JPH04266345A - Size detector for paper sheet to be carried - Google Patents

Abstract

PURPOSE:To reduce the burden on a software of a microprocessor when the size of a paper sheet to be carried is judged by the microprocessor. CONSTITUTION:A stepping clock SCK1 from an inter-motor driving circuit 35 on which a paper sheet passes a feed sensor, is counted by a step counter 40. The carrier condition of the paper sheet is counted by a mode counter 43 as a mode value corresponding to the signal from the feed sensor. When the paper sheet completely passes through the feed sensor, the complete passing is judged by a complete passing judging circuit 34, and a microprocessor is interrupted. The microprocessor reads the value of the step counter, and the size of the paper sheet is thus judged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a size detection device for detecting the size of conveyed paper in, for example, a laser printer or a copying machine.

0002

[Prior Art] For example, in a laser printer, a photoreceptor of a photoreceptor drum is charged in a charging section, information is recorded on the photoreceptor as a electrostatic latent image using a laser beam, and toner is attached to the electrostatic latent image in a developing section. It looks like this. On the other hand, the paper is sent out from a paper feed section equipped with a paper feed cassette, the paper is conveyed via a conveyance path to a transfer section where the toner image from the photoreceptor drum is transferred, and when the paper reaches the transfer section, it is exposed to light. The toner image is transferred from the body drum to the paper. After the transfer is completed, the paper is fixed in a fixing device and then discharged.

[0003] In such a laser printer, the size of the paper being conveyed is detected and the operator is notified of the size. For this reason, in the past, a feed sensor was installed in the middle of the conveyance path, and a timer was installed in the microprocessor that constitutes the main body of the control unit to manage the time it took for the paper fed from the paper feeder to pass through the feed sensor. The paper size was determined based on the relationship with the transport speed.

0004

However, when paper size judgment is managed by a microprocessor by counting the time using a timer, there is a problem in that the burden on the microprocessor's software increases.

[0005] Therefore, the present invention aims to reduce the burden on the software of the microprocessor in a device in which the size of the paper to be transported is determined by a microprocessor, and therefore allows the use of a microprocessor with low performance. The purpose of this invention is to provide a size detection device.

[0006]

[Means for Solving the Problems] The present invention includes a feed motor that controls the conveyance of paper on a conveyance path, a feed sensor that detects the paper passing a predetermined position on the conveyance path, and a clock pulse generation means that generates clock pulses. Then, the clear state is canceled by the ON signal of the feed motor, the clock pulses from the clock pulse generation means are counted in response to the paper detection signal from the feed sensor, and the clock pulses are counted in response to the paper non-detection signal from the feed sensor. A clock counter that stops counting pulses, a mode counter that counts the transport state mode in response to the paper detection signal and paper non-detection signal from the feed sensor, and a mode counter that counts the transport state mode in response to the paper non-detection signal. A passing completion judgment circuit that judges whether the paper has passed the feed sensor in response to the value when counting the mode and the paper non-detection signal and outputs an interrupt signal, and a clock in response to the interrupt signal from the passing completion judgment circuit. It is equipped with a microprocessor that determines the size of the transported paper based on the count value of the counter.

[0007]

In the present invention, when the feed sensor detects a sheet of paper being conveyed along the conveyance path, the clock counter starts counting clock pulses, and when the sheet passes the feed sensor, the clock counter stops counting the clock pulses. Further, a mode counter counts the transport state mode in response to a paper detection signal and a paper non-detection signal from the feed sensor. Then, in response to the paper non-detection signal, the mode counter counts the transport state mode in response to the paper non-detection signal, and in response to the paper non-detection signal, the passage completion determination circuit determines that the paper has passed the feed sensor and outputs an interrupt signal. This interrupt signal causes the microprocessor to read the count value of the clock counter and determine the paper size.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as applied to a laser printer.

As shown in FIG. 1, a photosensitive drum 12 whose surface is made of a photoconductive material is disposed approximately at the center of the housing 11. As shown in FIG. This photoreceptor drum 12 is rotated in one direction, that is, clockwise in the figure, by a feed motor 13 composed of a stepping motor.
a charging unit 14 that charges the photoconductor of the photoconductor drum 12; a laser scanner unit 15 that irradiates the photoconductor charged by the charging unit 14 with a laser beam to record information by exposure to form a static latent image; A developing section 16 that attaches toner as a developer to the electrostatic latent image formed on the photoconductor, a transfer section 17 that transfers the toner image from the photoconductor drum 12 to the fed paper, and a transfer section 17 that transfers the toner image from the photoconductor drum 12 to which the photoconductor drum 12 has already been transferred. A cleaning device 18 that removes residual toner and a static eliminator 19 that neutralizes the transferred photosensitive drum 12 are arranged in this order.

A paper feed section 20 is provided on one side of the casing 11, and the paper 2 stored inside is fed to the paper feed section 20.
A paper feed roller 22 that can move toward and away from the paper feed roller 22 and a paper feed solenoid 23 that moves the paper feed roller 22 toward and away from each other are provided on the upper surface of the paper feed roller 1 .

The paper feed roller 22 rotated by the paper feed solenoid 23 contacts the paper 21 for a predetermined time, so that the paper 21 is removed from the paper feed section 20 at a predetermined timing.
The paper 21 is fed out sheet by sheet, and the fed paper 21 is conveyed to the transfer section 17 via a conveyance path 24 provided with conveyance rollers (not shown). A feed sensor 25 is provided in the middle of the conveyance path 24.

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

FIG. 2 is a block diagram showing the circuit configuration.
Reference numeral 1 denotes a microprocessor constituting the main body of the control unit, 32 an input/output port, and these are connected by a bus line 33.

The input/output port 32 includes a paper feed solenoid drive circuit 34 that drives the paper feed solenoid 23, a motor drive circuit 35 that drives the feed motor 13,
A high-voltage power supply 36 that supplies high voltage to the laser scanner unit 15, the charging section 14, and the transfer section 17, a fixing heater 37 of the thermal fixing section 26, and an operation section 38 provided with a start key, a key for setting the number of prints, etc. , mode counter circuit 39
, a step counter 40 as a clock counter, and a sensor circuit 42 for controlling various sensors 41 including the feed sensor 25 are connected to the sensor circuit 42 . Further, an output terminal of a passage completion determination circuit 43 is connected to an interrupt terminal of the microprocessor 31.

FIG. 3 shows the main part configuration, and the mode counter circuit 39 consists of a mode counter 43, a one-shot timer 44, and a rising/falling detection circuit 45.
A signal FSO outputted from the sensor circuit 42 and indicating whether or not the feed sensor 25 detects whether the paper 21 is passing is supplied to the rise/fall detection circuit 45 and also to the enable terminal EN of the step counter 40. We also supply This signal FSO is at a high level (paper non-detection signal) when the feed sensor 25 does not detect the paper 21, and is inverted to a low level (paper detection signal) when the feed sensor 25 detects the paper 21. .

A feed motor on/off signal ST1/STOP is supplied from the I/O port 32 to the enable terminal EN1 of the motor drive circuit 35, and the feed motor on/off signal ST1/STOP is further applied to the mode counter. 43 and step counter 4
It is also supplied to the 0 clear terminal (low active) CL.

The motor drive circuit 35 also serves as a clock pulse generating 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 rise and fall of the signal FSO from the sensor circuit 42 using a rise/fall detection circuit 45 and supplies the detection signal to the one-shot timer 44 . This one-shot timer circuit 44 converts the detection signal into a pulse signal MCK of sufficient width.
It is converted to 1 and supplied to the mode counter 43. This mode counter 43 counts the number of input pulse signals MCK1, and supplies the counted value to the I/O port 32 as a transport state mode value MD.

Further, the pulse signal MCK1 from the one-shot timer circuit 44 and the transport state mode value MD from the mode counter 43 are supplied to the passage completion judgment circuit 43. The passage completion judgment circuit 43 receives the pulse signal MCK1 and determines the conveyance state mode value MD at that time.
When is "2", it is determined that the paper has passed and the interrupt signal IN is sent.
is supplied to the microprocessor 31.

When the microprocessor 31 receives an interrupt signal IN from the pass completion determination circuit 43, it uses the count value of the step counter 40 as a step value SD to determine the paper size to be taken in by interrupt processing. There is.

In this embodiment having such a configuration, the feed motor on/off signal ST1/STOP from the I/O port 32 is off and at a low level before printing starts, so the mode is Counter 43 and step counter 40 are in a 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 in this state to start printing, the microprocessor 31 outputs the feed motor on/off signal ST via the I/O port 32.
Turn 1/STOP into a high-level on signal. As a result, the clear state of the mode counter 43 and the step counter 40 is released, and the motor drive circuit 35 starts rotating the feed motor 13. In this way, the photosensitive drum 12, the conveyance roller, the paper feed roller 22, etc. begin to rotate. The polygon motor of the laser scanner unit 15 is also started.

Next, the microprocessor 31 controls the paper feed solenoid drive circuit 34 via the I/O port 32 to operate the paper feed solenoid 23 for a certain period of time. As a result, the paper feed roller 22 is attracted for a certain period of time and comes into contact with the upper surface of the paper 21. In this way, one sheet of paper 21 is sent from the paper feed section 20 to the conveyance 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 edge of this signal FSO is detected by the rising/falling detection circuit 4.
Detected at 5. Then, a detection signal is supplied from the rising/falling detection circuit 45 to the one-shot timer 44, and the one-shot timer 44 generates a pulse signal MCK1 with a sufficient width.
mode counter 43 and passage completion judgment circuit 3
4. As a result, the mode counter 43 counts up by one and outputs the mode value "1". Further, at this time, since the mode value from the mode counter 43 inputted to the passage completion determination circuit 34 is "1", no passage completion determination is made.

Further, when the signal FSO falls from the high level to the low level, the step counter 40 is enabled and starts counting the stepping clock SCK1 output from the motor drive circuit 35.

After that, when the paper 21 passes 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 45. Then, the detection signal from the rising/falling detection circuit 45 is supplied to the one-shot timer 44, which converts it into a pulse signal MCK1 of sufficient width, and supplies it to the mode counter 43 and the passage completion determination circuit 34. As a result, the mode counter 43 counts up by one and outputs the mode value "2". Further, since the mode value from the mode counter 43 inputted to the passage completion determination circuit 34 is "2", the passage completion determination circuit 34 makes a passage completion determination and outputs the interrupt signal IN.

Further, when the signal FSO rises from the low level to the high level, the enable state of the step counter 40 is released, and the step counter 40 stops counting the stepping clock SCK1. In this way, the step value SD of the step counter 40 is fixed.

Interrupt signal IN from passage completion judgment circuit 34
When input, the microprocessor 31 reads the step value SD of the step counter 40 by interrupt processing. Then, the step value SD is compared with a numerical range corresponding to a preset paper size to determine which size the paper to be transported is.

Also, the paper 2 that has passed through the feed sensor 25
1 is then transferred by the transfer unit 17 and thermally fixed by the heat fixing unit 26, and then discharged from the housing from the paper discharge port 28 by the discharge roller 27.

The microprocessor 31 then processes the paper 21
The feed motor on/off signal ST1/STOP from the I/O port 32 is turned off, that is, set to a low level, at a timing sufficient for the paper to be discharged from the paper discharge port 28. As a result, the operation of the feed motor 13 is stopped, the mode counter 43 and the step counter 40 are cleared, and the mode value of the mode counter 43 becomes "0". The above operation is shown in a timing chart as shown in FIG.

That is, as shown in FIG. 5, if the mode value MD is "0", the microprocessor 31 determines whether or not it is in a state to start feeding paper, and if it is in a state to start feeding paper, it is in the operating state. (A) That is, it is determined that the paper feed roller 22, the conveyance roller, and even the polygon motor in the laser scanner unit 15 have started to start and are ready to feed paper. Further, if the state is not such that paper feeding is to be started, the operating state (D), that is, the state in which paper transport is not performed at all, is determined.

Further, if the mode value MD is "1", the operating state (B) is reached, that is, the feed sensor 25 detects the paper 2.
1 is detected, and it is determined whether the paper conveyance control is continuing.

Further, if the mode value MD is not "1", if the interrupt signal IN is input, it is determined that the mode value MD is "2", and the operating state (C), that is, the feed sensor 2 is determined.
It is determined that the paper 21 has passed through the step counter 40 and the step value SD of the step counter 40 is now read.

When the step value SD is read, it is checked whether the step value is in the range of paper 1, paper 2, . . . paper n, based on a preset numerical range. If there is a corresponding range, the paper size corresponding to that range is determined. Further, if the size does not fall within any range, an error is generated as a paper size detection failure.

In this way, the microprocessor 31 reads the step value SD from the step counter 40 to determine the size of the paper 21 when the interrupt signal IN is input, so that the feed sensor 25 detects the size of the paper 21 as in the conventional case. There is no need to operate an internal timer using software to manage time while detecting the conveyance of 21. Therefore, the software burden on the microprocessor 31 can be reduced.

Therefore, the microprocessor 31 can sufficiently cope with the increase in paper conveyance speed for high-speed printing, and can perform sufficient control even when the microprocessor is switched from an 8-bit type to a 4-bit type. In other words, it is also possible to use a microprocessor with low performance. Also microprocessor 3
1 can also easily know what state of conveyance the paper 21 is currently in by reading the mode value MD. In the above embodiments, the present invention was applied to a laser printer, but it is needless to say that the present invention is not limited thereto.

[0037]

Effects of the Invention As detailed above, according to the present invention, in a system in which a microprocessor determines the size of conveyed paper, the burden on the software of the microprocessor can be reduced, and therefore the software load on the microprocessor can be reduced. It is possible to provide a size detection device for conveyed paper that can also be used.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a laser printer in an embodiment of the present invention.

FIG. 2 is an overall block diagram of the same embodiment.

FIG. 3 is a block diagram of main parts in the same embodiment.

FIG. 4 is a timing diagram showing the operation timing of each part in FIG. 3;

FIG. 5 is a flowchart showing a process of determining the state of paper conveyance by the microprocessor in the same embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 13... Feed motor, 21... Paper, 25... Feed sensor, 31... Microprocessor, 35... Motor drive circuit, 40... Step counter, 43... Mode counter.

Claims (1)

[Claims] 1. A feed motor that controls the conveyance of paper on a conveyance path, a feed sensor that detects the paper passing a predetermined position on the conveyance path, a clock pulse generation means that generates a clock pulse, and a feed motor that controls the conveyance of the paper on the conveyance path. The clear state is canceled by the signal, the clock pulses from the clock pulse generating means are counted in response to the paper detection signal from the feed sensor, and the clock pulses are counted in response to the paper non-detection signal from the feed sensor. a mode counter that counts the transport state mode in response to the paper detection signal and paper non-detection signal from the feed sensor; and a mode counter that counts the transport state mode in response to the paper non-detection signal. a passage completion determination circuit that determines whether the paper has passed the feed sensor in response to the counted value and the paper non-detection signal and outputs an interrupt signal; What is claimed is: 1. A size detection device for conveyed paper, comprising a microprocessor that determines the size of the conveyed paper based on the count value of a clock counter.