JPH06312852A - Automatic document feeder - Google Patents

Abstract

PURPOSE:To perform accelerating control of a stepping motor in accordance with a physical quantity of making a change in a motor load of document size, recording mode, etc. CONSTITUTION:When document size information detected by a width sensor, length sensor, etc., is input (S100), a document size is judged for whether large or small (S101), to set an acceleration characteristic A for the large size (S102), and a time required for an operating frequency of a stepping motor to reach a stationary region is lengthened, to drive the motor (S104). An acceleration characteristic B is set for the small size (S103), and a time required for the operating frequency of the stepping motor to reach the stationary region is shortened, to drive the motor (S104). That is, in the case of the large size, by starting conveying a document at small acceleration, a step-out in a high load by the large size can be prevented. In the case of the small size, the document is conveyed at large acceleration from starting conveying the document, and a system speed is increased to enhance the productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder used in an image processing apparatus, and more particularly to an automatic document feeder which automatically performs optimum acceleration control when a roller for conveying a document is rotationally driven by a stepping motor. Document feeder

[0002]

2. Description of the Related Art In an automatic document feeder, as a driving source such as a roller for conveying a document, a pulse motor is used for registration control for stopping the document at a document reading position provided on a platen glass. There are many cases. However, in controlling the pulse motor, attention must be paid to the load and inertia. Among the pulse motors, the stepping motor causes a phenomenon of step-out and stops the machine when an excessive load is applied to the motor. Especially, in the acceleration stage where the motor starts to rotate, the above points must be carefully considered. Therefore, conventionally, acceleration control has been performed according to the maximum load that the machine can generate, that is, motor control with a long acceleration time.

[0003]

However, when a document is conveyed by an automatic document feeder of a type that feeds from below a document (document stack) stacked on the document table, the larger the document stack or the document size. Is larger, the generated load is larger. If the acceleration time is determined in accordance with the maximum weight of the original stack and the maximum size of the original, the medium and small size documents, such as A4 and B5 size documents, which are used most frequently are conveyed. Even if there is a margin in load compared to the original, the acceleration time will be longer.

Further, even if the original size is the same, the motor load changes depending on the recording mode. For example, in a double-sided original recording mode (hereinafter referred to as a double-sided mode), a large load is generated when the motor is switched from reverse rotation to forward rotation when reversing the front and back of the original. Therefore, if the motor acceleration control is performed according to the recording mode (hereinafter referred to as the single-sided mode) in which an image is read and recorded from only one side of the document,
The motor stops when reversing in double-sided mode.
Usually single-sided mode is used more frequently than double-sided mode,
When the acceleration control of the motor is performed in accordance with the double-sided mode in which the maximum load occurs, the motor is rotationally driven for an acceleration time longer than the acceleration time allowed by the motor characteristics, thereby reducing the productivity in the single-sided mode.

In this way, in controlling the stepping motor, if a long acceleration time is set in accordance with the maximum load,
The system speed of the entire apparatus decreases in a recording mode or document size that is frequently used under a load lower than the maximum load. As a countermeasure against this, a motor having a torque characteristic with a margin for the load may be used, but in this case, there is a problem that the motor becomes large and power consumption increases. SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic document feeder which controls acceleration of a stepping motor according to a physical quantity that changes a motor load such as a document size and a recording mode.

[0006]

In order to achieve the above object, the present invention as set forth in claim 1, is a platen glass for feeding out originals one by one from a bundle of originals stacked on a mounting table and reading the images of the originals. In an automatic document feeder including a document transporting unit for transporting the document on an upper side, a stepping motor as a driving source of the document transporting unit, a document size detecting unit for detecting the size of the document, and a document size detecting unit for detecting the size of the document. Motor control means for changing the acceleration characteristic of the stepping motor based on the document size signal and controlling the rotational acceleration according to the acceleration characteristic. According to a second aspect of the present invention, in an automatic document feeder including a document conveying unit for performing at least a single-sided original recording mode and a double-sided original recording mode, a stepping motor as a drive source of the document conveying unit is provided. A motor control means for controlling the stepping motor with at least two types of acceleration characteristics, the motor control means changing the acceleration characteristics according to the recording mode, and controlling the rotational acceleration by the acceleration characteristics. It is in the configuration. Further, the invention according to claim 3 is the configuration in which the motor control means changes the acceleration characteristic at the time of document reversal in the double-sided document recording mode.

[0007]

According to the above construction, the motor control means makes the acceleration of the stepping motor small when the document size is large or when the load is high in document transport such as a recording mode in which the document is transported by switching from reverse rotation to forward rotation. Control to prevent the motor from stepping out, and also when the document size is small or medium or when the document is transported without switching from reverse rotation to forward rotation, the motor is operated during light load that occurs during document transport. By controlling the stepping motor so that the acceleration of the stepping motor is increased, the document transport time is shortened and the productivity is improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main configuration of a double-sided automatic document feeder to which the control device of the present invention is applied. The double-sided automatic document feeder includes a document table 1 on which a plurality of documents (a bundle of documents) 2 are set by controlling a position in the width direction by a document guide 3.
The originals are fed one by one from under the original bundle set on the original placing table and stopped at the original reading position 10A on the platen glass 10, and after the reading is completed, the originals are ejected from the platen glass (not shown). ).

As a document size detecting means on the document table 1, the width sensor 4 for detecting the position of the document 2 in the width direction by the movement of the document guide 3 and the time when the document passes over the document table are determined. A sensor 5 for detecting the length of 2 is provided. That is, when detecting the length of a document on the mounting table, a plurality of sensors 5 are provided and the length is detected without being conveyed. Alternatively, in the case of carrying and detecting, the sensor 18 arranged on the upstream side of the pull-out roller 9 detects.

In the conveying path 15 extending from the original placing table 1 to the platen glass 10, a feeding roller 6, a feeding roller 7 and a separating roller 8, and a pair of pulling rollers 9, 9 are sequentially arranged from the upstream side of the original conveying. Has been done. The paper feed roller separates one original 2 from the plurality of originals fed by the intake roller 6 and conveys it to the pull-out roller 9. The conveyed original 2 hits the nip zone of the stopped draw-out roller 9, and after the skew is corrected, the draw-out roller 9 rotates at the document reading timing and is conveyed onto the platen glass 10.

Further, an original conveyed from the platen glass side is pulled out to the reverse conveying path 16 leading to the conveying path 15 on the platen glass loading side and on the upstream side of the pulling roller via the conveying path upstream of the pulling roller. A plurality of pairs of reversing rollers 13 and 14 for transporting to the rollers are arranged. In the single-sided mode, the original 2 conveyed from the original placing table 1 onto the platen glass 10 via the pull-out roller 9 is stopped at the original reading position on the platen glass 10 by the conveying belt 11 to read the original image. After being told,
By re-driving the conveyor belt 11, it is carried out from the side opposite to the carrying-in side to the platen glass, and is discharged to the document discharge tray by rotationally driving an exit roller (not shown).

In the double-sided mode, after the reading of the original on one side is completed, the conveyor belt roller 12 for driving the conveyor belt 11 is rotated in the reverse direction, and each reversing roller in the reversing conveying path 16 is rotated, and at the same time, the reverse conveying is performed. When the path gate 17 is opened, the document is conveyed from the trailing end of the document through the reverse conveyance path to the pull-out roller in the direction opposite to the discharge direction. After that, the conveyance belt is switched to the normal rotation drive, and the pull-out roller is kept in the normal rotation. Therefore, the reversed document is conveyed onto the platen glass and stopped at the document reading position to read the document image.

FIG. 2 is a block diagram of a drive system for controlling the motor according to the acceleration characteristic determined from the document size.
FIG. 3 is a flow chart showing the flow of motor control processing according to the document size. Width sensor 4 and length sensor 5
The signal detected by is input to the controller 20 and the document size is detected. On the other hand, the pull-out roller 9 is rotationally driven by a stepping motor 22 via a motor drive unit 21. At this time, the controller 20 changes and controls the time until the operating frequency of the stepping motor 22 reaches the steady region, that is, the acceleration characteristic, according to the detected document size.

An example of processing for changing the acceleration characteristic will be described with reference to the flowchart shown in FIG. In this example, two acceleration characteristics, that is, an acceleration characteristic A having a long acceleration time and an acceleration characteristic B having a short acceleration time are changed depending on the size of the document. When the document size information detected by the width sensor or the length sensor is input (S100), the size of the document is determined (S10).
1) In the case of a large size, the acceleration characteristic A is set (S10
2) Drive the motor by increasing the time required for the operating frequency of the stepping motor to reach the steady range (S).
104). That is, in the case of the large size, by starting the conveyance of the document with a small acceleration, it is possible to prevent the step-out which occurs due to the increase of the motor load due to the large size. On the other hand, if a small size is determined in S101, the acceleration characteristic B is set (S103), and the motor is driven by shortening the time required for the operating frequency of the stepping motor to reach the steady region (S104). That is, in the case of a small size, the document is conveyed at a high acceleration from the start of conveyance and the system speed is increased to improve the productivity.

FIG. 4 shows an example in which the document size is divided into two sizes, large and small, and the acceleration characteristics of the stepping motor are changed and controlled according to the large and small sizes. When the size of the original 2 is large, as shown by the acceleration characteristic A, the increase in the operating frequency at the time of startup is moderated and the acceleration is decreased.
At this time, the motor torque and the load torque change as indicated by characteristics C and D, respectively. As a result, step-out of the motor can be prevented. When the document size is small, the increase in the operating frequency at startup is increased as shown by the acceleration characteristic B, and the acceleration is increased within the range in which the motor does not step out. At this time, the motor torque and the load torque are characteristic E,
Indicated by F.

In the above embodiment, the case where the acceleration of the stepping motor is changed in two steps has been described, but it may be changed in multiple steps corresponding to each size of the original. Further, the case where the document size is detected by the width sensor and the length sensor provided on the document placing table has been described.
The original size may be detected by another method before the operation of the drawing roller.

Next, a case where the acceleration of the stepping motor is changed and controlled according to the recording mode will be described. FIG. 5 is a block diagram of a drive system that controls a motor according to the acceleration characteristic determined from the recording mode. In the present embodiment, the acceleration control of the motor in two types of recording modes, that is, a one-sided mode in which an original image is read from only one side of the original to perform recording and a two-sided mode in which the original image is read from both sides of the original to perform recording will be described. When the recording mode is set by the user interface UI for inputting settings such as various operations, the controller 20 changes and controls the acceleration characteristic of the stepping motor 22 according to the recording mode. A specific example of the process of changing the acceleration characteristic will be described. In this example, acceleration control is performed by using acceleration A in FIG. 4 when the load is high and acceleration B in FIG. 4 when the load is light.

(1) When selecting either acceleration A or B according to the single-sided or double-sided mode In FIG. 6, when the recording mode is input (S200), it is determined whether the mode is the double-sided mode (S201). In the double-sided mode, acceleration A is set (S202), and the motor is driven (S20).
4). On the other hand, if the one-sided mode is determined in S201, the acceleration B is set (S204) and the motor is driven (S20).
204).

(2) When the acceleration A is selected only when the double-sided mode is reversed In FIG. 7, when the recording mode is input (S30
0), it is determined whether or not it is the single-sided mode (S301),
In the single-sided mode, acceleration B is set (S302) and the motor is driven (S307). On the other hand, in S301, when the single-sided mode is not set, it is determined whether the double-sided mode is set (S
303), if not in any mode, the process ends. S
When the double-sided mode is determined in 303, it is determined whether or not the conveyance belt is being switched from reverse rotation to normal rotation (S304). The general process here is to switch to normal rotation after performing reverse rotation with a predetermined number of pulses.

If the document is laid on the platen glass or is driven in reverse when it is discharged from the platen glass, acceleration B is set (S306) and the motor is driven (S307). Further, if the document is driven in the normal direction to reversely convey the document from the platen glass to the carry-in side, the acceleration A
Is set (S305) and the motor is driven (S30
7). FIG. 8 shows the motor reverse rotation and the motor forward rotation in the double-sided mode. In FIG. 8, the relationship between the acceleration A and the acceleration B is as follows, where the time to reach the operating frequency in the steady region during motor reverse rotation is t1 and the time to reach the operating frequency in the steady region during motor forward rotation is t2, for example, t2 = 2
It is set to t1. In the above embodiment, the motor control is performed by changing the acceleration characteristic depending on the document size or the recording mode. However, the acceleration characteristic is selected in consideration of the document size and the recording mode, and the optimum motor control is performed. You can also

[0021]

As described above, according to the present invention, the acceleration of the stepping motor as the drive source of the document transporting means such as the pull-out roller, the reversing roller, and the transport belt is a document size which is a physical quantity for changing the motor load. Since the change is made according to the recording mode and / or the recording mode, a small stepping motor can be used to convey a medium-sized document or a document in the single-sided mode at a high speed to improve productivity. Step-out does not occur even when a large-sized document that causes a load is started to be conveyed or when the motor rotation direction is switched in the double-sided mode.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of an automatic document feeder according to the present invention.

FIG. 2 is a block diagram showing a configuration of a drive control system that performs acceleration control according to a document size.

FIG. 3 is a flowchart showing the flow of processing for changing the acceleration characteristic depending on the size of a document.

FIG. 4 is a diagram showing operating frequency and torque characteristics of a stepping motor depending on the size of a document.

FIG. 5 is a block diagram showing a configuration of a drive control system that performs acceleration control according to a recording mode.

FIG. 6 is a flowchart showing a flow of processing for changing an acceleration characteristic in a single-sided mode and a double-sided mode.

FIG. 7 is a flowchart showing the flow of processing for changing the acceleration characteristic when reversing a document in the double-sided mode.

FIG. 8 is a diagram showing an acceleration characteristic of a stepping motor when the acceleration characteristic is changed when reversing an original in the double-sided mode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original placing table, 2 ... Original, 4 ... Width sensor, 5 ... Length sensor, 7 ... Feed roller, 8 ... Separation roller, 9 ... Extraction roller, 10 ... Platen glass, 11 ... Conveyor belt, 12
... conveying belt rollers, 13, 14 ... reversing rollers, 20 ...
Controller, 21 ... Motor drive unit, 22 ... Stepping motor

Claims (3)

[Claims] 1. An automatic document feeder including a document feeder for feeding a document one by one from a bundle of documents stacked on a mounting table and transporting the document onto a platen glass for reading the document image. A stepping motor as a drive source, a document size detecting means for detecting the size of the document, and an acceleration characteristic of the stepping motor are changed based on a document size signal detected by the document size detecting means to change the acceleration characteristic. And a motor control means for controlling the rotational acceleration by the automatic document feeder. 2. An automatic document feeder including a document conveying means for performing at least a single-sided original recording mode and a double-sided original recording mode, wherein a stepping motor as a drive source of the original conveying means and the stepping motor are provided. An automatic document feeder, comprising: a motor control unit that controls at least two types of acceleration characteristics, wherein the motor control unit changes the acceleration characteristics according to a recording mode. 3. The automatic document feeder according to claim 2, wherein the motor control means changes the acceleration characteristic when reversing the document in the double-sided document recording mode.