JP6827759B2 - Fixing device and image forming device having it - Google Patents

Description

The present invention relates to a printer, a copying machine, and a facsimile that form an image by electrophotographic technology, and more particularly to a technique for peeling a recording material from a fixing member of a fixing device included in these devices.

Generally, an image forming apparatus for forming an image using an electrophotographic method has a fixing device (fixing apparatus) for fixing a toner image transferred to a sheet (for example, paper) surface. The fixing device applies heat and pressure as the paper on which the unfixed toner image is formed passes through the nip portions of the heating roller and the pressure roller that have heated the surfaces arranged opposite to each other. In this way, the unfixed toner is melted and fixed on the paper.
However, due to the adhesive force generated by the melting of the unfixed toner, the paper may wrap around the heating roller and cause jam.

In order to prevent the occurrence of jam, conventionally, in the fixing device as described above, a separating claw in contact with the heating roller is used to peel off the paper wound around the heating roller.
The separation claws can easily peel off the paper from the heating roller when the image density is low or when there is a gap between the edge of the paper and the image (hereinafter referred to as a margin).
However, for example, in the case of thin paper with a small basis weight, especially coated paper with a coated surface, a high-concentration image with a large amount of toner on the paper, and an image with a small tip margin, the molten toner is heated. The adhesive force to the roller increases.

Therefore, it is difficult for the separation claws to enter between the paper and the heating roller, and the edges of the paper are damaged, so that the output paper may not be used as a deliverable. Further, there is also a problem that the toner image is scratched because the separation claws come into contact with the molten toner image, and the image quality of the output paper, which is a product, is deteriorated. Further, since the separation claw is in contact with the heating roller, the surface of the heating roller is scratched, and the scratch may cause deterioration of the image quality of the output paper.

In response to such a problem, in the devices disclosed in Patent Document 1 and Patent Document 2, compressed air is discharged from the nozzle of the peeling guide plate which does not come into contact with the heating roller and the heating roller in the vicinity thereof, and the compressed air sticks to the heating roller. Separate the top of the paper from the heating roller. After that, the entire paper is peeled from the heating roller by a peeling device.
In the apparatus disclosed in Patent Document 1, compressed air compressed by an air pump (compressor) is output in a pulse shape via a solenoid valve and applied to the tip of the paper. Further, in the apparatus disclosed in Patent Document 2, the pulse duty and the period when the pulse-shaped discharge control is performed are changed to adjust the discharge air amount to an appropriate value according to the media type.

Japanese Unexamined Patent Publication No. 2004-212954 JP-A-2007-199462

For example, in a fixing device, there is a problem that a scratch on the surface layer of a heating roller generally causes a streak-like image defect in the product and deteriorates the quality of the product.
In order to deal with this problem, that is, to cancel the scratches caused by the edge of the paper, the fixing device is provided with a cleaning roller that scrapes the surface layer of the heating roller. In addition, keeping the surface roughness of the cleaning roller constant is important for continuing to use the heating roller without image defects.
Therefore, it is necessary to remove resin and toner deposits generated by the cleaning roller scraping the surface of the heating roller, and a configuration in which compressed air is blown onto the surface of the cleaning roller is adopted.
As a result, the surface roughness of the cleaning roller is kept constant, and the heating roller is stably scraped, so that the fuser can be used for a long life without causing scratches on the surface of the heating roller.

On the other hand, if compressed air leaks due to improper assembly or deterioration over time in members such as hoses that distribute compressed air to each part, poor separation jam may occur due to the above-mentioned insufficient separation performance of paper, or cleaning rollers It may be difficult to keep the surface roughness constant. Therefore, there remains a problem that image defects due to the fixing roller may occur.
In addition, in order to detect abnormalities in the pressure and amount of compressed air discharged from the compressor, it is necessary to separately install a sensor and an accompanying mechanical mechanism, which causes problems such as an increase in manufacturing cost and an increase in size of the device. Remain.

A main object of the present invention is to provide an image forming apparatus capable of determining the state of airtightness between a compressor and a solenoid valve with high accuracy.

The image forming apparatus of the present invention includes a fixing means for heating and pressurizing a toner image on a sheet with a rotating body to fix the toner image on the sheet, a cleaning means for collecting deposits on the surface of the rotating body, and a surface of the cleaning means. Air supply means that discharges compressed air toward the cleaning air discharge part that blows air to the air supply means, detection means that detects the current value of the drive current flowing into the air supply means, and compressed air discharged by the air supply means. A first valve means that opens or closes to the outside air, a second valve means that supplies or stops the compressed air discharged by the air supply means to the cleaning air discharge portion, and the air. It has a determination means for determining the state of airtightness between the supply means and the second valve means, and the determination means includes the discharge air pressure of the air supply means and the current detected by the detection means at that time. Information representing the characteristics of the air supply means derived based on the value, and the current value detected by the detection means when the state of the first valve means is closed and the air supply means is activated. It is characterized in that the state of airtightness between the air supply means and the second valve means is determined based on the comparison result.

According to the present invention, the state of the member that distributes the compressed air of the compressor can be determined by monitoring the drive current when the compressor is started. This makes it possible to determine the state of airtightness between the compressor and the solenoid valve with an inexpensive and simple configuration, and prevent the life of the device (particularly the fixing roller) from being shortened due to deterioration of separation performance and cleaning performance. Can be done.

The figure which shows an example of the main configuration of the image formation system which concerns on this embodiment. (A) and (b) are diagrams for explaining an example of the configuration of the first and second fixing portions included in the image forming apparatus. The figure for demonstrating the peripheral structure which concerns on the separation discharge part, the 1st cleaning discharge part, and the 2nd cleaning discharge part of each fixing part which an image forming apparatus has. The block diagram for demonstrating an example of control of the separation discharge part, the 1st cleaning discharge part, the 2nd cleaning discharge part, etc. of an image forming apparatus. The flowchart which shows an example of the processing procedure which adjusts the pressure (discharged air pressure) of the compressed air discharged by a compressor. (A) and (b) are graphs for explaining the characteristic formula derived by the process shown in FIG. The flowchart which shows an example of the processing procedure for determining the state of airtightness between a compressor and a solenoid valve. A graph for explaining the relationship between the state of airtightness between the compressor and the solenoid valve, the voltage conversion value of the current, and the output air pressure.

Hereinafter, a case where the present invention is applied to an image forming system including an image forming apparatus which is an electrophotographic laser beam printer will be described as an example.
In the present embodiment, an electrophotographic image forming apparatus will be described as an example, but the present invention will also be applied to a device such as an inkjet printer or a sublimation printer that fixes an image by a heat drying method. Can be applied.

[Example of Embodiment]
FIG. 1 is a diagram showing an example of a main configuration of an image forming system according to the present embodiment.
The image forming system S shown in FIG. 1 presents information to a sheet feeding device 301 for feeding sheets (for example, paper), an image forming device 300 for forming an image, and operations from the user. It includes an operation unit 4 for receiving and a post-processing device 394.
The post-processing device 394 performs a desired post-processing (processing such as folding, stapling, drilling, etc.) set by the user via, for example, the operation unit 4 on the sheet.

In the image forming system S, the operations of the sheet feeding device 301 and the image forming device 300 are controlled by a CPU (Central Processing Unit) 400 described later, and the post-processing device 394 is different from this. The description will proceed assuming that it is controlled by the CPU.
In addition, the user can perform sheet type information (media information) such as sheet size, basis weight, and type (high quality paper, coated paper, recycled paper, special paper), and post-processing after paper ejection, for example, via the operation unit 4. Specify, set the operation for the image formation system such as image quality, and set the status of the fixing device.

The image forming system S is a job (sheet processing setting, external) set by a user inputting an instruction via the operation unit 4 or an external host PC (not shown) connected to the image forming system S via a network. Accepts image information, etc. sent from the host PC). The image forming system S performs paper feed transfer, image formation, and post-processing of the sheet based on the received job. The outline of a series of processes performed by the image forming system S that has received the job will be described below.

The sheet feeding device 301 includes two-stage paper feeding units 311 and 312. Each paper feed unit stores a bundle of sheets in storages 11 and 12. The paper feeding operation of the sheet feeding device 301 is performed via the suction transport units 51 and 52 provided in each paper feeding unit.

In this embodiment, a plurality of fans (not shown) are arranged on the suction transfer units 51 and 52 for air feeding control. Further, during the paper feeding operation, the sheets are separated by controlling the fan so as to send air between the sheets from the upstream in the transport direction with respect to the sheets in the storages 11 and 12. Further, the sheet is sucked to the endless belt via a fan for sucking the sheet arranged inside the endless belt in the suction transport units 51 and 52. In this way, the sheets are separated one by one, fed and conveyed.

For example, in the case of paper feeding from the upper paper feeding unit 311, the paper is conveyed via the upper paper feeding unit 317. Further, in the case of paper feeding from the lower paper feeding unit 312, the paper is conveyed via the lower feeding unit 318. The sheets fed from the upper paper feed unit 311 or the lower paper feed unit 312 are conveyed to the image forming apparatus 300 via the merging transfer unit 319.

A catoptric sheet detection sensor (not shown) is provided on each transport path to detect the passage of the front and rear ends of the sheet. In this way, the position of the sheet is detected in each transport path.
In addition, each transport unit has a stepping motor (not shown) for transport. The sheets are fed and conveyed by controlling the drive of these motors and rotating the transfer rollers of each part.

In this way, the sheet feeding device 301 sequentially separates one sheet from each storage according to the sheet request information included in the received job, and feeds and conveys the sheets one by one. The sheet feeding device 301 ends the paper feeding operation when the requested number of sheets has been fed.

In addition, media information indicating the type of sheet such as sheet size, basis weight, and type (high-quality paper, coated paper, recycled paper, special paper) according to the sheet stored in each paper feeding unit 311 or 312 of the sheet feeding device 301. Is set by the user, for example, via the operation unit 4.

Further, the image forming apparatus 300 receives sheets one by one from the sheet feeding apparatus 301, and forms an image based on the setting information of the sheet size, the basis weight, and the type designated via the operation unit 4. Hereinafter, an example of the operation of image formation will be described.

After receiving the sheet from the sheet feeding device 301, the image forming apparatus 300 controls each transport unit to transport the sheet. Further, the image is formed based on the received image data starting from the sheet detection via the registration sensor 50.
Specifically, the image forming apparatus 300 controls the lighting and the amount of light of the semiconductor laser in the laser scanner unit 354, and controls the scanner motor that rotates and controls the polygon mirror (not shown). In this way, the image forming apparatus 300 forms a latent image image on the photoconductor drum 353 inside the image forming unit 387 by the laser light based on the image data.

Further, as shown in FIG. 1, the image forming apparatus 300 has hopper portions 351Y and 351M for accommodating toner bottles of each color of yellow (Y), magenta (M), cyan (C) and black (K) on the upper portion thereof. , 351C and 351K are arranged.
The image forming apparatus 300 develops the toner on the latent image image on the photoconductor drum 353 by the developing unit 352 to which the toner is supplied from each hopper unit 351 and first transfers the developed toner image to the intermediate transfer belt 355. To do. These primary transfers are performed on each color of YMCK, and are sequentially transferred onto the intermediate transfer belt 355 so that the positions of the colors match.

The transferred toner image is secondarily transferred to the sheet to form a toner image on the sheet.
The image forming apparatus 300 has an image adjusting unit 370 for adjusting the density and alignment of the toner image of each color, and the density patch and the register patch on the intermediate transfer belt 355 are provided via the image adjusting unit 370. Is detected. The image forming apparatus 300 adjusts the amount of laser light and the position of the latent image image based on the detection result of the image adjusting unit 370.

Further, the image forming apparatus 300 corrects the skew amount of the sheet with respect to the sheet immediately before the transfer position, and finely adjusts and matches the toner image formed on the intermediate transfer belt 355 with the sheet tip position. It can be done without stopping.
Specifically, the image reference sensor 385 of the image forming apparatus 300 detects the position of the tip of the sheet and aligns the tip.

The sheet after the secondary transfer is conveyed toward the first fixing unit 308 via the belt transfer unit 386. In the first fixing section 308, heat and pressure are applied to the sheet to melt the toner, and the toner is fixed to the sheet.
Depending on the type of sheet, for example, when the sheet is thick plain paper of 157 [gsm] or more, or when it is coated paper, the sheet is conveyed toward the second fixing portion 309. By performing re-fixing in the second fixing portion 309, the fixability of the toner can be improved and the gloss can be adjusted. In this way, the first and second fixing portions function as fixing means.

The temperature control temperature and pressing force for fixing in the first fixing unit 308 and the second fixing unit 309 are determined based on media information set by the user, for example, via the operation unit 4. Further, the first fixing portion 308 is provided with a separation discharge portion 205 for discharging compressed air for separation and a release guide plate 204, which will be described later. The separation discharge unit 205 and the release guide plate 204 function as a separation air unit. Details of these configurations will be described later with reference to FIG.

The sheet after the toner is fixed is conveyed to the reverse transfer section 310 when the back surface is continuously printed according to the content of the job, or when the front and back sides of the sheet need to be inverted. When printing is completed, the sheet is conveyed to the post-processing device 394 via the reverse transfer unit 310.

The post-processing device 394 receives the sheet after image formation from the image forming device 300. The post-processing device 394 performs a desired post-processing set by the user on the sheets, and sequentially outputs the sheets (sheet bundle) after the post-processing to any one of the output trays 360 as a deliverable.
Next, the details of the configurations of the first fixing portion 308 and the second fixing portion 309 will be described with reference to FIG.

FIG. 2 is a diagram for explaining an example of the configuration of the first and second fixing portions included in the image forming apparatus 300. Note that FIG. 2A shows the configuration of the first fixing portion 308, and FIG. 2B shows the configuration of the second fixing portion 309.

The first fixing portion 308 shown in FIG. 2A includes a heater 201, a heating roller 151 heated by the heater 201, and a pressure belt 152 for applying pressure toward the surface of the heating roller 151. Will be done.
The first fixing unit 308 also has a temperature detection thermistor 208 arranged near the surface of the heating roller 151 in order to control the heater 201. In the image forming apparatus 300, the lighting / non-lighting of the heater 201 is controlled according to the detection result of the temperature detection thermistor 208.

In the first fixing portion 308, a sheet (recording paper 10 shown in the figure) having unfixed toner on the surface is conveyed in the direction of arrow A, and a nip formed between the heating roller 151 and the pressure belt 152. It is heated and pressurized when passing through the portion 209. As a result, the unfixed toner on the recording paper 10 is fused and the toner is fixed on the sheet. That is, the toner image on the sheet is heated and pressurized by the rotating body to be fixed on the sheet.

Further, as shown in FIG. 2A, a peeling guide plate 204 is installed on the paper ejection side of the heating roller 151 (the direction in which the recording paper 10 that has passed through the nip portion 209 is ejected).
The peeling guide plate 204 is provided with a separation discharge unit 205 for discharging compressed air into the gap between the peeling guide plate 204 and the heating roller 151.

Further, as shown in FIG. 2A, a transmissive paper detection sensor 207 is arranged in the belt transport section 386 that transports the recording paper 10 toward the first fixing section 308.
The paper detection sensor 207 is a sensor used to generate the discharge timing of the compressed air blown from the separate discharge unit 205 to the tip of the recording paper 10.
The timing at which the compressed air is discharged toward the tip of the recording paper 10 is, for example, the timing after the paper detection sensor 207 detects the tip of the paper and the time has elapsed for the recording paper 10 to pass through the nip portion 209.

The first fixing roller 210 is also provided with a first refresh roller 210 for rubbing the surface of the heating roller 151 to refresh the roller surface scratches.
Further, when the surface layer of the heating roller 151 is rubbed, the resin material or toner on the roller surface layer adheres to the surface of the first refresh roller 210. If these deposits remain, the surface of the first refresh roller 210 will be leveled, and the refresh performance of the surface of the heating roller will deteriorate. Therefore, as shown in FIG. 2A, the first cleaning duct 212, which is a hollow pipe in which the first cleaning discharge portion 211 is formed facing the first refresh roller 210, is installed.
The first cleaning duct 212 discharges compressed air from the first cleaning discharge unit 211 to remove the resin material and toner on the roller surface layer adhering to the surface of the first refresh roller 210.

The second fixing portion 309 shown in FIG. 2B includes a heater 251 and a heating roller 161 heated by the heater 251 and a pressurizing roller 162 rotating in the direction opposite to the heating roller 161.
The second fixing unit 309 also has a temperature detection thermistor 258 near the surface of the heating roller 161 in order to control the heater 251. In the image forming apparatus 300, the lighting / non-lighting of the heater 251 is controlled according to the detection result of the temperature detection thermistor 258.

In the second fixing portion 309, the sheet (recording paper 10 shown in the figure) primaryly fixed in the first fixing portion 308 is conveyed in the direction of arrow B and formed between the heating roller 161 and the pressurizing roller 162. When passing through the nip portion 259, it is heated and pressurized to perform re-fixing. As a result, the fixability of the toner can be improved and the gloss can be adjusted.

Further, in the second fixing portion 309, a second refresh roller 260 for rubbing the surface of the heating roller 161 to refresh the roller surface scratches is installed in the same manner as in the first fixing portion 308. Further, the second fixing portion 309 is provided with a second cleaning duct 262 which is a hollow pipe in which the second cleaning discharge portion 261 is formed so as to face the second refresh roller 260.
In this way, the first and second refresh rollers function as cleaning means for collecting the deposits on the surface of the rotating body, that is, the deposits on the surface of the heating roller, respectively. Further, the first and second cleaning discharge portions and the first and second cleaning ducts function as cleaning air discharge portions, respectively.
Regarding the configuration of the second refresh roller 260, the second cleaning discharge unit 261 and the second cleaning duct 262, the first refresh roller 210, the first cleaning discharge unit 211, and the first cleaning duct of the first fixing unit 308 have. Since the configuration is equivalent to 212, the description thereof will be omitted.

FIG. 3 is a diagram for explaining peripheral configurations of the image forming apparatus 300, which are related to the separate discharge unit 205, the first cleaning discharge unit 211, and the second cleaning discharge unit 261 of each fixing portion.
In the first fixing section 308 and the second fixing section 309, the first cleaning discharge section 211 and the second cleaning discharge section 261 have the same configuration, but the first fixing section 308 has a peeling guide plate 204. It differs in that. Therefore, the first fixing unit 308 will be taken up and described in detail as a representative.

The compressor 371 (air supply means) shown in FIG. 3 compresses the air sucked through the input filter 372 to generate compressed air, and the generated compressed air is inside the pipe 320 connected via each connecting member 321. Discharge to. In this embodiment, a compressor using an AC motor is used, but the present embodiment is not limited to this.

The input filter 372 is for preventing internal deterioration and damage of the compressor due to suction of foreign matter, or for preventing generation of suction noise when sucking air from the compressor.
The atmospheric release valve 302 is a solenoid valve for making the atmospheric pressure in the pipe 320 the same as that of the atmosphere when the compressor 371 is started. Specifically, the valve is electrically opened and closed in order to open the space inside the pipe 320 to the outside air. This is because when the compressor 371 is started, it is necessary to make the pressure in the pipe 320 the same as the atmospheric pressure to reduce the load on the discharge side of the compressor.

The pressure gauge 322 measures the atmospheric pressure in the pipe 320.
The pressure adjusting valve 306 adjusts the pressure of the compressed air discharged from the compressor 371. The pressure adjusting valve 306 is configured so that the pressure in the pipe 320 can be manually adjusted based on the measured value of the pressure gauge 322 so as to be constant.

The relief valve 303 is connected to the downstream side of the pressure adjusting valve 306, and releases unnecessary compressed air equal to or higher than the pressure adjusting value to the atmosphere. In this embodiment, it is assumed that the pressure adjustment value of the pressure adjustment valve 306 is adjusted to 0.3 [MPa].

The separation solenoid valve 304 switches whether to send compressed air toward the separation discharge unit 205 via the inside of the release guide plate 204 by opening and closing the valve. For example, the separation solenoid valve 304 is controlled to be opened at a predetermined timing. When the separation solenoid valve 304 is opened, the compressed air passes through the release guide plate 204 and reaches the separation discharge portion 205 in which the arranged discharge holes are formed. The compressed air that has reached the separation discharge unit 205 is discharged between the heating roller 151 and the recording paper 10.

Similar to the separation solenoid valve 304, the first cleaning solenoid valve 305 switches whether or not compressed air is sent to the first cleaning discharge unit 211 via the inside of the first cleaning duct 212 by opening and closing the valve. ..
Similarly, whether or not the second cleaning solenoid valve 307 of the second fixing portion 309 sends compressed air to the second cleaning discharge portion 261 via the inside of the second cleaning duct 262 by opening and closing the valve. To switch.

After starting the compressor 371, the atmosphere release valve 302, the separation solenoid valve 304, the first cleaning solenoid valve 305, and the second cleaning solenoid valve 307 are all closed. As a result, the pressure in the pipe 320 is maintained at the pressure (pressure adjustment value) set via the pressure adjustment valve 306.

FIG. 4 is a block diagram for explaining an example of control of the separation discharge unit 205, the first cleaning discharge unit 211, the second cleaning discharge unit 261, and the like included in the image forming apparatus 300.
The image forming apparatus 300 includes a CPU 400, a memory 401, a compressor drive circuit 403, a current detection circuit 404, and drive circuits 410 to 413.
The CPU 400 comprehensively controls each functional configuration of the image forming apparatus 300.
The memory 401 is a non-volatile memory, and stores, for example, various parameter data for controlling the operation of the image forming apparatus 300.

The compressor drive circuit 403 drives the compressor 371 in response to a control signal output from the CPU 400. Specifically, the compressor drive circuit 403 supplies AC to the compressor 371 in response to an ON signal from the CPU 400 to start driving the compressor 371, shuts off the AC supply in response to an OFF signal, and shuts off the AC supply to the compressor 371. Stop driving.
Further, a current detection circuit 404 is arranged between the compressor drive circuit 403 and the compressor 371. The current detection circuit 404 detects the current value of the drive current flowing into the compressor 371.

The CPU 400 controls the opening and closing of the atmospheric release valve 302 via the drive circuit 410. The CPU 400 also controls the opening and closing of the separation solenoid valve 304 via the drive circuit 411. The CPU 400 also controls the opening and closing of the first cleaning solenoid valve 305 via the drive circuit 412. The CPU 400 also controls the opening and closing of the second cleaning solenoid valve 307 via the drive circuit 413.

In this way, in the various solenoid valves, the drive / stop of the solenoid inside the solenoid valve is controlled according to the ON / OFF signal from the CPU 400, and the valve is released or closed.
The separation solenoid valve 304, the first cleaning solenoid valve 305, and the second cleaning solenoid valve 307 are normally closed types (NC type) in which the valve is released in response to an ON signal from the CPU 400 and the valve is closed in response to an OFF signal. ) Solenoid valve. The atmospheric release valve 302 is a normally open type (NO type) solenoid valve that closes the valve in response to an ON signal from the CPU 400 and releases the valve in response to an OFF signal.

The current detection circuit 404 is configured as a current transformer, rectifies its output, amplifies it, and converts it into a voltage signal. The converted voltage signal is notified to the CPU 400 as a current detection signal whose voltage value changes linearly according to the drive current of the compressor 371.
The current detection signal is input to the AD converter of the CPU 400 and digitally converted. In this way, the drive current of the compressor 371 can be detected.

FIG. 5 is a flowchart showing an example of a processing procedure for adjusting the pressure (discharged air pressure) of the compressed air discharged by the compressor 371. Each process shown in FIG. 5 is mainly performed by the CPU 400.
For example, in the manufacturing process of the image forming apparatus, it is necessary for the operator to manually set the discharge pressure of the compressor to an arbitrary value by adjusting the pressure adjusting valve. An example of the processing procedure until the characteristic formulas of the discharged air pressure and the current value are derived in the discharge air pressure adjusting process in the manufacturing process will be described.

The CPU 400 starts driving the compressor 371 in the standby state in which the power of the image forming apparatus 300 is turned on (S501).
In this case, when the compressor 371 is started, the state of the atmospheric release valve 302 is changed to the valve open state as described later. Further, after the compressor 371 is started, the state of the atmospheric release valve 302 is changed to the valve closed state. Further, the pressure adjusting valve 306 is manually adjusted by the operator in advance so that the pressure becomes sufficiently low.

The CPU 400 sets the state of the atmospheric release valve 302 to the valve release state (S502). As a result, the air pressure on the discharge side of the compressor 371 becomes equivalent to 0 [Mpa] (at the first predetermined pressure), and the driving state of the compressor 371 becomes a no-load state.
The CPU 400 samples and measures the current detection signal corresponding to the no-load current value I0 of the compressor 371 in the no-load state via the current detection circuit 404 (S503).
The CPU 400 measures the no-load voltage V0 corresponding to the no-load current value I0 obtained by averaging a plurality of sampling results, and stores the value in the memory 401 (S504).

After the state of the atmospheric release valve 302 is changed to the valve closed state again, the CPU 400 notifies the operator via the operation unit 4 to adjust the discharge air pressure to 0.2 [Mpa] (S505).
The operator operates the pressure adjusting valve 306 to adjust the discharge air pressure so that the indicated value of the pressure gauge 322 becomes 0.2 [Mpa]. The operator sets that the adjustment has been completed via the operation unit 4.

After accepting the adjustment end setting, the CPU 400 measures the drive current value I1 of the compressor 371 when 0.2 [MPa] is set (at the second predetermined pressure) in the same manner as the no-load current value I0 (S506). The CPU 400 measures a 0.2 [Mpa] voltage V1 corresponding to the drive current value I1 and stores the value in the memory 401 (S507).

The CPU 400 notifies the operator via the operation unit 4 to adjust the discharge air pressure to 0.3 [Mpa] (S508).
The operator operates the pressure adjusting valve 306 to adjust the discharge air pressure so that the indicated value of the pressure gauge 322 becomes 0.3 [Mpa]. The operator sets that the adjustment has been completed via the operation unit 4.

After accepting the adjustment end setting, the CPU 400 measures the drive current value It of the compressor 371 when 0.3 [MPa] is set (at the third predetermined pressure) in the same manner as the no-load current value I0 (S509). The CPU 400 measures a 0.3 [Mpa] voltage Vt corresponding to It and stores the value in the memory 401 (S510).
The CPU 400 stops driving the compressor 371, derives the acquired characteristic formulas of V0, V1, Vt and the air pressure on the discharge side by an approximate formula (S511), and stores the derived result in the memory 401 (S512). ..

FIG. 6 is a graph for explaining the characteristic formula derived by the process shown in FIG. In both FIGS. 6A and 6B, the vertical axis represents the current detection signal [V], and the horizontal axis represents the compressor discharge side air pressure (discharge air pressure) [Mpa].

The graph shown in FIG. 6A shows the result of quadratic polynomial approximation based on the three values of the no-load current value I0, the drive current value I1, and the V0, V1, and Vt measurement points corresponding to the drive current value It. It is a graph which shows.
Further, FIG. 6B is a graph in which the actual measurement results adjusted to the air pressure on the discharge side different from the measurement points are plotted as the actual measurement points. In the graph shown in FIG. 6B, it can be seen that the results correspond to the characteristic formula derived based on the measurement result of the drive current of the compressor 371.

In this way, the discharge side pressure of the compressor 371 is adjusted so as to have a predetermined pressure at two or more points in addition to the no-load state, and the drive current of the compressor 371 at that time is measured. Then, the characteristic equations of the compressor discharge side pressure and the drive current are derived based on the measurement result. This makes it possible to compare the characteristic formula with the result of sampling and measuring the drive current and estimate the air pressure on the discharge side (discharge air pressure) with high accuracy based on the comparison result.

FIG. 7 is a flowchart showing an example of a processing procedure for determining the state of airtightness between the compressor and the solenoid valve, which is performed by the image forming apparatus 300 based on the characteristic formula derived in the processing shown in FIG. Each process shown in FIG. 7 is mainly performed by the CPU 400. Further, when the power is turned on to the image forming apparatus 300, leakage detection, that is, determination of the airtightness state is started. Further, as described above, the compressor 371 needs to reduce the load on the discharge side of the compressor when it is started. Therefore, normally, the state of the atmospheric release valve 302 is set to the valve open state and started.

The CPU 400 sets the state of the atmospheric release valve 302 to the valve closed state (S7001).
The CPU 400 turns on the power supply (AC supply) to the compressor 371 for a short time in the valve closed state, and measures the current value at that time (S7002).
When the air release valve 302 is in the valve closed state, there is no escape place for air on the discharge side. Further, if the compressor is driven in that state, the load becomes larger than in the state of the discharge pressure of 0.3 [MPa] during normal operation. Therefore, if there is no leakage of compressed air on the discharge side of the compressor, that is, if the airtightness is not lost, a current larger than the current It flows as compared with the case where the discharge pressure is 0.3 [MPa]. It will be.

The CPU 400 determines whether or not the drive current / voltage conversion value is Vt or more (S7003). When the drive current / voltage conversion value is Vt or more (S7003: Yes), the CPU 400 determines that there is no leakage of compressed air, that is, the airtightness is not lost (S7004). After that, the determination process ends.
If the compressor is driven for a long time in this state, a load is applied to the compressor. Therefore, the process is completed in a short time, and the state of the atmospheric release valve 302 is quickly changed to the valve open state.

When the drive current / voltage conversion value is less than Vt (S7003: No), the CPU 400 determines that there is leakage of compressed air, that is, the airtightness is lost (S7005). This is because, for example, when the airtightness between the compressor 371 and each solenoid valve is lost, such as when there is an air escape place on the discharge side of the compressor, the load becomes light even when the valves are closed.

The CPU 400 presents information (for example, an alarm) indicating that the airtightness between the compressor 371 and each solenoid valve is lost and a compressed air leak occurs via the operation unit 4, or a component. Notify that a replacement is required. Further, the acceptance of jobs using the compressor 371 is restricted (S7006). In this way, it is possible to prevent a decrease in the life of the device (particularly, the fixing roller) due to deterioration of the separation performance and the cleaning performance.

FIG. 8 is a graph for explaining the relationship between the state of airtightness between the compressor and the solenoid valve, the voltage conversion value of the current, and the output air pressure. In both FIGS. 8A and 8B, the vertical axis represents the output air pressure (discharge air pressure) [Mpa] of the compressor and the voltage conversion value (voltage) [V] of the drive current at the same atmospheric pressure, and the horizontal axis represents the main body. The elapsed time [t] after the power is turned on is set. The solid line in each figure indicates the discharge air pressure, and the alternate long and short dash line indicates the change in the voltage value with the passage of time.

The graph of FIG. 8A shows the relationship between the voltage conversion value of the current and the output air pressure when there is no “leakage” of the compressed air on the compressor discharge side.
As shown in FIG. 8A, when the state of the atmospheric release valve is set to the valve closed state and the power of the compressor 371 is turned on, as described in the explanation of FIG. 7, the current at 0.3 [Mpa] is applied. It can be seen that a voltage larger than the voltage conversion value Vt is detected.

Further, when the state of the atmospheric release valve 302 becomes the valve open state, the detection voltage becomes the voltage V0 in the no-load state due to the opening of the valve. At this time, when the compressor 371 is driven, the voltage at 0.3 [Mpa] set in the manufacturing process is detected.

Further, the graph of FIG. 8B shows the relationship between the voltage conversion value of the current and the output air pressure when a “leakage” of compressed air occurs on the compressor discharge side.
As shown in FIG. 8 (b), when the compressed air leaks, that is, when the airtightness is lost, even if the air release valve 302 is in the valve closed state, it is the same as the valve open state. There is almost no load. Therefore, it can be seen that the detected voltage is very small.

As described above, the image forming system S (image forming apparatus 300) according to the present embodiment is in a state of a member that distributes compressed air of the compressor by monitoring the drive current of the AC motor at the time of starting the compressor, that is, the compressor and electromagnetic waves. The state of airtightness between the valves can be determined.
This makes it possible to determine the state of airtightness between the compressor and the solenoid valve with an inexpensive and simple configuration, and a device (particularly, a fixing roller) due to deterioration of separation performance and cleaning performance due to abnormal pressure of compressed air. ) Can be prevented from shortening its life.

The embodiments described above are for more specific explanation of the present invention, and the scope of the present invention is not limited to these examples.

4 ... Operation unit, 300 ... Image forming device, 301 ... Sheet feeding device, 304 ... Post-processing device, S ... Image forming system.

Claims (7)

Fixing means for fixing the toner image on the sheet to the sheet by heating and pressurizing it with a rotating body.
A cleaning means for collecting deposits on the surface of the rotating body and
An air supply means that discharges compressed air toward a cleaning air discharge portion that blows air onto the surface of the cleaning means, and an air supply means.
A detection means that detects the current value of the drive current flowing into the air supply means, and
A first valve means for opening the compressed air discharged by the air supply means to the outside air or closing the compressed air from the outside air,
A second valve means for supplying or stopping the compressed air discharged by the air supply means to the cleaning air discharge portion.
It has a determination means for determining the state of airtightness between the air supply means and the second valve means.
The determination means includes information representing the characteristics of the air supply means derived based on the discharge air pressure of the air supply means and the current value detected by the detection means at that time, and the state of the first valve means. The airtightness between the air supply means and the second valve means is compared with the current value detected by the detection means when the air supply means is activated in the closed state, and based on the comparison result. The feature is to judge the state,
Image forming device. The information representing the characteristics of the air supply means includes the first current value at the first predetermined pressure detected by the detection means, the second current value at the second predetermined pressure, and the third predetermined pressure. It is characterized in that it is derived based on the third current value of time.
The image forming apparatus according to claim 1. The determination means compares the third current value with the current value detected by the detection means when the state of the first valve means is closed and the air supply means is activated. It is characterized in that the state of airtightness between the air supply means and the second valve means is determined based on the comparison result.
The image forming apparatus according to claim 2. It has an operation unit that presents information to the user and accepts operations from the user.
The determination means is characterized by presenting to the user information indicating that the airtightness between the air supply means and the second valve means is lost via the operation unit.
The image forming apparatus according to claim 1, 2 or 3. It has a control means for controlling the operation of the image forming apparatus.
When the determination means determines that the airtightness between the air supply means and the second valve means is lost, the control means limits the acceptance of jobs using the air supply means. Characteristic,
The image forming apparatus according to any one of claims 1 to 4. A separate air section that blows air toward the rotating body when the sheet is peeled off from the rotating body,
The air supply means has a third valve means for supplying or stopping the compressed air discharged toward the separated air portion.
The determination means determines the state of airtightness between the air supply means and the second and third valve means.
The image forming apparatus according to any one of claims 1 to 5. A fixing device that heats and pressurizes a toner image on a sheet with a rotating body to fix it on the sheet.
The fixing device is
A cleaning means for collecting deposits on the surface of the rotating body and
An air supply means that discharges compressed air toward a cleaning air discharge portion that blows air onto the surface of the cleaning means, and an air supply means.

A detection means that detects the current value of the drive current flowing into the air supply means, and
A first valve means for opening the compressed air discharged by the air supply means to the outside air or closing the compressed air from the outside air,
A second valve means for supplying or stopping the compressed air discharged by the air supply means to the cleaning air discharge portion.
It has a determination means for determining the state of airtightness between the air supply means and the second valve means.
The determination means includes information representing the characteristics of the air supply means derived based on the discharge air pressure of the air supply means and the current value detected by the detection means at that time, and the state of the first valve means. The airtightness between the air supply means and the second valve means is compared with the current value detected by the detection means when the air supply means is activated in the closed state, and based on the comparison result. The feature is to judge the state,
Fixing device.