Copying machine with selective illuminations

A copying machine having a first plurality of individual light emitting elements can be selectively illuminated depending on the copy size desired. Corresponding second array of light emitting elements can define an erasing apparatus positioned adjacent a photosensitvie member. An operator can designate the area to be copied. Control apparatus can control the individual light emitting elements based on the set predetermined copying conditions.

FIELD OF THE INVENTION 
The present invention relates to a copying machine and more particularly to 
a copying machine comprising an illumination device having a plurality of 
light emitting elements aligned in a row with each of the light emitting 
elements being independently turned on or off. 
BACKGROUND OF THE INVENTION 
In a conventional electrophotographic copying machine, only one straight 
elongated linear tubular lamp is used for illuminating an original to be 
copied. The light image of the original can be transferred to a 
photosensitive member by scanning the tubular lamp with a scanning mirror 
under a platen on which the original is placed. The lamps most frequently 
used have such arrangement that a plurality of filaments for illumination 
are suspended in the tube with a predetermined equal space and the 
respective filaments are connected in series. In the copying machine using 
only one tubular lamp of the type as described above, if one of the 
filaments is cut, the copying machine can not be used. 
In the technical field to which the present invention pertains, it has been 
considered that only such elongated lamp could be used and the lamp should 
illuminate over the entire width of the platen simultaneously. However, 
according to the technical knowledge of the present inventors, there is no 
reason to illuminate the over all width of the platform for all kinds of 
size of an original. 
SUMMARY OF THE INVENTION 
An essential object of the present invention is to provide a copying 
machine which is able to make a copy by illuminating only a desired part 
of the original. 
Another object of the present invention is to provide a copying machine 
which is able to make a copy even if there occurs a partial fault in the 
light emitting device for illuminating the original. 
A still further object of the present invention is to provide a copying 
machine which is able to notice whether the required part of the original 
can be copied on the selected paper prior to actually making the copy. 
To accomplish the above objects, according to the present invention there 
is provided a copying machine for copying an image of an original placed 
on a transparent platform by illuminating the original and projecting the 
image of the original on a photosensitive member using a slit system, said 
copying machine comprising; 
an original illuminating means having a plurality of light emitting 
elements lined up in a row and movable relative to the original; 
erasing means having a plurality of light emitting elements disposed 
corresponding to the respective light emitting elements of the original 
illuminating means with one to one relation and lined up in a row so as to 
oppose the photosensitive member, and 
control means for controlling turning on and off of the respective light 
emitting elements of the original illuminating means and the erasing means 
based on copying conditions. 
The present invention has been made on the basis of the knowledge of the 
inventors as described above using a plurality of illumination lamps 
divided in the direction of the width of the platform. 
Actually when a plurality of light emitting elements divided in the width 
direction of the platform are used, there can be obtained various 
advantages. 
In case one of the light emitting elements is damaged, copying machine is 
still available using the light emitting elements that are operating well. 
The user of the copying machine can still make a copy even if there is 
some fault in the copy in case of an emergency. 
Further, the number of the light emitting elements that can be turned on 
can be defined as desired for example depending on the size of the 
original so as to prevent unnecessary light from entering to the operators 
eyes even if a copy is performed with the cover for covering the original 
opened. In addition, turning on the light emitting elements partly enables 
to illuminate only the necessary part of the original for making a partial 
copy. 
In case of a partial copy, by turning on only the necessary part of the 
light emitting elements, and by scanning the original by the light 
emitting elements which are turned on with a low speed, the user can see 
whether or not the necessary part of the original is scanned by the light 
passing through the original. 
Still further, the light intensity of each of the light emitting elements 
can be changed independently. Therefore, by controlling the light 
intensity of each of the light emitting elements by the signals of the 
light receiving elements each disposed to receive the light reflected from 
a part of the original illuminated by the corresponding light emitting 
element so that a copy having a uniform printing density can be obtained 
even if the density of the original is different part by part.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Copying Mechanism 
Referring to FIG. 1 of the drawings, there is shown an example of an 
electrophotographic copying apparatus. The electrophotographic copying 
apparatus comprises a photoreceptor drum 1 provided substantially at the 
central portion of the apparatus for rotation in the counterclockwise 
direction, and a main eraser lamp 2, a sub corona charger 3, a sub eraser 
lamp 4, a main corona charger 5, LED (light emitting diode) array 800 for 
erasing unnecessary charges, a developing device 6, a transfer charger 7, 
a copy paper separation charger 8 and a blade type residual toner cleaning 
device 9 disposed around the photoreceptor drum 1. The photoreceptor drum 
1 has a photosensitive layer formed on its cylindrical surface, which is 
sensitized and charged by passing through the eraser lamps 2 and 4 and the 
corona chargers 3 and 5. The photoreceptor drum 1 receives an exposed 
image transferred from an original to be copied through an optical system 
10. 
The optical system 10 is provided under an original platform 16 for 
scanning an image of the original, which platform 16 is formed by 
transparent material such as glass, the optical system 10 comprises a 
light source 700, movable mirrors 11, 12 and 13, a projection lens 14 and 
a projection mirror 15. A DC motor M3 drives the light source and the 
movable mirrors 11, 12 and 13 so that the light source 700 and the movable 
mirror 11 are moved to the left in FIG. 1 at the same speed as the 
circumferential speed v of the photoreceptor drum 1 which is constant 
regardless of changes in copying magnification while the movable mirrors 
12 and 13 are moved to the left in FIG. 1 at a speed of v/2n (n represents 
copying magnification and V represents the circumferential speed of the 
photoreceptor drum 1 and is constant regardless of changes in copying 
magnification). When the copying magnification is changed, the projection 
lens 14 is moved along the optical axis and the projection mirror 15 is 
moved along the optical axis with pivotal movement thereof, as hereinafter 
described with reference to a device for varying the copying 
magnification. 
In the left-hand direction in FIG. 1 of the copying apparatus, there are 
provided copy paper cassettes 20 and 22 respectively having copy paper 
feeding rollers 21 and 23 while a path for the copy paper is formed by 
pairs of rollers 24 and 25, a pair of timing rollers 26, a transport belt 
27, a fixing device 28 and a pair of discharged rollers 29. 
Referring to FIG. 3, showing the top face of the copying machine, on which 
a first knob 650 and a second knob 651 are slidably provided in slots 652 
and 653 defined along the lateral side 654 and the longitudinal side 655 
of the original platform 16. The position of each of the knobs 650 and 651 
is sensed by switches 601 through 604 so that the signal representing the 
position of the knobs that is the size of the original can be input to a 
control device shown in FIG. 5. The switches 601 through 606 are so 
arranged that when the knobs 650 and 651 are shifted along the slots 652 
and 653 corresponding to the any one of the sizes A5, A4, B5 and so on, 
any one of the switches 601 through 606 can be turned on. In order to 
detect the longitudinal attitude or lateral attitude of the original of A4 
or B5, any one of the switches 605 or 606 is turned on by shifting the 
knob 651. The terms of longitudinal attitude or lateral attitude of the 
original, means that the original is placed on the platform 16 with its 
longitudinal direction aligned to the longitudinal direction X of the 
platform 16 or the original is put on the platform 16 with its 
longitudinal direction aligned to the lateral direction Y. 
By combination of the operation of the switches 601 through 604, 605 and 
606 what papers of any one of A3 size or A4 size papers in the 
longitudinal attitude, A4 size paper in the lateral attitude, A5 size 
paper, B4 size paper or B5 size paper in the lateral attitude is placed on 
the original platform 16 can be detected. 
In the preferred embodiment, the copying magnification can be set within 
the range from .times.0.647 to .times.1.414 by a change of the 
magnification unit of 0.001, so that the copying magnification can be 
changed substantially continuously. In order to perform the magnification 
change, the lens 14 is adapted to be moved in the light path by the motor 
M4. Further, the mirror 15 can be moved in the light path for correction 
of the complex length of the lens and the mirror 15 also can be slightly 
vibrated so as to make the incident point of the light to the 
photoreceptor drum 1 at the same position. The arrangement is the same as 
disclosed in the U.S. Pat. No. 4,543,643, which is cited in this invention 
for reference. When the lens 14 and mirror 15 are moved to the position 
corresponding to the designatied magnification value, the speed of the 
scanner can be set corresponding to the designated magnification, and the 
scanner performs the scanning upon application of a signal of starting the 
scan. As the control device for the scanning, the arrangement disclosed in 
U.S. Pat. No. 4,561,771 can be used. 
FIG. 4 shows an LEDs array 700 for illumination with the respective LEDs 
designated 701 through 730 and another LED array 800 for erasing 
unnecessary images present in the space between two images or in the space 
of the edge parts of the photoreceptor drum 1 with the respective LEDs 
designated by 801 through 830. 
The respective LEDs are so arranged that a portion of the photoreceptor 
drum 1 to which the image of the portion of the original illuminated by 
the LED 701 corresponds to the area on the photoreceptor drum 1 to which 
the light of the LED 801 is projected. LEDs 702 through 730 and 802 
through 830 are respectively arranged in the same manner as described 
above. In an optical path of the optical system 10, there is provided a 
photo diode array 900 which is constructed from a plurality of photo 
diodes 901 through 930 lined up in a row and disposed corresponding to the 
respective LEDs 701 through 730. 
Contro1 Device 
In FIG. 2, there is shown a control panel 70 of the copying apparatus with 
the arrangement of a print key 71 for starting a copying operation, a 
numerical value display device 72 indicative of a number of four figures, 
ten keys 80 through 89 respectively corresponding to 1, 2, . . . 9, 0, an 
interruption key 90 for designating an interruption of the copying 
operation, a clear stop key 91, a copy paper selection key 92 for 
selectively designating the size of the copy paper provided in a plurality 
of stages and a plurality of keys 95 to 103 forming the copying 
magnification setting selecting device. 
A first group of copying magnification setting selection keys 95 through 98 
are arranged for selectively setting the copying magnification, and when 
one of the keys 95 to 98 is operated in a condition that a first switching 
key 99 for switching a magnification setting mode is operated to switch 
the control mode of the copying apparatus to a first magnification setting 
mode, the numerical value input through the ten keys 80 to 89 and 
displayed on the display device 72 is stored as the copying magnification 
value in a memory location corresponding to the operated key 95 to 98. 
With respect to a second group of magnification setting keys 100 through 
103, a predetermined copying magnification is previously set in each of a 
plurality of respectively corresponding memory locations so that a copying 
operation can be carried out on the basis of a preset value, without the 
necessity of setting of such value as in the case of the aforementioned 
first group of keys. Therefore, the present copying magnification can be 
selected and set in e.g., the manufacturing process with values generally 
used by the user as hereinafter described in detail. 
Thus, the first group of keys function to selectively set the copying 
magnification required by the user while for particular copying needs the 
second group of keys function to select preset copying magnification in 
the ratio of, e.g., A4 size to B5 size, B4 size to A4 size, A3 size to A4 
size or A4 size to A3 size in case of copying apparatuses to be used in 
Japan. However, since the values preset with respect to the second group 
of keys are general or calculated copying magnifications, a mechanical 
error or an error in design might cause the magnification of an actually 
obtained copy to slightly deviate from the preset copying magnification. 
That is, even if an equal size magnification of .times.1 is selected, the 
actually obtained copy might be, e.g., in an enlarged size magnification 
of .times.1.004 or in a reduced size magnification of .times.0.996. In 
such a case, a desired copying magnification can be obtained by operating 
a second switching key 104 (FIG. 1) to switch the control mode of the 
copying apparatus to a second copying magnification setting mode and 
setting selected values in the memory locations corresponding to the keys 
100 to 103 in a similar manner to the operation of the aforementioned 
first copying magnification setting mode. More particularly, a value of 
1.002 or 0.998 may be set with respect to an equal size magnification key. 
An original illuminating button 108 is provided on the control panel 70 for 
instructing to illuminate the original placed on the original platform 16 
by the light of the LED array 700 so that the image of the original can be 
seen from above. 
109 denotes a service man call lamp and 111 is a lamp for indicating that 
there is a fault of any one of the LEDs. A copy available display 110 
(described as copiable original in FIG. 2) shows, with size indicators 
such as A3, B4 and so on, the available copy size under a condition that 
any one of the LEDs is in a failure mode. 
In FIG. 5, there is shown a circuit for controlling the copying operation 
according to the present invention, which comprises a first CPU (central 
processing unit) 201, a second CPU 202, a RAM (random access memory) 203 
backed up by batteries, a switch matrix 204, a driving circuit 205 for 
driving the DC motor M3 for scanning an original document to be copied, a 
driving circuit 206 for driving the stepping motor M4 for changing the 
copying magnification and a decoder 207. Output terminals A1 through A7 
are respectively connected to switching transistors (not shown) for 
driving a main motor M1, a developing motor M3, a timing roller clutch 26 
(CL1), an upper paper feeding clutch CL2, a lower paper feeding clutch 23 
(CL3), the charger 5 (HV.1) and the transfer charger 7 respectively. 
In general, the various data are processed in CPU in the form of a binary 
code. Therefore, the input data entered from the peripheral equipments or 
sensors are represented by predetermined binary codes. Table 1 shows 
examples of the binary codes indicating the size of the copy paper used in 
the copying machine in this preferred embodiment. 
TABLE 1 
______________________________________ 
decimal code 
binary code paper size 
______________________________________ 
0 0 0 0 0 
1 0 0 0 1 A6 longitudinal 
2 0 0 1 0 B6 longitudinal 
3 0 0 1 1 A5 longitudinal 
4 0 1 0 0 B5 longitudinal 
5 0 1 0 1 A4 longitudinal 
6 0 1 1 0 B4 longitudinal 
7 0 1 1 1 A3 longitudinal 
8 1 0 0 0 
9 1 0 0 1 A5 lateral 
10 1 0 1 0 B5 lateral 
11 1 0 1 1 A4 lateral 
12 1 1 0 0 B4 lateral 
13 1 1 0 1 A3 lateral 
14 1 1 1 0 
15 1 1 1 1 cassette empty 
______________________________________ 
In FIG. 5, a drive control circuit 208 is provided for controlling light 
emitting of the LED arrays 700 and 800 the detail of the circuits is shown 
in FIG. 6. 209 denotes a control circuit for receiving the light 
measurement value fed from the photo diode array 900 which is provided for 
detecting the density of the original to be copied, the detail of which is 
shown in FIG. 7. 
Referring to FIG. 6, the terminal is connected with the LEDs 701 
through 730 through a photo coupler PHB1. The LEDs 701 through 708 are 
connected with the terminals PB0 through PB7. Similar to this arrangement, 
LEDs 709 through 730 are connected with the ports PA and PB. LEDs 801 
through 830 are respectively connected with the ports through and 
PD0 through PD7. Photo couplers PHB1 through PHB8 are connected with the 
ports PE0 through PE7 for detecting the fault condition of the respective 
LEDs. Referring to FIG. 7, photo diodes 901 through 930 are divided into 
four groups and connected with interfaces IC10 through IC13. The 
respective outputs of the interfaces IC10 through IC13 are connected with 
the fourth CPU 209 for inputting the light measurement values of the photo 
diodes 901 through 930. 
FIG. 8 through FIGS. 21 and 23 shows the flow chart showing an operation 
performed by the CPU 201 for a copying operation. FIG. 8 generally shows 
the respective operation. 
The first CPU 201 and the second CPU 202 communicates together by 
interruption. A scanning instruction of the optical system, scan size, 
copying magnification, timing signals, return signal and position signal 
etc. are communicated. The third and fourth CPUs 208 and 209 also 
communicate with the first CPU 201 by interruption. 
In FIG. 8, when it is detected that the switch 107 which is disposed in the 
left-hand in FIG. 1 of the copying apparatus is on in the step S0 after 
initialization, the process goes to a step S1, wherein copying 
magnification can be entered for storing various copying magnification 
values in the memories Q1 through Q4 in the manufacturing process of the 
copying machine particularly at the time of forwarding thereof. The detail 
of this operation is shown in FIG. 9. 
In a step S2, it is judged whether or not the respective LEDs 701 to 730 
and 801 to 830 are operative. The detail of the operation is shown in FIG. 
10. 
In steps S3 and S4, when the copying machine is not busy, the respective 
keys 95 to 98 and 100 to 103 are assigned to the magnification values 
corresponding to the magnification values stored in the memories Q5 to Q8 
and Q1 to Q4. The detail of the operation is shown in FIGS. 11 to 13. 
In the step S5, various data for controlling the position of the lens of 
the optical system 10 and the speed of the motor for setting the 
magnification values and so on based on the data entered in the step S4 
are transferred to the second CPU 202, which processes the entered data by 
interruption. The detail of this process is shown in FIGS. 14 and 15. 
In the step S6, the size of the original to be copied can be entered, the 
detail of which is shown in FIG. 16. The step S7 is a routine for 
illumination of the original to be copied, the detail of which is shown in 
FIG. 17. The step S8 is a routine for display of the fault condition of 
the LEDs, the detail of which is shown in FIG. 18. The step S9 is a 
routine for erasing unnecessary image in the space between two adjacent 
images of the original or in the space of the edge parts of the 
photoreceptor drum 1, the detail of which is shown in FIG. 19. The step 
S10 is a preliminarily scanning routine, the detail of which is shown in 
FIG. 20. The step S11 is a copying routine, the detail of which is shown 
in FIG. 21. The step S12 judges whether or not the predetermined time 
period for one routine is expired. The step S13 is conducted by the timer 
interruption to the first CPU 201 and is a LED duty control routine for 
controlling the periods of light emission of the respective LEDs, the 
detail of which is shown in FIG. 23. 
Said initialize switch 107 in the step S0 is provided in the interior of 
the copying machine so that only an engineer in the manufacturing process 
or service man can access the switch. When this switch 107 is operated, 
the operation routine shown in FIG. 9 is executed. 
FIG. 9, shows for presetting the various copying magnification value in the 
memories Q1 to Q4 corresponding to the keys 100 to 103. The copying 
magnification values preset in the memories Q1 to Q4 can be determined by 
on state or off state of the switches 105 and 106 which are disposed 
beside the switch 107. Specifically, when the switches 105 or 106 are made 
on or off corresponding to the contents of the specification of the 
copying machine in the process of the production or at the time of 
fowarding of the copying machine, the magnification values can be selected 
by the combination of the on state and off state of the switches 105 and 
106. Storing the copying magnification values in the memories Q1 through 
Q4 are executed after OFF operation of the initialize key 107. Table 2 
shows an example of the magnification values corresponding to the states 
of the switches 105 and 106. 
TABLE 2 
______________________________________ 
switch magnification 
105 106 Q1 Q2 Q3 Q4 
______________________________________ 
0 0 0.707 0.816 1.414 
1.000 
0 1 0.707 0.785 1.414 
1.000 
1 0 0.647 0.785 1.297 
1.000 
1 1 1.000 1.000 1.000 
1.000 
______________________________________ 
Referring to FIG. 10 showing the process of finding the fault condition of 
the LEDs, D register stores the serial number indicating the respective 
LEDs for example, with the initial value of the D register. The serial 
number 701 is set and the serial number is increased from 701 to 730 as 
the D register is operated. 
B register stores the serial number of the the LED groups. In the preferred 
embodiment the LEDs 701 to 730 and 801 to 830 are grouped so that each 
group consists of eight LEDs, and the fault of LEDs is detected in the 
group basis with eight LEDs dealt as one unit. The content of the B 
register represent the serial number of the groups. C register stores the 
serial number of the LEDs in each group. 
In the process of the flow chart of FIG. 10, steps S21 to S31 serve to 
detect the fault of the LEDs 701 to 730 and steps S32 to S43 serve to 
detect the fault of the LEDs 801 to 830. 
In this process, detection of the fault of the LEDs 701 to 708 is made 
first. In the step S21, a value 701 representing the LED 701 is entered in 
the D register. Also in the step S12, 0 is entered in the B register as 
the initial value. In the step S23, pulses are generated at the terminal 
of the control device 208 so as to illuminate the LEDs 701 to 708. 
What terminals of to generates the pulse depend on the content of 
the B register. Subsequently, the content of the C register is set to 0. 
In the step S25, the terminals PB1 to PB7 generate pulse signal 
sequentially and the content of the photo coupler PHB1 is input to the 
terminal PE0, so that it is judged in the step S26 whether the terminal 
PE0 is 1 or 0 for detecting whether or not each of the LEDs 701 to 708 is 
in the fault condition. In case of the presence of the fault in the LEDs, 
the content of the D register is transferred to a trouble memory so as to 
store the serial number of the fault LED. The same operations of the steps 
S23 to S31 are repeated so as to examine the respective LEDs 709 to 716, 
717 to 724 725 to 730. When the content of the B register becomes 4 the 
process advances to the step S32 for examining the LEDs 801 to 830 
repeating the same operations as described above to find the fault of the 
light emitting diodes. 
In the step S44, the trouble memory is examined and when a numeral except 
for 0 is stored, it is judged that there is a fault in LEDs and a timer TA 
is set in the step S44. The timer TA is used for displaying the available 
size of the original for copy and the selected paper size alternately in 
cooperation with a timer TB described in the explanation of FIG. 8. 
Referring to FIGS. 11 to 13, for setting the copying magnification in the 
memory locations Q1 to Q8 for the keys 100 to 103 and 95 to 98, at steps 
S101 and S102 in FIG. 11, a determination is made as to which group of 
keys setting of magnification is required when the switch 99 or 104 is 
operated to switch the control mode to the copying magnification setting 
mode. When the control mode is switched to the first copying magnification 
setting mode upon operation of the key 99, a value "1" is set in a flag A. 
On the other hand, when the key 104 is operated, the value "1" is set in a 
flag B showing the second copying magnification setting mode. 
When either the key 99 or 104 is thus operated, a process is effected for 
making the thousands digit flag "1" at the step S103 while making the 
units digit display "0" at the step S105. That is, when the control mode 
of the copying apparatus is switched to either magnification setting mode, 
a display "bbb0" (b indicates a blank) is shown on the display device 72, 
and the copying apparatus is in a stand-by condition for receiving an 
input from the thousands digit column. 
When the ten keys 80 to 89 are operated in the aforementioned condition, 
which of the keys 80 to 89 is operated is determined at a step S107, and 
the process is advanced to a step S108 only when a "1" key 80 is selected 
to indicate that the thousands digit flag is "1". The input values are 
expressed herein as the thousands digit, the hundreds digit, the tens 
digit and the units digit in consideration of the relation with the 
numerical value display device 72, though, it is to be noted that values 
indicating the copying magnifications are processed as decimal numbers 
ranging from down to three decimal places up to an effective number of 
four figures with three decimal places. 
In a case where the thousands digit flag is "1" and the input value is 0 or 
one of 2 through 9, the process is advanced to a step S110 for displaying 
"0" as the thousands digit. Then, if the input is "0", the process is 
advanced to a step S109 as in the case of "1" to make the thousands digit 
flag "0" while making the hundreds digit flag "1" for standing by an input 
to the hundreds digit column. On the other hand, when the input is one of 
2 through 9, the thousands digit display is made "0" at a step S112 and 
then the process is advanced to a step S115 to display the input value as 
the hundreds digit. 
The aforementioned process, effected when the thousands digit flag is "1", 
is based on the premise that values within the range of 0.647 to 1.414 are 
considered effective as the copying magnification values. Consequently, 
only "1" or "0" can be displayed as the thousands digit. By virtue of 
this, operation for inputting "0" as the thousands digit may be 
simplified. However, it is to be noted that, even in the aforementioned 
process, the copying magnification value might deviate from the 
aforementioned range depending on the values input below the hundreds 
digit. Such a case is hereinafter described with reference to a sub 
routine shown in FIGS. 11a through 11c and FIG. 12. 
The hundreds digit flag is made "1" upon input of a value to the thousands 
digit column, and when one of the ten key 80 to 89 is operated under this 
condition, a value corresponding to the operated key 80 to 89 is input in 
the hundreds digit column so that said value is displayed at a step S115 
and a process is effected at a step S116 to make the hundreds digit flag 
"0" while making the tens digit flag "1". Input of values to the tens 
digit and units digit columns is effected in a similar manner by operation 
of the ten keys 80 to 89. 
FIGS. 12a through 12c show a flow chart showing a process of storing the 
value input and displayed by the process of FIGS. 11a and 11b in a memory 
location corresponding to the selection key 95 to 98, 100 to 103 operated 
in the subsequent stage. 
At a step S201, a determination is made as to whether the control mode is 
in the first magnification setting mode or in the second magnification 
setting mode. Since the process of the step S201 is effected only when 
either the flags A or B is at "1", determination at the step S201 is 
carried out as to only whether or not, e.g., the flag A is "1". When the 
flag A is "1", the control mode is in the first magnification setting mode 
and the process is advanced to a step S218 for determination based upon 
operations of the first group of keys 95 through 98. When the flag A is 
not "1", i.e., when the flag B is "1", the control mode is in the second 
magnification setting mode and the process is advanced to a step S202 for 
determination based upon operations of the second group of keys 100 
through 103. 
In each of the steps as shown in FIGS. 12a through 12c, a basic process is 
effected in which a displayed value is stored in a memory location 
corresponding to the operated selection key 95 to 98, 100 to 103. However, 
in such a stage, a value deviating from an allowable range of the copying 
magnification might be displayed as hereinabove described. Therefore, in 
the process of FIGS. 12a through 12c, a sub routine indicated by a step 
S203 is effected following determination of the operation of each key 95 
to 98, 100 to 103 so that the deviating value is not stored in the RAM 
memory. FIG. 13 shows the process effected at the step S203. 
When the displayed value is not "0" in FIG. 13, a determination is made as 
to whether or not the displayed value is smaller than 0.647, and if the 
determination is "Yes", the value 0.647 is displayed at a step S231. 
Further determination is made at a step S232 as to whether or not the 
displayed value is larger than 1.414, and if the determination is "Yes", 
the value 1.414 is displayed at a step S233. 
Thus, with reference to FIGS. 12a through 12c, when a predetermined 
selection key is operated in a magnification setting mode and a displayed 
value is out of the allowable range, the display is considered an 
allowable limit value, and thereafter the displayed value is stored in a 
memory corresponding to the selection key. Upon effecting of the process 
for storing the value in the memory, the flag A is made "0" in case of the 
first magnification setting mode while the flag B is made "0" in case of 
the second magnification setting mode, and the process is advanced to a 
step S206. 
Steps S206 through S208 relate to processes effected upon operation of the 
clear stop key 91 (FIG. 5). When the clear stop key 91 is operated, "bbb1" 
is displayed in the display device 72 at the steps S207 and S208 while the 
flags A and B are made "0". That is, upon operation of the clear stop key 
91, the value that has been displayed is cleared and the magnification 
setting mode is released. Therefore, the value "1" displayed in this 
process is indicative of a reference value of the copy number. 
In FIGS. 14a through 15b, there are shown processes effected upon operation 
of the second group of selection keys 100 through 103 and the first group 
of selection keys 95 through 98 respectively. 
When one of the keys 100, 101, 102 and 103 is operated in FIGS. 14a and 
14b, one of light emission diodes 100a, 101a, 102a and 103a (FIG. 6) 
provided respectively in correspondence to the keys 100 to 103 is turned 
on so that the value stored in the corresponding memory location is 
transferred as the magnification data to the second CPU 202, and the 
process is advanced to a step S406 in FIGS. 15a and 15b. 
When one of the selection keys 95 through 98 is operated in FIGS. 15a and 
15b, the corresponding light emitted diode 95a to 98a is turned on while 
the values set in the memory locations Q5 through Q8 corresponding to the 
key is displayed in the display device 72 at steps S402, S408, S415 and 
S420 since the magnification can be selectively set in this condition. 
Such a display is effected only when, e.g., each of the respective keys 95 
to 98 is depressed, and upon releasing of the key 95 to 98, a selected 
magnification ratio stored in the other memory device is accessed to be 
displayed in the display device 72. 
FIG. 16 shows the original size input routine. In this routine, the size of 
the original can be detected by the combination of the states of the 
switches 601 to 606. The detected original size is stored in the memory. 
For example, in the steps S450 and S451 if it is detected that the 
switches 601 and 606 are on, it can be noticed that the size of the 
original is A4 with the lateral attitude. The way of other sizes and the 
attitudes of the original placed on the platform 16 can be understood by 
the description of FIG. 16. 
FIG. 17 shows the original illuminating routine. In this routine, LED array 
700 is turned on with the full light emission. Then the size of the 
original is compared with an effective image area which is decided by the 
paper size and the copying magnification value and the smaller one is 
adopted for illuminating any of the LEDs 801 to 830 for illuminating the 
original. The original is scanned by the optical system 10 with the slow 
speed so that the operator of the copying machine can notice the area of 
the original to be actually copied by seeing the light passing through the 
original. 
When the switch 108 is turned on, an edge of the signal of the switch 108 
is detected in the step S461 and the process advances to the step S462 to 
calculate the following equation. 
EQU paper length/copying magnification (1) 
The value of the equation (1) is stored in a A register. 
The paper length can be obtained by the table 3 stored in the memory. 
TABLE 3 
______________________________________ 
size length (mm) 
width (mm) 
______________________________________ 
A3 420 297 
B4 364 257 
A4 297 210 
B5 257 182 
A4 lateral 210 297 
B5 lateral 182 257 
______________________________________ 
In the step S463, the paper length obtained from the table 3 is compared 
with the content of an A register i.e., the divided value of the equation 
(1), then if the paper length is larger than said divided value, the 
process advances to the step S464. With the paper length to be smaller 
than said divided value, the process advances to the step S465. By this 
operation, the smaller value obtained in the manner as described above is 
stored in the memory as the scan length of the scanner and the stored 
value is transferred to the CPU 202. 
In the step S466, the paper width obtained by the table 3 is compared with 
another divided value of 
EQU (paper width)/(copying magnification) (2) 
and a comparison between the paper width and the another divided value of 
the equation (2) and the smaller one is stored in the memory as the number 
of the LEDs of the LED array 700 to be turned on and the main motor is 
driven. 
A low speed scan signal is transferred to the second CPU 202 in the step 
S470. 
And then the required number of LEDs 701 to 730 is turned on in the step 
S471 for illuminating the original. 
The illumination to the original can be made by turning on the required 
number of LEDs stored in the memory in the steps S468 or S469. The scan 
length of the scanner can be controlled by the scan length data set in the 
step S464 or S465. 
When the scanner returns to the home position, the low speed scan signal is 
made 0, so as to stop the main motor with the LED array 700 turned off in 
the steps S472 to S474. 
By this low speed scanning of the original, displacement of the original 
relative to the required position on the platform 16 can be detected. 
The work of detecting the displacement of the original may be performed in 
such a case that, for example, an operator wishes to make a copy of a part 
of an original of B4 size (the said part original may be A4 size) on a 
copying paper of A4 size. In this case, the required number of the LEDs to 
be illuminated in the LED array 700 is coincided with the size of the 
width (210 mm) of A4 size and the scan length is coincided with the length 
(297 mm) of A4 size, so that by scanning the original with the said number 
of LEDs turned on, the area of the original which is illuminated by the 
LEDs corresponds to A4 size. Thus it can be recognized whether the 
required part of the original is coincided with the available copy area 
(in this case the area of A4 size) by seeing the light pattern passed the 
original. 
Referring to FIG. 18 showing the trouble display routine, if the content of 
the trouble memory is 0, which means that fault of the LED array 700 is 
not present, the process advances to the step S481 wherein an image fault 
display unit 111 for displaying the presence of possibility of the fault 
of the image on the copying paper is turned off and the process advances 
to the step S482 so as to cause the normal selected paper size to be 
display in the paper size display. If the content of the trouble memory is 
not 0, a serviceman call display 109 is turned on. 
A process for displaying the available copy size and the selected paper 
size alternately by the timers TA and TB is described hereinafter. 
When the time counted by the timer TA is lapsed, if the content of the 
trouble memory that is the serial number of the fault LED is any of 801 to 
830 and/or 701 to 719, the copy is impossible and the display is kept 
unchanged in the steps S484 and S485. If there occur states other than the 
state mentioned above in the memory, the process moves to the step S486 to 
turn the copy available display 110 on. 
If the content of the trouble memory is 720 or 721, since a copy of the 
original of B5 size with the lateral attitude is possible, B5 lateral 
attitude display is turned on. If the original size is other than B5 size 
with the lateral attitude, the image fault display 111 is turned on in the 
steps S489 and S490. In case of another content of the trouble memory, the 
process is conducted as shown in FIG. 18. Then the timer TB is set. When 
the time set in the timer TB is finished, the copy available display 110 
is made off, and the selected paper size can be displayed in the paper 
size display 109 and the timer TA is set again. By repeating the routine 
mentioned above, the timers TA and TB are set alternately, the copy 
available size display with the copy available display and the selected 
size display without the copy available display are alternately displayed. 
Thus by seeing the display, the user is able to determine whether or not 
the selection of the paper should be made again. 
FIG. 19 shows the routine for controlling the erasure of the image in the 
space between the two adjacent images of the original or in the space of 
the edge parts of the drum 1. 
LED array 800 is used for this purpose. LED array 800 is entirely turned on 
during rotation of the photoreceptor drum 1 on which the image part of the 
original is not projected. While the necessary part of the original is 
illuminated, the value of (blank part of the original)/(copying 
magnification) is stored in the memory as the number of the LEDs to be 
illuminated. 
When the image fault display is turned on, that is when the copy is made 
under the condition that one of the LEDs of the LED array 700 is in 
failure, there is formed a black strip in the potential image on the 
photoreceptor drum 1. In order to erase the black strip, the corresponding 
LED in the LED array 800 is illuminated. 
FIG. 20 shows a preliminary scanning routine. 
When it is detected that the print switch 71 is turned on in the step S500, 
a preliminary scanning is performed for memorizing the density of the 
image of the original. In the step S501 the operation mode of the copying 
machine is set to the preliminarily scanning mode and the signal 
representing the preliminary scanning mode is transferred to the second 
CPU 202. The number of the LEDs of the LED array 700 corresponding to the 
width of the original to be copied is stored in the memory in the step 
S502 for exposure of the width of the original to be copied. Since the 
width of the original is indicated by the knobs 650 and 651, it may be 
different from the actual original size. The scan signal is made 1 in the 
step S503 to start the scanning of the scanner. 
Subsequently, when it is detected in the step S504 that the scanner 
finishes the necessary scan length, the scan signal is turned off and the 
copy start flag is made 1. 
During execution of the preliminary scanning, the density of the original 
is detected by the photo diode array 900 and the detected density is 
stored in the respective areas corresponding to the respective LEDs of the 
LED array 900 (see the steps S507 to S509). The stored density is used for 
adjusting the light amount of each LEDs of the LED array 700. 
Copying Operation 
FIGS. 21a through 21c show a flow chart showing an example of operational 
control of the copying apparatus. This chart is now briefly described with 
reference to a time chart of FIG. 22. 
In a block 10, when a print switch is turned on, the main motor M1, the 
developing motor M2, the corona charger 5 and the transfer charger 7 are 
respectively operated while a copy flag showing that the device is in 
copying operation is set at "1" and control timers T-A and T-B are driven 
to turn on the clutch of a selected paper feed roller. 
In a block 11, a determination is made on completion of the operation of 
the timer T-A, to turn off the paper feed roller. 
In a block 12, a determination is made on completion of operation of the 
timer T-B, to turn on a scan motor M3 for initiating the scanning 
operation. 
In a block 13, a process is effected to turn on a timing roller clutch CL1 
when a timing signal is generated during the scanning operation while 
setting a timer T-C. A copy sheet is transported in synchronization with 
an image on the photoreceptor drum 1 by a timing roller 26. 
In a block 14, a determination is made on completion of operation of the 
timer T-C, to turn off the corona charger, and the timing roller clutch 
CL1, turning the return signal 1 so as to cause the scanner to return. The 
timer T-C may be set variable depending on factors such as the size of the 
utilized copy sheet. 
In a block 15, the developing motor M2 and the transfer charger 7 are 
respectively turned off and the copy flag is set at "0" while a timer T-D 
is set when the optical system is returned to a home position following a 
returning operation to turn on a set position switch. The scan length and 
the number of LEDs to be lit in the copying routine are determined by the 
data set in the steps S464 and S465 and steps S468 and S469. 
In a block 16, a determination is made on completion of operation of the 
timer T-D, to turn off the main motor M1. 
In a block 17, a process is effected for various kinds of outputs. 
The timers T-A through T-D described with respect to the aforementioned 
flow chart and time chart are digital timers which are programmed to be 
counted up by "1" per one routine of processing effected within a time 
period defined by an internal timer, and the time-up period is stored as a 
numerical data. 
In the copying routine the respective LEDs are lit according to a pulse 
width modulation. 
The operations mentioned above are shown in FIG. 23. 
FIG. 23 shows a timer interruption routine in the first CPU 201, wherein 
the brightness of the LEDs 701 to 730 of the LED array 700 can be 
controlled by controlling the duty time thereof. First, the serial number 
of the LEDs 701 to 730 to be lit is set as the illuminating data. 
Subsequently if the copying machine is in the preliminary scanning mode for 
detecting the original density or original illumination mode for 
confirming the copy available area, the LEDs to be illuminated is 
illuminated with a full power of 100% duty. 
In the copying mode, in order to effect an exposure with a suitable 
exposure value for the entire original pattern obtained in the preliminary 
scanning, each of the LED is illuminated with a predetermined and 
calculated duty timing by counting the number of times of the interruption 
executed. For example, the LED for illuminating the high density part of 
the original is lit with a high duty cycle near 100% for a high brightness 
illumination, to the contrary, the LED illuminating the low density part 
of the original is lit with a low duty cycle for a low bright 
illumination. 
Various functions provided in the copying machine mentioned above are 
explained below. 
A copy can be made by turning on only the necessary number of LEDs of the 
LED array 700 conforming to the size of the original to be copied. This 
function enables to make a copy with the cover of the copying machine 
opened preventing the light from reaching the operator's eyes. The size of 
the original can be set by adjusting the position of the knobs in FIG. 3 
and is taken in the control device according to the sub routine shown in 
FIG. 16. The number of LEDs to be turned on can be determined in the step 
S502 corresponding to the width of the original. The scan length also can 
be set corresponding to the input value by the arrangement shown in FIG. 
3. Necessary number of the erasing LEDs of the LED array 800 are turned on 
corresponding to the area in which the LEDs of the LED array 700 are kept 
turned off so as to erase the charge on the photoreceptor 1. 
When a part of the LEDs of the LED array 700 for illuminating the original 
are damaged, a copy can be made using the healthy LEDs. Detection of the 
fault of the LEDs is performed by the subroutine shown in FIG. 10. The 
available copy size can be displayed by the subroutine shown in FIG. 18 
corresponding to the position of the fault LEDs. The user of the copying 
machine can select or change the size of the copying paper based on the 
display of the fault LEDs. In this case missing of the image on the 
copying paper does not occur. On the other hand, the operator can select a 
copy size larger than the size which is displayed as the available copy 
size. In this case, the image of the copy includes the missing part 
corresponding to the fault LED or LEDs. Assume that the LED 725 is in the 
fault condition. The LED 725 is situated in a position between one side 
edge of the A4 paper and one side edge of the B4 paper with other sides of 
both papers coincided with the standard line of the platform 16. The 
available copy sizes in this case are A4 and B5. If the user makes a copy 
directly, LEDs 701 to 726 receive the order of turning on corresponding to 
the size of B4 paper. However the fault LED 725 can not emit the light. 
Under such a state, instructions to turn on are fed to the erasing LED 825 
corresponding to the fault LED 725 and the LEDs 827 to 830 corresponding 
to the blank space of the original of B4 size according to the sub routine 
shown in FIG. 19. By this operation, the part of the copied paper 
corresponding to the fault LED 725 is made white. 
The width of the LEDs 701 to 730 to be turned on for illuminating the 
original can be defined by the input original size by the arrangement of 
FIG. 3 and the erasing LEDs of the array 800 corresponding to the LEDs of 
the array 700 which are kept turned off are turned on. 
By setting the size of the original to be smaller than the actual size of 
the original, or by setting the size of the copy paper to be smaller than 
the size obtained by the multiplication between the size of the original 
and a copying magnification value, a partial copy can be made. By setting 
the size of the original smaller than the actual size, since only the LEDs 
for illuminating the original corresponding to the size thus set are 
turned on, the part corresponding to the turned on LEDs can be copied. If 
a small size paper is selected, despite that the image of the original is 
formed on the photoreceptor drum 1, the actual copy is made on the copy 
paper which is smaller than the original. In this way, a partial copy can 
be made. 
In making the partial copy as mentioned above, it is difficult to place the 
original on the platform 16 so as to adjust the required part of the 
original. In order to facilitate to adjust the original in position for 
the partial copy, the original illuminating routine shown in FIG. 17 is 
provided. The routine can be executed by operation of the switch 108. In 
this sub routine, the entered width and length of the original are 
compared with the converted value obtained by the division of the width 
and length of the selected copy paper by the magnification value and the 
smaller length and width are selected and any of the LEDs 701 to 730 
corresponding to the selected width are turned on and the original is 
scanned with the selected length. The scan speed is low for enabling to 
see the scanned area easily. The user can notice the relative position 
between the available copy area and the desired area of the original for 
copy by seeing the light of the LEDs passing the original. 
Various modification can be made without departing from the spirit of the 
copying machine of present invention. For example, although in the above 
embodiment, LEDs for illuminating the original are turned on or off 
corresponding to the Japanese standard sizes such as A4, B5, B4, the LEDs 
can be turned on individually corresponding to the desired size of the 
copy. Also the copying machine according to the present invention can be 
applied to the center to center registration system. 
Further, the light value of the respective LEDs can be controlled by 
varying the current applied to the respective LEDs instead of controlling 
the duty cycle ratio. The control of the light value of the respective 
LEDs can be varied so as to depend successively on detection of the 
original density. Furthermore, it may be considered in the illumination 
control of LED array 700 to add the characteristics of the optical system 
10 such as cos.sup.4 .theta.law.