Trimming copying machine

In a trimming copying machine, a document is scanned in one direction and a copy paper is fed corresponding to this scanning motion such that an image of only a specified area of the document is obtained. The user sets the distance between the starting point of the scan and the backward edge of the specified area away from the starting position of the scan and the machine's control system determines whether the image will protrude from the copy paper position. The feeding of the copy paper is appropriately delayed such that the enlarged image will not stick out of the paper position.

BACKGROUND OF THE INVENTION 
This invention relates to a trimming copying machine and more particularly 
to a copying machine capable of preventing an enlarged image from sticking 
out of the copy paper position when only a specified area of an original 
document is copied. 
There have been known trimming copying machines capable of copying only a 
specified portion of an original document and also those capable not only 
of trimming but also of enlargement and reduction. With a conventional 
trimming copying machine, however, the enlarged image of a specified area 
frequently sticks out of the copy paper position and this occurs 
especially when the specified area is near the backward edge of the 
scanned range. This is illustrated in FIG. 5 wherein G indicates an 
original document to be scanned in the direction indicated by the arrow 
.alpha., g.sub.1 and g.sub.2 respectively indicate the starting position 
and the end position of the scan and L indicates the width of the document 
G in the direction of the scan. Let us assume that a rectangular area A is 
to be copied with magnification M. The sides of the specified area A 
proximal to the starting position g.sub.1 and to the end position g.sub.2 
of the scan (the left-hand and right-hand sides in FIG. 5) are indicated 
respectively by a.sub.1 and a.sub.2 and are hereinafter also referred to 
as the forward edge and the backward edge, respectively. The distance 
between the starting position g.sub.1 of the scan and the forward edge 
a.sub.1 of the specified area A is indicated by l and that between the 
starting position g.sub.1 and the backward edge a.sub.2 of the area A is 
indicated by l'. 
With a conventional trimming copying machine, not only the specified area A 
but also the distances l and l' of its boundaries from the starting 
position g.sub.1 of the scan are magnified by the same factor M. Thus, if 
B indicates the enlarged image of the specified area A, its forward edge 
b.sub.1 is at a magnified distance lM from the starting position p.sub.1 
of the scan on the copy paper P and its backward edge b.sub.2, likewise, 
is at another magnified distance l'M from the starting position p.sub.1 of 
the scan. If the dimension of the paper P in the direction of the scan is 
also L and if L is smaller than l'M, the image B sticks out of the copy 
paper position and the protruding portion of the image becomes lost. With 
a trimming copying machine of a conventional type, therefore, a larger 
copy sheet is sometimes required to be used. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a trimming 
copying machine with which the loss of image of the type described above 
can be prevented. 
The above and other objects of the present invention are achieved by 
providing an improved trimming copying machine which, being of the 
conventional type as far as it feeds a copy paper corresponding to the 
scanning of an original document in one direction, comprises end distance 
setting means for setting the distance between the starting position of 
the scan and the backward edge of the specified area, calculating means 
for obtaining a difference by subtracting the length of the copy paper in 
the direction of the scan from the product of the aforementioned distance 
and specified magnification, and paper feed delay means for delaying the 
timing for starting to feed to copy paper by a time period which 
corresponds to the aforementioned difference, if this difference is 
positive. 
With a trimming copying machine thus comprised according to the present 
invention, the aforementioned product represents the distance between the 
starting position p.sub.1 of the scan of the copy paper and the backward 
edge b.sub.2 of the image B and the aforementioned difference, if it is 
positive, indicates the distance by which the image protrudes from the 
copy paper position, that is, the length of the portion of the image which 
is lost. In other words, there is no loss of image if this difference is 
zero or negative because the image does not stick out of the paper 
position in this situation. If the difference is positive, therefore, the 
aforementioned delay means serve to delay the feeding of the copy paper 
according to the distance by which the image sticks out of the paper 
position. This delay in timing is equivalent to moving the end position of 
the scan backwards to the backward edge of the image so as to prevent the 
loss of image.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 wherein symbols defined above in connection with FIG. 5 indicate 
equivalent or similar parts and values, numeral 1 generally indicates a 
trimming copying machine embodying the present invention. A portion of the 
original document G placed on the glass plate 2 is optically taken out by 
means of a mirror 3, etc. and is made incident into a zoom lens 4 which 
forms a slit-like image on the surface of a photosensitive body 5. The 
mirror 3, etc. move in the direction of the arrow .alpha. to scan the 
entire surface of the document G and the photosensitive body 5 
correspondingly rotates in the direction of the arrow .beta. such that the 
image of the entire document G is formed on the photosensitive body 5. 
Magnification of the image is determined by the magnification by the zoom 
lens 4 and also by the ratio between the scanning speed of the mirror 3, 
etc. and the speed of rotation of the photosensitive body 5. 
The image formed on the photosensitive body 5 is an electrostatic latent 
image which is made visible as a toner image by a developing device (not 
shown). When trimming is effected, static charge is erased by means of a 
charge erasing device (not shown) everywhere except for a predetermined 
specified area such that the image becomes visible as a toner image only 
in such a specified area. 
Copy paper is taken out of a paper cassette 6 by the operation of a feeder 
roller 7. After it is made to wait by stopping rollers 8 so that its 
motion will be synchronized with the rotation of the photosensitive body 
5, it is moved at the same speed as the speed of rotation of the 
photosensitive body 5. In other words, if l.sub.1 is the distance between 
the image forming point I.sub.1 on the photosensitive body 5 corresponding 
to the starting position g.sub.1 of the scan and the image transfer 
section 9 and if l.sub.2 is the distance between the stopping rollers 8 
and the image transfer section 9, the paper waits at the stopping rollers 
8 until the photosensitive body 5 rotates by l.sub.1 -l.sub.2 before it is 
advanced to the photosensitive body 5. This is how the position on the 
photosensitive body 5 corresponding to this starting point g.sub.1 of the 
scan is made to coincide with the forward edge of the paper. The toner 
image on the photosensitive body 5 is transferred onto the paper at the 
transfer section 9. The transferred image is fixed thereafter and this 
completes the process of copying. 
In FIG. 2 which is a block diagram of the control system of the trimming 
copying machine 1, numeral 12 indicates a microcomputer which controls the 
motion of the mirrors 3, etc., the setting and motion of the zoom lens 4, 
the rotation of the photosensitive body 5, the driving of the rollers 7 
and 8, etc. on the basis of the user's commands from a signal input device 
10 as well as a program stored in ROM 11. 
Next, the operation which characterizes the present invention for 
preventing the loss of image at the time of trimming is explained by way 
of FIGS. 3 and 4. Firstly, the operator enters through the signal input 
device 10 the distance l from the starting position g.sub.1 of the scan of 
the document G to the forward edge a.sub.1 of the specified area A. 
Secondly, the distance l' from the starting position g.sub.1 of the scan 
of the document G to the backward edge a.sub.2 of the specified area A is 
similarly entered. Next, magnification M is set and the size of the copy 
paper P is selected. For the sake of simplicity of explanation, it will be 
assumed hereinafter that the paper P is of the same size as the document 
G. 
When a print switch is pressed thereafter, the microcomputer 12 switches on 
the feeder roller 7 and a sheet of copy paper is taken out of the paper 
cassette 6 (S1). When the paper reaches the position of the stopping 
rollers 8, it is made to wait (S2) and the mirror 3, etc. are moved in the 
direction of the arrow .alpha. to start a scan (S3). The motion of the 
zoom lens 4 and the rotation of the photosensitive body 5 are also started 
simultaneously. Next, the distance l' and the magnification M are 
multiplied together (S4) and the distance L of the copy paper P in the 
direction of the scan is subtracted from the product l'M and it is checked 
whether the difference thus calculated is positive or negative (S5). If 
the product l'M is not greater than L, the backward edge b.sub.2 of the 
enlarged image B would be on the left-hand side of the backward edge 
p.sub.2 of the paper P. Thus, the paper is held at the stopping rollers 8 
for a time period given by (l.sub.1 -l.sub.2)/V.sub.0 where V.sub.0 
represents the speed by which the paper is transported to the 
photosensitive body 5 (S6 to S8). This situation is no different from the 
operation by a conventional trimming copying machine. 
If the product l'M is greater than L, a loss of image would result if the 
paper were fed in the conventional manner because a portion of the image B 
near its backward edge b.sub.2 sticks out of the paper position. The 
distance by which protrusion occurs is l'M-L. Thus, the paper P is made to 
wait at the stopping rollers 8 for a longer period of time given by 
{(l'M-L)+(l.sub.1 -l.sub.2)}/V.sub.0 before it is advanced to the 
photosensitive body 5 (S7 to S8). With this waiting period, the backward 
edge b.sub.2 of the image coincides with the backward edge p.sub.2 of the 
paper P and hence there is no loss of image. This operation is repeated 
until the specified number of copies have been made (S9). 
The foregoing description of a preferred embodiment of the invention has 
been presented for purposes of illustration and description. It is not 
intended to be exhaustive or to limit the invention to the precise form 
disclosed, and many modifications and variations are possible in light of 
the above teaching. Such modifications and variations that may be apparent 
to a person skilled in the art are intended to be included within the 
scope of the invention.