Copying machine

Disclosed is a copying machine which is provided with a cassette-loading area for allowing the loading of copy paper cassettes into a plurality of loading positions, a device for selecting any of these cassette-loading positions, and a timing roller that controls the timing of the transfer of copy paper fed from a selected cassette. The copying machine embodied by the present invention features a circuit for storing the timing data corresponding to the respective copy paper cassette loading positions and a device for driving the timing roller.

BACKGROUND OF THE INVENTION 
The present invention relates to a copying machine such as an 
electrophotographic copying machine. 
When operating any conventional copying machine capable of loading 
copy-paper cassettes into a plurality of loading compartments, the copying 
paper delivered from any of these cassettes temporarily stops at the 
position of the timing roller which is installed immediately before the 
photorecepter drum. Strictly speaking, the position where the copying 
paper completely stops slightly varies depending on the cassette's 
position. The copying paper delivered from the cassette comes into contact 
with the timing roller at different angles and loads. Therefore, the 
period of time it takes for the paper to arrive at the photoreceptive drum 
varies, thus causing each sheet of paper to reach the predetermined 
position of the photoreceptor drum at a different time. As a result, 
conventional copying machines often cause copy paper to deviate from the 
transference position according to the individual cassette-loaded 
position. In other words, if a specific cassette-loaded position slightly 
deviates within the allowance, the range of the entire deviation cannot be 
ignored taking the entire cassette-loaded positions into account. This 
eventually results in defective copying of the needed data such as more 
ineffective areas or failure in the image development. FIG. 6 is a typical 
representation of the deviation of the image transference positions taking 
place with conventional copying machine. As is clear from this, the 
deviation takes place with copy paper delivered from individual cassettes 
within 3 mm of the range. However, as a whole, a deviation of nearly 4 mm 
can be noted. 
SUMMARY OF THE INVENTION 
To eliminate the disadvantages inherent in conventional copying machines as 
described above, the present invention provides a useful copying machine 
capable of minimizing the deviation in the transference position. 
According to the present invention, the preferred embodiment provides means 
for storing the timing data dealing with each loaded position of the copy 
paper cassette as well as means for driving the timing roller in response 
to the timing data.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a simplified sectional view of an electrophotographic copying 
machine incorporating an automatic paper-feeding device with upper and 
lower cassettes. The reference numeral 1 indicates a copying lamp, a first 
mirror 2, fifth charger 3 for discharging the AC current, a first lamp 4, 
a first charger, 6 a lens, 7 the second charger for discharging the AC 
current, a light-exposure slit 8, a light-exposure self-compensating 
shutter 9, a fourth mirror 10, a second lamp 11, a post lamp 12, an upper 
paper-feeding roller 13, a weight roller 14, a lower paper-feeding roller 
15, a development unit 16, a timing roller 17, a photoreceptor drum 18, a 
third charger 19, a toner-stripping claw cleaning brush 20, a fourth 
charger 22 for discharging the AC current, 22 a suction unit 22, a cleaner 
unit 23, a toner-fixation roller 24, a heater lamp 25, a paper-delivery 
roller 26, a lock lever 27, a main motor 28, the third mirror 29, a second 
mirror 30, and a drum scraping claw 31. The reference numerals 32 and 33 
respectively indicate upper cassette loading position and lower cassette 
loading position, which load copy paper cassettes 34 and 35, respectively. 
FIG. 2 is a schematic sectional view of the upper cassette loading position 
32, the lower cassette loading position 33, the timing roller 17, and the 
transference position (arrowed A) of the photorecepter drum 18 of the 
entire mechanism shown in FIG. 1. As is clear from these drawings, the 
copy paper loaded in the lower cassette is fed by the lower paper-feeding 
roller 15 so that it comes into contact with the timing roller 17 in the 
horizontal direction. On the other hand, the copy paper loaded in the 
upper cassette is fed by the upper paper-feeding roller 13, which is then 
delivered to the timing roller 17 via the weight roller 14 before coming 
into contact with the timing roller 17. The reference numerals 36 and 37 
respectively indicate switches for detecting whether or not both the upper 
and lower cassettes have been loaded in their designated positions. 
FIG. 3 denotes the state in which the copying paper comes into contact with 
the timing roller 17. The reference numerals 38 and 39 respectively 
indicate copying papers fed from the upper and lower cassettes. The 
copying paper 38 fed from the upper cassette comes into contact with the 
timing roller 17 by force of the rotation of the weight roller 14 and the 
weight of the copy paper itself. Conversely, the copy paper 39 fed from 
the lower cassette is sent forward by the lower paper-feeding roller 15. 
After coming into contact with the timing roller 17, this copying paper is 
again sent forward for a specific period of time so that a wave can 
eventually be formed as shown in the arrowed position B of FIG. 3. The 
loop is formed because the lower paper-feeding roller 15 can no longer 
send forward the copy paper and the copy paper 39 is delivered only by 
means of rotation of the timing roller 17. A detector switch 40 detects 
whether or not the copying paper 39 correctly comes into contact with the 
timing roller 17. As is clear from FIG. 3, the copy paper 38 comes into 
contact with the lower roller of the timing roller 17 whereas the copy 
paper 39 has a tendency to come into contact with the interim position 
between the upper and lower rollers of the timing roller 17 or with the 
upper roller of the timing roller 17. Even under such conditions the 
control system of the copying machine sets the timing for activating the 
timing roller 17 so that the copy paper 39 can be forwarded to the 
transfer position (A in FIG. 2) at a specific time after being delivered 
from the timing roller 17. 
FIG. 4 is an operation flowchart describing the operation procedure for the 
copying machine related to the present invention. First, when the power is 
on, step 1 is entered, and the status of all the controller units and the 
contents of the memory are initialized. When the mode enters step 2, the 
heat roller is warmed up in step 3, and the controller identifies whether 
the warming-up operation is completed or not. If the warming-up operation 
is completed, the operator selects the cassette containing the designated 
copy paper by loading the required cassette or by pressing the 
cassette-select button. The loaded position of the selected cassette is 
stored in a specific area of the memory. 
FIG. 5 denotes the contents of the memory. Data related to the selection of 
the cassette-loaded position is stored in position M0-cassette of the 
memory shown in FIG. 5. If the print switch is pressed in this condition, 
the controller identifies this during step S5 as shown in FIG. 4 and then 
sets the required timing during step S6. Timing setting is executed by 
causing the value of the memory M0-pointer, shown in FIG. 5, to be 
designated by either memory M1 or M2. Memory area M1 stores the timing 
data when the copying paper is delivered from the lower cassette loaded 
position, whereas memory area M2 stores the timing data when the copying 
paper is delivered from the upper cassette loaded position. When step S7 
in FIG. 4 is activated, the controller causes optical units including the 
copying lamp and mirrors to shift. After a specific period of time, 
following departure of these units from their home positions, the timing 
roller 17 is rotated. Counting of this specific period of time is executed 
in accordance with the timing data mentioned above. The specific period of 
time is counted in accordance with the contents of the memory (either 
timing A or timing B) as designated by the M0-pointer shown in FIG. 5. 
In other words, after transferring the designated timing data to the 
counter of memory 3 as shown in FIG. 5, the contents of memory 3 are 
periodically increased, while the incremental content is identified by 
checking to see if it actually overflows. When the incremental content 
overflows, the controller rotates the timing roller. As is clear from the 
foregoing description, a copying machine incorporating the preferred 
embodiments of the present invention minimizes deviation of the image 
transference position to the copy paper by designating the cassette-loaded 
position and accordingly setting the optimum timing for the timing roller. 
Note that said timing data can also be adjusted independently after 
completing assembly of the copying machine. Even if the copy paper 
delivered from the selected cassette comes in contact with the timing 
roller at a different angle, since the tip positions of the copying papers 
eventually remain in accord with the latent image on the photoreceptor 
drum, the copying machine incorporating the preferred embodiments of the 
present invention eliminates any deviation in the image transfer position 
that might be caused by different paper cassette positions. 
While only certain embodiments of the present invention have been 
described, it will be apparent to those skilled in the art that various 
changes and modifications may be made therein without departing from the 
spirit and scope of the present invention as claimed.