JPH05216136A - Position detecting device for platen - Google Patents

Abstract

PURPOSE:To reduce the number of components and the cost of a platen position detection device and enable the position of a platen to be detected with accuracy by forming the platen position detection device using those members which constitute a platen driving device. CONSTITUTION:In a position detection device 22 for the platen 2 of a platen moving type copying machine, a position detection portion 21 is provided in the sliding surface of an endless rack 8 in contact with a bracket 11 and in the portion in contact with the bracket 11 when the platen 2 locates at a scan starting position P2, and in such a manner that the bracket 11 and the sliding contact surface are not in conduction to each other, and an electrically conductive portion 31 is provided in the other part, and a position detection circuit 23 which detects the conducting state of the bracket 11 and the sliding contact surface is connected and setting of the platen 2 in P2 is detected according to a signal output from the position detection circuit 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, in a platen moving type copying machine in which a platen moves during a copying operation.
The present invention relates to a document table position detecting device that detects the position of a document table.

[0002]

2. Description of the Related Art Generally, in an original table moving type copying machine, when an original on the original table is scanned by an optical system, the original table first moves from an initial position to a scanning start position in a return direction, and then, After the document is scanned by moving in the feed direction to the scanning end position, it is moved from the scanning end position to the original initial position in the return direction.

As shown in FIG. 6, a document table driving device 51 for moving the document table 52 as described above is provided below the document table 52 and has a structure as shown in FIG. When moving from the scanning start position to the feed (F) direction, the feed solenoid 53 is turned on, whereby the latch 54 engages with the clutch brake 56 of the feed spring clutch 55, and the feed spring clutch 55. Becomes a combined state.

Therefore, the driving force input to the input gear 57 is transmitted to the output gear 58 and further to the document table driving gear 59. The original table drive gear 59 meshes with a rack (not shown) fixed to the lower surface of the original table 52, and the original table 52 provided therein moves in the feed direction as the rack moves.

After that, when the document table 52 reaches the scanning end position, this state is detected by the detection switch 60,
The feed solenoid 53 is turned off and the return solenoid 61 is turned on. As a result, the latch 62 causes the clutch brake 63 of the return spring clutch 67 to be released.
And the return spring clutch 67 is engaged. Therefore, the driving force input to the input gear 57 is transmitted to the platen drive gear 59 via the gear 64, the input gear 65, the output gear 66, and the output gear 58, and the platen 52 moves in the return (R) direction. Move to the initial position.

However, in the above conventional structure, the feed spring clutch 5 is used to reciprocate the document table.
5, devices such as the return spring clutch 67, the feed solenoid 53, and the return solenoid 61 are required, and the cost ratio occupied by each of the above devices becomes high, leading to an increase in the cost of the device. Had.

Therefore, in order to reduce the number of parts, an original platen moving type copying machine provided with an endless rack type original platen drive device has been considered. As shown in FIG. 8, this endless rack type document table driving device 71 includes two rack portions 73a provided in parallel with their tooth surfaces facing each other.
73b, and two semi-circular gear portions 73 having inner teeth arranged in a semi-circular shape that connect the end portions of both rack portions to each other
The endless rack 73 composed of c · 73d receives the driving force from the input gear 75 to which the driving force of the motor provided inside the endless rack 73 is input, between the input gear 75 and the endless rack 73. Is linearly moved by being transmitted through a planetary gear 76 provided so as to mesh with both of these gears.
2 is moved back and forth.

The detection of the scanning start position of the document table 72 required at the start of the copying process in the copying machine to which the document table driving device 71 of the above endless rack system is applied detects the endless rack 73 of the document table driving device 71. Of the two rack portions 73a and 73b, provided on the rack portion that meshes with the planet gear 76 and moves the document table 72 in the feed direction (for example, the rack portion 73b when the input gear rotates in the direction of arrow A). Detection switch operating unit 77
And a detection switch 78 provided at a predetermined position near the rack section, when the document table 72 is located at the scanning start position, the detection switch operating section 77 presses the detection switch 78 to turn it on. ing.

[0009]

However, in the above-mentioned structure, the detection switch 78 which is activated by being pressed.
Therefore, it is necessary to accurately position the mounting positions of the detection switch 78 and the switch actuating portion 77 provided on the rack portion 73b, resulting in high assembly cost and difficulty in obtaining high accuracy. Further, since the detection switch 78 is separately provided only for detecting the scanning start position, the number of parts is increased, and the cost of the apparatus is increased in the document table moving type copying machine, which is generally small and has many low-priced models. There is a problem in that

[0010]

In order to solve the above problems, a document table position detecting device according to the present invention includes a rack that reciprocates integrally with the document table, and a drive-side gear that meshes with the rack. A bracket that supports the drive-side gear and that is in sliding contact with the end surface of the rack is provided, and the sliding surface of the rack that is in sliding contact with the bracket is located at the contact portion of the bracket when the document table is in a predetermined position. A position detection circuit for generating a contact resistance different from that when the document table is located at a position other than the predetermined position, and a position detection circuit for generating an electric signal according to the electric resistance between the bracket and the sliding contact surface. Is provided.

[0011]

According to the above construction, when the document table is located at a predetermined position such as the scanning start position, the electric signal from the position detection circuit changes, whereby the document table is located at the predetermined position. It is detected that And in this case
The rack and brackets share the same structure as the conventional switch mechanism for switching between conduction and non-conduction in the detection switch.Because there is no need to separately provide a conventional switch operating member, the number of parts is reduced, and more It can be manufactured at low cost. Further, since the position detection area corresponding to a predetermined position of the document table is directly provided on the rack that reciprocates integrally with the document table, the conventional detection switch attached separately from the document table is used. It is possible to detect the position more accurately than the detection.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In the copying machine provided with the position detecting device of the original table of this embodiment, as shown in FIG. 2, the original table 2 on which the original 25 is placed is placed in the return direction on the upper surface of the main body 1 of the copying machine. Alternatively, it is provided so as to be movable in the feed direction, and the document placing portion of the document table 2 is formed of a transparent member such as a glass plate.

An optical system 20 including an irradiation lamp 15 and a rod lens array 24 is provided above the copying machine body 1. Below the optical system 20, an optical system 20 is provided.
The photoconductor 13 is provided. The photoconductor 13 is rotatably provided, and the original 2 is fed from the irradiation lamp 15.
5 is exposed by the reflected light of the light emitted toward 5, and the residual potential is removed by the direct light from the irradiation lamp 15.

Around the photoconductor 13, a main charger 14 for charging the photoconductor 13 is disposed in contact with the photoconductor 13, and a stirring roller 26 rotatably provided.
And toner conveying rollers 27 and 28, and toner carrier 2
9 and the like are internally provided, and the photoconductor 1 is exposed by the exposure operation of the optical system 20.
Developing device 30 for developing the electrostatic latent image formed on the toner image 3 with toner, a transfer roller 12 for transferring the toner image formed by this developing operation onto a transfer sheet, and the photoreceptor 1.
3 collects the residual toner on the surface of the toner and the toner storage unit 1
A cleaning device 17 and the like to be accommodated in the No. 8 are provided.

A transfer section 32 is provided in the supply direction of the transfer paper to the photoconductor 13, and further in the supply direction.
A paper feeding unit 33 is provided. The paper feed unit 33 includes a manual feed tray 34 for storing transfer paper, and the manual feed tray 34.
It is composed of a paper feed roller 35 for taking out the transfer papers one by one from the paper, a paper feed solenoid 35a (not shown) for controlling the rotation of the paper feed roller 35, and the like. It is supposed to do.

On the other hand, the transport section 32 has a sheet input sensor 36 that is turned off when detecting the transfer sheet, a registration roller 16 that temporarily stops the transfer sheet, and a registration roller solenoid 16 (not shown) that controls the rotation of the registration roller 16.
a transfer paper supplied from the paper supply unit 33 and the transfer roller 12 and the photoconductor 1 at a predetermined timing.
It is designed to be transported to and from the equipment.

Further, jam sensors 38 and 39 for detecting the position of the jammed paper when a jam occurs and a fixing device 19 for fixing the toner image on the transfer paper in the conveying direction of the transfer paper from the photoconductor 13. Etc., and further,
A paper discharge sensor 37 is provided in the conveyance direction of the fixing device 19 to detect that the transfer paper has passed through the fixing device 19 and has reached a paper discharge unit (not shown) with an OFF signal.

During the copying operation, the original table 2 on which the original 25 is placed has a position in which the end on the feed (F) side substantially coincides with the end of the copying machine main body 1, that is, the initial position. P ₁
Therefore, _first, it moves to the scan start position P ₂ in the return direction (R), then moves to the scan end position P ₃ in the feed direction, and then moves to the original position P ₁ .
While the document table 2 moves from the scan start position P ₂ to the scan end position P ₃ , the optical system 20 scans the document with light, and the irradiation lamp 15 irradiates the document, and the reflected light is reflected by the rod. Photoreceptor 1 via lens array 24
It is incident on 3.

As a result, the main charger 14 exposes the photoconductor 13 uniformly charged to a predetermined potential, and an electrostatic latent image corresponding to the original image is formed on the surface of the photoconductor 13. This electrostatic latent image is developed by the developing device 30 and becomes a toner image. The toner image formed on the photoconductor 13 is transferred to the transfer roller 12,
The transfer paper is charged by applying a voltage having a polarity opposite to that of the toner, and is transferred onto the transfer paper. After that, the fixing device 1
The sheet is conveyed in the direction 9 and is thermally fixed on the transfer sheet by the fixing device 19, and then discharged to the outside of the copying machine main body 1.
The above document scanning is started after the document platen position detection device described later detects that the document platen 2 has passed the scanning start position P ₂ .

On the other hand, the movement of the document table 2 during the copying operation as described above is performed by the drive output gear 9 (driving side gear), the two-stage gear 10 (driving side gear), and the endless rack 8 shown in FIG. This is performed by a document table driving device 3 having a (rack).

The document table driving device 3 is arranged on one side of the copying machine main body 1 in the reciprocating direction of the document table 2 so as to hang down from the edge of the document table 2. The document table driving device 3 is provided with two first and second racks 5 and 6 whose teeth are inwardly parallel to each other, and semicircles extending from both ends of one first rack 5 at the same pitch. Internal teeth 7
7 are formed toward the opposite end portions of the second rack 6 on the other side, and the end faces are connected to each other. These first and second racks 5 and 6, and each internal tooth portion 7
An endless rack 8 is formed by 7 and such an endless rack 8 is formed integrally with the support body 4 connected to the document table 2. The outer periphery of the endless rack 8 has a bent portion 1 of a bracket 11 described later.
The sliding contact surface 8a is in contact with the sliding contact surface 1a. The endless rack 8 of the present embodiment is formed of a non-conductive member, and as will be described later in detail, the scanning of the document table 2 is started at a predetermined portion of the sliding contact surface 8a that is in sliding contact with the bracket 11. In order to detect the position P ₂ , the position detection unit 21
(Position detection area) is provided.

Inside the endless rack 8, a drive output gear 9 having a center at an intermediate portion from the outer peripheral surfaces of the first and second racks 5 and 6 is rotatably provided. Between the gear 9 and the first and second racks 5 and 6, there are provided two-stage gears 10 having different pitch circle diameters that integrally rotate on the same rotary shaft 10c. A rotary shaft 9a, which is a gear shaft of the drive output gear 9, is inserted into a guide hole 4a formed at a position parallel to and equidistant from the outer peripheral surfaces of the racks 5 and 6 in the support 4. .. The power of the main motor 45 (FIG. 4) is transmitted to the rotary shaft 9a via a drive transmission mechanism (not shown).

The above-described two-step gear 10 is a small and large gear 1.
0a and 10b, the small gear 10a of the two-stage gear 10 has a pitch set so as to mesh with the first rack 5 and the internal tooth portions 7 and 7, while the large gear in the two-stage gear 10 is provided. The pitch of 10b is set so as to mesh with the second rack 6. That is, as a result, the moving speed of the endless rack 8 when the large gear 10b and the second rack 6 mesh with each other becomes faster than when the small gear 10a and the first rack 5 mesh with each other, The moving speed of the document table 2 can be changed between the feed direction and the return direction.

The drive output gear 9 and the two-stage gear 10 are connected and supported by a bracket 11 that rotatably supports the respective rotary shafts 9a and 10c. A bent portion 11a is formed at one end of the bracket 11 and is bent substantially at a right angle so as to be parallel to the outer peripheral surface of the endless rack 8. The bent portion 1
1 a slides the inside of the bent portion 11 a and the outer peripheral surface of the endless rack 8 to move the outer peripheral surface, whereby the two-stage gear 10, the drive output gear 9 and the endless rack 8 are moved.
It is designed to ensure the meshing with. In this embodiment, in order to detect the scanning start position P ₂ of the document table 2, this bracket 11 is made of a conductive member and is grounded.

The operation of the document table driving device 3 will be described. The small gear 10a of the two-stage gear 10 is the first rack 5
, The driving force is input to the rotary shaft 9a of the driving output gear 9, and the driving output gear 9 rotates in the direction of arrow B.

At this time, the drive output gears 9 and 2 are used.
Since the bracket 11 that rotatably supports the rotary shaft 10c of the step gear 10 is provided so that the bent portion 11a that is one end thereof slides on the outer periphery of the endless rack 8, the two-step gear 10 Rotates in the direction opposite to the drive output gear 9, and the endless rack 8 linearly moves in the rotation direction of the two-step gear 10. Along with this, the endless rack 8
The document placing table 2 connected to the linearly moving unit moves linearly in the feeding direction (F).

After that, when the drive output gear 9 is further driven, the small gear 10a of the two-stage gear 10 has a tooth portion 7 on the return side from the first rack 5 in the endless rack 8.
Meshing with each other and rotating about the drive output gear 9 about 180 ° about the rotary shaft 9a of the drive output gear 9,
The small gear 10a reaches the end of the internal tooth portion 7 on the return side, and the positional relationship between the drive output gear 9 and the two-stage gear 10 in the endless rack 8 is reversed upside down.

After the small gear 10a reaches the end of the internal tooth portion 7 on the return side, the meshing between the small gear 10a and the internal tooth portion 7 is released, while the large gear 10b in the two-step gear 10 is released.
Engages with the second rack 6. As a result, when the drive output gear 9 is further driven, the document table 2 moves together with the endless rack 8 in the return direction, which is the opposite direction to the previous direction.

Here, the structure of the document table position detecting device for detecting the position of the document table 2 will be described with reference to FIGS. 1 and 3.

The document table position detecting device 22 is composed of the endless rack 8 and the bracket 11, which are the components of the document table driving device 3 described above, and the position detecting circuit 23.

A position detecting portion 21 formed by exposing a material surface of the endless rack 8 made of a non-conductive member on a sliding contact surface 8a which is an outer peripheral surface of the endless rack 8 with the bracket 11, and a position detecting portion. A conductive portion 31 formed by covering a portion other than 21 with a conductive member such as a copper plate is provided.

The position detector 21 is provided on the first rack 5 with which the bracket 11 slides when the document table 2 moves in the feed direction, and the leading end of the document table 2 in the feed direction is at the scanning start position P. _The bracket 11 is formed at a portion that comes into sliding contact when passing through ₂ . That is, the bent portion 11a of the bracket 11 and the position detection portion 21 contact each other only when the document table 2 moves in the feed direction and is positioned at the scanning start position P ₂ , and in other cases, the bent portion 11a. The conductive portion 31 is in contact with the conductive portion 31.

A position detecting circuit 23 is connected to the conductive portion 31 to detect conduction and non-conduction between the endless rack 8 and the bracket 11 and to output a signal corresponding to conduction and non-conduction. There is. This position detection circuit 23
It is composed of a power supply E and a resistor R having a predetermined resistance value, and when both are electrically connected, the power supply E is grounded via the bracket 11, so that the voltage applied to the conductive portion 31 is lowered and turned off. While outputting a signal, when both are insulated, current flows only through the resistor R, and the conductive portion 31
The voltage applied to is high and outputs an ON signal. That is,
The ON signal is output only when the document table 2 is located at the scanning start position P ₂ .

In this way, the signal sent from the position detection circuit 23 is input to the control system 42 provided in this copying machine. As shown in FIG. 4, the control system 42 includes the print switch 4 in addition to the position detecting device 22 for the document table.
1, ON / O from paper input sensor 36, paper discharge sensor 37, etc.
The FF signal is input, and based on these ON / OFF signals, the ready lamp 44, the main motor 45,
Copy lamp 43, main charger 14, sheet feeding solenoid 35
a, the operation of the registration roller solenoid 16a, etc. is controlled.

The operation of the copying machine under the control of the control system 42 will be described with reference to FIGS. 4 and 5.
The power switch (not shown) is turned on in advance, and
The ready lamp 44 is lit as shown in FIG. When the print switch 41 is turned on by the operator, the main motor 45 is turned on, and at the same time, the copy lamp 43 is turned on instead of the ready lamp 44.

When the print switch 41 is turned on, the timer provided in the control system 42 is activated by the control operation of the control system 42, and after the set time t ₁ , the paper feed solenoid 35a is turned on for a predetermined time to feed the paper. The roller 35 is rotated to convey the transfer sheet from the recording material feeding section 33 to the recording material conveying section 32. When this transfer paper reaches the paper input sensor 36 of the recording material transport unit 32, the paper input sensor 36 detects the transfer paper and turns off.

When the main motor 45 is turned on, the drive output gear 9 is driven, the two-stage gear 10 rotates, and the endless rack 8 moves in a predetermined direction. Along with this, the bracket 11 makes the sliding contact surface 8a of the endless rack 8
Slide. While the bracket 11 slides on the conductive portion 31, the output signal from the document table position detection device 22 is OF
It is F. And the bracket 11 is the non-conductive part 2
When sliding 1b, the output signal from the position detecting device 22 of the document table is turned on. From the platen position detection device 22 O
When the N signal is output, the main charger 14 is turned on and the charging of the photoconductor 13 is started. In the case of a single copy,
Since the potential of the photoconductor 13 is difficult to stabilize, an ON signal is output from the document stage position detection device 22 and the main charger 1
4 is turned on, but since the photosensitive member 13 is easily stabilized during continuous copying, it is turned on after a predetermined time.

When an ON signal is output from the position detection device 22 of the document table, a timer provided in the control system 42 in advance operates as in the case of the paper feed solenoid 35a, and after a set time t ₂ . , Registration roller solenoid 16
a is turned on for a predetermined time, the registration rollers rotate, and the transfer paper is sent between the transfer roller 12 and the photoconductor 13. After that, the transfer paper is transferred to the fixing device 19 after the toner image is transferred, and when passing through the fixing device 19, the paper discharge sensor 37 detects the transfer paper and turns off, and the transfer paper is the main body of the copying machine. 1 is discharged to the outside. Since the present copying machine is small, the paper input sensor 36 and the paper discharge sensor 37 are longer in the transporting direction of the transfer paper than in the transporting distance of the transfer paper. 36 and the paper ejection sensor 37 detect the rear end and the front end of the same document and are temporarily turned off at the same time.

As described above, in the copying machine, the position detecting area 21 made of a non-conductive member is provided at a predetermined portion of the sliding contact surface 8a of the endless rack 8 of the document table driving device 3, and the other portions are provided. Covered with copper plate 31 and sliding contact surface 8a
And a signal corresponding to the electrical connection between the bracket 11 and
The position detection circuit 23 outputs to the control system 42. Then, the document table 2 moves in the feed direction at a predetermined portion of the sliding contact surface 8a, and the scanning start position P ₂
By setting the bracket 11 to be in sliding contact with the document table 2, it is possible to detect that the document table 2 is located at the scanning start position P ₂ .

Therefore, unlike the conventional case, the detection switch for detecting the scanning start position P ₂ and the switch actuating portion are not separately provided, and the components of the platen drive device 3 are used as the components of the platen. The position detection device 22 can be configured, the number of parts is reduced, and the manufacturing cost can be reduced. Further, the scanning start position P _{2 of} the document table 2 is set on the endless rack 8 that reciprocates integrally with the document table _2.
Since the position detection area 21 corresponding to is directly provided, the position can be detected more accurately than the detection by the detection switch attached separately from the document table 2.

In the present embodiment, the endless rack 8 is formed of a non-conductive member, and the position detecting portion 21 is provided by covering the area other than the predetermined area of the sliding contact surface 8a with a copper plate, but the present invention is not limited to this. However, the position may be detected by forming the endless rack 8 from a conductive member and covering only a predetermined area of the sliding contact surface 8a with an insulating plate.

[0043]

As described above, the platen position detecting device of the present invention supports the rack that reciprocates integrally with the platen, the drive-side gear that meshes with the rack, and the drive-side gear. At the same time, a bracket is provided on which the end surface of the rack is slidably contacted. A position detection area that generates a contact resistance different from that when the position is other than the position is provided, and a position detection circuit that emits an electric signal according to the electric resistance between the bracket and the sliding contact surface is provided. ..

As a result, the position of the platen can be detected by using the member for driving the platen, the number of parts can be reduced, and the cost can be reduced. Further, since the position detection area corresponding to a predetermined position of the platen is directly provided on the rack which reciprocates integrally with the platen, the detection by the detection switch attached separately from the platen Also enables more accurate position detection.

[Brief description of drawings]

FIG. 1 is a schematic view of a document table position detecting device in a copying machine according to an embodiment of the present invention.

FIG. 2 is a schematic overall configuration diagram of the copying machine.

FIG. 3 is a perspective view of a document table driving device applied to the copying machine.

FIG. 4 is a schematic block diagram showing a configuration of a control system in the copying machine.

FIG. 5 is a timing chart showing the operation timing of each means in the copying machine.

FIG. 6 is a front view showing a structure near a document table of a copying machine equipped with a conventional document table driving device.

FIG. 7 is a front view of the document table driving device shown in FIG.

FIG. 8 is a schematic configuration diagram showing a configuration of a conventional document table position detecting device.

[Explanation of symbols]

 2 Document Plate 5 First Rack (Rack) 6 Second Rack (Rack) 7 Internal Teeth (Rack) 8 Endless Rack (Rack) 8a Sliding Contact Surface (End Face) 9 Drive Output Gear (Drive Side Gear) 10 2 Stages Gear (driving side gear) 11 Bracket 11a Bending part 21 Position detecting part 22 Position detecting device of document table 23 Position detecting circuit E Power source (position detecting circuit) R Resistor (position detecting circuit)

Claims (1)

[Claims] 1. A rack that reciprocates integrally with a platen, a drive-side gear that meshes with the rack, and a bracket that supports the drive-side gear and is in sliding contact with an end surface of the rack. Position detection that causes a contact resistance different from that when the platen is located at a position other than the above predetermined position on the sliding contact surface of the rack that slides against the A position detecting device for a document table, wherein a position detecting circuit is provided which is provided with a region and which generates an electric signal according to an electric resistance between the bracket and the sliding contact surface.