JPH05158305A - Original carrier - Google Patents

Abstract

PURPOSE:To accurately and easily judge the abnormality of a carrying means by comparing a counted value until the detection of an original end part with a specific reference value and checking a decrease in carrying force, etc., according to the comparison result. CONSTITUTION:When a motor is driven and the tail end of a carried original D passes a register sensor S2, an output pulse signal begins to count. A ROM incorporated in the carrier is stored with the number of standard pulses, outputted from the sensor S2, as the reference counted value when the original is conveyed by a conveyor belt by the distance from the sensor S2 to a sensor S3. The counted value is compared with the reference counted value and when the reference value is exceeded, information indicating that a carrying defect occurs is inputted to a RAM as a storage means. A similar comparison is made for a following originals and the storage contents of the RAM has a carrying defect frequency rewritten in order according to whether or not the actual counted value exceeds the reference value. When the defect frequency is increased, the deterioration in the ability of the conveyor belt is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder used in an image forming apparatus such as a copying machine, and more particularly to a document feeder capable of easily checking a decrease in the feeding force of a feeding means.

[0002]

2. Description of the Related Art Conventionally, there is known an original document conveying apparatus which is provided with a conveyor belt which covers the entire surface of a platen of an image forming apparatus and which conveys and sets an original on the platen by driving the conveyor belt. And in this type of device, as a maintenance item of the device, replacement work of the conveyor belt is mentioned,
Regarding the timing of exchanging the conveyor belt, the number of originals to be conveyed, the surface stain of the belt, and the like were used as criteria.

[0003]

However, there is no item for checking the conveyance force of the conveyor belt in the conventional judgment standard. Even if there is a check item, is the conveyance force of the conveyor belt actually reduced? Further, it was difficult to accurately determine how much the deterioration was.

Further, the original force is not conveyed to a predetermined exposure position because the conveying force of the conveying belt is further reduced, and it is not possible to easily know the time when the phenomenon such as image misalignment starts to occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an original document conveying device capable of accurately and easily determining a decrease in the conveying force of an original document conveying belt.

[0006]

In order to achieve the above object, a first aspect of the present invention comprises a conveying means for feeding an original document to an exposure position and discharging it after the exposure operation is completed, and a motor means for driving the conveying means. The means for counting the output pulses from the pulse generating means synchronized with the rotation of the motor means, the means for detecting the edge of the document discharged from the exposure position, and the edge of the document set at the exposure position. Means for comparing the count value of the counting means with a predetermined reference count value until being detected by the detecting means, means for storing at least part of the comparison result, and the means for storing the contents of the storage means. And a determination unit that determines a transport abnormality such as a reduction in the transport force of the transport unit.

Further, according to the second aspect of the invention, a conveying means for feeding the document to the exposure position and discharging it after the exposure operation, a motor means for driving the conveying means, and a pulse generating means synchronized with the rotation of the motor means. Means for counting the output pulses from the first conveying means, a first detecting means provided on the upstream side of the conveying means in the sheet feeding direction to detect the end portion of the document, and an end portion of the document discharged from the exposure position. The counting from the time when the second detecting means and the edge of the document conveyed by the conveying means pass through the first detecting means until the edge of the document is detected by the second detecting means. A means for comparing the value with a predetermined reference count value, a means for storing at least a part of the comparison result, and a judgment for judging an abnormal conveyance such as a decrease in the conveying force of the conveying means according to the stored contents of the storage means. And means .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention can be applied to an image forming apparatus such as a copying machine, various printers, and facsimiles. As an example, a document feeding apparatus applied to the copying machine will be described with reference to the accompanying drawings.

A document feeder F is placed and mounted above the copying machine M shown in FIG. The document feeder F has a substantially square outer shape so that the document feeder F does not largely project to the left and right when viewed from the front of the copying machine M.

A platen P is provided in the upper part of the copying machine M, and a document feeder F mounted so as to cover the platen P covers a certain area corresponding to approximately half of the platen P. Conveyance means, for example, the conveyance unit 10, a platen cover unit 20 that also covers the remaining area of the platen P, and a document that is provided above the platen cover unit 20 and set on the document tray unit 30 is separated toward the platen P. A separating / feeding unit 40 for feeding, a paper discharging unit 50 for receiving the exposed document conveyed by the conveying unit 10 and discharging it from the platen P, and a storing unit 60 for storing the document discharged by the paper discharging unit 50. And a hinge portion 7 that supports the document feeder F above the platen P of the copying machine M so as to be openable and closable.
0, and a drive / control unit 80.

FIG. 12 shows a state in which the document feeder F shown in FIG. 1 is released above the platen P, and the effective reading range (reading section T: length X-Z) is defined on the upper surface of the transparent platen P. Therefore, one end of the reading unit is determined as a reading reference point X as an exposure position. At the time of copying, by arranging one end of the manuscript D with this reference point X, a copy corresponding to the manuscript can be obtained.

The reading section T is the maximum size that can be copied, and is indicated by a chain line in the figure. For example, the A3 size (297 mm x 420 mm) is the maximum size that can be copied, the A3 size is a large size, and the A4 size (210 mm x 29 mm).
7mm) is assumed to be a small size. Therefore, the entire length of the reading section T (between X and Z) is for large-sized documents, and half (X-
(Between Y) is for small size originals. In FIG. 12, the small-sized document D is positioned in the reading unit T in accordance with the reference point.

In FIG. 2, two drive motors M1 and M2 provided in the document feeder F and sensors S1 to S for collecting information necessary to control the operation of the document feeder F.
5 and control board 89 are shown.

The drive motor M1 is drivingly connected to the separating / feeding unit 40, and is driven and controlled mainly based on output signals from the sensors S1 and S5.

The drive motor M2 is drivingly connected to the carrying section 10 and is driven and controlled mainly based on output signals from the sensors S2, S3 and S4.

The sensor S1 is an empty sensor for detecting the presence / absence of a document set on the document tray section 30.

The sensor S2 is provided on the way of the conveying path for conveying the originals separated by the separating / feeding unit 40 to the platen P, and detects the leading edge or the trailing edge of the original passing through the conveying path. 1 is a registration sensor as a detection unit.

The sensor S3 is a switchback sensor as a second detecting means for detecting the leading edge or the trailing edge of the original conveyed in the paper discharge section 50.

The sensor S4 is an output shaft 8 of the drive motor M2.
6 is a photo sensor that detects the amount of rotation of an interrupter 871 (described later) provided in FIG. Sensor S4 is an interrupter
The pulse generating means 87 is configured together with 871 and generates an output signal (pulse) synchronized with the rotation of the drive motor M2.

The sensor S5 is provided on the hinge portion 70 so that the document transport device F can move the platen P against the copying machine M.
It is detected whether the upper state of the platen P is in the open state or the upper side of the platen P is in the closed state as shown in FIG.

Further, the accommodating portion 60 for accommodating the copied document is provided with a projecting member 62 extending in a direction substantially parallel to the document conveying direction. This protruding member 62
Is for leaning a document stored in the storage section 60. When the stored document is longer than the storage section 60, the leading edge of the document is projected from the storage section 60, and the leading edge of the projected document is the document tray section. This is to prevent the material from hanging down on 30.

Next, the document feeder F will be described in detail with reference to FIGS.

As shown in FIGS. 3 and 4, the document feeder F
Is a document tray unit 3 for stacking documents from upstream (right side in FIG. 3) to downstream (left side in the same direction) in the document transport direction.
0, a separation feeding unit 40 as a separating unit that separates and conveys the original on the tray into one sheet, and the separation feeding unit 40.
A document transport unit 10 is provided as a transport unit that receives a document transported by and transports the document further downstream.

A platen cover 20 is provided below the separating / feeding unit 40 on the platen P side, and an original received from the original conveying unit 10 is placed on the front and back sides above the original conveying unit 10. Paper ejection unit 5 that conveys paper while reversing it
0 is provided. Above the separating / feeding unit 40 and the document conveying unit 10, there is provided a storing unit 60 as a second supporting unit for storing the document conveyed by the paper discharging unit 50.

In the document feeder F, the document tray section 30
Is composed of a loading tray 31 on which a document is placed, a pair of side edge guides 32L and 32R for regulating the side edges of the document set on the loading tray 31, and an auxiliary tray 33.

The side edge guides 32L and 32R are arranged along the guide guide 321 in the width direction of the document (vertical direction in FIG. 4).
Move to. A rack and pinion mechanism (not shown) is connected to the side edge guides 32L and 32R, and the central portion of the original set on the loading tray 31 is positioned at the reference line K shown in FIG.

The auxiliary tray 33 is rotatably attached to the placing tray 31 by a rotary shaft 331, and stably supports the rear end side of a large-sized document placed on the placing tray 31.

The separating / feeding section 40 is provided with an original conveying path R1 for guiding the separated original from the predetermined position of the platen P (point Y at the center of the reading section T) to the platen P. R1 is partitioned by the guide plates 410 and 411. Then, the separating / feeding unit is arranged along the document conveyance path R1.

That is, the pick-up roller 42 is provided at the entrance side of the conveying path R1 so as to be able to move forward and backward on the mounting tray 31.
Further, the paper feed roller 43 and the separation belt 44 enter the conveyance path R1 from the guide plates 410 and 411 so as to be in non-contact with each other and to be overlapped with each other.
Further, a registration roller 451 and a pinch roller 452 are provided facing each other on the exit side of the transport path R1.

The exit portion of the transport path R1 is located substantially at the center (point Y) of the reading section T defined on the upper surface of the platen P.

At the entrance of the conveying path R1, the presence or absence of a document on the loading tray 31 in cooperation with a document stopper 46 provided so as to be movable back and forth with respect to the guide plate 411 and the sensor S1 (see FIG. 2). A lever 47 is provided to detect the error, and a sensor S2 is provided between the paper feed roller 43 and the registration roller 451 on the conveyance path R1.

As shown in FIGS. 5 and 10, the document stopper 46, the pickup roller 42, the paper feed roller 43, and the separation belt 44, which are provided along the conveyance path R1, have a motor M1.
Power from the belt drive transmission means 810, 811 and a plurality of gears G
It is configured to rotate / rotate in a predetermined direction via.

Assuming that one original is pulled out from the loading tray 31 and sent to the transport path R1, the motor M
1 rotation (normal rotation) is transmitted to the shaft 831 via the gears G2, G3, G4, and the rotation of the shaft 831 drives the drive transmission member 832 to rotate the shaft 833 in a predetermined direction.

At this time, since the document stopper 46 moves to the position shown by the chain line in FIG. 3, the document on the placing tray 31 can be separated and fed. When the document stopper 46 rotates (falls) and abuts on a stopper (not shown), the spring clutch 834 prevents the shaft 833 of the document stopper 46 from being driven with a certain driving force or more.

The pickup roller 42 has a shaft 82 for holding the paper feed roller 43 by means of a swing arm member 821.
Since it is pivotally supported on the shaft 8, the rotation of the lever 836 that is fixed to the shaft 831 and comes into contact with the swing arm member 821 causes the swing arm member 821 to rotate downward toward the document, and Contact the surface. When the pickup roller 42 comes into contact with the document, the contact pressure of the pickup roller 42 with respect to the document is maintained constant by the spring clutch 834.

Further, the forward rotation of the motor M1 is performed by the gears G1, G5, G
It is transmitted to the shafts 82 and 84 via 6, G7, and the paper feed roller 43
And the separation belt 44 are rotated in different directions.

A one-way clutch 822 is incorporated in the gear G7, and even if the rotation of the gear G7 is stopped, when the document is forcibly conveyed forward, the paper feed roller 43 advances the document. It is designed to rotate following it.

Further, the one-way clutch 823 is also incorporated in the gear G6, and even if the rotation of the gear G5 is stopped, when the document is forcibly conveyed forward, the separation belt 44 follows the forward movement of the document. It is designed to rotate.

The gear G1 has a built-in one-way clutch 824. When the motor M1 rotates in the reverse direction, the gear G1 idles, and the drive is not transmitted to the rollers 42, 43 and the separation belt 44, but the document stopper 46 and the lever Drive is transmitted to 836, and the motor M1 is rotationally driven in a direction opposite to that when the motor M1 is normally rotated.

Further, a spring clutch 837 is provided on the shaft 838, and when the motor M1 reversely rotates, the document stopper 4 is inserted.
6 and the lever 836 are prevented from being driven upward by a predetermined force or more.

With the structure of the separating and feeding section 40 described above,
When the motor M1 rotates in the normal direction, only the pickup roller 42 and the paper feed roller 43 rotate in the forward direction (original conveying direction),
The separation belt 44 rotates in the reverse feeding direction. As a result, the documents placed on the loading tray 31 are conveyed one by one from the entrance to the exit of the conveyance path R1.

When the motor M1 reversely rotates, the lever 836
Is rotated to separate the pickup roller 42 from the surface of the original.

The document conveying section 10 comprises an endless belt-shaped conveying belt 13, a pair of pulleys 11 and 12 for driving the conveying belt 13 so as to be able to rotate forward and backward, and a plurality of press rollers 14 for pressing the conveying belt 13 against the platen P. Become. Further, the document transport unit 10 has approximately half (X) of the maximum copy document size (reading unit T) on the upper surface of the platen P on the reading reference point X side.
(Between Y and Y).

A conveyor belt 13 is provided at the exit of the conveyor path R1. The conveyance belt 13 forms a document path R2 between itself and the platen P, and the entrance of the document path R2 is at the center of the reading unit T (Y
Point), and the exit is located substantially at the reading reference point X defined at the front end of the reading unit T.

By this document transport section 10, the document discharged from the exit of the transport path R1 is transported to the reference point X of the reading section T, or is transported in front of the reference point X and discharged. Can be transported in the opposite direction.

As shown in FIGS. 3 and 7, the original feeding section 10
Behind the exit (reference point X) of the above, a paper discharge section 50 is provided in series with the document conveying section 10. The paper discharge unit 50 is
An endless belt-shaped paper discharge belt 51, a pair of pulleys 52 and 53 that drive the paper discharge belt 51 so as to be able to rotate forward and backward, and a rolling roller 5 that transmits the drive of the conveyor belt 13 to the pulley 53.
4 and the document discharged from the exit of the document path R2 in the storage section 60
Has guide members 55 and 56 for guiding to
A discharge path R3 for guiding the document sent out from the document transport unit 10 is formed between 5 and 56.

A leaf spring member 57, one end of which is fixed to the guide member 55 and the other end of which presses the document against the paper discharge belt 51, is provided at a position away from the facing portion of the paper discharge belt 51. The transfer roller 54 is urged directly by a spring member (not shown) on the surface of the conveyor belt 13 at a position facing the driven pulley 12, and the fourth and seventh rollers are also provided.
As shown in the figure, they are in contact with each other at substantially the center of the conveyor belt 13.

Further, the discharge belt 51 and the pair of pulleys 5
2, 53 and the rolling contact roller 54 are integrally supported by the pair of left and right side plates 58, and can be fixed to the outer cover of the conveyance device F as a unit, which facilitates assembly.

In this embodiment, the document discharged from the document path R2 between the conveyor belt 13 and the platen P is introduced into the paper discharge path R3 and conveyed to the storage section 60.

The storage section 60 includes a storage tray 61 and a projecting member 62 extending in a direction substantially parallel to the document transport direction.
It consists of Since the storage tray 61 is disposed above the loading tray 31, the copying machine F is in a state where the document D to be separated and fed and the copied document D1 overlap each other as shown in FIG. Placed above the platen of
It is stored. In other words, it is possible to configure a document conveying device which is small and lightweight, is not particularly limited in the size of the document to be conveyed, and can easily handle the processed document.

Referring to FIG. 3, the platen cover section 20 is provided below the separating / feeding section 40 on the platen P side, and an area on the upper surface of the platen P other than the area covered by the document conveying section 10 is also described. That is, the reading reference point X of the reading unit T
It has a size that covers approximately half (between Y and Z) on the opposite side.

With reference to FIGS. 5 and 6, the drive system of the document conveying section 10, the platen cover section 20 and a part of the drive system of the separation feeding section 40 will be described.

The output shaft 86 of the motor M2 is provided with an interrupter 871 formed by forming slits on a disk at equal intervals, and a photosensor for generating a pulse in response to light passing through the slit of the rotating interrupter 871. A pulse generator 87 composed of S2 is provided.

The conveyor belt 13 forming the document path R2 receives the power from the motor M2 as belt drive transmission means 850, 851 and the shaft 8
The drive side pulley 11 is rotated via the gears 52 and the gears G8, G9, G10 so that the drive side pulley 11 is driven in the forward direction (original conveying direction) and the backward feeding direction. In addition, the rolling roller 54 provided above the driven pulley 12 of the conveyor belt 13 is
Drive is directly transmitted from the surface of the transport belt 13, and the paper discharge belt 51 is driven in the same document transport direction at the same peripheral speed as the transport belt 13.

A registration roller 451 is fixed to the shaft 852, and is driven in the same document conveying direction at the same peripheral speed as the conveying belt 13.

That is, the registration roller 451, the driving pulley 11, and the paper discharge belt 51 are one driving source (motor M2).
And the registration roller 451 rotates at a substantially equal peripheral speed so that the registration roller 451 can convey the original document path R2 and the paper ejection path R3 at the same speed as the original document sent through the conveyance path R1. That is,
The originals conveyed in the passages R1, R2, R3 are
It is designed to move at a constant speed. The rotary drive system described above can be controlled based on the clock signal of the pulse generating means 87.

On the other hand, the drive of the shaft 852 is transmitted to the drive shaft 242 via the gears G11, G12, G13. The drive shaft 242 is gear-coupled so as to rotate in the same direction as the pulley 11 that drives the conveyor belt 13, and connects the platen cover 21 to the conveyor belt 1.
Slide in the same direction as the transport direction in the reverse order of 3. When the transport belt 13 is driven in the forward direction (document transport direction), the platen cover 21 is held at a position close to the platen P by the forward rotation of the drive shaft 242. The platen cover 21 is held in the proximity position with a constant force by the torque limiter 853 incorporated in the shaft 852.

When the conveyor belt 13 is driven in the reverse feeding direction, the platen cover 21 is held at a position separated from the platen P by the reverse rotation of the drive shaft 242. The platen cover 21 is held in the separated position with a constant force by the torque limiter 854 incorporated in the shaft 242.

The hinge portion 70 shown in FIGS. 1, 4 and 12 is composed of a spring-equipped hinge 71 for supporting the document feeder F on the upper surface of the copying machine M so as to be openable and closable, and a springless hinge 72. The spring-equipped hinge 71 includes a main body fixing portion 711 fixed to the copying machine M side, an attached fixing portion 712 fixed to the conveying device F side, a pin 713 connecting both portions 711, 712, and both portions 711, 7
It is composed of spring means 714 that biases 12 in the opening direction around the pin 713.

Further, it is provided at a position slightly upstream (right side in the figure) from the central portion of the apparatus F with respect to the document conveying direction of the document conveying apparatus F (horizontal direction in FIG. 4). This hinge position corresponds to the positions of the motors M1 and M2 and the motors M1 and M.
The position of the center of gravity shifted from the position of the rotary drive system or the like connected to 2 to the upstream side in the transport direction of the apparatus F is approximately corresponded.

The springless hinge 72 is composed of a support member 721 fixed to the copying machine M side, a concave support portion 722 provided in the document feeder F, and a pin 723 connecting both members 721, 722.
The hinge 72 is provided at a position downstream (on the left side in FIG. 4) of the document transport device F in the document transport direction, and includes a support member 721 fixed to the copying machine M and a concave support portion 722 of the frame cover of the document transport device F. It is rotatably connected by a pin 723.

The operation of the document feeding device F having the above structure will be described below.

FIGS. 8 and 9 (A) to (C) show the case where a relatively small size original such as the A4 to letter size horizontal is handled.

FIG. 8A shows a state in which the document D is set on the placing tray 31 prior to copying, and when a copy command is given to the copying machine M, the presence of the document D is confirmed by the empty sensor S1. , The document stopper 46 is the guide plate 411.
, And the pickup roller 42 rotates and descends to come into contact with the document D on the tray 31.

As a result, the document D is sent forward,
The document D is moved forward by the paper feed roller 43 which is inserted between the paper feed roller 43 and the separation belt 44 and rotates in the transport direction. At this time, a plurality of documents D are placed on the loading tray 31 as shown in FIG.
When a plurality of originals are simultaneously sent out by the separation belt 44, the separation belt 44 rotating in the reverse feeding direction prevents the lower original that contacts the separation belt 44 from advancing. Therefore, only one original is allowed to pass forward by the paper feed roller 43.

In this way, the document D sent out is contacted with the registration roller 451 and the pinch roller 452 in the stopped state after the leading edge of the original is detected by the registration sensor S2. Document D
By stopping the rollers 42, 43 and the belt 44 after a lapse of a predetermined time from the detection of the leading edge of the document, the document D is bent to some extent, and the leading edge is evenly distributed between the registration roller 451 and the pinch roller 452.
It is pressed against the tangent part of.

As a result, the document D is drawn in with the leading ends parallel to the registration roller 451 and the pinch roller 452, which start rotating after contacting the document D, and is sent out forward (skew correction action).

The document D transported through the transport path R1 as described above is guided to the entrance of the document path R2 at substantially the center (point Y) of the reading section T of the platen P. The document D that has entered the entrance of the document path R2 formed between the transport belt 13 and the platen P in this way is sent forward along the document path R2 by the transport belt 13 that is driven in synchronization with the registration rollers 451.

At this time, the length of the document D in the carrying direction is determined by counting the output pulse signals from the pulse generating means 87 from when the motor M2 is activated until the trailing edge of the carried document passes the registration sensor S2. it can.

That is, since at least the registration roller 451 and the conveyor belt 13 that are involved in the conveyance of the document D maintain the same conveyance speed in synchronization with the pulse of the pulse generation means 87, the reading reference point X is reached from the activation of the motor M2. When the registration sensor S2 detects the trailing edge of the document D while the leading edge of the document D is on the way from the point Y to the point X, the conveyed document is at least at the point X-. It can be seen that it is less than or equal to the length between Y. That is, in this case, it is determined that the document has a small size. If the original is small in size, the conveyor belt 13 is stopped after the pulse generation means 87 has counted a predetermined pulse (A pulse) after the rotation of the motor M2 is started. As a result, the document D can be stopped at the reading position in which the leading edge of the document is accurately aligned with the reference point X, as shown in FIG. 8C.

Next, it is judged whether or not the empty sensor S1 detects the original, and when the presence of the original D is not detected, the copying machine M is operated to execute copying.

When copying is completed, the conveyance belt 13 and the paper discharge belt 51 are operated to guide the document D to the paper discharge path R3 and discharge it to the storage tray 61.

When the empty sensor S1 detects a document, the motor M1 is activated to send the next document D from the loading tray 31 toward the registration rollers 451 and the copying machine M is operated to make a copy. Run. (Fig. 9
(Refer to (A)) When the copying is completed, the conveyor belt 13 is stopped after the pulse generation means 87 has counted a predetermined number of pulses (A pulse) from the start of the motor M2. At this time, the first (first) original document is stored in the storage tray 6 with the rear end thereof being restrained by the paper discharge unit 50.
No. 1 is discharged on the tip side. (See FIG. 9B) When the empty sensor S1 detects the document D to be copied on the mounting tray 31, the above-described operation is repeated as appropriate,
As shown in FIG. 9C, the copied documents D are sequentially accumulated in the storage tray 61.

Further, in the above-mentioned document conveying step, the following functions are working.

As shown in FIGS. 15 and 16, when the motor M2 is activated and the trailing edge of the conveyed document passes the registration sensor S2, the passage is detected, and at the same time, the pulse generating means 8 is detected.
The output pulse signal from 7 is started to be counted by the counting means (not shown). (Step 3) Next, the conveyor belt 13 is temporarily stopped, and the number of output pulses from the start of counting to the exposure position is held and the number of output pulses is added to the subsequent output pulses, although the copying operation is involved.

When the copying operation is completed, the conveyor belt 13 is driven again by the motor M2, and the counting means again starts counting output pulses.

When the leading edge of the conveyed document passes through the switchback sensor (paper discharge sensor) S2, the counting means stops counting the output pulses from the pulse generating means 87.
(Step 4) On the other hand, the nonvolatile memory (R
In the OM (not shown), the standard number of pulses output from the pulse generating means 87 when the distance from the sensor S2 to the sensor S3 is conveyed by the conveyor belt 13 is stored as a reference count value.

The reference count value is preferably set to a value obtained by adding or subtracting a certain allowable value to the standard number of pulses from the characteristics of the device or other factors.

The value counted by the counting means is compared with the above-mentioned reference count value by the comparing means (not shown). If the value is counted beyond the reference count value, the storage provided in the carrying device. A volatile memory (RAM, not shown) as a means inputs / stores information indicating that one conveyance failure by the conveyance belt 13 has occurred. At this time, the content stored in the volatile memory (RAM) is "conveyance failure frequency 1". Regarding the extent to which the actual count value exceeds the reference count value described above, it is determined that the conveyance belt 13 is defective in conveyance and the contents of the volatile memory are rewritten. A predetermined amount of margin (adding about 10% to the theoretical count value) may be set in advance in the count value itself, or a predetermined amount of margin may be considered in the comparison step. Further, the reference count value and the actual count value are compared with respect to the succeeding document, and if the actual count value exceeds the reference count value, the stored content of the volatile memory indicates “conveyance failure frequency 2”, It is sequentially rewritten as "conveyance failure frequency 3" .... On the contrary, when the actual count value does not exceed the reference count value, the contents stored in the volatile memory are sequentially rewritten as "conveyance failure frequency 3", "conveyance failure frequency 2", and so on. (However, rewriting is not performed after the content stored in the volatile memory becomes "conveyance failure frequency 0".) This indicates that the frequency of occurrence of conveyance failure of the conveyor belt 13 has decreased within a certain period. ing. The contents stored in the storage means are constantly monitored, and the above-mentioned defective conveyance frequency is, for example, "1".
When it reaches 0 ″, it is determined that the document conveyance failure due to the conveyor belt 13 has occurred relatively continuously, that is, the conveyance force of the conveyance belt 13 has decreased. If it is determined that the transport belt F is being operated, the display means I provided in the transport device F is turned on to let the operator or service person recognize that cleaning, replacement, etc. of the transport belt 13 is required. It is also possible to output a predetermined signal to the copying machine M to display that effect on the display panel of the copying machine M (step 5).

It is possible to execute the above steps without interposing a copying operation in the above steps, that is, in a test mode in which the transporting device alone operates without interlocking with the main body copying machine M.

Further, as shown in FIGS. 13 and 14, after the document is stopped at the exposure position of the platen P and the copying operation is completed, the conveyance belt 13 is driven by the motor M2, and the leading edge of the document passes the sensor S3. Until then, the number of pulses output from the pulse generating means 87 is counted (step 1), and the conveyance force of the conveyance belt 13 may be checked by comparing the count value with the reference count value. (Step 2).

Each of (A) to (D) in FIGS. 10 and 11 shows a case of handling a large-sized document longer than the X-Y interval on the platen P defining a relatively small-sized area.

Subsequent to the start of the above-described document conveyance (FIG. 8A), the document D is moved forward along the document path R2 between the conveyance means 13 and the platen P.

The document D moving forward on the document path R2 is read at the reference point X.
Even if it is just before passing through the sheet, the trailing edge of the document is
If it does not pass 2, the document D is determined to be large.
In this case, the document D is continuously conveyed until the pulse generation means 87 counts a predetermined pulse (B pulse) after the trailing edge of the document passes the registration sensor S2.

When the trailing edge of the document reaches the entrance (point Y) of the document path R2, the leading edge of the document D passes through the paper discharge section 50 and is conveyed to the upper surface of the storage tray 61 as shown in FIG. 10C. There is. Next, the transport belt 13 is rotated in the reverse direction, and the document D is fed backward along the upper surface of the platen P. As a result, the document D is printed on the platen P and the platen cover 2 between the points Y and Z of the reading unit T.
Enter between 1 and.

The document D is fed backward by the conveyor belt 13 until the leading edge of the document passes the reference point A of the reading section T by a predetermined amount. The backward feeding of the document D is controlled based on the detection signal of the trailing edge of the document (the leading edge during the forward feeding; the left side in the drawing) of the switchback sensor S3. That is, after the trailing edge of the document to be fed back passes the switchback sensor S3, the conveyance belt 13 is fed backward until the pulse generating means 87 counts a predetermined pulse (C pulse), and the trailing edge of the document is read by the reading section T. The conveyor belt 13 is stopped at the point W. (Fig. 1
0 (D)) The conveying belt 1 is provided until the pulse generating means 87 counts a predetermined pulse (B pulse) after the trailing edge of the document (the trailing edge during forward feeding; the right side in the figure) passes the registration sensor S2.
In consideration of the size of the used document, the switchback sensor S3 is provided in the vicinity of the downstream side of the platen P in the forward feeding direction so that the leading edge of the document is always detected by the switchback sensor S3 when the document 3 is conveyed. It is arranged.

When the document is fed back by the conveyor belt 13, the drive system of the platen cover 21 is simultaneously driven, and the platen cover 21 moves in the direction away from the platen P. This makes it easier for the document D to enter between the platen P and the platen cover 21 between the points Y and Z of the reading unit T.

Thereafter, the document D is conveyed again in the forward direction by the conveyor belt 13, and the trailing end of the document D fed in the forward direction is read by the reading portion T.
When it is located at the reference point X, the conveyor belt 13 is stopped. That is, after the pulse generator 87 counts a predetermined pulse (D pulse) that is overrun from the reference point X in the backward feeding, the feeding of the feeding belt 13 in the forward feeding direction is stopped. (See FIG. 11A.) As described above, when the document D is conveyed by D pulses by the forward rotation of the conveyance belt 13, the platen cover 21 moves in the direction approaching the platen P. As a result, the point Y-Z of the reading unit T
The document D that has entered between the platen P and the platen cover 21 in between is pressed to the platen P side. Then, copy is executed.

After the copy is completed, when the empty sensor S1 detects no original on the tray 31, the conveyor belt 13 and the discharge belt 51 are driven in the forward feeding direction to store the original D through the discharge path R3. Send it to the tray 61.

When the succeeding copy document D is detected by the empty sensor S1, the motor M2 is driven by a predetermined pulse (E pulse) according to the size of the document to be copied, as shown in FIG. 11B. The trailing edge of the document (the trailing edge at the time of forward feeding) is conveyed to the substantially central portion (point Y) of the reading unit T by the forward feeding of the discharge belt 13.

Next, the next document is conveyed to the position of the registration roller 451 by the above-described document separating and feeding operation.
(FIG. 11C) Here, the motor M2 is activated to rotationally drive the registration roller 451, the transport belt 13, and the paper discharge belt 51 at the same time.
As a result, the copied document D1 is sent to the storage tray 61, and the subsequent document D2 is transferred to the point Y of the reading unit T.
The document D is fed forward by the transport belt 13 until the trailing edge of the document is located at the point Y of the reading section T, as described above. (FIG. 11D) According to the document feeder F having the above-described configuration, a relatively small small document feeder system having a size smaller than about half (the size between X and Y) of the reading unit T on the platen P and having a large size. Manuscript (X
It is possible to effectively carry out the transfer process even between (Z size), and it is possible to rationalize the system, reduce the cost of the device, and reduce the size and weight.

In the above embodiment, about twice the small size is set as the large size. Needless to say, even if the large size (between X and Z) is made larger than twice the small size (between XY), Alternatively, it can be practically made small.

[0093]

According to the present invention described above, a means for comparing the count value of the counting means with a predetermined reference count value until the detecting means detects the edge of the document set at the exposure position, or The count value from when the edge of the document conveyed by the conveying means passes the first detecting means to when the edge of the document is detected by the second detecting means is defined as a predetermined reference count value. Since a means for comparing, a means for storing at least a part of the comparison result, and a determination means for determining a conveyance abnormality such as a reduction in the conveyance force of the conveyance means according to the stored contents of the storage means are provided. It is possible to accurately and easily determine a conveyance abnormality such as a reduction in the document conveyance force of the means.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment in which a document feeder according to the present invention is applied to a copying machine.

FIG. 2 is a perspective view showing an embodiment showing the internal structure of a part of the same document feeder.

FIG. 3 is a side sectional view of the same document feeder as above.

FIG. 4 is a plan view of the same document feeder as above.

FIG. 5 is a plan view showing a drive system of a part of the separation supply unit.

FIG. 6 is a plan view showing a drive system of a part or all of a separation / feed unit, a document conveyance unit, and a platen cover unit.

FIG. 7 is a perspective view illustrating a main configuration of a paper discharge unit.

FIG. 8 is an explanatory diagram showing a feeding state of a small-sized document.

FIG. 9 is an explanatory diagram showing a feeding state of a small-sized document.

FIG. 10 is an explanatory diagram showing a feeding state of a large-sized document.

FIG. 11 is an explanatory diagram showing a feeding state of a large-sized document.

FIG. 12 is a perspective view showing an embodiment in which a document feeder according to the present invention is applied to a copying machine with a platen released.

FIG. 13 is an explanatory diagram showing a document feeding state when confirming the conveyance force of the conveyance belt.

FIG. 14 is a flowchart illustrating an operation of confirming a conveyance force of a conveyance belt.

FIG. 15 is an explanatory diagram showing a document feeding state when confirming the conveyance force of the conveyance belt.

FIG. 16 is a flowchart illustrating an operation of confirming a conveyance force of a conveyance belt.

[Explanation of symbols]

 M Copying machine (image forming apparatus) F Document transporting device P Platen D Document 10 Document transporting part (transporting means) 20 Platen cover part 30 Document tray part 40 Separation feeding part 50 Paper discharging part 51 Paper discharging belt 60 Storage part 70 Hinge Part X reference point

Claims (3)

[Claims] 1. A conveyance means for feeding an original document to an exposure position and discharging it after the exposure operation, a motor means for driving the conveyance means, and an output pulse from a pulse generation means synchronized with the rotation of the motor means. Means, a means for detecting the edge of the document discharged from the exposure position, and a predetermined count value of the counting means until the edge of the document set at the exposure position is detected by the detection means. Means for comparing with a reference count value of, a means for storing at least a part of the comparison result, and a determination means for determining a conveyance abnormality such as a reduction in the conveyance force of the conveyance means according to the stored contents of the storage means An original document feeding device comprising: 2. A transport means for feeding an original document to an exposure position and discharging it after the exposure operation, a motor means for driving the transport means, and an output pulse from a pulse generating means synchronized with the rotation of the motor means. Means, first detecting means provided on the upstream side in the paper feeding direction of the conveying means for detecting the edge of the original, and second detecting means for detecting the edge of the original discharged from the exposure position. After the end portion of the document conveyed by the conveying means has passed the first detecting means,
Means for comparing the count value with a predetermined reference count value until the end portion of the document is detected by the second detecting means, and means for storing at least a part of the comparison result,
A document transporting apparatus, comprising: a determination unit that determines a transport abnormality such as a reduction in the transport force of the transport unit according to the stored content of the storage unit. 3. The document conveying apparatus according to claim 1, further comprising display means for displaying a judgment result when the judging means judges that the conveying force of the conveying means has decreased. ..