JPS63180651A - Sheet holding device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of picture quality and a paper jam from occurring, by maintaining the relational actuation between a gripper of a sheet holder and a feeding means of the sheet held by this gripper into an optimum condition all the time, in case of a sheet holding means for a color copying machine. CONSTITUTION:A sheet P passes through a conveying passage 2 and advances forward to a sheet holder 1, and it comes into a stand-by state at the position of a resist roller 3. On the other, hand a gripper 1a is set up in this sheet holder 1. The resist roller 3 is designed so as to make the sheet P capable of taking respective modes such as almost equal speed with peripheral speed of the sheet holder 1, and the double speed, or stopping by a variable speed driving means 8 on the basis of driving force out of a driving source 9 and a signal out of a controlling means 10. In addition, a lamp 6 and a sensor 7 are set up in guide members 4 and 5, whereby passing time of the sheet P is detectable. Moreover, a signal out of the sensor 7 is impressed on the controlling means 10 together with an output pulse of a clock pulse generating means 12, and the generated pulse of an encoder 11 is also impressed likewise.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet material gripping device applicable to, for example, a color copying machine, and more particularly to a sheet material gripping device for gripping a sheet material on a moving sheet material carrier.

(Prior Art) For example, in the development and transfer processes of a color copying machine, in order to develop and transfer multiple color images in a superimposed manner, a sheet material is held by a recording material support member that moves endlessly. Conventionally, methods have been proposed in which image forming operations are repeatedly performed at predetermined positions on the image forming apparatus.

Such a device in which a sheet-like member is held by a moving carrier is applied not only to the above-mentioned color copying machine but also to printer units of computers, facsimile machines, and the like. This kind of sheet-like member gripping means, as exemplified by the above-mentioned color copying machine, is generally constructed by disposing a gripper on a rotating cylindrical transfer drum and opening and closing the gripper at a predetermined position. However, the sheet-like transfer material is usually fed in synchronization with the opening and closing of the gripper, and is gripped by the transfer drum.

To describe this more specifically, the transfer material supplied from a cassette or the like is conveyed by a conveyance means, reaches the position of the stopped registration roller, comes into contact with the nip part, the leading end stops, and the following part stops. The traveling direction is corrected by receiving the conveying force. Thereafter, the registration roller rotates at a second speed, which is a circumferential speed similar to that of the transfer drum, to convey the transfer material, and the tip thereof reaches the gripper part, which is in an open state and can be gripped by this time. Then, a speed approximately twice as high as the second speed is applied to the transfer material, and the leading end of the transfer material enters the grip. Thereafter, the gripper closes and grips the transfer material, and the registration rollers return to the second speed again to wind the transfer material around the transfer drum without bending.

(Problems to be Solved by the Invention) In this conventional example, the distance that the transfer material travels from once it stops at the position of the registration roller until it is gripped by the transfer drum is, for example, The time it takes for the registration rollers to start up and rotate at a predetermined speed after receiving a drive signal, and the time it takes for the transfer material to be gripped by the rotation of the rollers from the position just before the nip of the registration rollers, etc. materials, environment.

Fluctuations are inevitable due to aging and wear of various drive parts. As a result, a deviation occurs in the relative positional relationship between the transfer material and the gripper on the carrier side that carries it, resulting in situations such as grip errors, grip failures, and poor loop formation of the sheet material when gripping. 1. This has the problem of deteriorating image quality and causing jams.

Therefore, the present invention has been made to solve the above-mentioned problems of the conventional example, and its purpose is to provide a gripper for a sheet material carrier and a feeding means for the sheet material gripped by the gripper. It is an object of the present invention to provide a sheet material gripping device that can maintain related operations in the best condition at all times.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a sheet material 1 that moves with a grip means that opens and closes at a predetermined position to grip or release the sheet material. - a special holiday, a feeding means for feeding the sheet material to the gripping means, a sheet material feeding speed of the feeding means to a first speed higher than a moving speed of the sheet material carrier; a speed change drive means for changing the speed to a second speed lower than the above speed; a detection means for detecting a relative positional deviation between the sheet material fed by the feeding means and the grip position of the sheet material carrier; and a control means for controlling the speed change time of the feeding means by the speed change drive means after the sheet material contacts the grip means based on the detection result of the detection means.

(Function) In the present invention having the above configuration, the detection means detects a relative positional deviation between the sheet material fed by the sheet material feeding means and the grip position of the sheet material carrier, and this detection means By controlling the speed change time of the feeding means after the sheet material comes into contact with the gripping means based on the detection result, the gripping means of the sheet material carrier and the feeding means for the sheet material gripped by the gripping means The aim is to maintain the relationship between the vehicle and the vehicle in the best condition at all times.

(Example) The present invention will be explained below based on the illustrated embodiments.

FIG. 1 is a side view of a main part of an image forming apparatus equipped with a rotating cylindrical sheet material carrier such as that seen in a transfer drum of a color copying machine, and the sheet material carrier rotates in the direction of arrow A. 1, a sheet material P supplied from a cassette (not shown) or the like passes through a conveyance path 2 and advances to the left in the figure.
Once at the position of the pair of registration rollers 3, 3 serving as feeding means, a standby state is established.

On the other hand, the sheet material carrier 1 is in an open state only at the time of gripping the conveyed sheet material P, and when separating it from the sheet material carrier 1, and at other positions, for example, by the action of a spring. A gripper 1a is provided as a gripping means which is biased toward the closed state. Although the specific opening/closing means for Glitz<la is not shown,
For example, a cam is fixedly arranged at an appropriate location on the sheet material carrier 1, and a cam follower provided integrally with the gripper la is actuated by the cam.
Known techniques such as opening and closing a can be used. In the figure, the vertical range is the open area of the gripper la, that is, the grippable area.

The pair of registration rollers 3, 3 carry the sheet material on the sheet material P based on the driving force from the drive source 9 and the signal from the control means 10 by means of variable speed drive means 8 constituted by a known clutch mechanism. A speed almost equal to the circumferential speed of body l (
(second speed), approximately twice the speed (first speed), or stop.

Also, the registration roller 3 is
, 3, a guide member 4.5 for guiding the sheet material P.
These guide members 4.5 are provided with openings 4a and 5a, respectively.
A lamp 6 as a light-emitting element and a sensor (detection means) 7 as a light-receiving element are disposed via the light-emitting element 5a, whereby the time when the sheet material P passes through the relevant position can be detected.
This position is assumed to be in a region where the sheet material P travels at the above-mentioned first speed.

Further, the output signal of the sensor 7 is transmitted to a clock pulse generating means 1 which generates a pulse synchronized with the rotational position of the sheet material P.
2 output pulses are applied to the control means 10. On the other hand, a rotary encoder 11 is connected to control the rotation of the drive source 9, and the generated pulses are transmitted to the sheet material P.
A pulse signal synchronized with the sending position of is generated, and this signal is also applied to the control means lO. And the control means 10
The outputs of CPIJ, ROM, RAM, and sensor 7 are
It is equipped with a comparator for converting into a value and an I10 port connected to each pulse generating section, and controls the rotational speed of the drive source 9 to a predetermined value based on the clock pulse from the above-mentioned input signal. 8. Determine and execute the speed switching timing.

Next, the grip operation of this embodiment will be explained based on the flowchart of FIG. It is assumed that the operation shown in FIG. 2 proceeds based on a clock pulse. First, in step 101, the sheet material P is appropriately fed by the conveying means and reaches the nip portion of the stopped registration roller pair 3.3. At this time, since the rear end of the sheet material P is still receiving the conveying force, the leading edge direction of the sheet material P is corrected to the normal direction by that force.Next, step 102
The pair of registration rollers 3, 3 rotate at the second speed to advance the sheet material P to the position of the guide member 4.5. Then, when the preset number of clock pulses is reached,
At step 103, the registration roller pair 3, 3 is shifted to the first speed by the variable speed driving means 8, and the sheet material P is conveyed at high speed. Immediately after that, in step 104, an initial value 0 is substituted into the contents of the register C of the counter in order to check the time at which the sensor 7 detects the sheet material P. Then, in steps 105 and 106, the contents of the register C are incremented by 1 as the number of clock pulses progresses until the sensor 7 generates a detection signal for the sheet material P. Then, when the sensor 7 issues a detection signal for the sheet material P, the process moves to step 107. In this step 107, according to the count value C obtained in the previous step, a table previously set in the ROM is referred to, and the registration roller pair 3.3 is
The clock pulse count value nj at the time when the speed returns to is calculated.

The settings for the above table are as follows. Here, when the sheet material P is detected at the ideal count value CQ, the sheet material P is detected at the center of the grippable area by the subsequent shift control.
starts contacting the gripper 1a and forms a moderate loop of the sheet material P (because the feeding speed of the sheet material is still higher than the speed of the gripper la), the clock at the time when the feeding speed returns to the second speed. If the number of pulses, that is, the number of clock pulses for the ideal return shift is nto, then nt is nt =
nto -(Co-C) (Ml/Y2
) By setting vl: first speed v2: second speed, even if there is a difference in the relative position of the sheet material P at the position of the sensor 7, after the sheet material P contacts the gripper 1a, The time required for the delivery speed to return to the second speed is constant. That is, the loop formed just before the grip of the sheet material P remains constant even if there are variations in the delivery state of the sheet material P, and a stable gripping operation is always performed within the grippable range inside the vehicle. and,
It is sufficient to store in the ROM of the control means IO a correspondence table between the count value C at the time of detecting the sheet material P and the number of clock pulses nt at the time of return shift, which is calculated from the count value C by the above equation.

Next, in step 108, the actual number of clock pulses is nl
When this is reached, the registration rollers are shifted to the second speed in step 109 and gripping in step 110 is completed.

In the above embodiment, an example was explained in which the application was applied to a color copying machine equipped with a rotating cylindrical sheet material carrier (transfer drum), but the present invention is not limited to this, and for example, an endless belt-shaped image carrier may be used. It can also be applied to image forming apparatuses, various printers, etc.

(Effects of the Invention) The sheet material gripping device according to the present invention has the above-described configuration and operation, and the operation of the relationship between the gripper of the sheet material carrier and the feeding mechanism for the sheet material gripped by the gripper is always maintained in the best possible manner. can be maintained in a state of In other words, even if there is a time difference in the delivery operation, the state of contact between the gripper and the sheet material can be kept constant within the gripping range of the gripper, without causing gripping errors, gripping defects, or poor loop formation of the sheet material during gripping. It is possible to stabilize the gripping operation by holding the grip in place. Conversely, this also means that the grippable range is expanded compared to the conventional gripping range, and has the effect of improving the redundancy of the gripping motion.

[Brief explanation of the drawing]

FIG. 1 is a side view of essential parts showing an example in which an embodiment of the sheet material gripping device according to the present invention is applied to a color copying machine, and FIG. 2 is a flowchart of the gripping operation in the same embodiment. Explanation of symbols 1... Sheet material carrier 1a... Gripper (grip means) 3.3... Registration roller (feeding means) 7... Sensor (detection means) 8... Variable speed drive means 9 ...Drive source 10...
Control means 11... Encoder 11... Clock pulse generation means Fig. 2

Claims (1)

[Claims] A sheet material carrier that moves with a grip means that opens and closes at a predetermined position to grip or release the sheet material, a feeding means that feeds the sheet material to the gripping means, and a sheet material feeding means of the feeding means. a variable speed driving means for changing the feeding speed to a first speed faster than the moving speed of the sheet material carrier and a second speed slower than the first speed; and a sheet material fed by the feeding means. and a detection means for detecting a relative positional deviation with respect to the grip position of the sheet material carrier, and the feeding by the variable speed driving means after the sheet material contacts the grip means based on the detection result of the detection means. 1. A sheet material gripping device comprising: a control means for controlling a speed change time of the means.