Image Forming Apparatus Capable of Selectively Optically Scanning One or More Documents to Be Copied During One Scanning Operation

1. Field of the Invention

The present invention relates to an image forming apparatus in which an image of a document is optically scanned and the image is formed on a recording medium.

2. Discussion of Background

A conventional image forming apparatus or copying apparatus using an optical scanner accommodates only one document on the document table at a time, and copies the document only one frame a time by means of a single scanning operation. Therefore, in copying plural documents, the optical scanner must scan the documents on the document table plural times corresponding to the number of documents. Such repetitious scanning of documents is time-consuming and troublesome work.

Accordingly, an object of the present invention is to provide an image forming apparatus in which two documents on the document table can be scanned during one scanning operation by an optical scanner, and a precise setting of the documents on the document table can be easily performed.

To achieve the above object, there is a provided an image forming apparatus according to the invention including a document table for holding a document placed thereon, optical scanning means movably provided along the document table to optically scan the document placed on the document table, first and second indicating means provided at respective ends of the document table to indicate the allowable copy ranges, designating means for designating a scanning area provided by placing the document on the document table in accordance with the first and/or second indicating means, and means for controlling the movement of the optical scanning means to scan the scanning area designated by the designating means.

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a plan view showing one embodiment of an image forming apparatus according to the present invention;

FIGS. 2-4 are respective views for explaining operation of the embodiment shown in FIG. 1:

FIG. 5 is a perspective view showing the outer appearance of the embodiment shown in FIG. 1;

FIG. 6 is a schematic cross-sectional side view showing a section of the embodiment of the invention shown in FIG. 1;

FIG. 7 is a plan view showing an operation panel of the embodiment of FIG. 1;

FIG. 8 is a perspective view showing driving portions of the embodiment of the invention of FIG. 1;

FIG. 9 is a perspective view of a scanning mechanism for moving an optical scanner in the embodiment of FIG. 1;

FIG. 10 is a perspective view of a driving mechanism for moving indicators in the embodiment of FIG. 1; and

FIG. 11 is a block diagram showing the overall control system for the embodiment of FIG. 1.

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, FIGS. 5 and 6 are schematic views of the image forming apparatus, for example an electrostatic copying apparatus, of the invention. A document table 2 made of transparent glass is fixed on an upper portion of a main body 1 for supporting a document. An optical scanner 3 is provided and reciprocatively moves in the direction of arrow A along a lower surface of document table 2. Scanner 3 includes an exposure lamp 4 to illuminate a document placed on table 2 and mirrors 5, 6 and 7 to reflect the light reflected from the document. When optical scanner 3 moves from the left side to right side in FIG. 6, optical scanner 3 optically scans the document placed on table 2. Mirrors 6 and 7 are moved at half the speed of exposure lamp 4 and mirror 5, whereby an optical path length from the document to a photosensitive drum 10, described later, is kept constant. The reflected light from the document is reflected by mirrors 5, 6 and 7 then passed through a copy magnification changing lens block 8. Further, the reflecting light is the reflected by a mirror 9, and led to the surface of photosensitive drum 10. At this time, photosensitive drum 10 is exposed to a slit of light.

Operation of the drum 10 is next described. First, drum 10 is charged by a charger 11 while drum 10 is rotated in the direction of arrow C. Then, drum 10 is illuminated with light reflected from the document to create an electrostatic latent image of the document on the surface thereof. The electrostatic latent image is then visualized by application thereto of toner from a developing unit 12. Then, either an upper cassette 13 or a lower cassette 14 is selected and copy sheets P contained therein are taken out sheet-by-sheet by means of a feed roller, either 15 or 16. Each sheet P is directed to a pair of aligning rollers 19 through a sheet guide 17 or 18, and then sheet P is fed to a transfer station. Cassettes 13 and 14 are removably inserted into the right lower portion of main body 1. One of cassettes 13 and 14 is selected by operation of an operation panel to be described later. Cassette size sensors 60.sub.1 and 60.sub.2 are provided in the insertion holes for cassettes 13 and 14. Cassette size sensors 60.sub.1 and 60.sub.2 each contain a plurality of microswitches which are turned on and off in response to the size of the inserted cassette.

Copy sheet P fed to the transfer station contacts with photosensitive drum 10. While contacting the drum 10, a charge transfer unit 20 applies charge to copy sheet P and the toner image is transferred from drum 10 onto copy sheet P. Copy sheet P with the transferred toner image is then separated from photosensitive drum 10 by a separating unit 21, and is transferred to a pair of fixing rollers 23 by a transfer belt 22. A pair of fixing rollers 23 apply heat and pressure to copy sheet P, thereby fixing the toner image. After fixing, copy sheet P is discharged to a tray 25 attached to the outside of main body 1 by a pair of discharge rollers 24. Photosensitive drum 10, after it is subjected to the toner image transfer process, reaches a charge remover 26. Charge remover 26 removes charges on photosensitive drum 10, then the residual toner on the surface of drum 10 is removed by a cleaner 27. Further, an after image (residual charge) is erased by a discharge lamp 28. At this point, drum 10 is returned to its initial state. A cooling fan 29 is provided near discharge roller pair 24 to prevent an excessive temperature rise in main body 1.

FIG. 7 shows an operation panel 30 provided on the upper surface of main body 1. Panel 30, as shown, includes a copy button 30.sub.1 for starting the copying operation, ten keys 30.sub.2 for setting a desired number of copies, a display 30.sub.3 for displaying states of the copying operation or jammed copy sheets, select keys 30.sub.4 for selecting copy sheets of a desired size and a size display 30.sub.5 for displaying a selected copy sheet size arranged on the panel. On the left side of the panel, copy magnification select keys 30.sub.6 are arranged for selecting copy magnifications of enlargement or reduction. Between display 30.sub.3 and size display 30.sub.5, scan direction designating keys 30.sub.7 and 30.sub.8 are arranged for designating the scanning direction of optical scanner 3 (i.e., moving direction of a first carriage 41.sub.1 to be described later) and LEDs (Light Emitting Diode) 30a and 30b are provided on the upper side of designating keys 30.sub.7 and 30.sub.8 to display the designation made by designating keys 30.sub.7 or 30.sub.8. In the case that main body 1 has applied thereto electric power and is in the normal mode, designating key 30.sub.7 is selected automatically and LED 30a is lit up.

FIG. 8 shows an allocation of drive sources which are made of pulse motors. The drawing of FIG. 8 is depicted as if viewed from the rear side of the copying apparatus, while the FIG. 5 drawing shows the front side of the copying apparatus. A magnification changing motor 31 is provided for changing the location of copy magnification changing lens block 8. A motor 32 changes the distance (optical path) between mirror 5 and mirror pair 6 and 7 when the copy magnification is changed. A scanning motor 33 moves exposure lamp 4 and mirror 5 and mirror pair 6 and 7 for scanning the document. A shutter motor 34 moves the shutter (not shown) to adjust the charging width of the charge on photosensitive drum 10 which is formed by the charger 11 when the copy magnification is changed. A developing motor 35 drives the developing roller of developing unit 12. A drum motor 36 drives photosensitive drum 10. A fixing motor 37 drives transfer belt 22, fixing roller pair 23 and discharge roller pair 24. A paper feed motor 38 drives feed rollers 15 and 16. A paper feed motor 39 drives aligning roller pair 19. A fan motor 40 drives cooling fan 29.

FIG. 9 shows a scanning mechanism for moving the optical scanner formed of exposure lamp 4 and mirrors 5, 6 and 7 along document table 2. Mirror 5 and exposure lamp 4 are supported by a first carriage 41.sub.1, and mirrors 6 and 7 are supported by a second carriage 41.sub.2. These carriages 41.sub.1 and 41.sub.2 can move in the direction of the arrow A along guide rails 42.sub.1 and 42.sub.2. Scanning motor 33 has a 4-phase pulse motor which drives a pulley 43. An endless belt 45 is wound around this pulley 43 and an idle pulley 44. First carriage 41.sub.1 supporting mirror 5 is fixed at one end to the midportion of endless belt 45. A couple of rotatable pulleys 47 and 47 are mounted to a guide 46 of second carriage 41.sub.2. A wire 48 is wound around pulleys 47 and 47. One end of wire 48 is fixed to a fixing piece 49, while the other end is fixed to fixing piece 49 via a coiled spring 50. One end of first carriage 41.sub.1 is fixed to the mid-portion of wire 48. With the rotation of pulse motor 33, belt 45 rotates causing first carriage 41.sub.1 to move. In turn, second carriage 41.sub.2 also moves. As this time, pulleys 47 and 47 serve as a fall block. Therefore, second carriage 41.sub.2 moves at half of the speed of first carriage 41.sub.1 while traveling in the same direction as first carriage 41.sub.1. The moving direction of first and second carriage 41.sub.1 and 41.sub.2 can be changed by reversing the rotating direction of pulse moter 33.

When the enlargement or reduction copy is established, the allowable copy ranges are indicated on document table 2 corresponding to designated size of the copy sheets. Namely, if Px and Py mean size of copy sheets selected by select keys 30.sub.4 and K means copy magnifications selected by copy magnification select keys 30.sub.6, copy allowable ranges X and Y can be expressed as follows.

X is indicated by indicators 51 and 52 provided under the transparent glass of document table 2 and Y is indicated by a scale 53 provided on the upper surface of first carriage 41.sub.1 as shown in FIG. 5.

As shown in FIG. 10, indicators 51 and 52 are fixed to a wire 57 wound around pulleys 54 and 55 via a coiled spring 56. Pulley 55 is rotated by a motor 58. When motor 58 drives pulley 55, the distance between indicator 51 and indicator 52 is varied in accordance with the copy magnification. Scale 53 (shown in FIGS. 5 and 9) provided on first carriage 41.sub.1 is moved to a desired position (a home postion) in accordance with the copy sheet size and copy magnification by driving motor 33.

FIG. 11 shows the overall control system of the present invention. This control system includes a main processor 71, and first and second sub-processors 72 and 73. Main processor 71 detects signals from operation panel 30 and cassette size sensors 60.sub.1 and 60.sub.2, and controls a high voltage transformer 76 for supplying high voltage to the various charging units, discharge lamp 28, a solenoid (BLD) 27a for actuating a cleaning blade of cleaner 27, a heater 23a of fixing roller pair 23, exposure lamp 4 and motors 31-40 and 58. Of the motors 31-40 and 58, motors 35, 37, 40 and a motor 77 for supplying toner to developing unit 12 are controlled by main processor 71 through a motor driver 78. Motors 31-34 are controlled by first subprocessor 72 through a pulse motor driver 79. Motors 36, 38, 39 and 58 are controlled by second subprocessor 73 through a pulse motor driver 80. Exposure lamp 4 is controlled by main processor 71 through a lamp regulator 81. A heater 23a is controlled by main processor 71 through a heater controller 82. Main processor 71 sends motor drive and stop commands to first and second sub-processors 72 and 73. These sub-processors 72 and 73 send status signals representing the drive and stop of motors to main processor 71. First sub-processor 72 is supplied with position data from a motor phase sensor 83 for detecting the initial position of each of motors 31-34.

The essential parts of the present invention will next be described. As shown in FIG. 1, scales 90 and 91 indicate locations of placing the documents at respective ends of document table 2. Each of scales 90 and 91 is marked with "A4" (210.times.297 mm) and "B5" (182.times.257 mm) indicating the upper and lower limits of the copy allowable ranges. The length L between scale 90 and scale 91 is set to a size slightly longer than the maximum size of documents (e.g. A3 size: 297.times.420 mm or LEDGER size: 11.times.17 inches). L1 is a width represents a half of the maximum size of the documents, namely L1 represents a width of A4 size: 210.times.297 mm or LETTER size: 81/2.times.11 inches. A relation between L and L1 is as follows:

In the case of actually making a copy, first carriage 41.sub.1 is located at a middle portion between scale 90 and scale 91. Namely, a length L0.perspectiveto.L/2 represents a home position of first carriage 41.sub.1. Documents G1 and G2 are placed along scales 90 and 91, respectively of the table as shown in FIG. 1. As discussed hereinafter, documents G1 and G2 will be called the left document G1 and the right document G2, respectively.

The copying operation in the case of left document G1 placed on table 2 will be described with the aid of FIG. 2. In this case, scan direction designating keys 30.sub.7 is depressed, whereby LED 30a is lit. In this state, when copy button 30.sub.1 is depressed, first carriage 41.sub.1 moves from a point H1 to a point H2 which is very close to scale 90, as shown by the arrow X. Upon turning point H2, the exposure lamp 4 provided on first carriage 41.sub.1 is energized and thereby produces exposing light. Then first carriage 41.sub.1 moves from the point H2 to the point H1, whereby left document G1 is optically scanned. In finished the optical scanning, exposure lamp 4 is de-energized and first carriage 41.sub.1 stops at the home position in the middle portion of document table 2.

FIG. 3 shows the state when a right document G2 is placed along scale 91 of table 2. In this case, scan direction designating key 30.sub.8 is depressed, whereby LED 30b is lit. In this state, when copy button 30 is depressed, exposure lamp 4 provided on first carriage 41.sub.1 is energized. Then first carriage 41.sub.1 moves from a point H3 to a point H4 which is very close to scale 91, as shown by the arrow Y, whereby right document G2 is optically scanned. When first carriage 41.sub.1 reaches point H4, optical scanning is finished. At this time, exposure lamp 4 is de-energized, then first carriage 41.sub.1 is returned to the home position in the middle portion of document table 2.

FIG. 4 shows a state where both the left and right documents G1 and G2 are placed along scales 90 and 91, respectively, of table 2. In this case, both of the scan direction designating keys 30.sub.7 and 30.sub.8 are depressed, whereby LEDs 30a and 30b are lit. In this state, when copy button 30.sub.1 is depressed, first carriage 41.sub.1 moves from the point H1 towards scale 90, as shown by the arrow Z. When first carriage 41.sub.1 reaches the point H2 which is very close to scale 90, exposure lamp 4 is energized. Then, first carriage 41.sub.1 moves from the point H2 to H1, whereby the left document G1 is optically scanned. The optical scanning of left document G1 is then finished, and then first carriage 41.sub.1 moves from the point H3 to H4 which is very close to scale 91 for optical scanning of the right document G2. At point H4, optical scanning of documents G1 and G2 is finished. After that, exposure lamp 4 is de-energized, and first carriage 41.sub.1 is returned to the home position H1.

While first carriage 41.sub.1 moves from the point H1 to H3 after the optical scanning and copying of the left document G1, a copy sheet is taken out from cassettes 13 or 14 and aligned by aligning roller 19. The copy sheet is transported to photosensitive drum 10. A toner image corresponding to right document G2 is transfered from drum 10 to the copy sheet upon the optical scanning by moving first carriage 41.sub.1 from the point H3 to H4.

If the gap size .delta. between the point H1 and H3 is small, the moving of first carriage 41.sub.1 is decelerated or stopped in between H1 and H3 so that the movement of first carriage 41.sub.1 from H3 to H4 coincides with the timing of copy sheet feeding.

As described above, first carriage 41.sub.1 is able to scan the document due to first carriage 41.sub.1 moving from middle portion of document table 2 in both the left and right directions. Therefore, two documents placed on document table can be copied by only one optical scanning operation. As a result, the copy speed can be improved.

As scales 90 and 91 are provided at respective ends of document table 2, a precise setting of both documents on document table 2 can be easily performed.

Further, as first carriage 41.sub.1 is standing by at the middle portion of document table 2, first carriage 41.sub.1 is able to scan the document quickly even if only one document is placed on the left or right portion of document table 2.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.