JP7178570B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, in image forming apparatuses such as printers and copiers, there has been known a technique for improving print quality by changing control contents of various devices according to atmospheric pressure. For example, the image forming apparatus disclosed in Patent Document 1 includes a detection sensor that detects the atmospheric pressure, and corrects the AC voltage applied to the transfer material separating means according to the atmospheric pressure detected by the detection sensor. ing.

JP-A-2001-249548

However, in the image forming apparatus disclosed in Patent Document 1, it is necessary to provide a dedicated sensor for detecting the atmospheric pressure, so there is a problem that the cost increases accordingly.

The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus capable of controlling a device according to the atmospheric pressure without providing a dedicated detection sensor for detecting the atmospheric pressure. It is to provide a device.

An image forming apparatus according to the present invention has an ultrasonic wave transmitting section and an ultrasonic wave receiving section arranged opposite to each other across a sheet conveying path, and ultrasonic waves are attenuated between the ultrasonic wave transmitting section and the ultrasonic wave receiving section. A multi-feeding detection sensor for detecting multi-feeding of sheets based on the amount of sheets, and determining the magnitude of the atmospheric pressure based on the output voltage output from the ultrasonic wave receiving section, and determining the magnitude of the determined atmospheric pressure. and a control unit for controlling devices related to image forming processing in response.

ADVANTAGE OF THE INVENTION According to this invention, an apparatus can be controlled appropriately according to atmospheric pressure, without providing a detection sensor for exclusive use for detecting atmospheric pressure.

FIG. 1 is an overall schematic diagram showing an image forming apparatus according to an embodiment. FIG. 2 is a longitudinal sectional view showing a schematic configuration of the document conveying device. FIG. 3 is a schematic diagram showing the configuration of a multi-feed detection sensor provided in the document conveying device and its control system. FIG. 4 is an example of correlation data between the voltage output from the receiving section of the double feed detection sensor (ultrasonic sensor) and input to the control section and the magnitude of the atmospheric pressure.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In addition, the present invention is not limited to the following embodiments.

<<Embodiment>>
FIG. 1 shows an image forming apparatus X according to the embodiment. The image forming apparatus X is a copier that reads an original image and prints the image data. Note that the image forming apparatus X is not limited to a copier, and may be a facsimile machine, a multifunction peripheral (MFP) capable of executing a plurality of types of jobs, or the like.

Specifically, the image forming apparatus X includes an image forming apparatus main body 1 having a rectangular box shape in appearance, and an image reading device 200 arranged above the image forming apparatus main body 1 .

The image forming apparatus main body 1 has a paper feeding section 2 , an image forming section 3 and a fixing section 4 . The paper feed unit 2 includes a paper feed cassette 5 containing a plurality of sheets P stacked in a bundle, and a pickup that pulls out the sheets P one by one from the paper feed cassette 5 and supplies them to a predetermined sheet transport path T. and rollers 6 . The sheet conveying path T extends upward from the sheet feeder 2 and then extends horizontally to connect to the document discharge tray 7 .

The image forming section 3 includes a photosensitive drum 8 , a charging device 9 , a developing device 10 , a toner container 11 , a transfer roller 12 and a neutralizing device 13 . Then, the image forming section 3 forms an image on the sheet P supplied from the paper feeding section 2 in the following procedure.

Specifically, first, the charging device 9 charges the photosensitive drum 8 to a predetermined potential. Next, a laser scanning unit (LSU) (not shown) irradiates the surface of the photosensitive drum 8 with light based on the image data. Thereby, an electrostatic latent image is formed on the surface of the photosensitive drum 8 .

Then, the developing device 10 supplies toner to the electrostatic latent image on the photosensitive drum 8 to develop it. The transfer roller 12 rotates in pressure contact with the surface of the photosensitive drum 8 with the sheet P therebetween. At this time, since a transfer voltage is applied to the transfer roller 12, the toner image on the surface of the photosensitive drum 8 is transferred to the sheet P. FIG. The static eliminator 13 eliminates charges on the surface of the photosensitive drum 8 after the toner image has been transferred onto the sheet P. FIG.

The fixing section 4 has a fixing roller 15 and a pressure roller 16 which are pressed against each other. A heater is built in the fixing roller 15 . The fixing unit 4 heats and presses the toner image to fix the toner image on the paper while sandwiching and conveying the paper between the fixing roller 15 and the pressure roller 16 .

The image reading device 200 has an image reading section 17 placed on the upper side of the image forming apparatus main body 1 and a document conveying device 100 mounted on the upper surface of the image reading section 17 .

The image reading unit 17 has a rectangular box shape in appearance. A contact glass 17a is attached to the upper surface of the scanner case forming the outer wall of the image reading section 17. As shown in FIG. The image reading unit 17 has a light source, a reflecting mirror, an image sensor, and the like.

Then, the image reading section 17 reads the image of the original sheet S by either a sheet fixing method or a sheet through method. In the reading operation by the sheet fixing method, the original sheet S placed on the contact glass 17a is irradiated with light from the light source. On the other hand, in the sheet-through type reading operation, the document sheet S supplied by the document conveying device 100 to the image reading position R on the contact glass 17a is irradiated with light from the light source. The image reading unit 17 reads the image of the document sheet S by reading the reflected light from the document sheet S with an image sensor, and generates the image data.

[Construction of Document Feeder]
As shown in FIG. 2 , the document conveying device 100 has a document set tray 21 , a sheet conveying path 22 and a document discharge tray 23 . A plurality of types of original sheets S having different width sizes (for example, A4 size, A4 size, etc.) can be set on the original set tray 21 .

The document conveying device 100 supplies the document sheet S placed on the document set tray 21 by the conveying mechanism 20 to the sheet conveying path 22 and discharges it to the document discharge tray 23 via the sheet conveying path 22 .

An image reading position R is set in the middle of the sheet conveying path 22 . Immediately below the image reading position R, an image reading unit (not shown) is on standby with the contact glass 17a interposed therebetween. The image of the facing side) is read. Further, on the upstream side of the image reading position R in the sheet conveying path 22, the other side of the document sheet S (the side opposite to the one side and directed downward when set on the document set tray 21). A contact image sensor 37 is provided for reading the image of the surface (surface).

The sheet transport path 22 is a substantially U-shaped transport path from the downstream end of the document set tray 21 to the upstream end of the document discharge tray 7 .

The transport mechanism 20 includes a sheet feeding unit 24, a pair of registration rollers 25, a pair of transport rollers 26, a pair of transport rollers 27, a pair of transport rollers 28, and a It has a paper discharge roller pair 29 .

The paper feeding unit 24 pulls out the original sheet S placed on the original set tray 21 , advances it in the sheet conveying direction, and supplies it to the sheet conveying path 22 . Specifically, the paper feeding unit 24 includes a feeding roller 24a for drawing out the document sheet S placed on the document set tray 21, and a sheet conveying path 22 for feeding the document sheet S drawn out from the document set tray 21 by the feeding roller 24a. It has a feeding roller 24b that supplies to.

The delivery roller 24a and the feeding roller 24b are connected by an arm member 24c. A base end portion of the arm member 24c is rotatably supported by a roller shaft 24d of the feeding roller 24b.

A delivery roller 24a is supported at the tip of the arm member 24c. Then, the arm member 24c rotates in the clockwise direction in FIG. It has become.

A separation pad 24e is provided below the feeding roller 24b. The separation pad 24e is pressed against the peripheral surface of the feed roller 24b to form a nip portion. Then, the multi-fed sheets can be separated one by one by the feeding roller 24b and the separation pad 24e and sent out to the downstream side.

The registration roller pair 25 temporarily stops the transport of the document sheet S supplied to the sheet transport path 22 and bends the document sheet S to correct the skew.

The conveying roller pairs 26 to 28 convey the document sheet S supplied to the sheet conveying path 22 by the sheet feeding section 24 . Also, the paper discharge roller pair 29 discharges the document sheet S transported to the downstream end of the sheet transport path 22 by the transport roller pairs 26 to 28 to the document discharge tray 23 .

Between the feed roller 24b and the pair of registration rollers 25, a multi-feed detection sensor 30 is provided to detect multi-feed of sheets. The double feed detection sensor 30 is connected to the control section 36 (see FIG. 3).

The control unit 36 consists of a microcomputer having a CPU 36a, a ROM 36b and a RAM 36c. When the controller 36 detects double feeding of the document sheets S based on the output signal (voltage signal in this embodiment) from the double feeding detection sensor 30, the control unit 36 stops the operation of the transport mechanism 20 and displays a display (not shown). Display an error in the part.

[Structure of double feed detection sensor]
Next, a schematic configuration of the double feed detection sensor 30 will be described with reference to FIG. The double feed detection sensor 30 is configured by an ultrasonic sensor. Specifically, the ultrasonic sensor (multiple feed detection sensor 30 ) is composed of a transmitting section 31 that transmits ultrasonic waves and a receiving section 32 that receives the sound waves from the transmitting section 31 . The transmitting unit 31 and the receiving unit 32 are arranged to face each other with the sheet conveying path 22 of the document sheet S interposed therebetween. The facing direction of the transmitting portion 31 and the receiving portion 32 is inclined with respect to the sheet conveying direction when viewed from the sheet width direction. A piezoelectric body is incorporated in each of the transmitter 31 and the receiver 32 . Examples of piezoelectric bodies include piezoelectric ceramics.

The transmitter 31 is connected to the controller 36 via the drive circuit 33 , and the receiver 32 is connected to the controller 36 via the amplifier circuit 34 and sample hold circuit 35 .

The control unit 36 outputs a pulsed transmission control signal to the drive circuit 33 when driving the ultrasonic sensor (multiple feed detection sensor 30). The drive circuit 33 amplifies the transmission control signal output by the control section 36 and applies a sinusoidal AC voltage to the piezoelectric body of the transmission section 31 . As a result, the piezoelectric body in the transmitting section 31 vibrates at a predetermined frequency, and the transmitting section 31 transmits ultrasonic waves. Ultrasonic waves emitted from the transmitter 31 are propagated to the receiver 32 using air as a medium. The receiving section 32 receives the ultrasonic wave from the transmitting section 31 and outputs the waveform signal as a voltage signal.

The amplifier circuit 34 amplifies the voltage signal output from the receiver 32 and outputs the amplified voltage signal to the sample hold circuit 35 . The sample hold circuit 35 has a capacitor, and charges the output signal from the amplifier circuit 34 to the capacitor. Thus, the sample hold circuit 35 converts the output signal of the amplifier circuit 34 to DC and holds the level for a certain period of time. The output terminal of the sample hold circuit 35 is connected to the A/D conversion port of the CPU 36a, and the controller 36 takes in the output of the sample hold circuit 35 at an arbitrary timing.

Based on the output voltage from the sample-and-hold circuit 35, the control unit 36 calculates the amount of attenuation of ultrasonic waves between the transmission unit 31 and the reception unit 32. FIG. Then, when the attenuation amount of the ultrasonic wave exceeds a predetermined value, the control section 36 determines that the document sheets S are multi-fed. This multi-feeding detection process utilizes the property that the more the number of overlapping document sheets S passing between the transmitting unit 31 and the receiving unit 32, the greater the amount of attenuation of ultrasonic waves.

The double feed detection sensor 30 is also used as a detection sensor for detecting the magnitude of the atmospheric pressure. This atmospheric pressure detection utilizes the fact that there is a correlation between the magnitude (amplitude value) of the voltage output from the receiving section 32 of the double feed detection sensor 30 and the magnitude of the atmospheric pressure.

That is, in an environment with low atmospheric pressure (for example, at high altitudes exceeding 2000 m), the density of air, which is a medium for transmitting ultrasonic waves, is low, so the attenuation of ultrasonic waves between the transmitting unit 31 and the receiving unit 32 is also As a result, the magnitude (amplitude value) of the voltage output from the receiving section 32 of the ultrasonic sensor also decreases. On the other hand, in an environment with high atmospheric pressure, the air density of the medium that transmits ultrasonic waves is high, so the amount of attenuation of the ultrasonic waves becomes small. amplitude value) also increases. Focusing on this fact, in the present embodiment, correlation data between the voltage output from the receiving unit 32 of the ultrasonic sensor and input to the control unit 36 and the magnitude of the atmospheric pressure is created in advance and stored in the ROM 36b. there is
The ROM 36b corresponds to a storage unit that stores correlation data.

FIG. 4 shows an example of the correlation data. Although the correlation data is shown in the form of graph data in this figure, it is not limited to this, and may be, for example, table data. The vertical axis of the graph indicates the magnitude of the voltage output from the receiving unit 32 and input to the control unit 36 (the voltage output from the sample hold circuit 35 in this embodiment), and the horizontal axis of the graph indicates the atmospheric pressure. shows the size. A solid line in the graph indicates the correlation between the input voltage and the atmospheric pressure. According to this graph, it can be seen that the input voltage to the control unit 36 and the magnitude of the atmospheric pressure are in a linear proportional relationship, and that the higher the input voltage, the higher the level of the atmospheric pressure. The two-dot chain line in the graph indicates a threshold line when the control unit 36 switches the control of various devices according to the atmospheric pressure. It is divided into 6.

Based on the input voltage from the receiving unit 32 of the ultrasonic sensor and the correlation data, the control unit 36 determines whether the atmospheric pressure in the environment where the image forming apparatus X is installed belongs to any of levels 1 to 6. determine whether Then, the control unit 36 controls each device related to the image forming process in accordance with the determined level of the atmospheric pressure.

As an example of this control, the lower the atmospheric pressure level, the higher the transfer voltage of the transfer roller 12 of the transfer roller 12, or the lower the atmospheric pressure level, the charge separator (not shown) that separates the sheet P from the transfer roller 12. ) can be controlled by increasing the voltage.

The process of determining the magnitude of the atmospheric pressure by the control unit 36 is performed when the document sheet S is not being conveyed by the document conveying device 100 . Further, this determination processing is performed immediately after the power of the image forming apparatus X is switched from off to on. Note that this determination process may be performed at regular intervals (for example, every 24 hours) while the image forming apparatus X is powered on. After determining the magnitude of the atmospheric pressure, the control unit 36 stores the acquired (determined) level of the atmospheric pressure until the next determination of the atmospheric pressure is performed. to update.

[Effect]
As described above, in the present embodiment, the control unit 36 determines the magnitude of the atmospheric pressure based on the output voltage output from the receiving unit 32 of the double feed detection sensor 30, and determines the magnitude of the determined atmospheric pressure. It is configured to control equipment related to the image forming process according to the state of the image forming process.
According to this configuration, the double feed detection sensor 30 is also used as a sensor for detecting the magnitude of the atmospheric pressure, so there is no need to separately provide a dedicated sensor for detecting the atmospheric pressure. Therefore, it is possible to appropriately control the equipment related to the image forming process according to the atmospheric pressure while keeping the product cost low.

Further, in the ROM 36b of the control unit 36, correlation data between the input voltage output from the receiving unit 32 of the double feed detection sensor 30 and input to the control unit 36 and the atmospheric pressure is stored in advance. .
Therefore, based on the input voltage from the receiving section 32 of the double feed detection sensor 30, the atmospheric pressure can be obtained by a simple calculation.

Further, the control unit 36 is configured to execute the atmospheric pressure determination process when the document sheet S is not being conveyed by the document conveying device 100 .
According to this configuration, it is possible to avoid performing atmospheric pressure determination processing while the original sheet S is passing through the double feeding detection sensor 30 . In addition, it is possible to prevent the controller 36 from erroneously determining the magnitude of the atmospheric pressure.

Further, the control unit 36 is configured to determine the magnitude of the atmospheric pressure when the power of the image forming apparatus X is switched from off to on.
According to this configuration, it is possible to prevent the image forming process from being interrupted due to the atmospheric pressure determination process being unnecessarily performed in the control section 36 . That is, the change in the atmospheric pressure usually occurs when the installation location of the image forming apparatus X changes (for example, from a flat ground to a high ground) due to moving, etc. In such a case, the image forming apparatus X is powered off. It is transported in the OFF state and is powered ON after arriving at the predetermined installation site. Therefore, by determining the atmospheric pressure only when the power of the image forming apparatus X is switched from off to on as in the present embodiment, unnecessary determination can be avoided.

<<Other embodiments>>
In the above embodiment, the multi-feed detection sensor 30 is provided inside the document conveying device 100 , but it is not limited to this, and may be provided inside the image forming apparatus main body 1 .
Further, in the above embodiment, an example in which the image forming apparatus X is a copier has been described, but the present invention is not limited to this. The image forming apparatus X may be a printer, facsimile machine, multifunction peripheral (MFP), or the like.

INDUSTRIAL APPLICABILITY As described above, the present invention is useful for image forming apparatuses, and is particularly useful when applied to printers, facsimiles, copiers, and the like.

S: original sheet T: sheet conveying path X: image forming apparatus 1: image forming apparatus main body 17: image reading section 22: sheet conveying path 30: double feeding detection sensor 31: transmitting section (ultrasonic transmitting section)
32: Receiving unit (ultrasonic receiving unit)
36: control unit 36b: ROM (storage unit)
100: document feeder

Claims (3)

a document conveying device for conveying a document sheet;
an image reading unit for reading an image of a document sheet conveyed by the document conveying device;
an image forming apparatus main body for printing an image of the document sheet read by the image reading unit;
An ultrasonic wave transmitting unit and an ultrasonic wave receiving unit are arranged opposite to each other across a sheet conveying path provided in the document feeding device, and ultrasonic waves are attenuated between the ultrasonic wave transmitting unit and the ultrasonic wave receiving unit. A double feed detection sensor that detects double feed of sheets based on the amount,
a control unit that determines the magnitude of the atmospheric pressure based on the signal output from the ultrasonic wave receiving unit, and controls equipment related to image forming processing according to the determined magnitude of the atmospheric pressure; prepared ,
The image forming apparatus, wherein the control section is configured to make the determination when the document conveying device is not conveying the sheet . The image forming apparatus according to claim 1, wherein
further comprising a storage unit storing in advance correlation data between magnitude of a signal output from the ultrasonic wave receiving unit of the double feed detection sensor and input to the control unit and magnitude of atmospheric pressure,
The image forming apparatus, wherein the control section is configured to execute the determination based on the signal output from the ultrasonic wave receiving section and the correlation data. 3. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the control unit is configured to perform the determination when the power of the image forming apparatus is switched from off to on.

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