JP2619974B2 - Conveyance paper size detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a size detecting device for detecting the size of a transport sheet in a laser printer, a copying machine, or the like.

[Prior art] For example, a laser printer charges a photoreceptor of a photoreceptor drum with a charging unit, records information as an electrostatic latent image on the photoreceptor by a laser beam, and attaches toner to the electrostatic latent image in a developing unit. It is made to let. 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.

In such a laser printer, the size of the sheet to be conveyed is detected and notified to the operator. For this reason, conventionally, a feed sensor is provided in the middle of the conveyance path, and a microprocessor provided in the control unit main body is provided with a timer to manage the time required for the paper sent from the paper feeding unit to pass through the feed sensor. The paper size is determined from the relationship with the transport speed.

[Problems to be Solved by the Invention] However, if the microprocessor manages the determination of the sheet size by counting the time with a timer, there is a problem that the software load on the microprocessor becomes large.

Accordingly, the present invention provides a method for detecting the size of a transport paper in which the size of a transport paper is determined by a microprocessor can reduce the load on the software of the microprocessor, and therefore, a low-performance microprocessor can be used. It is intended to provide a device.

Means for Solving the Problems The present invention relates to a feed motor for controlling conveyance of a sheet on a conveyance path, a feed sensor for detecting a sheet passing a predetermined position on the conveyance path, and a clock pulse generating means for generating a clock pulse. The clear state is released by the feed signal of the feed motor, the clock pulse from the clock pulse generating means is counted in response to the sheet detection signal from the feed sensor, and the clock is counted in response to the sheet non-detection signal from the feed sensor. A counter for stopping pulse counting, and switching from a paper non-detection signal from a feed sensor at the start of paper detection to a paper detection signal and switching from a paper detection signal from a feed sensor at the end of paper detection to a paper non-detection signal Mode switching means for sequentially switching operation modes in accordance with the operation mode, and an operation mode by the mode switching means. The microprocessor is provided with a microprocessor for monitoring the load mode and judging the size of the conveyed sheet based on the count value of the counter when judging that the operation mode is the mode after the end of the sheet detection.

[Operation] In the present invention, the counter starts counting clock pulses when a sheet conveyed through the conveyance path is detected by the feed sensor, and the counter stops counting clock pulses when the sheet passes through the feed sensor. At this time, the mode of the mode switching means is sequentially switched as the feed sensor starts and ends the sheet detection. Then, when the mode is changed to the mode after the end of the sheet detection, the microprocessor reads the count value of the counter and determines the sheet size.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In this embodiment, an embodiment in which the present invention is applied to a laser printer will be described.

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. A charging unit 14 for charging the photoconductor 12; a laser scanner unit 15 for irradiating a laser beam to the photoconductor charged by the charging unit 14 to expose and record information to form an electrostatic latent image; A developing unit 16 for attaching a toner as a developer to the formed electrostatic latent image; a transfer unit 17 for transferring a toner image from the photosensitive drum 12 to a sheet to be fed; a transferred photosensitive drum
A cleaning device 18 for removing the residual toner from the photosensitive drum 12 and a charge removing unit 19 for removing charge from the transferred photosensitive drum 12 are arranged in this order.

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
Motor drive circuit 35 for driving the laser scanner unit 15, the charging unit 14, a high-voltage power supply 36 for supplying a high voltage to the transfer unit 17, a fixing heater 37 of the heat fixing unit 26, a start key and a setting for the number of printed sheets. An operation unit 38 provided with keys and the like, a mode counter circuit 39 as mode switching means, a step counter 40, and a sensor circuit 42 for controlling various sensors 41 including the feed sensor 25 are connected to each other.

FIG. 3 shows the configuration of the main part. The mode counter circuit 39 includes a mode counter 43, a one-shot timer 44, and a rise / fall detection circuit 45. The feed sensor 25 passes from the sensor circuit 42 through the paper 21. A signal FSO indicating whether or not the inside is detected is supplied to the rising / falling detection circuit 45 and also to the enable terminal EN of the step counter 40. 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.

A feed motor on / off signal ST1 / STO from the I / O port 32 to an enable terminal EN1 of the motor drive circuit 35.
In addition to supplying P, the feed motor on / off signal ST1 / STOP is also supplied to a clear terminal (low active) CL of the mode counter 43 and the step counter 40.

The motor drive circuit 35 also serves as a clock pulse generating means, and supplies a stepping clock SCK1 used for phase switching of the feed motor 13 to the clock input terminal CK of the step counter 40 as a clock pulse.

The mode counter circuit 43 detects the rise and fall of the signal FSO from the sensor circuit 42 as a rise / fall 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 the pulse signal MCK1 to the mode counter 43. This mode counter 43 outputs a pulse signal MC.
Counts the number of K1 inputs, and counts the count value as the mode value MD.
To the I / O port 32.

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 sets the feed motor on / off signal ST1 / STOP to a high level on signal via the I / O port 32. Thereby, the clear state of the mode counter 43 and the step counter 40 is released, and
The motor drive circuit 35 drives the feed motor 13 to rotate.

In this way, the photosensitive drum 12, the transport roller, and the paper feed roller 22
Etc. start to rotate. Also laser scanner unit
15 polygon motors are also activated.

Subsequently, the microprocessor 31 controls the sheet feeding solenoid drive circuit 34 via the I / O port 32 to operate the sheet feeding solenoid 23 for a certain 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, the signal FSO from the sensor circuit 42 falls from a high level to a low level. The falling of the signal FSO is detected by the rising / falling detection circuit 45. The detection signal from the rise / fall detection circuit 45 is a one-shot timer
The pulse signal MCK1 is supplied to the one-shot timer 44, and is converted into a pulse signal MCK1 having a sufficient width by the one-shot timer 44 and supplied to the mode counter 43. As a result, the mode counter 43 counts up by one and outputs the mode value “1”.

When the signal FOS falls from a high level to a low level, the step counter 40 is enabled and counts the stepping clock SCK1 output from the motor drive circuit 35. Then, the step counter 40 supplies the count value to the I / O port 32 as a step value SD.

Thereafter, when the sheet 21 passes through the feed sensor 25, the signal FSO from the sensor circuit 42 rises from a low level to a high level. The rise of this signal FSO is detected by the rise / fall detection circuit 4.
Detected at 5. A detection signal is supplied from the rise / fall detection circuit 45 to the one-shot timer 44, which converts the signal into a pulse signal MCK1 having a sufficient width and supplies the pulse signal MCK1 to the mode counter 43. As a result, the mode counter 43 counts up by one and outputs the mode value “2”.

When the signal FSO rises from a low level to a high level, the enable state of the step counter 40 is released, and the step counter 40 stops counting the stepping clock SCK1.

Thus, the step value SD output from the step counter 40 to the I / O port 32 is fixed.

Thus, the microprocessor 31 only has to read the step value SD from the step counter 40 when the mode value MD from the mode counter 43 is "2". And its step value
By comparing the SD with a numerical range corresponding to a preset paper size, it is possible to determine the size of the transport paper.

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.

When the feed motor on / off signal ST1 / STOP from the I / O port 32 is turned off, that is, when the feed motor on / off signal goes low, the operation of the feed motor 13 is stopped, and the mode counter 43 and the step counter 40 are cleared. Becomes “0”.

FIG. 4 shows the above operation in a timing chart.

Therefore, by reading the mode value MD from the mode counter 43 via the I / O port 32, the microprocessor 31 can easily know what transport state the paper 21 is currently in. When the mode value MD from the mode counter 43 is “2”, the step value SD from the step counter 40 is
By reading, the paper size can be determined.

That is, as shown in FIG. 5, if the mode value MD is "0", the microprocessor 31 determines whether or not the paper feeding is to be continuously started. If the paper feeding is started, the microprocessor 31 operates (A). That is, it is determined that the paper feed roller 22, the transport roller, and the polygon motor in the laser scanner unit 15 have started to be started and the paper is being fed. If the sheet feeding is not started, the operation state (D), that is, the state in which the sheet is not conveyed at all, is determined.

If the mode value MD is "1", the operation state (B), that is, the state in which the feed sensor 25 detects that the sheet 21 is passing and the sheet conveyance control is being executed is determined.

If the mode value MD is "2", it is determined that the operation state (C), that is, the state where the paper 21 has passed the feed sensor 25 and the step value SD of the step counter 40 has been read.

When the step value SD is read, it is checked whether the step value is in the range of the sheet 1, the range of the sheet 2,... If there is a corresponding range, the paper size corresponding to the range is determined.

If it does not fall within any of the ranges, an error is detected as a paper size detection failure.

As described above, the microprocessor 31 simply reads the mode value MD of the mode counter 43 via the I / O port 32, and reads the step value SD from the step counter 40 when the mode value MD is "2". Since the size of the sheet 21 can be determined, there is no need to operate the internal timer by software to manage the time while the feed sensor 25 detects the conveyance of the sheet 21 unlike the related art. 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, the control can be sufficiently performed. That is, it is possible to use a microprocessor having a low performance as the microprocessor.

Even if the counter is provided separately from the microprocessor, the microprocessor can easily know the count status of the counter only by monitoring the operation mode, and can determine the sheet size at an accurate timing. Thereby, the load on the software of the microprocessor can be further reduced.

Next, another embodiment of the present invention will be described with reference to the drawings.
The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

This is the clock generator as shown in FIGS. 6 and 7.
46, and a clock CK1 from the clock generator 46 is supplied to a clock counter 40 'having the same configuration as the step counter 40.
To be counted. That is, in the above-described embodiment, the clock generator is shared by the motor drive circuit 35, whereas in the present embodiment, the clock generator is independently provided.

The count value of the clock counter 40 'is supplied to the I / O port 32 as a clock value CD.

Also in the present embodiment, the clock counter 40 'is provided with the clock generator 46 while the feed sensor 25 is detecting the paper 21.
And the clock value CD is supplied to the I / O port 32. When the paper 21 passes through the feed sensor 25 and the mode value MD becomes "2", the microprocessor 31
Since the paper size is determined based on the clock value CD, the same effect as in the above embodiment can be obtained.

In each of the embodiments described above, the present invention is applied to a laser printer, but it is needless to say that the present invention is not necessarily limited to this.

[Effects of the Invention] As described above in detail, according to the present invention, in determining the size of a transport paper by a microprocessor, the load on the software of the microprocessor can be reduced, and therefore, the performance of the microprocessor is low. It is possible to provide an apparatus for detecting the size of a transported paper that can also use the size.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a laser printer, FIG. 2 is an overall block diagram, FIG. FIG. 5 is a timing chart showing the operation timing of each part in FIG.
FIGS. 6 and 7 show another embodiment of the present invention. FIG. 6 is an overall block diagram, and FIG. FIG. 13 ... Feed motor, 21 ... Paper, 25 ... Feed sensor, 31 ... Microprocessor, 35 ... Motor drive circuit, 39 ... Mode counter circuit, 40,40 '... Counter, 46 ... Clock generation vessel.

Claims (1)

(57) [Claims] 1. A feed motor for controlling the conveyance of a sheet on a conveyance path, a feed sensor for detecting a sheet passing a predetermined position on the conveyance path, clock pulse generating means for generating a clock pulse, and turning on the feed motor. The clear state is released by the signal, the clock pulse from the clock pulse generating means is counted in response to the sheet detection signal from the feed sensor, and the clock pulse is counted in response to the sheet non-detection signal from the feed sensor. A counter for stopping the operation, and switching from a paper non-detection signal from the feed sensor at the start of paper detection to a paper detection signal and switching from a paper detection signal from the feed sensor to a paper non-detection signal at the end of paper detection. Mode switching means for sequentially switching the operation mode by operation, and operation by the mode switching means And a microprocessor for monitoring the load mode and determining a size of the conveyed sheet based on the count value of the counter when the operation mode is determined to be a mode after the end of the sheet detection. Size detection device.