JPS62167151A - Device for preventing document from slipping out of place - Google Patents

Abstract

PURPOSE:To adjust a pressing force of pressing means based on detected values, by providing comparison and adjustment means for detecting and comparing rotating speeds of a drive roller and a free rotating roller. CONSTITUTION:When there is a difference between a value from a drive roller rotating speed measuring unit 10 and a value from a free rotation roller rotating speed measuring unit 11, it is determined that a slip occurs while a transmitted document 1 is being transferred and then a signal for increasing a pressure to be applied to a free rotation roller 5 is applied to a pressurizing unit 9. On the contrary, when there is a difference between a value from a drive roller control unit 3 and a value from the drive roller rotating speed measuring unit 10, it is determined that since an excessive pressing force is applied to the free rotation roller 5 by the pressurizing unit 9, a drive roller 2 is difficult to rotate, and then a signal for decreasing a pressing force is applied to the pressurizing unit 9. The pressurizing unit 9 varies a pressing force applied to the free rotation roller 5 suitably based on these signals.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a document slippage prevention device that prevents a document from slipping in a document reading device such as a facsimile transmission device, an image input device, or a scanner.

2. Description of the Related Art Conventionally, in facsimiles and the like, a device for moving a transmitted document for reading has a drive roller that directly moves the document 1 and a drive roller 2, as shown in FIGS. 2(a) and 2(b). A drive roller control circuit 3 that controls the rotation speed, and a support plate 4 that presses the document 1 against the drive roller 2 (Fig. 3(a)
1) or a freely rotating roller 5 (in the case of FIG. 3(b)), and a pressurizing device 6 that applies a constant pressing force between the drive roller 2 and the support plate 4 or the freely rotating roller 5. death,
In order to move the document 1, the support plate 4 is moved by the pressure device 6.
Alternatively, the freely rotating roller 5 is pressed against the drive roller 2 with a constant force to prevent slippage between the drive roller 2 and the document l, and the drive roller 2 is pressed by a command from the drive roller control circuit 3.
The original was moved at a speed corresponding to the reading speed while the original was being sent, and at a constant speed during the rest of the original movement.

Problems to be Solved by the Invention However, according to this configuration, the paper quality of the document to be moved,
Depending on the smoothness of the surface, slipping may occur between the drive roller 2 and the document, which may prevent normal transmission, and may significantly limit the thickness of documents that can be transmitted. .

The above problem arises for the following reasons. That is, in the conventional structure, the pressure device 6 that presses the support plate 4 or the freely rotating roller 5 against the drive roller 2 always applies the same pressing force, and in this case, the pressure may vary depending on the paper quality or surface smoothness of the document. This is because even if the drive roller 2 rotates normally, the document may slip. If such slippage occurs, the document will be sent longer than the original length.

As a countermeasure to this problem, there is a method of increasing the pressing force of the pressure device 6 to increase the frictional force between the document and the drive roller 2, or increasing the diameter of the drive roller so that the force applied to the document is increased. One possibility is to increase the pressure.

However, this method has the disadvantage that a large load is applied to the drive roller 2 and a high-output motor is required for rotating the drive roller 2.

Furthermore, as mentioned above, if the pressing force from the pressure device 6 is kept constant, there is a problem in that the pressure is too large and wrinkles occur in the case of thin originals, while on the other hand, in the case of thick originals, The leading edge of the document cannot enter between the drive roller 2 and the support plate 4 or the freely rotating roller 5, and as a result, the thickness of the document that can be transmitted is severely limited.

The present invention has been made in view of the above-mentioned problems, and even if the paper quality and surface smoothness of the document to be read are extreme, or even if these factors change significantly during transmission, the document can be read easily. The document can be moved at a speed determined by the speed of the drive roller without slippage between the drive roller and the drive roller, and the document can be prevented from slipping by making it possible to sufficiently widen the allowable width of the document thickness. The purpose is to provide equipment.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention uses a drive roller that directly moves the document, and a freely rotating roller that presses the document against this drive roller, and this freely rotating roller has a , a pressure means capable of adjusting the pressing force for pressing the free rotation roller against the drive roller is connected, and a comparison adjustment means for detecting and comparing the rotational speeds of the drive roller and the free rotation roller is provided, and this comparison is performed. The pressing force of the pressurizing means is adjusted based on the value detected by the adjusting means.

With the above-described structure, the present invention constantly monitors the difference in rotational speed between the drive roller and the freely rotating roller when moving a document at a reading speed or at a constant speed, and if there is a speed difference between the two rollers. When this occurs, it is determined that the speed of the freely rotating roller that is driven through the document is slowed down due to slippage between the drive roller and the document, which slows down the moving speed of the document, and the pressure is applied to the pressure means. By increasing the pressing force of the freely rotating roller, slippage of the original can be minimized and the original can be moved reliably. At this time, if there is no speed difference between the two rollers, the pressing force of the freely rotating roller by the pressure means is reduced. As a result, the document does not always slip, but the document is moved with a relatively low pressing force, which makes it possible to keep the load required on the drive motor small, and also improves the paper quality and surface smoothness of the document. It is possible to prevent slippage between the document and the drive roller even if the factors are extreme, or even if these factors change during transmission, and furthermore, the allowable width of the document thickness is sufficiently widened. becomes possible.

EXAMPLES The present invention will be described in detail below. FIG. 1 shows a schematic configuration of a document slippage prevention device according to an embodiment of the present invention, in which ■ is a transmitted document, 2 is a drive roller that directly drives the transmitted document 1, and 3 is a drive roller that moves the drive roller 2 at a reading speed. Alternatively, a drive roller control circuit controls the rotation speed at a constant speed and outputs a signal regarding the rotation speed to a comparison circuit 8, which will be described later. 5 is a freely rotating roller that presses the transmission document 1 against the drive roller 2. . A pressure device 9 for pressing the free rotating roller 5 against the drive roller 2 is connected to the free rotating roller 5. This pressing device 9 is capable of adjusting the pressing force with which the freely rotating roller 5 is pressed against the drive roller 2, and the pressing force can be changed based on a signal from a comparison circuit 8, which will be described later. The pressurizing device 9 is not particularly limited, but may include, for example, a spring that presses a bearing that supports a freely rotating roller, and a support base that supports one end of the spring.
It consists of a screw shaft for moving the position of the support base, a drive motor for the screw shaft, etc., and the screw shaft is rotated by the drive motor to move the support base and change the pressing force of the spring. The drive roller 2 is provided with a drive roller rotation speed measuring device 10 that detects the rotation speed of the drive roller 2 and outputs it to the comparison circuit 8. On the other hand, the free rotation roller 5 is also provided with a drive roller rotation speed measurement device 10 that detects the rotation speed of the free rotation roller 5. A free rotating roller rotation speed measuring device 11 is provided which outputs the rotation speed to the comparison circuit 8.

The comparison circuit 8 compares the respective rotation speed signals output from the drive roller rotation speed measurement device 10 and the free rotation roller rotation speed measurement device 11, and depending on the difference, the pressure device 9
It also provides the necessary commands to the drive roller control circuit 3 and the rotation speed instruction signal from the drive roller rotation speed measuring device 10.
The rotational speed signals from the pressurizing device 9 are compared, and a necessary command is given to the pressurizing device 9 based on the difference. The comparison circuit 8, the drive roller rotation speed measuring device 10, and the free rotating roller rotation speed measuring device 11 collectively constitute a comparison adjustment means.

The operation of the document slippage prevention device configured as described above will be described below.

First, the transmission document 1 is transferred between the driving roller 2 and the freely rotating roller 5.
Before inserting it between
Set to the initial state. The initial state at this time is a state in which the freely rotating roller 5 is pressed against the drive roller 2 with a relatively low pressing force.

Next, the transmission document 1 is placed between the drive roller 2° and the freely rotating roller 5, and the drive roller control circuit 3 is operated to rotate the drive roller 2 to a desired reading speed (or a constant speed), and The roller control circuit 3 outputs a desired rotational speed to the comparison circuit 8. As the driving roller 2 rotates, the transmission document 1 moves, and the freely rotating roller 5 rotates in response to the movement.

At this time, the rotational speed of the drive roller 2 is measured by the drive roller rotational speed measuring device 10, and the result is output to the comparison circuit 8. Similarly, the rotation speed of the free rotation roller 5 is measured by the free rotation roller rotation speed measurement device 11, and the result is output to the comparison circuit 8.

The comparison circuit 8 compares the value of the desired rotation speed output from the drive roller control circuit 3 with the drive roller rotation speed measuring device 1.
Compare the value of the actual rotation speed of the drive roller 2 output from 0 and the value of the rotation speed of the free rotation roller 5 corresponding to the movement of the actual transmission document 1 output from the free rotation roller rotation speed measuring device 11. Drive roller rotation speed measuring device 1
If there is a difference between the value from 0 and the value from the free rotation roller rotation speed measurement device 11, it is determined that slipping has occurred during the movement of the transmission document 1, and the free rotation roller 5 is moved against the pressure device 9.
On the other hand, if there is a difference between the value from the drive roller control device 3 and the value from the drive roller rotation speed measuring device 10, the pressure device 9 outputs a signal to increase the pressure applied to the pressure device 9.
Since the pressing force applied to the freely rotating roller 5 is too high, it is determined that the driving roller 2 is difficult to rotate, and outputs a signal to the pressing device 9 to reduce the pressing force. The pressure device 9 changes the pressing force applied to the freely rotating roller 5 as appropriate based on these signals.

By performing such operations, it is possible to always maintain the pressure applied to the transmitted document 1 at a state just before slippage occurs, and the paper quality and surface smoothness of the transmitted document 1 are extremely higher than normal values. Even if the original 1 to be sent is separated, or even if these factors change significantly during transmission, the original 1 to be sent will not slip while moving, and even if the original is thick to some extent, the original 1 to be sent will not slip. This has the effect that it becomes possible to transmit the information, and also that the capacity of the drive motor for rotating the drive roller 2 can be reduced to the minimum necessary.

In the above embodiment, if there is a difference between the instruction signal from the drive roller control circuit 3 and the actual rotational speed measurement value of the drive roller, the comparison circuit 8 reduces the pressing force by the pressure device 9. However, instead of this, when the difference between the measured rotational speed of the drive roller and the measured rotational speed of the freely rotating roller becomes less than a predetermined value, the pressing force of the pressing device 9 is reduced. Good too. Further, in the above embodiment, the pressure device 9 was shown as being able to change the pressing force of the freely rotating roller 5 steplessly, but the pressing device 9 does not necessarily have to be able to change the pressing force steplessly. It may be possible to change the pressing force in stages, or it may be possible to simply change the pressing force in two stages, low and high.

When performing a two-step change in this way, when the difference between the rotational speed of the drive roller and the rotational speed of the freely rotating roller exceeds a predetermined value, the pressing force by the pressing device 9 is switched to high, and the difference is changed. When the value falls below a predetermined value, the pressure is switched to low, increasing the pressing force for slippery documents to prevent slipping, and reducing the amount of pressure needed by the drive motor by using a lower pressing force for documents that are less likely to slip. This makes it possible to keep the output output small.

Effects of the Invention As is clear from the above description, the present invention provides a drive roller that directly drives a document, a free rotation roller that presses the document against the drive roller, and a pressure means that presses the free rotation roller against the drive roller. and is further configured to detect the difference between the rotational speed of the drive roller and the rotational speed of the free rotation roller, and change the pressing force by the pressing means according to the difference. Normally, the document can be moved with a low pressing force, and if the pressing force is too low and slippage occurs between the document and the drive roller, and the rotation speed of the free-rotating roller becomes lower than the rotation speed of the drive roller. This can prevent slipping by increasing the pressing force using the pressing means. Therefore, in the normal case where no slipping occurs, the pressing force by the pressing means can be reduced, and the output of the drive roller driving motor can be kept low. In addition, it is possible to feed thin originals that are difficult to slip without causing wrinkles, and it is also possible to reliably insert thick originals between the drive roller and the freely rotating roller. Even if slipping occurs, by immediately increasing the pressing force, slipping between the document and the drive roller can be prevented and reliable movement can be achieved.

In this way, it is also possible to make the allowable range of document thickness sufficiently large.

[Brief explanation of drawings]

FIG. 1 is a side view showing a schematic structure of a document slipping prevention device according to an embodiment of the present invention, and FIG. 2 is a side view showing a schematic structure of a conventional document drive device. DESCRIPTION OF SYMBOLS 1... Document, 2... Drive roller, 3... Drive roller control circuit, 5... Free rotation roller, 8... Comparison circuit, 9... Pressure device, 10... Drive Roller rotational speed measuring device, 11... Name of agent for free rotating roller rotational speed measuring device Patent attorney Satoshi Nakao and 1 other person Already 2 Kneading roller 5- Confession speed ξ roller Fig. 1 9-ρro/ I cane de lθ-fast-acting roller masturbation 1 Borimata-cho N Self E 11 times I roller rotation yo tai tai Shinjo!

Claims (1)

[Claims] a drive roller that conveys a document; a freely rotating roller that presses the document against the drive roller; and a pressure means that can adjust the pressing force that presses the freely rotating roller against the drive roller;
Comparing and adjusting means for detecting and comparing the rotational speeds of the drive roller and the free rotating roller, and the pressing force of the pressing means is adjusted based on the detected value by the comparing and adjusting means. Features a document slip prevention device.