport rollers 134 and 136 drive the cut length of stencil or master 130 to a printing section 132. In the printing section 132, a damper 140 clamps the stencil 130. As a print drum 138 is rotated by a motor in a direction indicated by an arrow in the figure, the stencil 130 clamped by the damper 140 is wrapped around the drum 138.Ink is supplied to the interior of the drum 138 from a reservoir, not shown, and oozes out through the holes of the drum 138 and the perforations of the stencil 130. A printing medium in the form of sheet 142 is fed by a feed roller 144. When the sheet 142 moves between the stencil 130 and a press roller 146, it is pressed with the result that the ink is transferred from the stencil 130 to the sheet 142. As a result, the image is transferred from the stencil 130 to the sheet 142. Then, the sheet or printing 142 is driven out to a tray 150 via a transporting section 148. The stencil 130 which has undergone the printing operation is released from the clamper 140 and drum 138 and then discharged to a box 152.

As shown in Figures 3A and 3B, assume that the operator desires to shift a particular point P0 on a document 102 to a different point P1 on a printing 154, twice enlarge the image 102a of the document 102 by using the point P1 as a reference and print out the enlarged image on the printing 154 as an image 154a. Both the document 102 and the printing 154 have a width of 2S (mm) in the main scanning direction (the scanning direction of the CCD 120 and the widthwise direction of the drum 138, respectively). The point P0 is located at a distance of X0 (mm) in the main scanning direction and a distance of g (mm) in the sub-scanning direction (transport direction) from the upper left origin P, of the document 102.The point P1 is located at a distance xl (mm) in the main scanning direction and a distance of y in the sub-scanning direction (transport direction) from the upper left origin P00 of the printing 154. The scanner 104 reads the point P0 by the image sensor 120 while the plotter 122 writes it in the stencil 130 as the point P1. In this instance, the shift and magnification change of the points P0 and P1 or the shift and magnification change of the image is carried out by an image moving means which includes first and second image movement control means, which will be discussed below. The first and second image control means may be considered in the main and sub-scanning directions independently.To begin with, the shift and magnification change in the main scanning direction (i.e. the first control means, will be described.

As shown in Figure 4, the position lo where the image sensor 120 reads the point P0 is represented by a unit called pel and produced by: ZO = 2532 + 15. 75 (xO - S) pels where 2532 indicates the center pel of the document 102 to be read, 15. 75 indicates the number of pels per 1 mm (i. e. 400 dots per inch or dpi), and S indicates a dimension which is one half of the width of the document 102. In the illustrative embodiment, the number of pels in the main scanning direction, i. e., the length of one line is assumed to be 5120 (5 x 210) pels.On the other hand, the position 11 where the thermal head 124 records the pel of the point P, is produced by: It = 2320 + 15. 75 (x1 - S) pels where 2320 is the position of the center pel of the stencil (i. e.

printing) to be written. In this manner, the pel positions of the points PO and P1 are determined by xO and xl, respectively.

As shown in FIG. 5, the image signal from the image sensor 120 of the scanner 104, including the point PO, is converted to a digital signal by an ADC 156. The digital signal is applied to an image processing section 158 to undergo shading correction, magnification change in the main scanning direction, binarization, etc. The output of the image processing section 158 is fed to the thermal head 124 of the plotter 122 to be written in the stencil 130. The shift of the image from the point PO to the point P1 in the main scanning direction as stated above is executed by the first image movement control means, hereinafter referred to as a main scanning direction magnification changing section which forms part of the image signal processing section 158.

As shown in FIG. 6 specifically, the main scanning direction magnification changing section has two line memories 160 and 162 and serves as a toggle memory, i. e., conditions the line memories 160 and 162 for a read mode and a write mode alternately. In this section, address counters 164 and 166 generate addresses independently of each other and delivers them to the line memories 160 and 162, respectively. The address counters 164 and 166 are each constructed to allow the associated line memory 160 or 162 to load a start address for starting reading out an image signal or starting writing an image signal. The line memories 160 and 162 are loaded with the start addresses at the beginning of each period of main scanning. The address counters 164 and 166 each has 13 bits and, in an enabled state, counts a clock CK which is synchronous to the pel signal. On reaching 213 = 8192, each of the address counters 164 and 166 returns to zero and starts counting the clock CK again. The address counters 164 and 166 each is enabled when the terminal E thereof is in a high level, counting up the clock CK. When the terminal E is in a low level, each address counter 164 or 166 is disenabled to stop counting the clock CK (neglects the clock CK).

First, the operation of the main scanning direction magnification changing section will be described with reference to FIGS. 6 and 7A and on the assumption that a document image should be written in a stencil in a reduced scale.

A signal ENLARGE changes to a high level when a document image should be written in a stencil in an enlarged scale. Rere, the signal ENLARGE is in a low level since the document image should be written in a reduced scale. In this condition, a signal YO is passed through an OR gate 168 to reach terminals S of selectors 170 and 172 and is directly applied to terminals S of selectors 174, 176, 178 and 180. The selectors 170-180 each outputs the input to a terminal A thereof via a terminal Y when the terminal S is in a low level or outputs the input to a terminal B when the terminal S is in a high level. The selector 176 outputs the inputs to terminals 1A and 2A via terminals 1Y and 2Y when the terminal S is in a low level or outputs the inputs to terminals 1B and 2B via terminals 1Y and 2Y.The signal YO indicates whether the line of a document being scanned in the main scanning direction is an odd line or whether it is an even line; it is in a high level when an odd line is scanned or in a high level when an even line is scanned. A signal WAIT periodically changes to a high level and a low level in a ratio corresponding to a magnification change ratio entered on an operation board 182, FIG. 5. The selector 170 selects either one of the signal WAIT and the high level in response to the signal YO from an Exclusive-OR gate 168 which indicates an odd line or an even line, delivering the selected input to the terminal E of the address counter 164.The selector 172 selects the signal WAIT or the high level in response to the signal YO from the OR gate 168 in the opposite manner to the selector 170, transferring the selected input to the terminal E of the address counter 162.

A signal LOAD changes to a low level when the last pel position (5119! of each even line of a document is main-scanned. The address counter 164 is loaded with data 0 selected by the selector 174 as a Start address. As the signal LOAD changes to a high level when the last pel position (5119) of each even line of a document is subscannned by the scanner 104, the address counter 166 changes to a high level and is loaded with data n selected by the selector 178 as a start address. A signal WR periodically changes to a high level and a low level in synchronism with the main scanning of each pel of the documents 102. The selector 176 selects the signal WR or the high level depending on the line being main-scanned, i. e.

an odd line or an even line and transfers it to the line memory 160. At the same time, the selector 3.76 selects the signal WAIT or the high level depending on the signal YO indicative of an odd line or an even line and delivers it to the line memory 162 in the opposite relation to the output to the line memory 160. As a result, when the scanner 104 scans an even line of a document, an image signal DATAIN from the image sensor 120 is written to the line memory 160 while an image signal written to the line memory 162 during the scanning of an odd line (preceding line) is read out of the memory 162 and outputted via the selector 180. At this instant, the address counter 164 receives the signal WAIT at the terminal E thereof via the selector 170 and, when the signal WAIT is in a low level, stops counting.As a result, the output signal AD1 of the address counter 164 changes, as shown in FIG. 7A. The line memory 160, therefore, writes one pel signal in a given address and then writes the next pel signal in the same address over the preceding pel signal. In this manner, the image signal DATAIN from the image sensor 120 is thinned to, for example, two-thirds in matching relation to the magnification change ratio, whereby the image is reduced in the main scanning direction.

The address counter 166 does not stop counting since the signal fed to the terminal E thereof from the selector 172 remains in a high level. Hence, the address counter 166 counts the clock CK continuously in an ordinary manner, using n as a start address. This causes the line memory 162 to read the image signal written thereto in a redu:ed scale and representative of the preceding line, according to the count of the address counter 166. When the scanner 104 main-scans an odd line of a document, the image signal DATAIN from the image sensor 120 is written to the line memory 162 while the image signal written to the line memory 160 during the main-scanning of an even line (preceding line) is read out of the line memory 160 and delivered via the selector 180.In this case, the address counter 162 receives the signal WAIT at the terminal E thereof via the selector 172 and, when the signal WAIT is in a low level, stops counting. As a result, the output signal AD2 of the address counter 166 changes, as shown in FIG. 7A. The line memory 162, therefore, writes a given pel signal in a given address and then writes the next pel signal in the same address over the preceding pel signal. Consequently, the image signal DATAIN from the image sensor 120 is thinned to, for example, two-thirds in matching relation to the magnification change ratio, reducing the image in the main scanning direction.The address counter 164 does not stop counting since the signal fed from the selector 170 to the terminal E thereof is in a high level, counting the clock CK one by one by using z as a start address.

Hence, the image signal written to the line memory 160 in a reduced scale and representative of the preceding line is read Out according to the count of the address counter 164. In this manner, the image signal DATAIN from the image sensor 120 is written to the line memories 160 and 162 alternately while being thinned on the basis of the magnification change ratio and is read thereoutof alternately to be delivered via the selector 180.

The main scanning direction magnification changing section allows a document image to be written in a stencil in an enlarged scale, as will be described with reference to FIGS. 6 and 7B.

To write a document image in a stencil in an enlarged scale, the signal ENLARGE changes to a high level while the signal YO is inverted by the OR gate 168 and then applied to the terminals S of the selectors 170 and 172. As a result, the signal WAIT is applied to the address counters 164 and 166 in the opposite relation to the reduction mode. Specifically, when an even line of a document is main-scanned by the scanner 104, the address counter 164 counts the clock CK one by one from zero with the result that the image signal DATAIN from the image sensor 120 is written to the line memory 160. On the other hand, the address counter 166 receives the signal WAIT at the terminal E thereof via the selector 172 and, when the signal RAIT is in a high level, counts the clock CK from the start address n. When the signal WAIT is in a low level, the address counter 166 stops counting and changes the output signal AD2 thereof, as shown in FIG. 7B. As a result, the line memory 162 reads out a given pel signal and then reads the same pel signal again out out of the same address. Consequently, the image signal is enlarged to, for example, three-seconds in the main scanning direction in matching relation to the magnification change ratio.

When the scanner 104 scans an odd line of a document, the address counter 164, receiving the signal WAIT via the selector 170 at the terminal E, counts the clock CK from the start address when the signal WAIT is in a high level. When the signal WAIT is in a low level, the address counter 164 stops counting the clock CK. As a result, the line memory 160 reads one pel signal out of a given address and then reads the same pel signal again out of the same address, thereby enlarging the image signal in the main scanning direction to, for example, three-seconds. The address counter 166 counts the clock CK one by one from zero in an ordinary manner, so that the image signal DATAIN from the image sensor 120 is written to the line memory 162 as it is.As stated above, the image signal DATAIN is written to the line memories 160 and 162 alternately as it is while the image signal DATAIN is read out of the line memories 160 and 162 alternately in an enlarged scale matching the magnification change ratio.

In the above-described manner, while an image signal is read Out of the line memories 160 and 162 from the start address n first, the start address n is set in association with the desired magnification change ratio. As a result, the point PO on the document 102 is shifted to the point P1 on the printing 154, i. e. , the pel signal at the point P, is read out of the line memories 106 and 162 at the adequate timing of pel position 1l.

How a document image is moved will be described by taking printing in a reduced scale as an example.

As shown in FIG. 8, assume that the pel positions of the points PO and P, are lo and li, respectively. When the image signal DATAIN is written to the line memory 160 or 162, it is thinned in matching relation to the magnification change ratio with the result that the pel signal representative of the point P0 is written to an address lo x a (a: magnification change ratio) in the line memory 160 or 162. At the time when such a pel signal is read out of the line memory 160 or 162, the Start address n is set up in association with the magnification change ratio a and other factors. The pel signal of the point PO is read out of the line memory 160 or 162 at the timing of a pel position corresponding to the point P,.The start address n is calculated by a calculating means from alpha, lo and l1, as follows: n = alO - 11 + 8196 Since Lo and lt are determined as stated earlier n = c (2532 + 15. 75 (xO - S)) - (2320 + 15. 75 (x1 - S)) + 8196 When n is equal to or greater than 8196, (n - 8196) is selected as n. By so determining n on the basis of the positions xO (mm) and X1 (mm) on the document 102 and the printing 154, respectively, it is possible to move the image of the document 102 such that the point Po coincides with the point P1.

To print out an image in an enlarged scale, it is moved by the following procedure. As shown in FIG. 9, to move the point PO on the document 102 to the point P1 on the printing 154, the image data DATAIN is written to the line memories 160 and 162 as it is. When the image data DATAIN is read out of the memories 160 and 162, the up-counting of the address is intermittently stopped with the result that part of the data DATAIN overlaps when read out. As shown in FIG. 9, the start address n is set in matching relation to the magnification change ratio a and other factors in the event of read-out. Hence, the pel signal of the point Po is read Out of the line memory 160 or 152 at the timing of a pel position corresponding to the point Pl.

The start address n is produced from a, Z0 and lt, as follows: n = 11 - lo /a Since 2o and li are determined as stated earlier, n = (2320 + 15. 75 (x, - S)} - (2532 + 15.75 (Xo - S)) / c If n is smaller than zero, (n + 8196) will be selected as n. In this manner, the image of the document 102 can be enlarged by being moved such that the point Po thereof coincides with the point P1 of the printing 154.

Hereinafter will be described the movement of an image in the subscanning direction, i.e. the second image movement control means.

In an ordinary stencil cutting mode which does not move an image, an image positioned at the leading edge of the document 102 is written in the stencil 130 from a line a, FIGS.

10A and 10B. As shown in FIG. 5, a microcomputer (CPU) 184 controls a document feed motor 188 and a stencil feed motor 190 in response to a magnification c entered on the operation board 182, a document width signal from a document width sensor 186, etc. As shown in FIG. 11c, the CPU 184 turns on the motors 188 and 190 at the same time. The transport speed of the stencil 130 is determined by the dot density particular to the thermal head 124 and the time necessary for one line of image to be formed in the stencil 130; the stencil 130 is transported at a constant speed with no regard to the magnification a. On the other hand, the document 102 is transported at the same speed as the stencil 130 when the magnification of the document 102 is xl.When the magnification is other than xl, the CPU 184 changes the speed of the document feed motor 188, i. e. , the transport speed of the document 102 in association with the magnification a, thereby changing the magnification in the subscanning direction. For example, when the magnification change ratio is 200 %, the transport speed of the document 102 is halved, compared to a magnification xl; when the former is 50 %, the latter is doubled. The document width sensor 186 determines the width of the document 102 whose image should be read by the scanner 104. It is, therefore, seen that the second image movement control means includes CPU 184, feed motors 188, 190, document width sensor 156 and operation board 182.

As shown in FIG. 10A, assume that an image positioned at the point of the document 102 which is I (mm) advanced from the ordinary point should be positioned at the line a of the stencil 130. Then, as shown in FIG. 11 A, the CPU 184 energizes the document feed motor 188 later than the stencil feed motor 190 by a time corresponding to the distance 1 (mm), advancing the point P, than the point PO. In this case, since the image extending over a distance yO (mm) on the document 102 in the subscanning direction is moved to a distance y, (mm) on the printing 130, (y0 - I) a = y, Therefore, 1 = Yo - Yi / a As shown in FIG. 10B, assume that the image at the leading image of the document 102 begins to be formed in the stencil 130 at a point where the stencil 130 has been transported by the distance 1 (mm). Then, the CPU 184 turns on the document feed motor 188 later than the stencil feed motor 190 by a time corresponding to the distance I (mm), advancing the point P, than the PO in the subscanning direction. In this case, 1 + yo a=yl Therefore, 1 = y, - y0 a Referring to FIG. 12, a specific operation of the CPU 184 will be described.When the user desires to move and change the magnification of the image of the document 102 on a printing, the user manipulates the operation board 182 to mark the desired point PO of the document 102 by coordinates as a first observed point, to mark the point P1 where the first observed point should be reproduced on a printing by coordinates as a second observed point, and to enter a desired magnification change ratio a. The CPU 184 determines a start address n in the main scanning direction and a displacement I in the subscanning direction by substituting PO, P1 and c entered on the operation board 182 for the previously stated equations.At the same time, the CPU 184 determines a direction in which the image should be moved in the subscanning direction (forward or rearward) . Then, the CPU 184 loads the image signal processing section 158 with such values and direction and deliver them to the selector 174 and 178, thereby moving the image in the main scanning direction. For this purpose, the CPU 184 feeds the previously stated signals YO, ENLARGE, WAIT and LOAD to the image signal processing section 158. Further, when the image should be moved forward in the subscanning direction, the CPU 184 turns on the document feed motor 188 and, after the document 102 has moved the distance 1 (mm) in the subscanning direction, turns on the stencil feed motor 190. At the same time, the CPU 184 sends a command to the plotter 122 for causing it to start cutting the stencil 130.As a result, the document image is written in the stencil 130 in an advanced position in the sub scanning direction. When the document image should be moved rearward, the CPU 184 turns on the stencil feed motor 190 and, after the stencil 130 has moved the distance I (mm) in the slsbscanning direction, turns on the document feed motor 188 while sending a start command to the plotter 122.

Consequently, the document image is formed in the stencil 130 in a retarded position in the subscanning direction.

It is, therefore, seen that CPU 184 includes a means for supervising the amount of feed of a document and the amount of feed of the stencil in the sub-scanning direction, a speed changing means for changing feed speed of a document in matching relation to a magnification change ratio, a calculating means for calculating a displacement of the stencil, and a timing changing means for changing the point at which an image is formed in the stencil in matching relation to the displacement of the stencil.

While the illustrative embodiment uses coordinates in marking the points P0 and P1, it may use tables or similar implement for the same purpose. The points P0 and P1 may be marked either before or after the entry of the magnification a.

Figure 13 is a block diagram schematically showing the principle of the present invention.

In summary, the embodiment described above allows a document image to be located in a desired position on a printing even if it has been changed in magnification.

Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof, as defined in the claims.

This application was divided from copending application number 91 21556.6 which relates to a stencil cutter. That application concerns a stencil cutter in which a stencil can be moved so that a desired image can be written a desired number of times in desired, designated positions on the stencil.

Claims (7)

1. A printer for reading image information from a document, writing said image information in a stencil by cutting said stencil, and printing out said image information in a predetermined position of a recording medium by said stencil having been cut, said printer comprising: marking means for marking a desired point on a document as a first observed point, and a position where said first observed point should be reproduced on a printing as a second observed point; and image moving means for moving an image carried on said document such that a pel of said first observed point on said documents coincides with a pel of said second observed point on said printing.

2. A printer as claimed in claim 1, further comprising magnification changing means for changing the magnification of said image information.

3. A printer as claimed in claim 2, further comprising first image movement control means for controlling the movement of said image performed by said image moving means in a main scanning direction.

4. A printer as claimed in claim 3, wherein said first image movement control means comprises: two line memories; address counters each being associated with respective one of said line memories for loading a count start address independently of the other address counter, and intermittently stopping up-counting the address on the basis of a magnification change ratio; and calculating means for calculating a start address by using said first and second observed points.

5. A printer as claimed in claim 2, 3 or 4, further comprising second image movement control means for controlling the movement of said image performed by said image moving means in a subs canning direction which is perpendicular to the main scanning direction.

6. A printer as claimed in claim 5, wherein said second image movement control means comprises: supervising means for supervising the amount of feed of a document and the amount of feed of a stencil; speed changing means for changing the feed speed of a document in matching relation to a magnification change ratio; calculating means for calculating a displacement by using said first and second observed points and a magnification change ratio; and timing changing means for changing the timing for starting forming an image in a stencil in matching relation to said displacement.

7. A printer constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in Figures 2 to 13 of the accompanying drawings.