JPH04193563A - Sheet feeder - Google Patents

Abstract

PURPOSE:To extremely accurately decide a sheet feeding amount by rotating a reference roller formed of a hard material having small dimensional change to a temperature at a circumferential speed coincident with the speed of a sheet, detecting a rotary angle by a rotary sensor, and controlling the operation of a motor. CONSTITUTION:A reference roller 7 is formed of a hard material having small dimensional change to a temperature. Thus, deformation of the roller 7 is prevented, and change in an outer diameter can be suppressed to a small allowable range. The roller 7 is rotated at a circumferential speed coincident with the speed of a sheet 5 to be conveyed to a sheet feed roller 1. Accordingly, the rotary angle of the roller 7 is detected by a rotary sensor 11, the detected result is fed back to a controller 14 to control the operation of a motor 3, and hence a sheet feeding amount can be extremely accurately determined. Further, since the roller 7 performs an object having a length opposed to part of the roller 1 in an axial direction, the entire length is shortened to be inexpensively manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a paper feeding device used in printing equipment and the like.

In conventional printing devices, the amount of paper feed must be accurately determined in order to accurately determine the printing position on the paper. Conventionally, the rotation angle of the paper feed roller is determined by managing pulses input to a step motor to which the paper feed roller is connected, or a rotary sensor is provided on the rotating shaft of the motor to which the paper feed roller is connected. A method is adopted in which the motor is driven based on the pulses output from the rotary sensor.

Problems to be Solved by the Invention In the conventional method, it is possible to determine the rotation angle of the paper feed roller, but the outer diameter of the paper feed roller varies due to manufacturing errors, temperature changes, changes over time, etc., and as a result, It is difficult to keep the peripheral speed of the paper feed roller constant, that is, the amount of paper feed. Especially when the outer periphery of the paper feed roller is formed of an elastic material such as rubber, variations in the outer diameter cause deviations in the amount of paper feed. Therefore, it is difficult to accurately determine the printing position. In order to solve this problem, reducing the tolerance of the outer diameter of the paper feed roller makes manufacturing difficult, and making the paper feed roller from a rigid material that is less susceptible to changes in temperature and over time. The cost increases because the paper feed roller needs to be longer than the width of the paper.

Means for Solving the Problems: A motor driver that drives a motor to which a paper feed roller is connected, and a rotatable motor that is made of a hard material that has no dimensional change due to temperature and is pressed against a portion of the paper being conveyed. The controller includes a reference roller, a rotary sensor connected to the reference roller, and a controller whose input side is connected to the rotary sensor and whose output side is connected to the motor driver.

The working reference roller is made of a hard material that exhibits small dimensional changes due to temperature, which prevents deformation of the reference roller and suppresses changes in outer diameter within a small tolerance range. The rotation angle of the reference roller is detected by a rotary sensor, and the inspection results are fed back to the controller to control the motor operation. It becomes possible to determine the amount of paper feed by the feed roller very accurately, and furthermore, as long as the reference roller has a length that makes contact with a portion of the paper, the purpose is achieved, and therefore it becomes possible to manufacture it at a low cost.

Example An embodiment of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 1 denotes a paper feed roller, and a fixed gear 2 and a gear 4 directly connected to a motor 3 are engaged with an end of the paper feed roller 1. Also, a plurality of paper press rollers 6 and a reference roller 7 press the paper 5 against the paper feed roller l.
is rotatably supported by a roller arm (not shown) which is biased towards the paper feed roller 1 and is displaceably provided. Here, the reference roller 7 is made of a hard material, such as aluminum or brass, whose dimensions change little with respect to temperature, and its surface is processed to increase the frictional force against the paper 5. In this embodiment, aluminum is used, and a predetermined frictional force against the paper 5 is maintained by means such as spraying tungsten carbide on its surface. Furthermore, a slit disk 9 is fixed to a shaft 8 that rotates integrally with the reference roller 7.
A rotary sensor 11 is provided which includes a transmission type photosensor 10 that detects a large number of slits formed on the outer periphery of the slit disk 9.

Next, FIG. 3 shows the electronic circuit. ROM12 where programs are written and RAM1 where print data is stored
3 and the controller 14 are connected to the CPU 15. The output side of this controller 14 is connected to the motor 3.
A motor driver 16 connected to the photo sensor 1 and a head driver 17 connected to a print head (not shown) are connected to the input side of the controller 14.
A rotary sensor/trigger circuit 18 to which 0 is connected is connected.

In such a configuration, the operation from the state in which the paper 5 is fed between the paper feed roller 1, the paper press roller 6, and the reference roller 7 will be described with reference to the flowchart shown in FIG. First, a moving amount A of the paper 5 is set according to the size of the paper 5, and an increment counter n is set to 0 (zero). Subsequently, since the motor 3 is driven by the motor driver 16, the paper feed roller 6 rotates, and the paper 5 is conveyed. At this time, the reference roller 7 rotates along with the slit disk 9 due to the frictional force with the transported paper 5, and the photosensor 10 detects a number of pulses corresponding to the rotation angle of the reference roller 7.

Each time this pulse is output, an increment counter n is added, and the paper feed roller 1 is driven by the motor 3 until the added count matches the movement amount A, and when the added count matches the movement amount A, the motor 3 is stopped.

Here, since the reference roller 7 is formed of a hard material whose dimensional change with respect to temperature is small, deformation of the reference roller rough can be prevented and changes in the outer diameter can be suppressed within a small tolerance range. Further, since this reference roller 7 rotates at a circumferential speed that matches the speed of the paper 5 conveyed by the paper feed roller l, the rotation angle of the reference roller 7 is detected by the rotary sensor 11, and the inspection result is sent to the controller 1.
Since the operation of the motor 3 can be controlled by feeding back to the motor 4, the paper feed amount can be determined extremely accurately. Furthermore, since the purpose of the reference roller 7 is achieved if it has a length that opposes a part of the paper feed roller 1 in the axial direction, the overall length can be shortened and manufactured at low cost. In addition,
The same objective can be achieved even if the paper 5 is brought into pressure contact with a conveyance body other than the paper feed roller 1 in the conveyance path of the paper 5 by the reference roller 7.

Effects of the Invention As described above, the present invention includes a motor driver that drives a motor to which a paper feed roller is connected, and a rotating motor that is made of a hard material whose dimensions change little with respect to temperature and is pressed against a portion of the paper being conveyed. Since it is composed of a freely movable reference roller, a rotary sensor connected to this reference roller, and a controller whose input side is connected to this rotary sensor and whose output side is connected to the motor driver, the dimensional change of the reference roller with respect to temperature is small. Since it is made of hard material, it is possible to prevent deformation of the reference roller and to suppress changes in the outer diameter within a small tolerance range, and this reference roller matches the speed of the paper being conveyed to the paper feed roller. Since it rotates at a circumferential speed, the rotation angle of the reference roller can be detected by a rotary sensor, and the inspection results can be fed back to the controller to control the motor operation, making it possible to determine the paper feed amount extremely accurately. Furthermore, since the purpose is achieved as long as the reference roller has a length that makes contact with a portion of the paper, the overall length of the reference roller can be shortened and it can be manufactured at low cost.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a front view, FIG. 2 is a side view, FIG. 3 is an electronic circuit diagram, and FIG. 4 is a flow chart. 1...Paper feed roller, 3...Motor, 5...Paper, 7...Reference roller, lO...Rotary sensor,
14... Controller

Claims (1)

[Claims] A motor driver that drives a motor to which a paper feed roller is connected; a rotatable reference roller made of a hard material whose dimensions change little with temperature; and which presses against a portion of the paper being conveyed; and a motor driver connected to this reference roller. A paper feeding device comprising: a rotary sensor, and a controller having an input side connected to the rotary sensor and an output side connected to the motor driver.