JP2524651B2 - Paper feeder - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding / conveying apparatus for performing sheet feeding / conveying management in, for example, a laser printer or a copying machine.

[Prior Art] For example, in a laser printer, after charging a photoconductor of a photoconductor drum at a charging unit, information is recorded on the photoconductor by a laser beam as an electrostatic latent image, and toner is recorded at the developing unit on the electrostatic latent image. It is designed to be attached. On the other hand, paper is sent from a paper feeding unit provided with a paper feed cassette, and the paper is conveyed to a transfer unit for transferring a toner image from a photosensitive drum via a conveyance path. The toner image is transferred from the body drum to a sheet. The paper after the transfer is fixed by a fixing device and then discharged.

A sheet feeding / conveying device used in such a laser printer is provided with a feed sensor in the middle of a conveying path, and a time period until a sensor detects a sheet sent from a sheet feeding section is a micro controller constituting a main body of the control section. The processor manages the time and the time from when the sensor detects the paper until when the paper is no longer detected is also managed by the microprocessor to detect a jam in the paper feed unit or the transport unit.

[Problems to be Solved by the Invention] However, in the case of relying on the time management by the microprocessor for the management of the paper feeding and the transportation state of the paper as described above, there is a problem that the software load of the microprocessor is increased accordingly.

Therefore, the present invention intends to provide a paper feeding / conveying device which can reduce the software load of the microprocessor in the management of the conveyance state of the paper and thus can use the one having low performance as the microprocessor. is there.

[Means for Solving the Problems] The present invention relates to a feed motor that controls the conveyance of a sheet sent from a paper feed unit to a conveyance path, a feed sensor that detects a sheet that passes a predetermined position of the conveyance path, and a feed motor. The clear signal is released by the ON signal of the feed sensor, the ON / OFF signal of the feed sensor is counted, the mode counter that outputs the count value as a mode value, the clock pulse generating means that generates the clock pulse, and the ON signal of the feed motor When the clear state is released by and the clock pulse from the clock pulse generating means is counted, and the count value is output as a step value, and when the step value from this step counter reaches a preset predetermined value The mode value from the mode counter of is judged and the paper is fed and conveyed normally. A determination means for determining whether or not there is is provided.

[Operation] In the present invention, the step counter starts counting when the feed motor is turned on to start feeding and conveying paper. When the sheet is conveyed and the sheet is detected by the feed sensor, the mode counter counts and changes the mode value output by the ON / OFF signal of the sensor.

Therefore, when the step value from the step counter reaches a predetermined value, the mode value from the mode counter should originally have changed, but if there is no change, it is determined that an abnormality has occurred in paper feeding and conveyance.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.
In this embodiment, the invention is applied to a laser printer.

As shown in FIG. 1, a photosensitive drum 12 whose surface is made of a photoconductive substance is arranged at a substantially central portion in the housing 11.
The photosensitive drum 12 is driven to rotate in one direction, that is, clockwise in the drawing by a feed motor 13 composed of a stepping motor, and the photosensitive drum 12 is surrounded by a photosensitive member according to an electrophotographic process. A charging unit 14 for charging the photosensitive member of the drum 12, a laser scanner unit 15 for irradiating a laser beam to the photosensitive member charged by the charging unit 14 to expose and record information to form an electrostatic latent image, From the developing unit 16 for adhering toner, which is a developer, to the electrostatic latent image formed on the body, the transfer unit 17 for transferring the toner image from the photosensitive drum 12 to the fed paper, and the transferred photosensitive drum 12 A cleaning device 18 for removing the residual toner and an erasing unit 19 for erasing the transferred photoconductor drum 12 are sequentially arranged.

A paper feed unit 20 is provided on one side of the housing 11, and the paper feed unit 20 includes a paper feed roller 22 and a paper feed roller 22 that can freely contact and separate from the upper surface of the paper 21 stored therein. A sheet feeding solenoid 23 for performing a contact / separation operation is provided.

The paper 21 is fed one by one from the paper feed unit 20 at a predetermined timing by the paper feed roller 22 being rotated by the paper feed solenoid 23 coming into contact with the paper 21 for a predetermined time, and the fed paper 21 is conveyed. The sheet is conveyed to the transfer section 17 via a conveyance path 24 provided with rollers (not shown). A feed sensor 25 is provided in the middle of the transport path 24.

The sheet 21 on which the toner image has been transferred from the photosensitive drum 12 in the transfer unit 17 is supplied to a heat fixing unit 26, and after being heat-fixed in the heat fixing unit 26, is discharged by the discharge roller 27 to the other side of the housing 11 The paper is discharged from the housing through a paper discharge port 28 provided in the printer.

FIG. 2 is a block diagram showing a circuit configuration. Reference numeral 31 denotes a microprocessor constituting a control unit main body, and 32 denotes an input / output port, which are connected by a bus line 33.

The input / output port 32 includes a feed solenoid driving circuit 34 for driving the feed solenoid 23, the feed motor
A motor drive circuit 35 for driving 13, a laser scanner unit 15, a high voltage power supply 36 for supplying a high voltage to the charging section 14 and the transfer section 17, a fixing heater 37 for the thermal fixing section 26, a start key and a number of prints setting. An operation unit 38 provided with keys and the like, a mode counter circuit 39, a step counter 40, and a sensor circuit 42 for controlling various sensors 41 including the feed sensor 25 are connected.

FIG. 3 shows the main configuration, and the mode counter circuit 39 comprises a mode counter 43, a one-shot timer 44 and a rising / falling detection circuit 45, and the sensor circuit 42.
Supplies a signal FSO for notifying whether the feed sensor 25 detects the passage of the paper 21 to the rising / falling detection circuit 45. The signal FSO is at a high level when the feed sensor 25 does not detect the sheet 21, and is inverted to a low level when the feed sensor 25 detects the sheet 21.

ON / OFF signal ST1 / STOP for feed motor from the I / O port 32 to the enable terminal EN of the motor drive circuit 35
And the ON / OFF signal ST1 / STOP for the feed motor is also supplied to the clear terminal (low active) CL of the mode counter 43 and the step counter 40.

The motor drive circuit 35 also functions as a clock pulse generation means, and supplies the stepping clock sck1 used for phase switching of the feed motor 13 as a clock pulse to the clock input terminal CK of the step counter 40.

The mode counter circuit 43 detects the rising and falling edges of the signal FSO from the sensor circuit 42 by the rising / falling detection circuit 4
The signal is detected at 5 and the detection signal is supplied to the one-shot timer 44. The one-shot timer circuit 44 converts the detection signal into a pulse signal MCK1 having a sufficient width and supplies it to the mode counter 43. This mode counter 43 outputs a pulse signal MC.
The number of K1 inputs is counted, and the count value is used as the mode value MD.
To the I / O port 32.

The microprocessor 31 constitutes a judgment means, and I / O
The step value SD is read via the port 32, and when the step value SD reaches the first predetermined value ER ₁ , the mode counter 4
Check whether the mode value from 3 has changed from "0" to "1", and if it has not changed, the paper feed section for paper 21
It is judged that some trouble has occurred in sending from 20 to the transport path 24, and a paper feed error occurs. If the mode value is changed from “0” to “1”, the paper 21 is fed from the paper feed section 20 to the transport path 24.
It is judged that the data has been sent normally.

Further, the microprocessor 31 has a step value SD of the second
When the predetermined value ER _{2 of} is reached, it is checked whether or not the mode value from the mode counter 43 has changed from “1” to “2”. It is judged that such a failure has occurred, and a transportation error occurs. If the mode value changes from "1" to "2", it is determined that the paper 21 has been conveyed normally.

It should be noted that the first predetermined value ER ₁ is set to the count value of the step counter 40 while the paper 21 is normally fed and conveyed, and the second predetermined value ER ₁ is set. The value ER ₂ is set to the count value of the step counter 40 when the paper 21 has been sufficiently conveyed and has passed the feed sensor 25.

In the present embodiment having such a configuration, before starting printing, the feed motor on / off signal ST1 / STOP from the I / O port 32 is off and at a low level, so that the mode counter 43 and the The step counter 40 is in the clear state. Therefore, the count value of the mode counter 42 is "0", that is, the mode value MD supplied to the I / O port 32.
Is "0".

When the start key is operated to start printing in this state, the microprocessor 31 sends the feed motor on / off signal ST1 / STOP through the I / O port 32 as shown in FIG. Use a high-level on signal. As a result, the clear states of the mode counter 43 and the step counter 40 are released, and the motor drive circuit 35 rotates the feed motor 13.

At this time, the motor driving circuit 35 generates a stepping clock sck1 as shown in FIG. 4 (b) and supplies it to the step counter 40. In this way, the step counter 40 starts the counting operation as shown in FIG. 4 (c) and supplies the count value to the I / O port 32 as the step value SD.

Further, the photosensitive drum 12, the transport roller, the paper feed roller 22 and the like are rotated. Furthermore, laser scanner unit 15
The polygon motor of is also started.

Subsequently, the microprocessor 31 controls the paper feeding solenoid drive circuit 34 via the I / O port 32 to operate the paper feeding solenoid 23 for a predetermined time. As a result, the paper feed roller 22 is sucked for a certain period of time and comes into contact with the upper surface of the paper 21. In this way, the paper 21 is sent out from the paper supply unit 20 to the single-sheet transport path 24.

When the paper 21 passing through the transport path 24 is detected by the feed sensor 25, as shown in FIG.
The signal FSO from 42 falls from high level to low level. The fall of the signal FSO is detected by the rise / fall detection circuit 45. Then, the detection signal is supplied from the rising / falling detection circuit 45 to the one-shot timer 44, which is converted into a pulse signal MCK1 having a sufficient width as shown in (e) of FIG. 4 and supplied to the mode counter 43. To be done.
As a result, the mode counter 43 counts up by 1 and outputs the mode value "1" as shown in (f) of FIG.

After that, when the paper 21 passes the feed sensor 25, the signal FSO from the sensor circuit 42 rises from the low level to the high level as shown in FIG. 4 (d). The rising edge of this signal FSO is detected by the rising edge falling edge detection circuit 45. The detection signal from the rising / falling detection circuit 45 is the one-shot timer.
The pulse signal MCK1 is supplied to the one-shot timer 44 and converted into a pulse signal MCK1 having a sufficient width by the one-shot timer 44 as shown in FIG. As a result, the mode counter 43 counts up by 1 and outputs the mode value "2" as shown in (f) of FIG.

The paper 21 that has passed through the feed sensor 25 is then transferred to the transfer unit 17.
After being transferred and thermally fixed by the heat fixing unit 26, the sheet is discharged from the paper discharge port 28 to the outside of the housing by the discharge roller 27.

Then, when the feed motor on / off signal ST1 / STOP from the I / O port 32 is turned off, that is, when it becomes a low level as shown in FIG. 4 (a), the operation of the feed motor 13 is stopped and the feed motor 13 shown in FIG. As shown in (b), the generation of the stepping clock sck1 is stopped. Also, the mode counter 43 and the step counter 40 are cleared, and the mode counter 43
The mode value of is 0.

Therefore, if the microprocessor 31 reads the mode value MD from the mode counter 43 when the step value SD from the step counter 40 reaches the first predetermined value ER ₁ , the current paper 21 is fed and conveyed without abnormality. You can easily know whether or not. Further, if the mode value MD from the mode counter 43 when the step value SD from the step counter 40 becomes the second predetermined value ER ₂ is read, it can be easily known whether or not the paper 21 is conveyed without any abnormality thereafter. be able to.

That is, as shown in FIG. 5, the microprocessor 31 continuously feeds paper when the mode value MD is "0",
That is, it is determined whether the feed motor on / off signal ST1 / STOP is an on signal or an off signal, and if it is an off signal, the operating state (A), that is, the state in which the sheet is not conveyed at all is determined.

If the feed motor ON / OFF signal ST1 / STOP is an ON signal, the operating state (B), that is, the paper feed roller 22, the transport roller, and the polygon motor in the laser scanner unit 15 are started to start feeding. Judge that it is in a state to be performed. And in this state the step counter 40
Wait until the step value SD of reaches the _first predetermined value ER ₁ ,
When the step value SD reaches the first predetermined value ER ₁ , the mode value MD at that time is read. As a result, if the mode value MD is "1", it is determined that the paper feeding is normally performed. However, if the mode value MD remains "0", it is determined that some abnormality has occurred in the sheet feeding, and a sheet feeding error occurs.

When the mode value MD is "1", the operating state (C),
That is, it is determined whether the feed sensor 25 detects that the paper 21 is passing and the paper conveyance control is continued. Then, in this state, the step counter 40 waits until the step value SD reaches the _second predetermined value ER ₂ , and the step value SD becomes the second value.
When the predetermined value ER _{2 of} is reached, the mode value MD at that time is read. As a result, if the mode value MD is “2”, it is determined that the conveyance is normally performed. However, if the mode value MD remains “1”, it is determined that some abnormality has occurred in the conveyance of the paper 21, and a conveyance error is generated.

Further, when the mode value MD is "2", it is determined that the operation state (D), that is, the sheet 21 has passed the feed sensor 25 and the conveyance control will be ended soon.

In this way, the microprocessor 31 simply reads the step value SD of the step counter 40 and the mode value MD of the mode counter 43 via the I / O port 32, and outputs the step value SD.
If the mode value MD remains “0” when the value reaches the _first predetermined value ER ₁ , an error is judged by determining a paper feed abnormality, and when the step value SD reaches the second predetermined value ER _2. If the mode value MD remains "1", it is judged that there is an error in the paper transport and an error has occurred.
It is not necessary to operate the internal timer by software to manage the time while detecting 21 transports. Therefore, the software load on the microprocessor 31 can be reduced.

Therefore, even if the paper transport speed increases for high-speed printing, the microprocessor 31 can sufficiently cope with it,
Even if the microprocessor is switched from the 8-bit type to the 4-bit type, it can be controlled sufficiently. That is, it is possible to use a microprocessor having a low performance as the microprocessor.

In the above-described embodiment, the motor pulse driving circuit is also used as the clock pulse generating means. However, the invention is not limited to this, and the clock pulse generating means may be separately provided.

In addition, although each of the above-described embodiments has been described as one in which the present invention is applied to the laser printer, it is needless to say that the invention is not necessarily limited to this.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to reduce the software load of the microprocessor in the management of the sheet conveyance state, and therefore it is possible to use a microprocessor with low performance. It is possible to provide a sheet feeding and conveying device.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a laser printer, FIG. 2 is an overall block diagram, and FIG.
FIG. 4 is a block diagram of a main part, FIG. 4 is a timing diagram showing operation timing of each part in FIG. 3, and FIG. 5 is a flow chart showing a state determination process at the time of sheet conveyance by the microprocessor. 13 …… Feed motor, 21 …… Paper, 25 …… Feed sensor, 31 …… Microprocessor, 35 …… Motor drive circuit, 40 …… Step counter, 43 …… Mode counter.

Claims (1)

(57) [Claims] 1. A feed motor for controlling the conveyance of a sheet sent from a sheet feeding section to a conveyance path, a feed sensor for detecting a sheet passing through a predetermined position of the conveyance path, and a clear state by an ON signal of the feed motor. Is released to count the ON / OFF signals of the feed sensor and output the count value as a mode value, a clock pulse generating means for generating a clock pulse, and a clear state by the ON signal of the feed motor. A step counter which is released and counts clock pulses from the clock pulse generating means, and outputs the count value as a step value, and the mode when the step value from the step counter reaches a preset predetermined value. The mode value from the counter is judged and the paper is fed correctly. Sheet transportation device characterized by a provided determination means for determining whether or not.