JPH03239197A - Manuscript conveyor - Google Patents

Abstract

PURPOSE:To enhance reliability and to convey at a high speed by using a through region by rapidly stopping the drive of a stepper motor when a step-out due to disturbance is detected by step-out detection means, decelerating a conveying speed as compared with that before the step-out occurs, and redriving it in a self-starting frequency range. CONSTITUTION:If a step-out occurs, this step-out is rapidly detected by step-out detection means 40, and its detection signal is output of a CPU 31. The CPU 31 once stops driving of a stepper motor 39 if a step-out signal is input from the means 40, and rapidly restart the motor 40 within the self-starting frequency range by referring to a table of a slow curve slower than that before the step- out occurs. Thus, even if a load torque applied at the time of step-out is interrupted, a manuscript can be frequently conveyed, and even if the step-out again occurs, it is shifted to a jam process to be coped with it.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a document conveying device, and more particularly to a document conveying device using a stepper motor as a drive source.

(Prior Art) In recent years, in the information age, facsimile machines, copying machines, OCR (Optical Character R)
Furthermore, slip processing devices and the like have become widespread.

Such devices are equipped with a document conveyance device, and in particular, in a document conveyance device that conveys sheet-like documents, in order to improve the convenience of document cents, multiple sheets set on the document table are used. The machine is equipped with an automatic document feeder that separates and transports documents one by one. In this way, document conveying devices that sequentially convey multiple sheets of documents are applicable to devices that can convey documents continuously, such as copying machines, and those that are applicable to devices that can convey documents continuously, such as facsimile machines and general-purpose scanners. There are cases where the document must be conveyed at the same time as the reading. A DC motor can be used as a drive source for a document conveyance device that is used in devices that can convey documents continuously, but a DC motor can be used as a drive source for a document conveyance device that has to convey documents in a timely manner. A stepper motor is commonly used.

On the other hand, in recent years, there has been a demand for higher processing speeds of devices, and there has also been a demand for higher document transport speeds for document transport devices. Therefore, when using a stepper motor as a drive source and trying to increase the transport speed, it is necessary to use a through area outside the self-starting area, but this through area does not respond even if a sudden application is applied to that area. In order not to
You need to start up and use it gradually.

However, in the through range, if a torque above a certain level is applied to the motor, so-called step-out occurs, and the motor still tries to continue rotating, so it continues to generate noise until it stops.

Therefore, conventionally, as shown in FIG. 6, a document sensor is provided on the document conveyance path, and if the document sensor does not detect the document within a predetermined time, the motor is stopped. That is,
As shown in FIG. 6, in the conventional document conveying device 1, a plurality of documents are stacked on the document table 2, and the lowest document on the document table 2 is lifted by the half-moon roller 3. , the sheets are separated one by one by a separation roller 4 and a separation plate 5 and fed to conveyance rollers 6.7. The transport rollers 6.7 transport the original to the reading line, and the original whose image has been read at the reading line position is further transported to the ejection roller 8.
．． It is discharged by 9. In order to detect the conveyance state of these documents, document sensors 10, 11, and 12 are provided on the document table 2, between the conveyance roller 6.7 and the reading line, and on the downstream side of the discharge roller 8.9, respectively. . All of these rollers and rollers are driven by one stepper motor, and after only the half-moon roller 3 has rotated once, it is released from the stepper motor by an electromagnetic clutch. therefore,
In this document conveying device 1, as shown in FIG.
When the original sensor 10 detects the original on the original platen 2 and a pulse is applied to the stepper motor, the half-moon roller 3 and separation roller 4 transport the original on the original platen 2 to the transport rollers 6.7, and the original sensor 10 detects the original on the original platen 2. 11 detects a document, the stepper motor continues to be driven to convey the document to the discharge roller 8.9.

In such a document conveying device 1, when more than a specified number of documents are placed on the document table 2, the half-moon rollers 3 and the separation rollers 4
Friction that exceeds the standard is applied to the stepper motor, and the torque in the stepper motor's through range exceeds the specified value, causing an immediate step-out.

However, if this step-out occurs within the stepper motor's self-starting frequency range, it is a so-called tooth skipping phenomenon.
- The instantaneous operation will stop, but it will start operating immediately if the overload is removed. However, if this step-out occurs during use in the through region, the stepper motor will not rotate again even if the overload is removed, and will continue to make loud abnormal noises unless the pulse application is stopped. Therefore, the conventional document conveying device 1
In this case, as shown in FIG.
CPU (Central Processing)
Unit) 14, counter 15, decoding circuit 16, and motor driver 17. The output of each original sensor 10.11.12 is input to this CPU 14, and the signal from each original sensor 10.11.12 is input to this CPU 14. The drive of the stepper motor 13 is controlled by determining whether a document is jammed. That is, as shown in FIG. 7, if the document sensor 11 does not detect the document within a predetermined time after the document conveyance starts, it is determined that a jam has occurred, and the drive of the stepper motor 13 is stopped. .

Therefore, driving of the stepper motor 13 can be stopped even when the stepper motor 13 is out of step.

In FIG. 6, reference numeral 21 denotes a light source, and the light projected from the light source 21 is reflected by the document at the reading line position and is input to the photoelectric conversion section 23 via the mirror 22.

(Problem to be Solved by the Invention) However, in such conventional document conveying devices, a document sensor provided in the document conveyance path detects the conveyance state of the document and indirectly prevents jams in the stepper motor. As shown in Figure 7, the stepper motor was stopped for a predetermined period of time after the stepper motor lost synchronization until the document sensor detected the document. keeps making abnormal noises as it tries to rotate. As a result, noise continues to be generated for a predetermined period of time until the stepper motor is stopped, causing discomfort to the operator and other people nearby. In particular, in the document transport system, there are many causes that apply more than a certain amount of torque to the stepper motor, such as the operator pulling back or pulling the document, inserting more than the specified number of documents, or inserting a document with a thickness greater than the specified value. Measures to address the above issues are requested.

(Object of the Invention) Therefore, the invention according to claim 1 provides high-speed input using a stepper motor in a through range outside the self-starting frequency range,
When the out-of-step detection means detects out-of-step due to external disturbance, it immediately stops driving the stepper motor, lowers the conveyance speed than before the out-of-step occurs, and re-drives the motor within the self-starting frequency range. Even if a synchronization occurs, the system can be restarted quickly, eliminating the discomfort caused by noise, and ensuring a reliable restart to prevent synchronization that cannot be recovered by itself, thereby improving reliability. In addition, the invention as claimed in claim 2 aims to enable high-speed conveyance using the through area, and when a stepper motor is used in the through area outside the self-starting frequency area and a high-speed input is made, When the step-out detection means detects a step-out, it immediately stops driving the stepper motor, increases the acceleration time of the step-up curve of the stepper motor to a longer time than before the step-out occurs, and restarts the stepper motor within the self-starting frequency range. By doing so, even if a step-out occurs, it can be restarted quickly, eliminating the discomfort caused by noise, and reducing inertia by taking a longer time to accelerate the startup after the occurrence of a tax adjustment. The purpose is to improve reliability by enabling restart, and to maintain high-speed retransportation after recovery.

(Structure of the Invention) In order to achieve the above object, the invention of claim 1 uses a stepper motor as a drive source,
In a document conveying device that transmits the rotational force to a roller and conveys a sheet-like document using the roller, a step-out detection means for detecting step-out of the stepper motor is provided, and the stepper motor is rotated through a step outside the self-starting frequency range. When the out-of-step detection means detects a step-out due to external disturbance when high-speed input is performed in the frequency range, the drive of the stepper motor is immediately stopped, the conveyance speed is made slower than before the step-out occurs, and the self-start frequency range is set. The invention according to claim 2 is characterized in that the stepper motor is re-driven within the drive source,
In a document conveying device that transmits the rotational force to a roller and conveys a sheet-like document by the roller, a step-out detection means is provided to detect step-out of the stepper motor, and the stepper motor is controlled to operate at a speed outside the self-starting frequency range. When the out-of-step detection means detects a step-out due to a disturbance when high-speed input is performed in the area, the stepper motor drive is immediately stopped and the acceleration time of the stepper motor's slow-up curve is made longer than before the step-out occurred. It is characterized by re-driving within the self-starting frequency region.

Hereinafter, a detailed description will be given based on examples.

1 to 3 are diagrams showing an embodiment of the invention according to claims 1 and 2. FIG.

This embodiment is applied to a document conveying device similar to the document conveying device shown in FIG. 6, and will be described using the same reference numerals as used in FIG.

FIG. 1 is a block diagram of a control circuit 30 of the document conveying device, and the control circuit 30 includes a CPU (Central P
processing IJnit) 31, counter 32
, a decoding circuit 33, a motor driver 34, a current detection circuit 35, a sampling circuit 36, a steady waveform memory 37, a comparator 38, and the like.

The CPU 31 receives signals from the document sensors 10, 11, and 12, as well as signals from other detection sensors and operation units of the document transport device (not shown), and also receives signals from the comparator 38. A step-out signal Sd is input. The CPU has a stepper motor 39 in the internal memory.
It has a slow-up curve table, which includes a plurality of tables with different transport speeds and a plurality of tables with different acceleration times. Referring to this table, the CPU 31 controls each part of the document feeder based on the above-mentioned signals to control the drive of the document feeder, and also controls the control circuit 30 to control the stepper motor 39.
The drive control is performed. CPU 31 outputs a clock signal CLK to counter 32, and counter circuit 32 and decode circuit 33 set drive pulses to be output to stepper motor 39 based on this clock signal CLK.

The motor driver 34 outputs a drive pulse to the stepper motor 38 based on the signal from the decode circuit 33, and the stepper motor 39 is rotationally driven.

The current detection circuit 35 detects the current flowing to the stepper motor 39, and the sampling circuit 36 detects the current flowing to the stepper motor 39.
5. Sample the current waveform of the detected current.

A waveform signal from the sampling circuit 36 and a waveform signal from the steady waveform memory 37 are input to the comparator 38, and the comparator 38 compares both waveforms to detect the presence or absence of step-out. That is, when the stepper motor 39 goes out of step, the magnetic circuit is restricted, resulting in a current waveform that is different from the normal one. By detecting this difference in waveform with the comparator 38, the step out can be detected. . Therefore, the current detection circuit 35 and the sampling circuit 36
, the standing wave memory 37, and the comparator 38 collectively constitute a step-out detection means 40, and when the comparator 38 detects step-out, it outputs a step-out signal Sd to the CPU 31.

Next, the effect will be explained.

When an original is set on the original transport device and the start button is pressed, the CPU 31 drives the stepper motor 39 to start transporting the original. At the beginning of the conveyance of this document, as shown in Fig. 2, the self-starting frequency range is used.
Increase the speed by referring to the table of predetermined slow-up curves.

That is, as shown in FIG. 3, the stepper motor 39 has a self-starting region and a through region based on the relationship between the applied drive pulse and torque, and in the through region it does not respond even if suddenly applied. , it is necessary to gradually raise it from the self-starting area.

However, because more originals than the specified number are set on the original table 2, a load exceeding the specified value is applied to the stepper motor 3.
9, and if it is in the through region at this time, step-out will occur.

However, in the present invention, this step-out is quickly detected by the step-out detecting means 40, and the detection signal is output to the CPU 31. The CPU 31 receives the step-out signal Sd from the step-out detection means 4o.
When inputted, the drive of the temperer motor 39 is stopped, and as shown in FIG. Start restarting the stepper motor 40.

Therefore, even if the load torque applied at the time of synchronization continues for m, the document can often be conveyed, and even if synchronization occurs again, it is possible to proceed to jam handling. As a result, the document can be transported at high speed using the stepper motor 39 as a drive source, and step-out that cannot be self-recovered can be prevented, and reliability can be improved. Furthermore, since startup after automatic recovery from synchronization is performed within the self-starting frequency, fail-safe operation is effective and reliable conveyance can be performed.

FIG. 4 is a diagram showing an embodiment of the invention as claimed in claim 2, and this embodiment is applied to a document conveying device similar to that shown in FIG. However, the slow-up curve when restarting after losing synchronization has been changed.

In this embodiment as well, the stepper motor is driven in the self-starting region, and the speed is gradually increased to shift to the through region. However, if a step-out occurs in this through region,
As mentioned above, it becomes impossible to convey the document.

Therefore, in this embodiment as well, the step-out detection means 40 promptly detects the step-out and stops the stepper motor 39. Therefore, it is possible to prevent the stepper motor 39 from continuing to rotate unnecessarily, and it is possible to prevent abnormal noise from occurring. As a result, it is possible to prevent discomfort from being caused to the operator and other people nearby.

Further, when the stepper motor 39 is stopped, the drive of the stepper motor 39 is immediately resumed. At this time, the CPU
31, as shown in FIG. 4, the stepper motor 39 is driven by referring to a table of slow-up curves with a longer acceleration time than before the step-out occurred, and the stepper motor 39 is gradually increased to the normal speed. .

Therefore, inertia during acceleration is reduced, it is possible to prevent recurrence of step-out, and high-speed conveyance can be continued. Note that it is possible to shift from step-out to jam processing.

FIG. 5 is a diagram showing another embodiment of the step-out detection means. In the description of this embodiment, the same reference numerals are given to the same components as in FIG.

In FIG. 5, the control circuit 50 includes a CPU 31, a counter 32, a decoding circuit 33, a motor driver 34, a counter 51, etc., and a rotary encoder 52 is attached to one of the shafts driven by a stepper motor 39. ing. The output of the rotary encoder 52 and a clock signal of a predetermined frequency are input to the counter 51, and the counter 51 detects step-out when the output of the rotary encoder 52 does not change even after applying a predetermined number of pulses to the stepper motor 39. It is determined that this has occurred and the counter 51 is activated.
The overflow is output to the CPU 31 as a step-out signal Sd. Counter 51 and rotary encoder 5
2 constitutes an out-of-step detection means 53 as a whole.

Therefore, also in this embodiment, the stepper motor 39
The stepper motor 39 can be quickly detected, and the stepper motor 39 can be quickly dealt with.

In each of the above embodiments, explanations have mainly been given of cases in which step-out occurs during document feeding; however, the case is not limited to this. The same can be applied when a tax adjustment occurs.In this case, a multi-line buffer is used for matching during acceleration/deceleration to read in the through area, but the absolute position where the step is out can be detected. , as soon as a step-out is detected, the memory (for example, RAM
) to stop writing image data. Thereafter, the problem can be dealt with by restarting the stepper motor and restarting writing of image data to the memory. Also, if a step-out occurs while reading the original,
This can also be handled by resetting the document by a predetermined amount and then driving the stepper motor again to resume reading.

Therefore, the level difference in the read image before and after the synchronization step can be completely eliminated.

(Effect) According to the invention described in claim 1, when the stepper motor is used in a through range outside the self-starting frequency range to perform high-speed input, and the step-out detection means detects step-out due to disturbance, the stepper motor is driven. It is possible to quickly stop the transfer speed, lower the conveying speed than before the step-out occurs, and restart the drive within the self-starting frequency range, and even if step-out occurs, it can be restarted quickly. Therefore, it is possible to eliminate the discomfort caused by the noise, and to restart the device reliably. the result,
Step-out that cannot be self-recovered can be prevented, reliability can be improved, and high-speed conveyance can be performed using the through area.

According to the second aspect of the invention, when the stepper motor is used in a through region outside the self-starting frequency region and high-speed input is performed, when the step-out detecting means detects step-out due to disturbance, the stepper motor is immediately stopped driving. The stepper motor can be restarted within the self-starting frequency range by increasing the acceleration time of the stepper motor's slow-up curve compared to before the stepout occurred, so even if a stepout occurs, the stepper motor can be restarted immediately. It is possible to eliminate the discomfort caused by noise. In addition, by taking a longer time to accelerate the start-up after the step-out occurs, inertia can be reduced and restart can be performed reliably. As a result, reliability can be improved, and high speed re-transport after recovery from synchronization can be maintained.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the invention as claimed in claim 1, in which FIG. 1 is a control circuit diagram thereof, and FIG. 2 is a diagram showing the relationship between the applied pulse rate and torque of the stepper motor. The figure shown in FIG. 3 is a diagram showing the relationship between the elapsed time, rotational speed, and drive pulse of the stepper motor. FIG. 4 is a diagram showing the relationship between elapsed time, rotational speed, and drive pulse of the stepper motor according to an embodiment of the invention as claimed in claim 2. FIG. 5 is a control circuit diagram showing another example of the step-out detection means applied to each of the inventions of claims 1 and 2. FIGS. 6 to 8 are diagrams showing a conventional document conveying device,
FIG. 6 is a schematic diagram of the document conveying device, FIG. 7 is a diagram showing the relationship between elapsed time, rotational speed, and drive pulse of the stepper motor, and FIG. 8 is a control circuit diagram thereof. 50.30... Control circuit, 31... CPU, 32... Counter, 33... Decode circuit, 34... Motor driver, 35... Current detection circuit, 36... Sampling circuit, 37... Standing wave memory, 38... Comparator, 39... Stepper motor, 40.53...Out-of-step detection means, 50...
・Control circuit, 51...Counter,

Claims (2)

[Claims] (1) In a document conveyance device that uses a stepper motor as a drive source, transmits its rotational force to a roller, and conveys a sheet-like document by the roller, an out-of-step detection means for detecting out-of-step of the stepper motor is provided, and the stepper motor When the stepper motor is used in the through range outside the self-starting frequency range to input high-speed input, and the step-out detection means detects step-out due to disturbance, the stepper motor drive is immediately stopped and the conveyance speed is adjusted to the level before the step-out occurs. A document conveying device characterized in that it re-drives within a self-starting frequency range at a slower speed than the previous one. (2) In a document conveying device that uses a stepper motor as a drive source, transmits its rotational force to a roller, and conveys a sheet-like document by the roller, an out-of-step detection means for detecting out-of-step of the stepper motor is provided, and the stepper motor When the motor is used in the through range outside the self-starting frequency range to input high-speed input, and the step-out detection means detects step-out due to disturbance, it immediately stops driving the stepper motor and adjusts the slow-up curve of the stepper motor. A document conveying device characterized in that the acceleration time is made longer than before the step-out occurs, and the device is driven again within a self-starting frequency range.