JPS59146067A - Image forming device - Google Patents

Abstract

PURPOSE:To make a beautiful copy of a thick original such as a book by performing manual switching so that an image formation area is reduced for a small original, and stopping the formation of a latent image corresponding to an ejected nonimage formation area. CONSTITUTION:For example, when a book 12 is placed on platen glass 11 and its scanning-directional width L' is smaller than the width P of a standard image formation area in the scanning direction, a solid black part is prevented from being formed at an end part of a copied form. When the magnet M on a lamp unit 16 comes right under a sensor S, the lamp unit 16 and moving mirrors 17 and 19 stop moving as shown by an arrow (a) and never make a scan on the original up to the width P. Further, a photosensitive drum 22 is exposed on blank basis by a blank exposure source 27 on the completion of the original scan, so the copied transfer material has no solid black part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus such as a copying apparatus that can neatly copy thick originals such as books.

Generally, in a copying machine, copy paper is selected according to the size of the original to be copied, and as shown in Fig. 1, when copying a book, especially a thick book 12, the center closed part Because of this, even if the book 2 is B4 size when spread, the size L when placed on the platen glass 11.
′ will be shorter than that. For example, for a book with a thickness of about 30 mm, L'≈320 mm compared to the original length of B4 size (P-364 mm). That is, as shown in FIG. 2, in the copied copy, a "solid black" portion with a width of about 40 mm appears on one side (on both sides depending on how the book is placed) (shaded area). This not only makes the copy look unsightly, but also increases toner consumption.

Moreover, light leaking from the gap between the document cover 3 and the document table glass 11 enters the operator's eyes, which is undesirable and dazzling. especially,
When copying a book, the operation is often performed without using the document cover 3, so these tendencies become even stronger.

The present invention has been made in view of the above-mentioned points and to eliminate the above-mentioned drawbacks, and provides an image forming apparatus configured to form a latent image in a predetermined standard image forming area. An image comprising: a manual switching means for reducing the standard image forming area according to a document smaller than the forming area; and a means for preventing the formation of a latent image corresponding to a non-image forming area excluded by the manual switching means. The purpose is to provide a forming device.

Embodiments of the image forming apparatus according to the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a schematic diagram of a copying machine as an image forming apparatus according to the present invention. Reference numeral 11 denotes an original platen glass capable of copying a maximum B4 size original; 13 refers to a member for placing the original, for example, a standard white plate for measuring standard exposure; 12, a plate placed on the original platen glass 11; The width L' in the operation direction of a B4 size book as a manuscript is the width P in the scanning direction of a standard image forming area for copying by scanning the optical system described later, as described above, that is, in this example. In this case, the width shall be smaller than that of B4 size. A slide rail 14 is provided along the scanning direction of the optical system beside the document table glass 11, and a magnetic sensor S is provided to be slidable on the slide rail 14. 16 is a lamp unit, which includes a lamp 16A and a reflecting mirror 16B installed behind it.
The lamp 16A is composed of a reflecting mirror 16C provided apart from the lamp 16A. This lamp unit 16 moves integrally in the direction of the arrow a in the figure, and the slide rail 14
The magnet M on the reflecting mirror 16C located below also moves in the same direction. 17 and 19 are movable mirrors for document scanning; 18
is a lens, and 20 and 21 are fixed mirrors. As shown in the figure, the positions of the lamp unit 16 and movable mirrors 17 and 19 indicated by dashed gold lines indicate the positions at the end of document scanning (positions before the maximum stroke of document scanning).

Reference numeral 22 denotes a photosensitive drum having a layer of photoconductive material and a layer of insulating material on the surface of a cylindrical metal cylinder, and is rotatably provided in the direction of the arrow in the figure about a shaft 22a. On the outer circumference of the photosensitive drum 22, a pre-exposure lamp 23, a pre-static eliminator 24, a primary charger 25, a secondary charger 26, a blank exposure source 27,
A full-surface exposure source 28, a phenomenon device 29, a registration roller 30, a transfer charger 31, and a cleaner 32 are arranged in this order.

Next, the operation of the copying apparatus according to the present invention will be explained.

A document, for example, a book 12 in this embodiment, is placed on the document table glass 11 . When the width L' of the book 12 in the scanning direction is smaller than the width P of the standard image forming area in the scanning direction, when copying with a conventional copying device, "solid black" appears at the edge of the copied paper as shown in FIG. This part occurs. Therefore, the sensor S is moved along the slide rail 14 and positioned so that its base point matches the end of the book 12 to be copied.

Next, the photosensitive drum 22 is rotated in the direction of the arrow shown in the figure in response to a copying command from an operator (not shown). Before scanning the original, the photosensitive drum 22 is exposed by the pre-exposure lamp 23 and at the same time has its charge removed by the pre-static eliminator 24. The photosensitive drum 22 is uniformly charged by the primary charger 25. Further, this uniformly charged photosensitive drum 22 is entirely exposed to light by a blank exposure source 27, and at the same time, it is charged to the opposite polarity by a secondary charger 26. Furthermore, after this, the entire surface of the photosensitive drum 22 is exposed by the entire surface exposure source 28, and the surface potential of the photosensitive drum 22 becomes the bias potential of the developing device 29.

Next, when scanning the document, the lamp unit 16 and movable mirror 17, which are lit, move in the scanning direction indicated by the arrow a in the figure at a speed corresponding to the copying magnification, which in this embodiment is equal to the speed of the same magnification. The image of the book 12 illuminated by the light is projected onto the image determining section 22' of the photosensitive drum 22 via the movable mirror 17, the lens 18, the fixed mirrors 20 and 21, and the secondary charger 26. At this time, the blank exposure source 27 is turned off and the blank exposure on the photosensitive drum 22 is not performed. In reality, the lamp unit 16 and the mirrors 17 and 19 should move to scan the width P of the standard image forming area in the scanning direction.
When comes directly under sensor S, that is, lamp unit 1
6 and movable mirrors 17 and 19 are at the position shown by the dashed line in FIG.
The lamp unit 16 and the movable mirrors 17 and 19 stop moving in the scanning direction in the direction of the arrow a in the figure and finish scanning the document in response to the detection signal of the magnetism of the magnet M by the sensor S, so that the width P etc. of the document are not scanned.

After scanning the original, the lamp unit 16 and moving mirror 1
7 and 19 move back in the direction opposite to the arrow a shown in the figure and return to the original position shown in practice. At this time, the blank exposure source 27 is turned on again, and the photosensitive drum 22 is blank exposed again through the secondary charger 26.

Incidentally, during the document scanning, the images of the book 12 on the photosensitive drum 22, which are successively projected onto the image forming section 22', are entirely exposed by the entire surface exposure source 28 and become electrostatic latent images.

This electrostatic latent image is reduced by a developing device 29 and developed as a toner image. This toner image is
The image is transferred to a transfer material (not shown) that is timed by 0 and sent to the photosensitive drum 22 side via a transfer charger 31. Furthermore, this transfer material is separated from the photosensitive drum 22 by a separator (not shown) and sent to a fixing device (not shown).

The toner image on the transfer material (not shown) sent to the fixing device (not shown) is fixed by the fixing device (not shown), and copying is completed.

On the other hand, after the photosensitive drum 22 has been transferred, the remaining toner is removed by the cleaner 32 and the remaining toner is removed by the cleaner 32 in preparation for the next copying cycle. Furthermore, the photosensitive drum 22 is blank exposed by the blank exposure source 27 at the same time as the scanning of the original is completed, so that "solid black" parts as shown in FIG. 2 do not appear on the copied transfer material. .

In the above embodiment, by setting the sensor S to an appropriate inland area, the lamp unit 16 can be used only within the original width or within the original width.
Since the optical system members such as the above move to scan the document and project the image onto the photosensitive drum 22, "solid black" parts do not occur due to unnecessary scanning by the optical system.

Further, in this embodiment, the document table glass 11 is of a fixed type, but the document table glass 11 serving as a document table may be of a movable type, and the lamp unit 16 and movable mirrors 17 and 19 may be of a fixed type. However, in this case, the slide rail 14 is fixedly provided on the document table glass side so as to move together with the document table glass 11.

In this operation, the document table glass 11 moves in the direction opposite to the arrow a shown in the figure to scan the book 12. The subsequent operation is exactly the same as the operation described above in FIG. 3, so the explanation will be omitted since it is self-explanatory.

FIG. 4 is an embodiment of a block diagram of a control system for carrying out the above operation. In the example shown in FIG. 4, the sensor S is configured to be variably movable as described above. M is a magnet, which moves together with the lamp unit 16 and movable mirror 17 shown in FIG. 3 when scanning an original. 34 is a control circuit;
Switching circuit 36 receives the detection signal from sensor S
and gives a control signal to the motor drive circuit 35. Reference numeral 35 denotes a motor drive circuit for rotating the motor 38 forward or backward to drive the members of the optical system. Reference numeral 39 denotes a scanning optical system drive mechanism for moving the lamp unit, movable mirrors 16 and 17, and movable mirror 19 at a speed corresponding to the copying magnification in response to the rotational driving force of the motor 38. 4
A driving means 37 for moving the optical system is a power supply for blank exposure, and is used to supply the power to the blank exposure source 27 via a switching circuit 36.

The sensor S is moved by an operator (not shown) and positioned at the scanning end position to be scanned. Next, a copying command is given to the control circuit 34 by an operator (not shown). When the photosensitive drum 22 in FIG. 3 is rotating before scanning the original, the control circuit 34 supplies a control signal to the switching circuit 36 to turn the switching circuit 36 on. As a result, the power of the blank exposure power source 37 is applied to the blank exposure source 27, and the blank exposure source 27 is turned on to perform blank exposure. Next, the control circuit 34 connects the motor 3 to the motor drive circuit 35.
8 is given a control signal to rotate in the forward direction. As a result, the motor drive circuit 35 energizes the motor 38 in the direction in which the motor 38 rotates in the forward direction, so that the motor 38 rotates in the forward direction. The scanning optical system drive mechanism 3 receives the driving force of the forward rotation of the motor 38
Reference numeral 9 moves the lamp unit, movable mirrors 16 and 17, and movable mirror 19 in the document scanning direction at a speed corresponding to the copying magnification. Immediately after giving the control signal to the motor drive circuit 35, the control circuit 34 also gives a control signal to the switching circuit 36 to turn off the switching circuit 36. As a result, the blank exposure source 27 is turned off during document scanning. Since the magnet M also moves in the document scanning direction together with the lamp unit 16, this magnet M is connected to the sensor S.
When the sensor S approaches the magnet M, the sensor S sends a detection signal indicating the magnetism of the magnet M to the control circuit 34. The control circuit 34 inputting this detection signal supplies a control signal to the switching circuit 36 to turn on the switching circuit 36. As a result, the power of the power supply 37 for blank exposure is again applied to the blank exposure source 27, and the blank exposure source 27
7 lights up and the photosensitive drum is exposed to blank light. Immediately after the control circuit 34 provides the above control signal to the switching circuit 36, the control circuit 34 provides the motor drive circuit 35 with a control signal for rotating the motor 38 in the reverse direction. The motor drive circuit 35 inputting this control signal energizes the motor 38 in a direction to rotate the motor 38 in the reverse direction. The scanning optical system drive mechanism 39 receives the driving force of the reverse rotation of the motor 38, and moves the lamp unit 16, the moving mirror 17, and the moving mirror 19 in the opposite direction to the original scanning direction. When the lamp unit 16, movable mirror 17, and movable mirror 19 return to their original positions before scanning the original, the control circuit 34 inputting this detection signal controls the motor 38 to stop by means not shown. A signal is given to the motor drive circuit 35 to stop the motor 38. As a result, the scanning optical system drive mechanism 39 stops the movement of the lamp unit, moving mirrors 16 and 17, and moving mirror 19.

In the case of a copying machine with a moving document table, the control system uses a document table drive mechanism instead of the scanning optical system drive mechanism 39 shown in FIG. A similar configuration may be provided by providing a document table. In this case, the sensor S moves together with the document platen,
This copy control operation is self-explanatory, so its explanation will be omitted.

Further, in the above embodiment, the positions of the sensor S and the magnet M may be reversed. For example, in FIG. 3, the sensor S may be placed on the reflecting mirror 16C of the lamp unit 16, and this position may be directly below the end portion of the document table glass 11. The same copying operation as in the embodiment described above can be achieved by eliminating the slide rail 14 and placing a magnet member with a magnet M embedded in the surface thereof on the document table glass 11 at the position where the sensor S moves. In this case, the magnet member including the magnet M can be freely placed on the document table glass by manual operation, making the setting operation simple.

FIG. 5 is an explanatory diagram of another embodiment of an image forming apparatus that prevents latent image formation in an axial direction perpendicular to the direction of document scanning. In FIG. 5, reference numeral 11' denotes a document table glass, 14 a slide rail, and S a sensor, and these structures are the same as those explained in FIG. 3 except for the size of the document table glass. In this case, the standard image forming area is the range B4, that is,
This is an area of width P×width (L″+l2) on document table glass 11.

Reference numeral 12' denotes a book as a manuscript, which is placed on the manuscript table glass 11', and its width is L' (in the manuscript scanning direction) in this embodiment.
and L'' (direction perpendicular to the document scanning direction).

However, since P>L' and L''+l2>L'', if this book 12' is placed on the platen glass 11' and the optical system is moved to the maximum stroke of B4 for copying, two points will be generated. The area shown by the chain line produces a "solid black" portion. In the embodiment shown in FIG. 3, the dimensions of the book 12 are L'×(L''+
12), only the area indicated by the two-dot chain line of width P-L' on the right side becomes a problem, and this is solved by moving the sensor S along the slide rail 14 to the practical position shown in the figure As explained, there were no "solid black" areas. In the case of this embodiment as well, by setting the sensor S at the position shown in FIG. 5, there is no problem in the area indicated by the two-dot chain line on the right side, but the area indicated by the two-dot chain line with the width l2 becomes a problem. This case can also be solved by providing a known position detector 41 along the document table glass 11' in a direction perpendicular to the document scanning direction (arrow a direction). This position detector 41 is a slide member 43
By moving the slider along the slide rail 42, a predetermined position detection signal is output. Reference numeral 44 denotes a light emitting diode element array as a blank exposure source, which has a large number of light emitting diodes arranged in a line. This light emitting diode element array 4
4 is used in place of the blank exposure source 27 shown in FIG. 3, and the view shown in FIG. 5 is a view seen from the photosensitive drum 22 side in FIG. 3. In addition, the position detector 4
The position detection signal from 1 is input to the control circuit 34 as shown by the dashed line in FIG. Although sharp cut exposure is actually necessary, the sharp cut exposure portion is omitted for the sake of simplicity. L″ is the book 12′ as a manuscript.
When projecting an image onto a photosensitive drum, the light emitting diode element array 4
4 is the width where the light emitting diode 4 is off, and L1 is the light emitting diode element row 44 that is lit when projecting an image.
The width of the light emitting diodes 11 is the width of the light emitting diodes of the light emitting diode element array 44 that are lit when copying in the standard image forming area and also projecting an image. Also L
is the width for blank exposure of the entire surface of the photosensitive drum 22 shown in FIG.

It is assumed that a light emitting diode element array 44 having the configuration shown in FIG. 5 is used in place of the blank exposure source 27 of FIG. 3, and that a book 12' is placed on the document table glass 11'. It is also assumed that the position detector 41 shown in FIG. 5 is connected to the control circuit 34 as shown in FIG. 4, and that the switching circuit 36 is connected to the light emitting diode element array 44.

In addition, in the other configuration of this embodiment, the position detector 41 can be changed only by changing the width of the other components that correspond to the width of the document table glass 11'.
The structure is the same as that shown in FIG. 3 except for the light emitting diode element array 44 and the like. Next, the operation of another embodiment of the copying apparatus as an image forming apparatus constructed as described above will be explained with reference to FIGS. 3 to 5. A book 12' as a manuscript is placed on the manuscript table glass 11'. Next, the sensor S is moved along the slide rail to the end of the book 12', and its base point is set at the position shown in FIGS. 3 and 5. Next, the slide member 43 of the position detector 41 is moved along the slide rail 42 and set so as to be located at the end of the book 12' as shown in FIG. Next, in response to a copy command, the photosensitive drum 22 is rotated forward. At this time, the light emitting diode element array 44 lights up over the width L, and the entire surface of the photosensitive drum 22 is exposed to blank light. Next, when the lamp unit 16 and movable mirrors 17 and 19 move in the document scanning direction, that is, in the direction of arrow a, the control circuit 34, which has input the position detection signal from the position detector 41, responds to this position detection signal. The light-emitting diodes of the light-emitting diode element array 44 having the width L'' are turned off via the switching circuit 36 so that the photosensitive drum 22 is not exposed to blank exposure.
The light emitting diode of only one light emitting diode element row 44 is lit to blankly expose the photosensitive drum 22 by this width L1. At the same magnification, images of the width L'' of the book 12' are successively projected onto the imaging portion 22' of the photosensitive drum 22 corresponding to the width L'' which is not subjected to blank exposure. Therefore, at this time, if there is no signal from the position detector 41, the light emitting diode 44 will light up only the width l1 portion, and the blank exposure element photosensitive drum 22 will have the width l2 portion illuminated by the book 12'.
Since the shadow of is projected, when this is copied, a "solid black" portion will appear over the width l2.

However, in reality, the light emitting diode of the light emitting diode 44 exposes the photosensitive drum 22 over the width L1 according to the signal from the placement detector 41, so the photosensitive drum 22 with the width l2
Since the part is exposed, the part with width l2 is "solid black"
This part does not occur. When the sensor S detects the magnetism of the magnet M, the lamp unit 1
6 and the movable mirrors 17 and 19 return in the direction opposite to the arrow a, and at this time, the light emitting diodes of the light emitting diode element array 44 light up over the width L to blankly expose the entire surface of the photosensitive drum 22, so that P-L' As shown in Figure 2 for the axis of “
Therefore, since the portion of the photosensitive drum 22 corresponding to the area indicated by the two-dot chain line in FIG. That's not to say there isn't.

FIG. 6 is a partial perspective view of another embodiment of the image forming apparatus according to the present invention. Reference numeral 11 indicates the document table glass, 45 indicates a part of the machine frame of the copying apparatus, and 46 and 47 indicate slide rails. Reference numeral 48 denotes a slide plate with a white lower surface that slides on slide rails 46 and 47, and is located closer to the upper part than the document table glass 11. A sensor S that senses magnetism is provided near the document table glass 11 on the lower surface of the slide plate 48 so as to move as the slide plate 48 moves.

16 is the lamp unit mentioned above, which includes a lamp 16A and a reflecting mirror 1.
Consists of 6B and 16C. A magnet M is installed on the upper surface of the reflecting mirror 16C of the lamp unit 16 so that it moves to a position below the sensor S when the lamp unit 16 scans. The two-dot chain line 16' shows the state when the lamp unit 16 has scanned to the maximum stroke position, and at this time, the magnet M is connected to the sensor S.
located directly below. 12 is a book which, when opened, has a width L' smaller than the width P of the standard image forming area in the scanning direction. The structure of the other copying apparatuses is the same as that shown in FIG.

In the case of the embodiment, first, the slide rail 46 is moved to the position shown by the dashed line in FIG.
, 47. At this time, the sensor S also approaches the book 12 together with the slide plate 48. Next, the lamp unit 16 moves in the direction of arrow a to scan the image of the book 12 as a document. When the magnet M comes directly under the sensor S, the sensor S detects the magnetism of the magnet M, and the lamp unit 16 moves back without reaching the maximum stroke position 16' as described above. When this magnetism is detected, the optical system including the lamp unit 16 projects the white surface of the lower surface of the slide plate 48 onto the photosensitive drum 22 as shown in FIG. That is, by moving the lamp unit 16 in the direction of arrow a, the optical system adjusts the image width L' of the book 12 and the slide plate 4.
A part of the white surface of 8 is read and projected onto the photosensitive drum 22. Incidentally, when the lamp unit 16 moves back in the direction opposite to the direction of the arrow a, the entire surface of the photosensitive drum 22 is exposed by the blank exposure source 27 as shown in FIG. Therefore, since the shadow of the end of the book 12 is not projected onto the photosensitive drum 22, a "solid black" portion as shown in FIG. 2 does not occur.

Note that the position detector 41 can be made unnecessary by setting the slide plate 48 so as to cover the area having the width l2 shown in FIG. However, in this case, the sensor S is not attached to the slide plate and has the configuration shown in Figure 5, but since the slide plate is moved from the bottom to the top of the drawing in a direction perpendicular to the direction of arrow a, A document table glass 11 is provided at the top shown.

In the embodiments described above, the document cover is not shown, but it is not necessary when a slide plate is used. Further, the sensor need not be magnetically sensitive, and it goes without saying that a micro switch may be provided instead. Further, it goes without saying that the configuration shown in FIGS. 5 and 6 can be applied to an image forming apparatus with a movable document table.

As explained above, when the document is a book, the present invention can erase the "solid black" part of the edge pattern caused by the book, and even if the document cover becomes dirty, unnecessary dyeing agent can be consumed, and the document cover can be removed. This has the effect of making it unnecessary.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams for explaining a conventional example, FIG. 3 is an explanatory diagram of an embodiment of a copying apparatus as an image forming apparatus according to the present invention, and FIG. 4 is an explanatory diagram for explaining an image forming apparatus according to the present invention. FIG. 5 is an explanatory diagram of another embodiment of the image forming apparatus according to the present invention, and FIG. 6 is a partial perspective view of another embodiment of the image forming apparatus according to the present invention. 11, 11'... Original table glass 12, 12'... Book (as an original) 16... Lamp unit 17, 19... Movable mirror 22... Photosensitive drum 27... Blank exposure source 34・
... Control circuit 40 ... Drive means 41 ... Position detector 44 ... Light emitting diode element array 48 ... Slide plate M ... Magnet S ... Sensor ■

Claims (1)

[Claims] In an image forming apparatus configured to form a latent image in a predetermined standard image forming area, the manual switching means can reduce or change the standard image forming area in accordance with a document smaller than the standard image forming area; An image forming apparatus comprising means for preventing the formation of a latent image corresponding to a non-image forming area excluded by the manual switching means.