Image recording apparatus with evening of the recording medium

An image recording apparatus includes a first recording unit, a second recording unit, and a control unit. The first recording unit scans an original image and records an image on a recording medium. The first recording unit has a first operation mode for evening a surface of the recording medium. The second recording unit records an image on the recording medium. The second recording unit has a second operation mode for evening the surface of the recording medium. The control unit controls the first and second recording units. The control unit controls the first recording unit so as to even the surface of the recording medium in the first operation mode at a start of image recording.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an image recording apparatus suitably used 
for a copying or facsimile machine for recording image information on a 
recording medium. 
2. Related Background Art 
A typical example of an apparatus of this type is a so-called dual mode 
copying machine in which information such as date and characters input 
from a host computer or the like is recorded by a sub-record optical 
system while an original is copied by a main record optical system. The 
sub-record optical system may comprise a laser having a larger output 
quantity of light than that of an LED (Light-Emitting Diode) to erase an 
unnecessary portion of an image, in addition to image recording. 
When a laser is used as a sub-record optical system, it is generally 
employed to adjust a value of a current supplied to the laser by properly 
controlling a time interval of a laser, because an optical output (light 
quantity) changes as a function of temperature. A typical conventional 
adjustment method is performed as follows. A sensor is arranged to monitor 
an optical output from the laser, and the laser is then deenergized. 
Thereafter, a current is gradually increased until a sensor output reaches 
a predetermined value. 
When such a conventional control method is employed, the optical output is 
temporarily erased (OFF), an unnecessary black image is formed in 
background scanning; that is, in the case where the portion irradiated 
with a laser beam is recorded in white, for example. 
When a laser is used in a sub-record optical system to erase an unnecessary 
image portion at the start of recording, copying cannot be started until a 
polygonal mirror for laser scanning is rotated and reaches a steady speed. 
In addition, the ON time of the laser is prolonged to shorten the 
mechanical service time of the apparatus, thus degrading reliability of 
the apparatus. 
In multifunctioning of an image recording apparatus such as a copying 
machine in recent years, functions such as a variable magnification 
function, an automatic density adjustment function, an automatic paper 
size selection function, an automatic magnification selection function, a 
multicolor copying function, an automatic both side recording function, an 
image editing function, a two-color development function accessible with 
an operation of one button, a page consecutive copying function, and a 
binding margin adjustment function have been, available. At present, 
combinations of these functions are also required. 
In such a conventional apparatus described above, it is expected to easily 
emphasize image information. 
Examples of an apparatus for recording an image on a common recording 
medium by using a plurality of light sources are described in U.S. Pat. 
Nos. 4,552,449, 4,434,982, 4,378,156, and U.S. Pat. No. 4,517,579, and 
U.S. Ser. No. 839,358 (Aug. 5, 1986) now abandoned. There is much room 
left for further improvements. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to eliminate the conventional 
drawbacks described above. 
It is another object of the present invention to improve an image recording 
apparatus having a plurality of light sources. 
It is still another object of the present invention to provide an image 
recording apparatus having high reliability. 
It is still another object of the present invention to provide an image 
recording apparatus having good operability. 
It is still another object of the present invention to provide an image 
recording apparatus having prolonged service life. 
It is still another object of the present invention to provide an image 
recording apparatus wherein recording operations can be started at earlier 
timings. 
It is still another object of the present invention to provide an image 
recording apparatus capable of forming a high-quality reproduced image. 
It is still another object of the present invention to provide an image 
recording apparatus capable of outputting an image in a desired form. 
It is still another object of the present invention to provide an image 
recording apparatus capable of obtaining a desired reproduced image. 
It is still another object of the present invention to provide an image 
recording apparatus capable of allowing light quantity control of a laser 
to always stabilize the laser quantity without formation of an unnecessary 
image portion even when consecutive copying. 
It is still another object of the present invention to provide an image 
recording apparatus capable of shortening a record time at the start of 
recording to hence prolong the laser service life and improve laser 
reliability. 
It is still another object of the present invention to provide an image 
recording apparatus capable of easily emphasizing image information 
recorded in a designated record area without degrading input image 
information in the designated record area. 
The above and other objects, features, and advantages of the present 
invention will be apparent from the following detailed description with 
reference to the accompanying drawings and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A preferred embodiment of the present invention will be described in detail 
with reference to the accompanying drawings. 
FIG. 1A shows a first basic arrangement exemplifying an embodiment of the 
present invention. The first basic arrangement includes a main record 
optical system 1a employed to scan an original, capable of erasing an 
image by irradiating a charged area on a photosensitive body with 
illumination light emitted from an original exposure lamp, a sub-record 
optical system 1c capable of erasing an image or a designated position by 
selectively irradiating the charged area with light, and an image erase 
control means 1b for causing the main record optical system 1a to perform 
image erase processing at the start of recording and thereafter the 
sub-record optical system 1c to perform image erase processing. 
The main record optical system 1a includes a white plate arranged at a 
predetermined position, for example. An original scanning system is 
stopped at the predetermined position under the control of the image erase 
control means 1b to reflect illumination light from the original exposure 
lamp by the white plate, thereby performing image erase processing. The 
sub-record optical system 1c includes, e.g., a laser generating means, a 
laser scan polygonal mirror, and a polygonal mirror rotation motor. 
FIG. 1B is a second basic arrangement exemplifying the embodiment of the 
present invention. The second basic arrangement includes a main record 
optical system 2a employed to scan an original, capable of erasing an 
image by irradiating a charged area on a photosensitive drum with 
illumination light emitted from an original exposure lamp, a sub-record 
optical system 2b capable of erasing an image on a designated position by 
selectively irradiating the charged area with the illumination light, a 
light quantity adjust means 2c for adjusting a light quantity of the 
sub-record optical system 2b to a predetermined value, and a control means 
2d for operating the light quantity adjust means 2c during image erase 
processing of the main record optical system 2a. 
The main record optical system 2a includes a white plate arranged at a 
predetermined position for example. An original scanning system is stopped 
at the predetermined position under the control of the control means 2d to 
reflect illumination light from the original exposure lamp by the white 
plate, thereby performing image erase processing. The sub-record optical 
system 2b includes, e.g., a laser generating means, a laser scan polygonal 
mirror, and a polygonal mirror rotation motor. 
FIG. 1C shows a third basic arrangement exemplifying the embodiment of the 
present invention. The third basic arrangement comprises a first image 
forming means 3a constituted by a first optical system, a second image 
forming means 3b constituted by a second optical system, and a record 
control means 3c for forming a dot image formed by the second image 
forming means 3b in a designated area of an original image formed by the 
first image forming means 3a. 
FIG. 2 shows an internal arrangement of a copying machine to which the 
present invention is applied. Referring to FIG. 2, the copying machine 
includes a copying machine main apparatus 1, and an image forming unit 
including a photosensitive drum 20 as a major component. A first paper 
feed unit 3 feeds a transfer sheet (paper) SH to the interior of the main 
apparatus 1 and comprises a detachable cassette 9, paper feed rollers 10 
and 11, and sensors S9 to S12, S22, and S23. An original scan optical 
system 4 serves as a main record optical system. The original scan optical 
system 4 includes a lens system for exposing and scanning an original and 
focusing an image on the photosensitive drum 20, and an original 
illuminating lamp 24. The original scan optical system 4 is driven by an 
optical motor 19 in a direction indicated by an arrow. The main apparatus 
1 also includes an original glass table 5 for supporting an original 
thereon, an end 34 thereof, and a cleaner 6 for removing residual toner 
particles from the photosensitive drum 20. 
A color development unit (second development unit) 7 stores a color toner 
such as a red toner. The unit 7 includes a development roller 7a. A black 
development unit (first development unit) 8 stores a black toner and 
includes a development roller 8a. The development units 7 and 8 are 
selectively brought into contact with the photosensitive drum 20 by a 
color development unit actuation solenoid 30 and a black development unit 
release solenoid 31. 
First registration rollers 12 feed the transfer sheet SH from the cassette 
9 or a second paper feed unit 23 to the photosensitive drum 20 at a proper 
timing corresponding to an image position on the photosensitive drum 20. A 
primary charger 13, a transfer charger 15, a separation charger 16, and a 
transfer unit 17 are arranged around the photosensitive drum 20. The 
transfer unit 17 comprises a transfer charger 15, a separation charger 16, 
and a paper transfer unit 17a. A main motor 18 drives the photosensitive 
drum 20, a fixing unit 25 incorporating a heater 21, the development units 
7 and 8, and various transfer rollers. 
A flapper 29 is disposed between eject rollers 26 and 27 to change a 
transfer path in multicopy and both side copy modes. An eject tray 32 is 
located outside the main apparatus. A path 33 is formed to re-feed the 
transfer sheet SH fixed by the fixing unit 25 to the photosensitive drum 
20. Second registration rollers 37 are arranged to synchronize the feed 
timing for feeding the transfer sheet SH through the path 33. An interim 
tray 40 is used for the multicopy mode or both-side copy mode for a 
plurality of sheets. The interim tray 40 comprises a path outlet port 42, 
a transfer path 43, a path switching flapper 49, an interim tray feed 
roller 52, a tray 53, a feed roller 56, interim tray feed rollers 57, and 
a transfer path 59. A shutter 70 shields at a predetermined position an 
original optical image projected onto the photosensitive drum 20. 
A laser unit 90 serves as a sub-record optical system (to be described 
later in FIG. 3). The laser unit 90 includes a laser 91, a polygonal 
mirror 93, a polygonal mirror drive motor 92, and a reflecting mirror 97. 
Referring to FIG. 3, a horizontal sync signal (BD signal) detect circuit 
for detecting the BD signal representing a beam scan position, a spherical 
mirror 95, and a toric lens 96 are shown. The laser unit 90 can erase 
unnecessary charge in an area (a "without area") excluding (i.e., not 
containing) an image area (herein sometimes termed), erase any location in 
the image, and write a simple character on the transfer sheet through the 
photosensitive drum 20. Sensors S1 to S12, S14, S15, and S19 to S23 shown 
in FIG. 2 will be described later. 
FIG. 4 shows a circuit arrangement of a control system for controlling the 
copying machine in FIG. 2. Referring to FIG. 4, the control system 
includes a control unit 60 which comprises a microcomputer, a program 
memory, a RAM (random access memory), and a timer. An AC driver 61 
controls an AC load 62 including such as the lamp 24 and the heater 21. A 
motor control unit 63 controls the main motor 18 and the optical motor 19. 
Loads 66 such as a solenoid, a clutch, and a fan are connected to the 
control unit 60. An original handling apparatus (DF, ADF, or RDF) 67 for 
performing automatic feed or other original handling and a sorter 68 are 
also connected to the control unit 60. An alarm buzzer 80, a console unit 
100 (to be described in detail with reference to FIG. 5), and a 
coordinates read unit (editor) (to be described later with reference to 
FIG. 6) are further connected to the control unit 60. A power switch 101 
is connected to a DC power source DCP to supply power to the control unit 
60 and the like. The sensors S1 to S12, S14, S15, and S19 to S23 are 
connected to the control unit 60 to supply detection singals thereto. A 
high-voltage generation unit HVT applies a high voltage to the primary 
charger 13, the transfer charger 15, and the separation charger 16. The 
control unit 60 controls the above components, the shutter 70 and the 
laser unit 90. 
An operation of the copying machine described above will be described 
below. 
When the power switch 101 is turned on, the heater 21 in the fixing unit 25 
is energized, and the control unit 60 waits until the fixing roller is 
heated to a predetermined temperature which allows fixing (wait state). 
When the temperature of the fixing roller reaches the predetermined 
temperature, the main motor 18 is energized for a predetermined period of 
time to drive the photosensitive drum 20 and the fixing unit 25, so that 
the roller in the fixing unit 25 is kept at a uniform temperature (wait 
release/rotation). Thereafter, the main motor 18 is stopped and the main 
unit 60 waits in a copy enable state (standby state). When a copy command 
is input from the console unit 100, copying is started. The speed of the 
main motor 18 can be switched in two steps in accordance with a command 
from the controller 60. 
(1) Description of Image Formation 
In response to a copy command, the main motor 18 is rotated and the 
photosensitive drum 20 is rotated in direction indicated by the arrow on 
the drum in FIG. 2. At the same time, a high voltage is applied from the 
high-voltage generation unit HVT to the primary charger 13. The 
photosensitive drum 20 is uniformly charged. The lamp 24 is then turned on 
to eliminate an image on the drum 20, and the optical motor 19 is driven. 
An original placed on the original glass table 5 is exposed and scanned in 
the direction indicated by the horizontal arrow to project an original 
image on the photosensitive drum 20. In this case, the laser unit 90 is 
used to erase an arbitrary location in the image or writes a simple 
document. In this manner, a latent image is formed on the photosensitive 
drum 20. 
The latent image is developed and visualized by the development unit 7 or 
8, and a toner image is transferred to the transfer sheet SH at a portion 
of the transfer charger 15. The transfer sheet is then separated from the 
photosensitive drum 20 at a portion of the separating charger 16. Residual 
toner particles left on the photosensitive drum 20 ar recovered by the 
cleaner 6. The photosensitive drum is uniformly discharged with a laser 
beam from the laser unit 90 capable of removing an unnecessary charge in 
an area excluding the image area and the illumination light from the 
optical system 4 capable of removing such necessary charge. Thereafter, 
the next copy cycle is repeated. 
During the above image formation, one of the black and color development 
units 8 and 7 is brought into contact with the photosensitive drum 20 in 
accordance with a selection command from the console unit 100. The black 
development unit 8 is released upon energization of the black development 
release solenoid 31. The color development unit 7 is brought into contact 
with the photosensitive drum upon energization of the color development 
unit actuate solenoid 30. A development bias voltage is applied from the 
high-voltage generation unit HVT to each development roller 7a or 8a. 
In the copying machine of this embodiment, both-side copy and multicopy 
operations can be performed in addition to a normal copy operation, i.e., 
a one side copy operation. The state of the transfer sheet which has 
passed through the fixing unit is changed from the original state. For 
example, the resistance of the paper is changed. In order to properly 
compensate for changes in paper conditions, a high voltage applied to the 
transfer charger 15 and the separation charger 16 during copying is varied 
in accordance with the obverse or reverse surface, or an order in a 
multicopying mode. The development bias voltages or the high-voltage value 
for transfer and separation is changed in accordance with a command from 
the control unit 60. 
The optical system 4 can be reciprocally driven such that the optical motor 
18 is rotated in the forward and backward directions through the motor 
control unit 63. A home position sensor S1 is arranged for detecting the 
home position of the optical system 4. The optical system 4 is stopped at 
the position of the home position sensor S1 in the standby state. A 
leading edge sensor S2 detects a leading edge of an original image and is 
used for timing control of a copy sequence. A limiter position (reverse 
position) sensor S3 is used to scan an original in a maximum size. The 
optical system 4 is reciprocally driven in a scanning stroke corresponding 
to a copy magnification and a cassette size in accordance with a command 
from the control unit 60. 
(2) Transfer Sheet Control 
FIG. 2 shows upper and lower paper detect sensors S9 and S11 arranged for 
the paper feed unit 3, upper and lower lifter position detect sensors S10 
and S11, and upper and lower cassette size sensors S22 and S23. 
The upper and lower sensors have identical operation sequences, and only 
paper feeding of the upper side will be described. When the cassette 9 is 
attached to the copying machine, the upper cassette size sensor S22 reads 
and discriminates the size of the cassette 9, and a "no paper" indicator 
in the console unit 100 is turned off to inform the user of the currently 
selected cassette size. 
When the copy operation is started in accordance with a copy command, the 
mid-plate lift clutch (not shown) is turned on to lift the mid-plate in 
the cassette 9 so as to lift the transfer sheets SH. When the transfer 
sheets SH are lifted and the uppermost sheet is brought into contact with 
the paper feed roller 10 and reaches a predetermined height, the sensor 
S10 generates an output. The mid-plate lift clutch is turned off, and at 
the same time, the feed roller 10 is driven to feed the transfer sheet in 
the interior of the main apparatus 1. 
After the sheets in the cassette are lifted to the predetermined height, 
they maintain this state. In the next copy operation, sheet lifting is not 
executed. When the position of the uppermost sheet is lower than the 
predetermined position, the clutch is turned on again in the same manner 
as described above, thereby lifting the sheets to the predetermined 
height. 
The transfer sheet fed in the main apparatus reaches a first 
anti-registration sensor S7. In this state, since the registration rollers 
12 are kept stopped, the sheet is stopped while forming a proper loop. The 
registration rollers 12 are driven in response to a timing signal from the 
sensor for the optical system 4 so as to align the sheet with the leading 
end of the image formed on the photosensitive drum 20. After alignment or 
registration is completed, the sheet is transferred to the transfer unit 
17. The image on the drum 20 is transferred to the sheet by the transfer 
charger 15 in the transfer unit 17, the sheet is separated from the 
photosensor drum 20 by the separation charger 16. The transfer sheet is 
fed to the fixing unit 25 through the transfer unit 17a. In the fixing 
unit 25, the surface of the fixing roller is heated to a predetermined 
temperature by a temperature sensor (not shown) arranged on the surface of 
the fixing roller and the heater 21. The toner image on the transfer sheet 
is fixed by the fixing unit 25. Thereafter, ejection of the sheet is 
detected by the eject sensor S4, and the sheet is then ejected to the 
external eject tray 32 by the eject rollers 26 and 27. 
The multicopy mode will be described below. In this case, the flapper 29 is 
switched by a solenoid (not shown) to the position indicated by the dotted 
line. The transfer sheet after feeding, image transfer, sheet separation, 
and image fixing as described above is guided to the flapper 29 and is 
transferred through the path 33. The sheet is then fed to the second paper 
feed path 23. After the second anti-registration sensor S5 detects passing 
of the transfer sheet, transverse registration of the sheet is performed 
by the paper end sensor S6, the transverse registration sensor S8, and a 
transverse registration solenoid in the second paper feed unit 23. 
The second registration rollers 37 are rotated in accordance with a 
multicopy command from the console unit 100, and the transfer sheet is 
re-fed to the first registration rollers 12. The subsequent operations are 
the same as those as described above, and the transfer sheet is ejected on 
to the eject tray 32. 
In the both side copy mode, although the transfer sheet is ejected by the 
eject rollers 27 in the same manner as in the normal copy operation as 
described above, the eject rollers 27 are rotated in the reverse direction 
after the trailing end of the transfer sheet passes by the flapper 29. The 
transfer sheet is guided to the flapper 29 and transferred to the path 33. 
This reverse driving is performed by a solenoid (not shown) for 
controlling the forward/reverse rotation. The subsequent operations are 
the same as those in the multicopy mode. In the both-side copy mode, the 
transfer sheet is temporarily ejected from the main apparatus 1 through 
the eject rollers 27. The side of the transfer sheet is reversed by the 
eject rollers 27, and the turned sheet is fed to the second paper feed 
unit 23. 
The above description is related to the multicopy and both-side copy 
operations for single sheets. However, in the multicopy or both-side copy 
mode for a plurality of sheets, the interim tray 40 is used. As shown in 
FIG. 2, a tray 53 is arranged in the interim tray unit 40 to temporarily 
store the transfer sheets located in the transfer paths 59 and 43 and in 
the interim state. 
In the multicopy mode for a plurality of sheets, each fixed sheet is 
partially ejected by the eject rollers 27 in the same manner as in the 
both side copy mode for a single sheet. This sheet then passes through the 
paths 33 and 43 upon reverse driving of the eject rollers 27 and is stored 
in the tray 53. This operation is repeated to store all sheets in the tray 
53. Each stored sheet has an image on one surface thereof. Each sheet with 
an image on one surface thereof is then fed by the feed rollers 56 to the 
photosensitive drum 20 through the path 59 and the second paper feed unit 
23. Therefore, the second copy cycle is started. 
In the both-side copy mode for a plurality of sheets, the transfer sheets 
are guided by the flapper 29, pass through the fixing unit 25 and then the 
paths 33 and 43, and are stored in the tray 53 in the same manner as in 
the multicopy mode for a single sheet. The subsequent operations are the 
same as those in the multicopy mode, and detailed description thereof will 
be omitted. 
An arrangement of the console unit 100 will be described with reference to 
FIGS. 5A and 5B. 
The console unit 100 includes a power switch 101 for energizing the copying 
machine, a reset/stop key 102 which serves as a copy stop key during 
copying and a key for restoring the standard mode in the standby state, a 
copy key 103, a color development unit selection key 104 for selecting the 
development unit 7 or 8, and a ten-key pad 105 for entering mainly the 
number of copies to be set. 
The console unit 100 also includes a key 106 for selecting the cassette 9, 
a copy density adjust key 107, a key 108 for selecting an equal-size copy 
operation, a zoom key 109 for designating a predetermined magnification by 
1%, for example, a fixed magnification key 110 for designating a fixed 
reduction or enlargement coefficient, a key 111 for designating frame 
erasure of a copy sheet, a key 112 for designating a binding margin at one 
end of a copy sheet, and a key 113 for designating a picture mode. 
The console unit 100 also includes a multicopy key 114 for designating the 
multicopy mode, a page consecutive copy key 115 for dividing a copy area 
of the original glass table 5 into two regions and designating a 
consecutive copy mode for automatically copying two images, keys 116 to 
118 for selecting the both side copy mode, keys 119 and 120 for 
designating an operation mode of the sorter 68, and keys 122 and 123 for 
designating a mode for writing predetermined character data in a copy 
image. The key 122 designates to write numbers, and the key 123 designates 
to write data. 
Indicators and/or displays 131, 132, 134 to 143 comprise respective LEDs 
(light-emitting diodes). More specifically, these indicators are the 
standby indicator LED 131 which is turned on in green in a copy enable 
state and red in a copy disable state, the color image indicator LED 132 
which is turned on when the development unit selection keys 104 is 
depressed and the color development unit 7 is selected, the number write 
mode indicator 134, the date write mode indicator 135, the display 136 for 
displaying the set number of copies, the alarm indicator 137 for 
indicating the absence of transfer sheets and jamming, the cassette size 
indicator 138 for indicating a selected cassette size, and a magnification 
display 139 for displaying a copy magnification. 
The indicators 140 to 143 are the frame erase, binding margin and picture 
mode indicators 140, the multicopy and page consecutive copy mode 
indicators 141, the both-side copy mode indicators 142, and the sorter and 
group mode indicators 143 for indicating the operation modes of the sorter 
68. 
An arrangement of the editor 180 will be described with reference to FIG. 
6. 
The editor 180 also serves as an original holding plate for holding an 
original, and FIG. 6 shows an outer appearance of the editor 180. The 
editor 180 includes an original set surface 170 (to be referred to a 
coordinates input panel hereinafter) for supporting an original an area of 
which is to be designated, a reference mark 171 which is abutted by the 
original end, a key 151 for designating an area designate mode, a key 152 
for storing a designated area, a mode select key 153 for copying the 
designated area by selectively using the two development units 7 and 8, a 
clear key 154 for clearing the area designate mode, and an area designate 
mode indicator 163. The editor 180 further includes indicators 161 for 
indicating designated areas (three areas in this embodiment), and LEDs 162 
for indicating a copy mode of the designated areas in combination with the 
color development unit 7. The LEDs are sequentially turned on by the mode 
select key 153. 
The editor 180 further includes a character input key 155 for designating 
an add-on mode (character input mode) for writing symbols such as 
characters in the copy image, a character size key 156 for designating a 
size of an input character (the character having a size of 8 mm or 4 mm 
can be designated in this embodiment), a character direction key 157 for 
designating a direction of an input character (a vertical or horizontal 
direction can be designated in this embodiment), a position key 158 for 
designating a start position of the input characters, a key 160 for 
designating an end of the character input, and a clear key 159 for 
clearing the character input mode. 
The editor 180 includes a character input mode indicator 164, indicators 
165 and 166 for indicating character sizes, respectively, indicators 167 
and 168 for indicating the character input directions, respectively, an 
indicator 169 for indicating the end of the position input, and a stylus 
pen 173 for designating an area and inputting data to be written by 
depressing the coordinates input panel 170 with the stylus pen 173. A 
character input area 172 is used to designate character data with the 
stylus pen 173. 
An operation of the editor 180 will be described below. 
FIG. 7 shows an arrangement of an internal control circuit in the editor 
180. A coordinates reader unit 181 reads coordinates of a position 
depressed with the stylus pen 173 when an area in the document placed on 
the coordinates input panel (the original set surface) 170 is depressed 
with the stylus pen 173. The read coordinates are supplied to an editor 
control unit 184. The editor control unit 184 controls the coordinates 
input according to the control sequence shown in FIGS. 8 and 9 or various 
modes upon reception of various key inputs and coordinates. The editor 
control unit 184 also controls displays (indicators) 183 on the editor 
180. 
Control operations in the area designate mode and the character input mode 
in the editor control unit 184 will be described below. 
(1) Area Designation Mode 
FIG. 8 is a flow chart showing a control operation of the editor control 
unit 184 in the area designate mode. When the area designate mode key 151 
is depressed, the area designate mode LED 163 is turned on to set the area 
designate mode (step 201-1). When the coordinate input panel 170 is 
depressed by the stylus pen 173, the coordinates of the depressed position 
are read. At this time, coordinate values of two points allow reading of a 
rectangular area having a diagonal line defined by the two input points. 
For this reason, the coordinates of the two points are read (step 201-2), 
and the coordinate values read as a first area are stored by a key input 
with the area memory key 152, and at the same time, the area LED 161- 
.circle.1 is turned on (step 201-3). When an additional coordinates input 
is detected (step 201-4), the above operation is repeated to store the 
input coordinate values as the second area. The area LED 161- .circle.2 
is turned on. 
The mode select key 153 is operated to set a copy mode (step 201-5). In 
this embodiment, eight copy modes are available as follows: 
.circle.1 Mode for copying the designated area ("within" area) in black; 
.circle.2 Mode for copying the designated area in a designated color; 
.circle.3 Mode for copying an area ("without" area) outside the 
designated area in black; 
.circle.4 Mode for copying an area outside the designated area in a 
designated color; 
.circle.5 Mode for copying the designated area in black and an area 
outside the designated area in a designated color; 
.circle.6 Mode for copying the designated area in a desired color and an 
area outside the designated area in black; 
.circle.7 Mode for copying the designated area with dots of a designated 
color and superposing a normal copy thereon; and 
.circle.8 Mode for copying the designated area with black dots and 
superposing a normal copy thereon. 
Modes .circle.5 to .circle.7 are set when the black and color copy 
modes are set in the multicopy mode. In step 201-5, these modes are 
sequentially selected to set a desired mode. The coordinates data 
(including the number of areas) obtained in steps 201-3 and 201-5 and the 
copy mode data are supplied to the control unit 60 (201-6). 
(2) Character Input Mode (Addon Mode) 
The flow chart in FIG. 9 shows a control operation of the editor control 
unit 184 in the character input mode. When the character mode key 155 is 
depressed, the character input LED 164 is turned on to set to character 
input mode (step 202-1). When the coordinates input panel 170 is depressed 
by the stylus pen 173, coordinates of the depressed position are read 
(step 202-2). Subsequently, the editor control unit 184 determines whether 
the read coordinates fall within the character input area 172. If the 
input coordinate values fall outside the character input area 172, the 
character input is neglected. However, if the input coordinate values are 
determined to fall within the character input area 172, they are 
determined to be character data and this character data is converted into 
a character code (step 202-3). 
The control unit 184 then determines in step 202-4 whether the character 
end key 160 is depressed. If not, the character data continues to be read 
until the character input end key 160 is depressed. When the character 
input end key 160 is depressed, key inputs from the size key 156 and the 
direction key 157 can be accepted. When the corresponding data are input, 
the corresponding LEDs 165 to 168 are turned on and the data corresponding 
to these keys are set in step 202-5. 
When the start position input key 158 is depressed in step 202-6, the 
corresponding LED 169 flashes, and at the same time, the corresponding 
coordinates are read (step 202-8). When the coordinate input panel 170 is 
depressed by the stylus pen 173, the LED 169 is turned on, and at the same 
time coordinates of the depressed point are set as the character input 
start position (step 202-9). Thereafter, the character code, the character 
size data, the character direction data , and the character write position 
data are sent in step 202-10. 
Various copy modes using the laser unit 90 will be described below. In the 
following description, an image obtained in the normal original copy mode 
is an analog image, and an image obtained by writing binary data with a 
laser is a digital image. 
In this embodiment, the following copy modes are performed while erasing 
unnecessary charges outside the image area by the laser unit 90. 
(1) Area Designate Copy Mode 
Eight modes are available in this copy mode as described with reference to 
the editor 180. FIG. 10 shows a copy result in the area designate copy 
mode. Areas a and b can be copied in combination between a designated 
color and a black together with image erasing in accordance with each of 
the eight modes. In the dot mode, an image in the area a can be copied as 
a dot or halftone image in a designated color or black in accordance with 
the digital image. The areas a and b can be copied to form analog images. 
(2) Simultaneous Copy Mode of Digital (Character) and Analog Image 
This mode allows formation of copies shown in FIGS. 11A and 11B. A digital 
image is copied (recorded) in a predetermined area indicated by hatched 
lines in FIG. 11C. 
FIG. 11A shows a mode in which the date write mode LED 135 is ON. In this 
mode, the normal analog image copy operation is started from the 
beginning. At the same time, the shutter 70 is operated by a solenoid (not 
shown) so that an end portion of an original optical image projected from 
the original onto the photosensitive drum 20 through the optical system is 
shielded by an area indicated by the hatched lines in FIG. 11C. In the 
portion indicated by the hatched lines, a digital image (date) is written 
using the laser 90. 
FIG. 11B shows a mode in which the number write mode LED 134 is ON. The 
image formation sequence in this mode is the same as that in FIG. 11A. 
Numbers as digital images are sequentially written in a copy. 
(3) Multicopy Mode of Digital Image 
This mode is shown in FIG. 11D. An image is obtained by mixing analog and 
digital images in the multicopy mode. More specifically, an original is 
set on the original table and a character input is designated with the 
editor 180. When the copy key 103 is depressed, the character at the 
position designated with the editor 180 is copied, and then the normal 
analog copy operation is performed. In this case, analog copy operation 
may be performed first. 
The above modes may be used in combination. 
The second paper feed unit 23 and the interim tray unit 40 which are used 
in the both side copy/multicopy mode will be described below. In this 
embodiment, in order to set the both-side copy or multicopy mode, a 
transfer sheet re-feed mechanism comprises two systems. One comprises the 
second paper feed unit 23, and the other comprises the interim tray 40. 
These systems can be selectively used in accordance with a selected copy 
mode. 
The proper system is selected in accordance with a transfer sheet size and 
the number of copies, as shown in a copy program (to be described later) 
shown in FIG. 12. The second paper feed unit 23 is an indispensable unit 
for the both side copy and/or multicopy mode. Since the transverse 
registration can be easily performed with the second paper feed unit 23 by 
a mechanism (to be described later), the paper size is not fixed. Two or 
more sheets cannot be stored in the paper feed unit 23. Although a 
plurality of sheets can be stacked in the interim tray 40, transverse 
registration can be performed for only the fixed size. 
The control sequence for selecting a proper paper path in the both side 
copy/multicopy mode will be described with reference to the flow chart in 
FIG. 12. 
When the copy operation is started in accordance with a copy command upon 
operation of the copy key 103, whether copying of the same original is 
performed in the both-side copy/multicopy mode is determined in step 
270-1. For example, when a predetermined portion of one original is copied 
in a designated color, and the remaining portion thereof is copied in 
black, YES (affirmative determination) is obtained. If YES in step 270-1, 
whether the original has a regular size is determined in step 270-2. If NO 
in step 270-2, the flow advances to step 270-5, and the second paper feed 
unit 23 is unconditionally selected. However, if YES in step 270-2, the 
flow advances to step 270-3, and whether the set number of copies is one 
is determined in this step. If YES in step 270-3, the flow advances to 
step 270-5. However, if NO (negative determination), whether the set 
number of copies is larger than 30 (i.e., the maximum number of copies 
stored in the interim tray 40) is determined in step 270-4. If YES in step 
270-4, the flow advances to step 270-5. However, if NO in step 270-4, the 
flow advances to step 270-8. In step 270-5, one sheet (paper) is copied, 
and the copied sheet is set in the second paper feed unit 23. The sheet is 
re-fed from the second paper feed unit 23 in step 270-6, copied, and then 
ejected from the copying machine. 
Whether copying for the number of copies set at the ten-key pad 105 is 
completed is determined in step 270-7. If NO in step 270-7, the operation 
loop of steps 270-5, 270-6, and 270-7 is repeated until the end of 
copying. When the number of copied sheets is equal to the set number of 
copies, this routine is ended. 
On the other hand, when the flow advances from step 270-4 to 270-8, the 
copy operation is performed using the interim tray 40. More specifically, 
copying is performed by the set number of copies in step 270-8, and the 
copied transfer sheets are set in the interim tray 40. The sheets are then 
re-fed from the interim tray 40 to the photosensitive drum 20 and copying 
is performed by the set number of copies. The copied sheets are ejected 
from the copying machine and this routine is ended. 
If NO in step 270-1, the flow advances to step 270-10. Whether the original 
has a regular size is determined in step 270-10. If NO in step 270-10, the 
set number of copies is set to be 1 in step 270-17, and the flow advances 
to step 270-18. If YES in step 270-10, whether the set number of copies is 
1 is determined in step 270-11. If YES in step 270-11, the flow advances 
to step 270-18, and the second paper feed unit 23 is selected. 
If NO in step 270-11, the interim tray 40 is selected, and the number of 
copies is determined in step 270-12. If the number of copies is 30 or 
more, the number of copies is set to be 30 in step 270-13, and the flow 
advances to step 270-14. Otherwise, the flow advances to step 270-14. 
The sheets (paper) are copied by the set number of copies in step 270-14 in 
the same manner as in step 270-8, and the copied sheets are set in the 
interim tray 40. 
The original is changed by another one in step 270-15. When a copy command 
is output, copying is performed in step 270-16 in the same manner as in 
step 270-9, and this routine is ended. 
When the second paper feed unit 23 is selected, copying is performed in 
step 270-18 in the same manner as in step 270-5. The original is changed 
by another one in step 270-19. Copying is performed in step 270-20 in the 
same manner as in step 270-6, and this routine is ended. 
In this embodiment, when copying is performed for a size excluding the 
regular size, i.e., when a sheet is fed from a universal cassette or 
during one-sheet copying, the sheet is not fed to the interim tray 40 but 
directly to the second paper feed unit 23. The sheet is then re-fed from 
the second paper feed unit 23. However, when a plurality of sheets having 
a fixed size are to be copied, they are temporarily stacked in the interim 
tray 40 and are fed to the second paper feed unit 23. The sheets are 
re-fed from the second paper feed unit 23. 
Selection of one of the two systems described above is not determined by 
the user but automatically by the sequence program shown in FIG. 12. The 
operator is not confused with selection of such a system, and control can 
always be performed by an optimal system. When a plurality of sheets 
having a size excluding the regular size are to be copied, it is possible 
to copy the originals one by one by the second paper feed unit 23 without 
using the interim tray 40. Inconvenience (e.g., an excessively small paper 
size) of the transfer sheet can be discriminated, the both-side 
copy/multicopy mode is not set, and the sheet can be ejected from of the 
copying machine, thereby preventing unnecessary trouble. 
The constituting components of this embodiment will be described in detail 
with reference to timing charts in FIGS. 13 to 22. 
FIG. 13 is a timing chart of a power-on operation. When the main switch 
(power switch) 101 is turned on, the fixing heater 21 and the black 
development unit release solenoid 31 are turned on. When the fixing unit 
temperature reaches 190.degree. C., the main motor 18 is rotated. Within 
one second ( .circle.3 ) upon rotation of the main motor 18, the black 
development unit actuate solenoid 32 is turned off. The black development 
unit 8 is moved to the release position and then comes close to the 
photosensitive drum 20. When the photosensitive drum 20 is rotated one 
revolution, the main motor 18 is stopped. At the start ( .circle.2 ) of 
rotation of the motor 18, if the mid-plate in the cassette 9 in the paper 
feed unit 3 is set in the lower position, the mid-plates of the upper and 
lower cassettes are moved upward, as shown in FIG. 14. When lifting of the 
mid-plates is completed, the main motor 18 is stopped ( .circle.4 ). 
FIG. 14 is a timing of mid-plate lifting. The timing for the upper cassette 
is the same as that for the lower cassette. When the mid-plate lift clutch 
(not shown) is turned on, the mid-plate in the cassette 9 is gradually 
moved upward. When an output from the mid-plate detect sensor (not shown) 
is set at logic "1", the mid-plate lift clutch (not shown) is turned off 
after 0.1 second. The paper defect sensors S9 and S11 are arranged to 
detect the presence of sheets by moving the mid-plates upward. If the 
sheets are present, an output from each paper detect sensor is set at 
logic "1" before the output from the mid-plate detect sensor is set at 
logic "1". An output from the paper detect sensor is detected when the 
mid-plate detect sensor is set at logic "1". If the output from the paper 
detect sensor is kept at logic "0", the indicator 137 in the console unit 
100 is turned on. However, if the cassette 9 is not attached to the main 
apparatus 1, the above operation cannot be performed. 
The copy operation will be described below. FIG. 15A is a timing chart for 
the copy operation. When the copy key 103 is depressed, the main motor 18, 
the high-voltage generation unit HVT, and the original handling apparatus 
67 are turned on. Paper feed and development unit actuating operations 
(both will be described in detail later) are started. After the 
photosensitive drum 20 is rotated about one revolution, the optical system 
4 is moved forward. The registration rollers 12 are turned on after t1 
upon detection of the leading edge of the image by the leading edge sensor 
S2. Thereafter, the registration rollers 12 are stopped after a 
predetermined period of time determined by the paper size. When the 
optical system 4 is located at the reverse position, it is moved backward. 
When the optical system 4 returns to the home position, the optical system 
4 is stopped, and the drum 20 is rotated in the reverse direction. After 
the transfer sheet is ejected out from the copying machine, the main motor 
18 is stopped. If a color copy operation is performed, the development 
unit is actuated (to be described later). The lamp 24 will also be 
described later. 
The development unit actuating operation will be described below. FIG. 15B 
shows a timing when a color copy operation is started from a state wherein 
the black development unit 8 is set. The black development unit release 
solenoid 31 is turned on to release the black development unit 8 from the 
photosensitive drum 20. Upon completion of the release of the unit 8, the 
color development actuate solenoid 30 is turned on to set the color 
development unit 7 on the drum 20. When the color copy operation is 
completed, the color development unit actuate solenoid 30 is turned off to 
release the color development unit 7. 
In this case, the black development unit 8 is kept released due to the 
following reason. In order to smoothly supply the color toner, the black 
development 8 is separated from the drum 20 at the end of color copying 
(see ii). When black or color copying is started from this state, both the 
development units 7 and 8 are kept released. After the black copy 
operation is completed, the black development unit 8 is kept set on the 
drum 20. 
The paper feed operation will be described below. FIG. 16 shows a timing of 
paper feeding. When an output from the mid-plate detect sensor is set at 
logic "0" at the start of copying, the mid-plate is lifted as described 
with reference to FIG. 14. Upon completion of mid-plate lifting, the paper 
feed clutches for the paper feed rollers 10 and 11 are turned on, and the 
transfer sheet is fed. Thereafter, when the transfer sheet reaches the 
anti-registration sensor S7, an output from the anti-registration sensor 
S7 goes to logic "1". When a predetermined period of time has elapsed, the 
paper feed clutch is turned off. Therefore, the transfer sheet abuts 
against and stops at the registration rollers 12 while the sheet forms a 
loop. 
Thereafter, when the copying operation progresses, the paper feed clutch is 
turned on within a predetermined period of time upon the ON operation of 
the registration rollers 12, thereby reducing the paper feed load of the 
registration rollers 12. Thereafter, the mid-plate is controlled in 
asynchronism with the copying operation. The mid-plate lift clutch is 
turned on when the output from the mid-plate detect sensor goes to logic 
"0". When a period of 0.1 sec has elapsed after the output from the 
mid-plate detect sensor goes to logic "1", the mid-plate lift clutch is 
turned off. The presence/absence of the cassette 9 is always monitored. 
When the cassette 9 is detached from the main apparatus, lifting of the 
mid-plate is immediately interrupted. 
First-page copying of the both side copy mode for single sheets will be 
described below. The operations of the high-voltage generation unit HVT, 
the original handling apparatus 67, and the optical system as well as 
paper feed operation are the same as described above. Feeding of the 
transfer sheet upon rotation of the registration rollers 12 will be 
described below. FIG. 17 shows a timing of transfer sheet feeding. The 
transfer sheet SH is fed to the fixing unit 25 upon rotation of the 
registration rollers 12. When the transfer sheet SH passes by the eject 
sensor S4, an output from the eject sensor S4 is change in a sequence of 
0, 1, and 0. At this time, a transverse registration means (to be 
described later) (second registration rollers 37) is moved to the home 
position. 
When a predetermined period of time has elapsed and a portion of the 
transfer sheet which is away by about 10 mm from the trailing end of the 
sheet is clamped between the eject rollers 27, the reverse solenoid is 
turned on to feed the sheet backward. In this case, the second transfer 
clutch is also turned on. The transfer sheet is transferred to the second 
paper feed unit 23, and an output from the second anti-registration sensor 
S5 goes to logic "1". When another predetermined period of time has 
elapsed upon the logic level change of this output, the second transfer 
clutch is turned off. Therefore, the transfer sheets abuts against the 
second registration rollers and stops while forming a loop of about 15 mm. 
In this case, the reverse solenoid is also turned off. The second paper 
feed unit 23 can feed only a transfer sheet having a length of about 180 
mm or more. When a universal cassette whose sheet size is unknown is used, 
an input from the anti-registration sensor S7 is detected after a time 
interval corresponding to a distance l=180 mm-24 mm (a distance between 
the anti-registration sensor S7 and the registration rollers 12 is 24 mm) 
upon the energization of the registration rollers 12. If no sheet is 
detected, the sheet size is determined to be 180 mm or less. In this case, 
a switch-back operation is not performed and the transfer sheet is ejected 
from the main apparatus. However, if the sheet is detected, it has a size 
of 180 mm or more and predetermined operations are performed. 
The first copy cycle in the multicopy mode for single sheets will be 
described below. Feeding of the transfer sheet upon ON operation of the 
registration rollers 12 will be described with reference to the timing 
chart of FIG. 18. When the registration rollers 12 are turned on, the 
solenoid of the flapper 29 is turned on to start moving the transverse 
registration means (second registration rollers 37) (to be described in 
detail later) to the home position. When the transfer sheet SH is moved by 
the distance L, the output from the anti-registration sensor S7 is checked 
in a manual paper insertion mode. If no sheet is detected, the solenoid of 
the flapper 29 is turned off, and the sheet is ejected from the main 
apparatus. 
When the transfer sheet is fed and the output from the paper eject sensor 
S4 goes to logic "1", the second transfer clutch in the second paper feed 
unit 23 is turned on. When the transfer sheet is transferred to the second 
paper feed unit 23 and when a predetermined period of time t4 has elapsed 
upon the logic level change in output of the ante-second registration 
sensor S5 to logic "1", the second transfer clutch is turned off. The 
transfer sheet abuts against and stops at the second registration rollers 
37 while forming a loop. Unlike in the both-side copy mode, the curling 
state of the transfer sheet and its direction are different. The time t4 
for stopping the second transfer clutch after the output from the 
ante-second registration sensor S5 goes to logic "1" is different from 
that in the both-side copy mode. 
The second copy cycle in the both-side copy/multicopy mode for single 
sheets will be described with reference to FIG. 19. The transfer sheet has 
located in the second paper feed unit 23 and is stopped at the second 
registration rollers 37 while forming a loop. When copying is started, a 
clutch for the second registration rollers 37, and a both-side transfer 
clutch are turned on. The transfer sheet is moved toward the first 
registration rollers 12. After 0.1 sec. upon movement of the transfer 
sheet, transverse registration adjustment is started while a transfer 
sheet portion which is away by 17 mm from the leading end thereof is 
clamped between the second registration rollers 37. 
When a time t6 has elapsed after an output from the anti-registration 
sensor S7 goes to logic "1", the clutch for the second registration 
rollers 37 and the both side transfer clutch are turned off. For this 
reason, the transfer sheet abuts against and stops at the second 
registration rollers 37 while forming a loop. Thereafter, the optical 
system 4 is moved forward and a timing for turning on the registration 
rollers 12 reaches. When the transfer sheet is fed by about 5 mm, both the 
clutch for the second registration rollers 37 and the both-side transfer 
clutch are turned on in the both-side copy mode. The transfer sheet is fed 
while the loop is reduced by 5 mm. 
In the multicopy mode, however, only the both-side transfer clutch is 
turned on, and the transfer sheet is pulled by the registration rollers 
12. In this case, the second registration rollers 37 serve as a load, so 
that the transfer sheet is transferred while a loop amount is zero. 
Thereafter, the transfer sheet is ejected from the main apparatus through 
the fixing roller, and the copy operation is completed. The time t6 for 
determining a loop amount in anti-registration varies depending on the 
image transfer conditions unlike in paper feed from the cassette 9. 
An operation for setting the second registration rollers 37 at the 
transverse home position will be described below. The second registration 
rollers 37 can swing such that a driving force of the main motor 18 is 
transmitted through a spring clutch to turn on a transverse registration 
solenoid. There are provided a transverse registration home sensor for 
detecting the position of the second registration rollers 37 and the 
transverse registration paper sensor S8 for detecting a transfer sheet 
clamped between the second registration rollers 37. 
The second registration rollers 37 are reciprocally moved along the axial 
direction of the photosensitive drum 20. In order to improve stop 
precision, the second registration rollers 37 are stopped by movement from 
one direction. As shown in the timing chart of FIG. 20-1, if an output 
from the transverse registration home sensor is at logic "1", the second 
registration rollers 37 are stopped when the sensor output is changed in a 
sequence of 1, 0, and 1. However, if the output is set at logic "0", the 
second registration rollers 37 are stopped when the output from the 
transfever registration home sensor is changed from 0 to 1. 
The transverse registration adjustment operation will be described below. 
FIG. 20-2 shows the positional relationship between the second 
registration rollers 37, the transverse registration paper sensor S8, and 
the transfer sheet. When the second registration rollers 37 are set at the 
home position, they are stopped at the central point in the operating 
range. When the transverse registration solenoid is turned on, the second 
registration rollers 37 swing in the sequence of arrows .circle.1 , 
.circle.2 , .circle.3 , and .circle.1 . When the transfer sheet SH is 
inserted between the second registration rollers 37 while these rollers 37 
are stopped at the home position, the transverse registration paper sensor 
S8 detects or does not detect the sheet in accordance with the insertion 
position of the transfer sheet SH. 
A case will be described in which the sensor S8 detects the transfer sheet. 
As shown in FIG. 20-3(i), the transverse registration solenoid is turned 
off when an output from the transverse registration paper sensor S8 is 
changed in an order of 1, 0, and 1, thereby stopping the second 
registration rollers 37. When the transfer sheet SH is inserted while 
coming extremely close to the transverse registration sensor, an output 
from the transverse registration paper sensor S8 tends to be set at logic 
"1". In this case, the following operation is performed to stop the second 
registration rollers 37 at an optimal position. As shown in FIG. 20-2, 
when the second registration rollers 37 are moved, as indicated by arrows 
.circle.1 and .circle.2 , the transfer sheet SH is moved away from the 
sensor S8 to a furthest position. In this case, if an output from the 
transverse registration paper sensor S8 is set at logic "1", the sheet is 
moved in a direction indicated by arrow .circle.3 . Therefore, the output 
from the transverse registration paper sensor S8 is not set at logic "0". 
The second registration rollers 37 are stopped at the above moment, so 
that an optimal position is set. Assume that a time interval corresponding 
to one period of transverse movement of the second registration rollers 37 
is given as T. If the output from the transverse registration paper sensor 
S8 is not set at logic "0" even if they are moved by 3/4T, that is, a time 
interval corresponding to a distance given by arrows .circle.1 and 
.circle.2 , the second registration rollers 37 are stopped. 
A case will be described in which the output from the transverse 
registration paper sensor S8 is set first at logic "0", that is, a 
transfer sheet is not present in the position of the transverse 
registration paper sensor S8. In this case, as shown in FIG. 20-3(ii), the 
second registration rollers 37 are stopped when the output from the 
transverse registration paper sensor S8 is changed in from 0 to 1. When 
the transfer sheet SH is inserted while it is, relatively, extremely far 
away from the the transverse registration paper sensor S8, the output from 
the transverse registration paper sensor S8 may be kept at logic "0". In 
this case, if the output from the transverse registration paper sensor S8 
does not go to logic "1" even if the second registration rollers are moved 
by a time interval of T/4 corresponding to arrow .circle.1 in FIG. 
20-3(ii), the second registration rollers 37 are immediately stopped. 
The first copy cycle in the both-side copy mode using the interim tray 40 
will be described below. After the copy operation is started, the 
operations of the paper feed system, the high voltage system, and the 
optical system are the same as described above. Feeding of the transfer 
sheet during the ON operation of the first registration rollers 12 will be 
described with reference to a timing of FIG. 21-1. When the first 
registration rollers 12 are turned on, the flapper solenoid and an interim 
tray flapper are turned on. The transfer sheet fed from the first 
registration rollers 12 passes through the fixing roller in the fixing 
unit 25 and is transferred toward the interim tray 40. The input sensor 
S19 of the interim tray 40 detects the number of transfer sheets SH stored 
in the interim tray 40. After the set number of transfer sheets is 
detected, the operation of the first registration rollers 12 is stopped. 
The first copy cycle in the multicopy mode using the interim tray 40 will 
be described with reference to a timing chart of FIG. 21-2. The first 
registration rollers 12 are turned on, and at the same time the flapper 49 
of the interim tray 40 is turned on to form a paper path for transferring 
the transfer sheet SH to the interim tray 40. When the transfer sheet SH 
is fed out from the first registration rollers 12 and passes through the 
eject sensor S4, the reverse solenoid is turned on. In the same manner as 
in the both-side copy mode for single sheets as described above, the 
transfer sheet SH is switched back (fed backward) and is transferred and 
stored in the interim tray 40. In this case, the number of sheets stored 
in the interim tray 40 is counted by the input sensor S19. When the set 
number of sheets is detected, the operation is ended. 
A second copy cycle in the multicopy/both-side copy mode using the interim 
tray 40 will be described below. The transfer sheets are stocked in the 
interim tray 40 and a timing for setting the transfer sheets in the second 
paper feed unit 23 is shown in FIG. 22. More specifically, a solenoid for 
an interim tray paper feed roller 56 is turned on. The paper feed roller 
56 is moved downward by a driving means (not shown), and the uppermost 
transfer sheet is brought into contact with interim tray paper send 
rollers 57. Thereafter, a solenoid for the interim tray send rollers 57 is 
turned on to cause the interim tray paper send rollers 57 to send the 
transfer sheet to the paper transfer path 59. When the leading end of the 
transfer sheet reaches the interim tray output sensor S21, the interim 
tray paper feed roller solenoid is turned off. The paper feed roller 56 is 
moved upward and is separated from the transfer sheet. In this case, the 
second transfer clutch is turned on, and the second registration rollers 
37 are started so as to set the second registration rollers 37 to the home 
position. 
The transfer sheet reaches the second anti-registration sensor S5. When a 
predetermined period of time has elapsed, the transfer sheet abuts against 
the second registration rollers 37 while forming a loop. The second 
registration rollers 37 are turned on and the transfer sheet is fed toward 
the first registration rollers 12. The subsequent operations are the same 
as those in the second copy cycle in the multicopy/both side copy mode for 
single sheets. 
A drive operation of the main motor 18 will be described with reference to 
FIG. 23. 
In this embodiment, a DC motor is used as the main motor 18 which functions 
as a variable speed drive source. Speed control is performed by PLL 
(Phase-Locked Control). More specifically, a signal from an oscillator 85 
is input to a PLL circuit 81 as a reference signal. A speed signal from an 
encoder 82 connected to the DC motor 18 is fed back to the PLL circuit 81 
as a feedback signal. An output from the PLL circuit 81 is transmitted to 
a driver 84 through an amplifier 83 so as to synchronize the reference 
signal with the feedback signal. The DC motor 18 is driven by the driver 
84. When the speed of the motor 18 is changed, input signals A and B 
control to change an output frequency of the oscillator 85. The input 
signals A and B are connected to a speed command circuit (not shown). 
A circuit arrangement of the laser unit 90 is shown in FIG. 24. Laser unit 
control information such as a copy mode designated by the mode select key 
153, the copy magnification, the paper size, the picture mode, the add-on 
character code, and the add-on position is supplied to a laser unit 
controller 700 through a known 2-port RAM 703. The laser unit controller 
700 alternately writes, for each line, area data BDATA (to be described 
later) for area designation in a blank RAM(0) 705 and a blank RAM(l) 706 
in accordance with a program of an external program ROM 701. An area data 
read-out control circuit 716 outputs a control signal to a blank address 
counter 715 and an 8-bit shift register 708. The area data BDATA is output 
from the 8-bit shift register 708 to a data control circuit 720 in units 
of bits. 
Each of the blank data RAM(0) 705 and RAM(l) 706 has a capacity for writing 
one-line area data BDATA and is addressed by the blank address counter 
715. While the laser unit controller 700 writes the area data BDATA in the 
blank RAM(0) 705 or the blank RAM(1) 706, the laser unit controller 700 
supplies a control signal to an address change circuit 704 and a blank 
data change circuit 707 so as to write the data BDATA in the 8-bit shift 
register 708. 
Add-on control for writing characters on the copy image will be described 
below. 
The laser unit controller 700 reads out data (character pattern) from a 
font ROM (character generator) 702 in accordance with an add-on character 
code from the controller 60 and sets it in an add-on RAM 723. The add-on 
RAM 723 comprises a bit map for storing dot patterns of, e.g., 30 
characters. The laser unit controller 700 writes add-on character print 
position designation data representing a print position of a character in 
the add-on controller 709. When the laser unit controller 700 supplies a 
start signal to the add-on controller 709, the add-on controller 709 reads 
out data (character pattern) FDATA from the add-on RAM 723 in accordance 
with the add-on character print position designation data, and the data 
FDATA is output to the data control circuit 720. 
As shown in FIG. 3, a laser beam emitted from the laser 91 is reflected by 
the polygonal mirror 93. The reflected beam is transmitted through the 
focusing lenses 95 and 96. A focused beam spot scans the surface of the 
photosensitive drum 20. In order to extract a horizontal sync signal, a 
horizontal sync signal (to be referred to as the BD signal) detect circuit 
94 is arranged on the laser scanning surface. The horizontal sync signal 
(BD signal) output from the BD detect circuit 94 is input to the laser 
unit 90. This horizontal sync signal (BD signal) is input to a pulse width 
shaping F/F (flip-flop) 710 shown in FIG. 24 and is waveshaped. The 
waveshaped signal is input to a pulse sync circuit(l) 711, an interrupt 
terminal of the laser unit controller 700, and a pulse sync circuit(2) 
712. The horizontal sync signal from the BD detect circuit 94, input to 
the pulse width shaping F/F 710 is called the IBD signal, and the 
waveshaped horizontal sync output from the pulse width shaping F/F 710 is 
called the BD signal hereinafter. 
The laser unit controller 700 generates an interrupt signal every time the 
BD signal is generated. The laser unit controller 700 writes the area data 
BDATA in the blank RAM(0) 705 and the blank RAM(1) 706. The laser unit 
controller 700 counts the number of interrupt singals in response to the 
BD signals and then outputs a control signal for the sub-scan direction. 
The pulse sync circuit(1) 711 outputs a reset pulse HSYNC1 to a horizontal 
sync clock generating circuit 713 in synchronism with a leading edge of 
the BD signal. The horizontal sync clock generating circuit 713 outputs a 
clock HCLK synchronized with the BD signal. The horizontal sync clock 
generating circuit 713 comprises a reference clock generator for 
generating a reference clock SCLK and a frequency divider for 
frequency-dividing the reference clock SCLK in response to the HSYNC1 and 
outputting the clock HCLK. 
The pulse sync circuit(2) 712 generates a BD signal sync singal HSYNC2 in 
accordance with the horizontal sync clock HCLK. A horizontal line counter 
714 is cleared in response to the signal HSYNC2 and counts the horizontal 
sync clocks HCLK. An output from the horizontal line counter 714 is input 
to a timing signal generating circuit 718 so that the horizontal timing 
signal is output in response to a count output from the horizontal line 
counter 714. 
Waveforms of the above-mentioned signals are shown in FIGS. 25 and 26. FIG. 
25 shows timings for causing the horizontal clock generating circuit 713 
to generate the horizontal sync clocks HCLK in response to the input 
signal IBD from the BD detect circuit 94. A shown in FIG. 25, The 
reference clock frequency-dividing counter (frequency divider) in the 
horizontal sync clock generating circuit 713 is reset in response to the 
leading edge of the detect pulse (reset pulse) HSYNC1 to generate the 
horizontal clock HCLK. The pulse sync circuit(2) 712 generates the BD sync 
signal HSYNC2 in response to the horizontal sync clock HCLK to reset the 
horizontal line counter 714. 
FIG. 26 shows waveforms of signals generated in the laser unit 90. As shown 
in FIG. 26, the timing signal generating circuit 718 generates signals 
UBSET and UBRST in accordance with an output from the horizontal line 
counter 714 to generate a blank signal BLANK for designating an effective 
image area. A clock for reading out data (dot pattern) from the addon RAM 
723 is generated using the horizontal sync clock HCLK. A clock for reading 
out the designated area data BDATA from the RAM(0) 705 and the RAM(1) 706 
is generated using a clock CLKM obtained by frequency-dividing the 
horizontal sync clock HCLK, thereby obtaining a variable resolution for 
blank area designation. 
The timing signal generating circuit 718 generates the BDSET and BDRST 
signals and the BDENB signal. These signals are input to the horizontal 
sync singal error detect circuit 717. When the horizontal sync singal BD 
is not input within a predetermined time interval, the BDENB signal is not 
generated. The horizontal sync signal error detect circuit 717 outputs the 
BD error signal to the laser unit controller 700. When the laser unit 
controller 700 detects the BD error signal, abnormal status is transferred 
to the control unit 60 through the 2-port RAM 703. 
A dot erase circuit 719 for forming a dot or halftone image will be 
described with reference to FIGS. 27-1 to 27-3. As shown in FIG. 27-1, the 
dot erase circuit 719 comprises an 8-bit shift register 724. The 
horizontal sync clock HCLK is input as a shift clock. Dots are formed on 
the basis of the timings of the horizontal sync clocks HCLK. As shown in 
the timing chart of FIG. 27-2, the dot data is loaded by the laser unit 
controller 700 to the shift register 724 through a data bus DB for a 
period from a leading edge of the BD signal to the leading edge of the 
blank signal BLANK representing the effective image area. It should be 
noted that data loading is performed on the basis of a load signal LOAD 
from the controller 700. An output from the shift register 724 is 
logically ANDed with the blank signal BLANK, and the AND signal is output 
to the data control circuit 720 as a dot signal DEDATA in the form of a 
dot pattern. 
The 8-bit dot data written in the 8-bit shift register 72 is cyclically 
shifted by the laser unit controller 700 in response to the sync clocks 
HCLK and is output to an AND gate 725. 
FIGS. 27-3A to 27-3C show output dot patterns. The 8-bit dot data stored in 
the shift register 724 is output as a repeated pattern of D0 to D7 in the 
main scan direction (laser scan direction). A designated (arbitrary) dot 
pattern can be generated by the laser unit controller 700 in the sub-scan 
direction (drum rotational direction) every BD interrupt signal by loading 
designated (arbitrary) dot data (e.g., DATA0 to DATA7) in the 8-bit shift 
register 724. 
The data control circuit 720 in the laser unit 90 comprises a gate circuit 
for controlling the character pattern FDATA from the addon controller 709, 
the area data BDATA, and the dot data DEDATA from the dot erase circuit 
719. The data control circuit 720 selectively supplies, e.g., the 
character pattern FDATA and the dot data DEDATA at a predetermined timing 
in accordance with a control signal from the laser unit controller 700. 
The laser drive circuit 721 modulates the laser in accordance with the 
data input from the data control circuit 720. 
The laser drive circuit 721 will be described with reference to FIG. 28. A 
laser 750 is driven by a current stabilizing circuit 753 so that a laser 
beam having a predetermined power is always output. The laser 750 performs 
ON/OFF modulation in accordance with the area data BDATA, the dot data 
DEDATA, and the character pattern or data FDATA. Since the 
current-emission quantity (power) characteristics of the laser 750 
(corresponding to the laser 91 in FIG. 1) vary, known APC (automatic power 
control) must be performed at a given timing, thereby constantly 
outputting a laser having a predetermined power. An operation of an APC 
circuit for performing APC will be described below. 
A laser ON signal is output from the laser unit controller 700 to cause the 
laser 750 to emit a laser beam. A monitor current of a photodiode PD in 
the laser 750 is input to a current-voltage conversion circuit 754 to 
extract a voltage proportional to the laser power. One of reference 
voltages Vref1 to Vref4 output from a voltage regulating circuit 760 is 
selected by an analog switch 759, and the selected voltage is input to 
comparators 756 and 757. Therefore, the laser power falls within the 
predetermined range. More specifically, the comparators 756 and 757 
compare the outputs from the current-voltage conversion circuit 754 with 
the reference voltage and output signals PDCMP1 and PDCMP2 according to 
comparison results. 
Outputs from the comparators 756 and 757 are input to an APC logic circuit. 
For example, if the laser power falls outside the predetermined range, an 
up/down counter 751 is controlled (a count value is switched) in 
accordance with an output APCG from the APC logic circuit 758, thereby 
changing the data input to a D/A (digital-to-analog) converter 752. The 
up/down counter 751 performs the count operation in response to the APC 
clocks when the signal APCG is input thereto. An output from the D/A 
converter 752 is changed upon a change in count value of the up/down 
counter 751, and therefore, a current value of the current stabilizing 
circuit 753 is changed. When the laser power range is controlled to the 
predetermined range, a stop signal STOP is output from the APC logic 
circuit 758. The count value of the up/down counter 751 is held as the 
predetermined data. When the laser unit controller 700 detects the signal 
STOP, i.e., the APCRDY (ready) signal, the controller 700 outputs the 
APCSTOP (stop) signal to the laser drive circuit 721 to turn off the 
laser. An APC end status signal is sent to the control unit 60 through the 
2-port RAM 703. An APC method is also disclosed in U.S. Pat. No. 
4,443,695. 
A laser scanner motor controller 722 (PLL circuit) in FIG. 24 performs 
speed control of the polygonal mirror 93 at a predetermined speed. For 
this reason, the controller 722 uses a known PLL circuit (not shown) and 
initializes rotation of the polygonal mirror 93 in response to the ON 
signal (LSCON) from the control unit 60. While the polygonal mirror 93 is 
rotated at the predetermined speed, the laser scanner motor controller 722 
uses the known PLL (Phase Locked Loop) clock to output the laser scanner 
ready signal (LSCRDY) to the laser unit controller 700. 
The laser unit controller 700 monitors the laser scanner motor ready signal 
at predetermined intervals. When a predetermined period of time has 
elapsed upon ON operation of the laser scanner motor 92 and the laser 
scanner motor ready signal is not output, the laser unit controller 700 
sends a laser scanner motor abnormal signal to the control unit 60. 
An operation for controlling a designated image area by using the blank 
RAM(0) 705 and the blank RAM(1) 706 will be described with reference to 
FIGS. 29A to 29C. 
When data (P1,P1') and (P2,P2') which designates areas shown in FIG. 29A 
are sent from the control unit 60 to the laser unit controller 700 through 
the 2-port RAM 703. Assume that each of the blank RAM(0) 705 and the blank 
RAM(l) 706 in the laser unit 90 has a one-line memory capacity at a 
predetermined area resolution. When the areas are designated, as shown in 
FIG. 29A, three line memory data (area data BDATA) are prepared. Line 
memory data 0 is read out from the RAM(0) 705 from a start point P0 to an 
x-coordinate x1 of the point P1. Line memory data 1 is read out from the 
blank RAM(l) 706 from the x-coordinate x1 of the point P1 to an 
x-coordinate x1' of the point P1'. The line memory data 0 is read out from 
the blank RAM(0) 705 from the x-coordinate x1' of the point P1' to an 
x-coordinate x2 of the point P2. Line memory data 2 is read out from the 
blank RAM(l) 706 from the x-coordinate x2 of the point P2 to an 
x-coordinate x2' of the point P2'. The line memory data 0 is read-out from 
the blank RAM(0) 705 from the x-coordinate x2' of the point P2' to an end 
point PE. As a result, the area excluding the areas (P1,P1') and (P2,P2') 
shown in FIG. 29A is irradiated with the laser beam, so that a copy image 
of the original is restricted to the areas (P1,P1') and (P2,P2'). 
Under the control of the laser unit controller 700, the line memory data is 
written in one of the blank RAMs which is not set in the read operation. 
In the reduction/enlargement mode, the following calculations using the 
data of the points P1, P1', P2, and P2' sent from the control unit 60 are 
performed in accordance with a magnification .alpha.: 
EQU P1.times..alpha., P2.times..alpha., P1'.times..alpha., and 
P2'.times..alpha. 
The line memory data 0, 1, and 2 are updated as shown in FIG. 29C. 
The control sequence of the laser unit controller 700 in area designation 
control will be described with reference to a flow chart in FIG. 30. Area 
designation data and magnification data are received from the control unit 
60 in step 800. The line memory data (area data BDATA) is set in the blank 
RAM(0) 705 by using the area designation data and the magnification data 
in step 801. In step 802, the laser unit controller 700 waits for an image 
formation start command from the control unit 60 in step 802. When the 
image formation start command is supplied from the control unit 60 in step 
802, the laser unit controller 700 starts reading out the data from the 
blank RAM(0) 705. 
The next line memory data (area data BDATA) is set in the blank RAM(l) 706 
in step 804. In decision steps 805 and 806, the laser unit controller 700 
determines whether the end of image formation and the area designation 
data change occur. This decision operation is performed such that the BD 
signals are counted from the start of image formation in the laser unit 
controller 700 and the count is compared with the sub-scan position data 
of the points P1, P1', P2, P2', and PE. 
If the area designation data change is determined, the read/write access of 
the RAMs is reversed in steps 806 and 807. The laser unit controller 700 
waits for the timing in steps 808 and 809 in the same manner as in steps 
805 and 806. If the affirmative determination is established in step 809, 
the flow returns to step 803, and the above operations are repeated until 
the end of image formation. 
The laser unit 90 will be described in more detail with reference to FIG. 
24. As described above, the laser unit controller 700 comprises a CPU for 
performing operations in accordance with programs stored in a program ROM 
701. The laser unit controller 700 performs controls the respective 
circuits in accordance with the control information input from the control 
unit 60 and performs (1) area designation operation, (2) dot formation 
operation, and (3) add-on (character input) operation. 
The above three operations are performed in accordance with a command from 
the console unit 100 or the editor 180. 
Referring to FIG. 24, the pulse width shaping F/F 710, the pulse sync 
circuit(1) 711, the pulse sync circuit(2) 712, the horizontal sync clock 
generation circuit 713, the horizontal line counter 714, and the timing 
signal generation circuit are arranged to generate timing signals serving 
as the reference clocks for the above three operations. As previously 
described, the sync signal BD generated by the horizontal sync signal 
detect circuit 94 is waveshaped by the pulse width shaping F/F 710 and is 
converted into the horizontal sync signal BD synchronized with the 
reference clock SCLK output from the horizontal sync clock generation 
circuit 713. The reset pulse HSYNC1 synchronized with the leading edge of 
the horizontal sync singal BD is output from the pulse sync circuit(1) 
711. The horizontal sync clock HCLK obtained by frequency-dividing the 
reference clock SCLK in synchronism with the reset pulse HSYNC1 is output 
from the horizontal sync clock generation circuit 713. The dot formation 
operation and the addon (character input) operation are controlled in 
synchronism with the horizontal sync clock HCLK. The area designation 
operation is controlled in synchronism with the clock CLKM obtained by 
frequency-dividing the horizontal sync clock HCLK. 
In this embodiment, since the horizontal sync clocks HCLK and CLKM 
synchronized with the sync signal IBD by using a high-frequency reference 
clock SCLK are generated, positional precision along the main scan 
direction (laser beam scan direction) can be improved. 
The pulse sync circuit(2) 712 generates the BD signal sync signal HSYNC2 
synchronized with the horizontal sync clock HCLK on the basis of the 
horizontal sync signal BD. Various counters (not shown) in the horizontal 
line counter 714 are reset in response to the signal HSYNC2, and the 
horizontal sync clocks HCLK are counted from zero. In the horizontal line 
counter 714, values of the various counters are compared with values 
(signal lines and the like are not illustrated) set from the laser unit 
controller 700. When a coincidence is established in each counter, the 
horizontal line counter 714 generates the UBSET and UBRST signals. 
In response to the UBSET and UBRST signals input from the horizontal line 
counter 714, the timing signal generating circuit 718 generates the blank 
signal BLANK for designating an effective image area. When the blank 
signal BLANK is set at logic "1", the area designation operation, the dot 
formation operation, and the addon operation are performed. In other 
words, the blank signal BLANK is a signal representing an area in which 
image formation can be actually performed on a transfer sheet. The laser 
unit controller 700 changes the set values in the horizontal line counter 
714 in accordance with the transfer paper size, the magnification, and the 
like and changes a generation timing of the blank signal. 
The area designation operation will be described below. Referring to FIG. 
24, the area designation operation is primarily performed using the laser 
unit controller 700, the address change circuit 704, the blank RAM(0) 705, 
the blank RAM(1) 706, the blank data change circuit 707, the 8-bit shift 
register 708, the blank address counter 715, and the area data read-out 
control circuit 716. As previously described, the area data BDATA 
representing the designated areas are written in the blank RAM(0) 705 and 
the blank RAM(1) 706. 
The blank data change circuit 707 selects an output from either the blank 
RAM(0) 705 or the blank RAM(1) 706 and writes the selected data in the 
8-bit shift register 708. The 8-bit shift register 708 performs 
parallel/serial conversion of the area data BDATA in accordance with a 
control signal from the area data read-out control circuit 716 and 
sequentially outputs the serial data. An address of the blank RAM in the 
read operation of the area data is accessed by the blank address counter 
715 and is input through the address change circuit 704. The blank RAM in 
the non-read access of the area data is connected to an address line (not 
shown) of the laser unit controller 700 through the address change circuit 
704, thereby allowing desired area data access. 
The operations of the data control circuit 720 for the area designation 
operation, the dot formation operation, and the addon operation will be 
described below. It should be noted that the data control circuit 720 
comprises known gate circuits and the like. 
(i) Only Area Designation Operation 
Only the area data BDATA is input to the laser drive circuit 721 in 
accordance with a control signal from the laser unit controller 700. 
(ii) Dot Formation Operation 
An OR signal of the area data BDATA and the dot signal DEDATA is input to 
the laser drive circuit 721 in accordance with a control signal from the 
laser unit controller 700. For example, if dots are formed within only the 
designated area (i.e., "within" area), the data BDATA for only the 
designated area are set at logic "0" and those in other areas are set at 
logic "1" in the same manner as in the area designation operation. As a 
result, the dot signal DEDATA for only the portion corresponding to the 
designated area is input to the laser drive circuit 721, and a dot image 
is formed within only the designated area. A drive signal of logic "1" for 
the area ("without" area) other than the designated area is input to the 
laser drive circuit 721, and the erase operation with laser radiation is 
performed. 
(iii) Simultaneous Copy Mode of Digital Image (Character) and Analog Image 
An AND signal of the area data BDATA and the character pattern FDATA is 
input to the laser drive circuit 721 in accordance with a control signal 
from the laser unit controller 700. For example, the following operations 
are performed to obtain an image shown in FIG. 11C. The area data BDATA 
are set in the area designation operation such that all "0"s are set in 
all areas excluding the area indicated by the hatched lines in FIG. 11C, 
and that "1"s are set in the area indicated by the hatched lines. The data 
BDATA "0" for the areas excluding the hatched area shown in FIG. 11C is 
input to the laser drive circuit 721, and an original image is copied 
without changes. Since the data BDATA is set at logic "1" for portions 
other than the character portion within the hatched area, and the erase 
operation with laser radiation is performed. The character portion within 
the hatched area is formed by the character pattern FDATA input to the 
laser drive circuit 721. 
(iv) Multicopy Mode of Digital Image 
The same operations as in mode (iii) ar performed except that the 
designated areas are different. In order to obtain the image shown in FIG. 
11D, in the first copy cycle, the area designation data BDATA for all 
image areas are set at logic "1". During the first copying cycle, only 
characters corresponding to the character pattern FDATA are formed. The 
area excluding the character portion is irradiated with the laser beam, 
and the erase operation is performed. In the subsequent or second copy 
cycle, the area designation data BDATA for all image areas are set at 
logic "0", and only the data BDATA is input to the laser drive circuit 
721. As a result, the area is not irradiated with the laser beam, and only 
the analog image corresponding to the original image is formed on the 
transfer sheet in addition to the characters formed in the first copy 
cycle. 
FIG. 36 shows a recording operation of this embodiment. An area B 
surrounded by dotted lines on an original A is designated by the editor 
180. 
The operator uses the mode select key 153 in the editor 180 to select on of 
the modes .circle.7 and .circle.8 .circle. represented by reference 
numeral 162. However, if the mode .circle.8 is selected, the user can 
further selects a development color with the development unit selection 
key 104. Therefore, the preliminary operations prior to actual copying are 
completed. 
When the operator depresses the copy key 103 on the console unit 100 shown 
in FIG. 5, an image on the original is exposed with light and scanned to 
form an image. A transfer sheet having a transferred image is transferred 
to the second registration rollers 37. As previously described, the dot 
image is formed for only the designated area, as shown in FIG. 36B, and a 
multicopy image is formed on the transfer sheet. As a result, a composite 
image shown in FIG. 36C is obtained. 
In the above description, when the operator selects dot recording in the 
multicopy mode, the original development is performed in the first copy 
cycle. In the second copy cycle, dot development is performed. However, a 
dot image may be developed and recorded in the first copy cycle, and the 
original image may be developed and copied in the second copy cycle. The 
dot image recording area may be designated in each copy cycle, and a 
plurality of portions may be designated for dot image formation. 
According to this embodiment as described above, since the dot image can be 
superposed on the original image information in a designated area of the 
original image, the original image information can be easily emphasized 
without impairing the original image information of the designated area. 
FIG. 31 shows the main part of this embodiment. The optical system 4 as a 
main record optical system is located at the home position. A white plate 
300 is disposed at the home position, in the end portion of the original 
glass table 5. When the exposure lamp 24 is turned on while the optical 
system 4 is stopped at the home position, light emitted from the exposure 
lamp 24 is reflected by the white plate 300 and guided to a reflecting 
mirror in the optical system 4. The reflected light is emitted on the 
photosensitive drum 20. The photosensitive drum 20 is rotated at a 
predetermined speed and the surface of the white plate 300 is coated with 
a white layer. In other words, the surface of the photosensitive drum 20 
has a high reflectivity, a "white" portion on the photosensitive drum 20 
is developed, and an unnecessary latent image portion is erased. 
A recording timing of a copy operation for a plurality of sheets in this 
embodiment is shown in FIG. 32, and its control sequences are shown in 
FIGS. 33A and 33B. An operation for starting recording in this embodiment 
will be described with reference to the flow charts in FIGS. 33A and 33B. 
When the copy key 103 for designating the start of copying is depressed, 
the copy start operation is started (step T1), and the photosensitive drum 
20, the chargers 13, 15, and 16, the exposure lamp 24, and a laser motor 
92 are turned on (steps T2 to T4). At the start of copying, the optical 
system 4 is stopped at the home position, as shown in FIG. 31. In this 
state, the erase operation for developing a "white" portion on the 
photosensitive drum 20 is performed. A timer is operated to detect until 
the laser motor 92 for rotating the polygonal mirror 93 is rotated at a 
constant speed (step T5), and laser quantity control of the laser 91 is 
started (step T6). Laser quantity control of the laser 91 is performed to 
set a laser output (beam output) to be constant. Laser quantity control is 
indicated by hatched portions in representation of the laser output in 
FIG. 32. 
When laser quantity control is completed (step T7), the laser 91 is turned 
on and kept on (step T8). The ON state is indicated by hollow rectangles 
in the representation of the laser output in FIG. 32. A residual image 
(history) on the photosensitive drum 20 is erased and the surface state is 
uniformed (step T9), the original scan optical system 4 is forwarded (step 
T10), and original exposure started. Thereafter, when the optical system 4 
reaches a position where it can detect the leading end of the original, 
the leading edge sensor S2 detects the leading edge (step T11). ON/OFF 
control of the laser 91 is started (step T12), and the specific image 
portion (latent image) on the photosensitive drum 20 is erased (image 
erase operation) or predetermined image information such as date or page 
numbers designated by the user is output on the photosensitive drum 20. 
This state is indicated by portions indicated by horizontal lines and 
included in the representation of the laser output in FIG. 32. 
The original is exposed with light and scanned by a length corresponding to 
the length of the transfer sheet SH, and the image is transferred to the 
transfer sheet. The optical system 4 reaches the reverse point (step T13), 
the laser 91 is turned on and kept on (step T14). The exposure lamp 24 is 
turned off (step T15), and the optical system 4 is fed backward (step 
T16). Therefore, the surface of the photosensitive drum 20 is clearly 
erased with the laser beam. 
When the optical system 4 returns to the home position (step T17), movement 
of the optical system 4 is stopped (step T18), and the exposure lamp 24 is 
turned on (step T19). Laser quantity control for setting the laser quality 
to be constant is started again (step T20). During this period, the 
residual image on the photosensitive drum 20 is erased by the exposure 
lamp 24. 
When laser quality control is completed (step T21) and the end of the set 
number of copies is not detected in step T22, the laser 91 is turned on 
and kept on (step T23), and the flow returns to step T10. The optical 
system 4 is forwarded. The same recording and copying operations as in the 
first copy cycle are repeated. Thereafter, the optical system 4 is fed 
backward and returns to the home position (steps T17 and T18). The 
exposure lamp 24 is turned on (step T19) and the erase operation is 
performed using the exposure lamp 24 and the white plate 300. The above 
operations are repeated, the end of the set number of copies is detected 
(step T22). The laser 91 is turned off (step T24), and the transfer sheet 
is ejected from the copying machine (step T25). The exposure lamp 24, the 
chargers 13, 15, and 16 and the laser motor 92 are turned off (steps T26 
to T28). Therefore, all the operations are completed. 
In the embodiment shown in FIG. 31, an operation for writing predetermined 
image information with the laser 91 without performing original exposure 
will be described with reference to the timing chart in FIG. 34 and the 
flow chart in FIG. 35. When the copy key 103 is depressed (step T31), the 
chargers 13, 15, and 16, the exposure lamp 24, and the laser motor 92 are 
turned on, and at the same time the clutch for the paper feed roller 10 or 
11 is turned on (steps T32 to T35). Since the optical system 4 is stopped 
at the home position, as shown in FIG. 31, the photosensitive drum 20 is 
erased by the exposure lamp 24. 
When the speed of the laser motor 92 reaches a constant speed (step T36), 
laser quantity control of the laser 91 is started (step T37). This control 
time is represented by a hatched portion in the laser output in FIG. 34. 
When the quantity of the laser 91 reaches a predetermined value (step T38), 
the laser 91 is kept on (step T39). This ON period is represented by 
hollow rectangles in the laser output in FIG. 34. Thereafter, when the 
leading edge of the transfer sheet SH abuts against the first registration 
rollers 12 and a loop (curve) having a predetermined amount is formed, the 
clutch for the paper feed roller 10 or 11 is turned off (steps T40 and 
T41). The surface of the photosensitive drum 20 is made uniform, or 
evened, by the ON operation of the exposure lamp 24 and the erase 
operation of the laser 91 (step T42), the exposure lamp 24 is turned off 
(step T43). The erase operation is started by only the beam from the laser 
91. When the exposure lamp 24 is completely turned off (step T44), the 
write operation of characters and the like is started by the ON/OFF 
control of the laser 91 (step T45). This write period is indicated by a 
portion represented by horizontal lines included in the laser output in 
FIG. 34. 
The copying machine waits for a predetermined period (step T46), and the 
clutch for the registration rollers 12 is turned on (step T47). The 
transfer sheet SH is fed to the photosensitive drum 20 in synchronism with 
the image. Since the write operation by the laser 91 is performed for part 
of the transfer sheet, this operation can be completed within a very short 
period t1 (step T48). 
The laser 91 is turned on (step T49) and the exposure lamp 24 is turned on 
(step T50). The surface of the photosensitive drum 20 is erased by the 
exposure lamp 24. In this case, the laser 91 is kept on with a maximum 
power within the period corresponding to the leading time of the exposure 
lamp 24 (steps T51 and T52). After the clutch of the registration rollers 
12 is turned on by a period corresponding to the length of the transfer 
sheet, this clutch is turned off. Thereafter, when the transfer sheet is 
ejected out from the copying machine or set in the interim tray 40 (step 
T53), the exposure lamp 24, the chargers 13, 15, and 16, and the laser 
motor 92 are turned off (steps T54 to T56). All the operations are thus 
completed. 
Since the erase operation at the start of recording is performed by the 
erasing means constituted by the exposure lamp 24 and the white plate 300, 
the copying machine can start charge sequence control without waiting 
until the rise time of the laser motor 92, thereby greatly increasing the 
recording speed. In addition, since the laser is kept off during the erase 
operation by the erasing means, the ON time of the laser can be reduced. 
Therefore, the copying machine can be used for a long period of time, 
machine reliability can be improved, and maintenance/service cost can be 
reduced. 
The present invention is not limited to the particular embodiment described 
above. Various changes and modifications may be made within the scope of 
the appended claims.