JP4435644B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine.

  In the image forming apparatus, an image can be formed on a sheet by transferring a toner image onto the sheet and performing heat treatment on the sheet after the toner image is transferred on the fixing unit. (For example, refer to Patent Document 1). The fixing unit includes, for example, a heating roller (fixing roller) and a pressure roller. The surfaces of the heating roller and the pressure roller are in contact with each other at a predetermined pressure, and at least one roller (for example, a heating roller) is heated by a heater. With such a configuration, the paper after the toner image has been transferred is subjected to a fixing process such as a heat process or a pressure process in the process of passing between the heating roller and the pressure roller, and transferred to the sheet. The toner image is fixed.

During the image forming operation, the heater is driven and the temperature of the heating roller is set to a predetermined fixing temperature (for example, about 170 ° C.), so that the fixing process (heating process) can be performed satisfactorily. On the other hand, during the non-image forming operation, that is, when the image forming operation (toner image transfer processing operation, fixing processing operation, etc.) is not performed on the paper, the driving power supplied to the heater is reduced, so that the heating roller Is a predetermined temperature (about 135 ° C. to 165 ° C.) lower than the fixing temperature. Thus, the power consumption of the fixing unit (heater) can be reduced, and when the image forming operation is started, the temperature of the heating roller can be raised to the fixing temperature in a short time.
JP 2000-221831 A

  When the size of the paper used is relatively large (for example, A3 size or B4 size), or when the paper used is of a type having a relatively large thickness (or weight ratio) (for example, an OHP sheet), Since the amount of heat given to the sheet is increased by performing the heat treatment in the fixing unit, the driving time of the heater is lengthened and the power consumption of the fixing unit is increased. On the other hand, when the size of the used paper is relatively small (for example, B5 size or A5 size), or when the used paper is of a type with a relatively small thickness (or weight ratio) (for example, tracing paper) In the case of thin paper, the amount of heat given to the paper is reduced by the heat treatment in the fixing unit, so that the heater driving time is shortened and the power consumption of the fixing unit is reduced.

Accordingly, when an image forming operation is performed using only a relatively large size paper or a relatively large thickness (or weight ratio) within a predetermined period, consumption of the fixing unit within the predetermined period is performed. The power increases and the power consumption of the entire image forming apparatus increases.
The present invention has been made under such a background, and an object thereof is to provide an image forming apparatus capable of suppressing an increase in power consumption.

In order to achieve the above object, according to the first aspect of the present invention, a toner image is transferred onto a sheet, and the sheet after the toner image is transferred is subjected to a heat treatment in a fixing unit, whereby an image is formed on the sheet. An image forming apparatus capable of forming, each time a heat treatment is performed on a sheet in the fixing unit, a coefficient corresponding to the area of the processed sheet and a weight ratio or thickness per unit of the sheet and integrating means for integrating the point where the coefficient a is obtained by multiplying, a determination unit for a certain period for integrating the power consumption is determined whether or not elapsed, the elapse of a predetermined period is determined by the determining means On the basis of this, power consumption control means for correcting the fixing control temperature at the time of non-image formation based on the point value accumulated by the accumulation means and clearing the point value accumulated by the accumulation means, Mukoto an image forming apparatus according to claim.

According to this arrangement, power consumption during the image forming operation in a constant during period, is determined based on the point value integrated by the integrating means, but when the power consumption is large, the power consumption during the non-image forming operation By controlling so as to decrease, an increase in power consumption of the entire image forming apparatus can be suppressed.

According to a second aspect of the present invention, the fixing unit (9) includes a heater (12) driven for heat treatment, and the integrating means (18, 19) is subjected to heat treatment in the fixing unit. The image forming apparatus according to claim 1 , further comprising a heater driving time integrating unit (19) that integrates a value corresponding to the heater driving time at the time.

If the driving time of the heater when the heat treatment is performed in the fixing unit is relatively long, the amount of heat given to the paper is increased by performing the heat treatment in the fixing unit, and the heater when the heat processing is performed in the fixing unit If the driving time is relatively short, the amount of heat given to the paper is reduced by performing the heat treatment in the fixing unit.
According to the configuration of the present invention, the power consumption in the fixing unit during the image forming operation within the predetermined period is determined based on the integrated value of the values corresponding to the heater driving time when the heating process is performed in the fixing unit. However, when the power consumption is high, an increase in power consumption of the entire image forming apparatus can be suppressed by controlling so that the power consumption in the fixing unit during the non-image forming operation is reduced.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus 1 according to an embodiment of the present invention.
Referring to FIG. 1, image forming apparatus 1 is, for example, a copying machine and can form (copy) an image based on image data of a document read by a scanner (not shown) on a sheet. is there.

  The outer shape of the image forming apparatus 1 is partitioned by a substantially rectangular parallelepiped housing 2. In the housing 2, an image forming unit 3 is disposed for transferring the toner image based on the image data of the document read by the scanner to a sheet to form an image. For the image forming unit 3, for example, a known configuration including a main charger and a developing device (not shown) in addition to the photosensitive member 4 and the transfer device 5 can be adopted. That is, at the time of image formation, the surface of the substantially cylindrical photoconductor 4 is uniformly charged by the main charger, and the surface of the photoconductor 4 is irradiated with light based on the image data, whereby the surface of the photoconductor 4 is irradiated. A so-called electrostatic latent image is formed. Toner is selectively attached to the surface of the photoreceptor 4 on which the electrostatic latent image is formed by a developing device, and a toner image is formed. The toner image formed on the surface of the photoconductor 4 is transferred to a sheet by the function of the transfer device 5.

  A paper storage unit 6 for storing paper used for image formation is disposed at the lower part of the housing 2. The paper storage unit 6 can store papers of different sizes (A3 size, B4 size, A4 size, B5 size, A5 size, etc.) and types (plain paper, OHP sheet, thin paper, etc.), for example. At the time of image formation, the sheets stored in the sheet storage unit 6 are sent one by one to the image forming unit 4 through the sheet transport path 7, and the toner image is transferred to the sheet in the image forming unit 4.

  The sheet on which the toner image has been transferred is guided to the fixing unit 9 by the transport belt 8. The fixing unit 9 is for fixing the toner image transferred to the paper, and includes a pair of fixing rollers (a heating roller 10 and a pressure roller 11) arranged rotatably. The surfaces of the heating roller 10 and the pressure roller 11 are in contact with each other with a predetermined pressure, and at least one of the rollers (for example, the heating roller 10) has one or more (for example, 2 for example) disposed therein. The fixing heater 12 is heated. With such a configuration, the paper after the toner image is transferred is subjected to a fixing process such as a heat process or a pressure process in the process of passing between the heating roller 10 and the pressure roller 11, and the sheet is subjected to the process. The transferred toner image is fixed. Reference numeral 13 denotes a fixing thermistor for detecting the temperature of the heating roller 10 (the surface thereof). The sheet after image formation (after the fixing process) is discharged to a discharge tray 14 disposed outside the apparatus.

FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus 1.
The operation of the image forming apparatus 1 is controlled by a control unit 15 including a microcomputer. In addition to the signal from the fixing thermistor 13 (a signal indicating the temperature of the heating roller 10), the control unit 15 includes a signal from the operation unit 16 for performing various input operations (for starting an image forming operation). An instruction signal) and a signal from a sheet passing sensor 17 for detecting whether or not the sheet has passed through the fixing unit 9 are input. When copying with the image forming apparatus 1, the size and type of paper to be used are input by operating the operation unit 16.

The fixing heater 12 is connected to the control unit 15 as a control target, and the control unit 15 turns on / off the driving of the fixing heater 12 based on an input signal from the fixing thermistor 13 and the like. 10 is adjusted to a predetermined temperature (fixing control temperature).
Further, the control unit 15 includes a number counter 18 for counting (accumulating) points according to the number of sheets on which the fixing process is performed by the fixing unit 9, and a fixing heater when the fixing process is performed by the fixing unit 9. A heater drive time counter 19 for counting (accumulating) points corresponding to 12 drive times (on times) and a timer 20 for measuring time are provided.

  If the number of sheets subjected to the fixing process (heating process) in the fixing unit 9 is relatively large, the amount of heat given to the sheet is increased by performing the fixing process in the fixing unit 9, and the fixing process (heating) is performed in the fixing unit 9. If the number of sheets to be processed is relatively small, the amount of heat applied to the sheet is reduced by performing the fixing process in the fixing unit 9. Further, if the driving time of the fixing heater 12 when the fixing process (heating process) is performed in the fixing unit 9 is relatively long, the amount of heat given to the sheet increases due to the fixing process being performed in the fixing unit 9. If the driving time of the fixing heater 12 when the fixing process (heating process) is performed in the unit 9 is relatively short, the amount of heat given to the sheet is reduced by performing the fixing process in the fixing unit 9.

  Therefore, a point counted by the sheet counter 18 (a point corresponding to the number of sheets to be fixed by the fixing unit 9) and a point counted by the heater driving time counter 19 (when the fixing process is performed by the fixing unit 9). The point corresponding to the driving time (on time) of the fixing heater 12) is an integrated value of a value corresponding to the amount of heat given to the sheet by performing the fixing process (heating process) in the fixing unit 9, in other words, For example, it represents an integrated value of values corresponding to power consumption (in the fixing unit 9) during an image forming operation within a predetermined period.

FIG. 3 is a time chart showing a specific example of a change in the fixing control temperature.
Referring to FIG. 3, the operation state of image forming apparatus 1 includes a standby state as a state during a non-image forming operation in which an image forming operation is not performed, in addition to a copy state in which an image forming operation is performed. Preheat state is included.
In the copy state, the fixing control temperature is set to a relatively high temperature (for example, about 170 ° C.) in order to heat the sheet after the toner image is transferred by the image forming unit 3. During the copying state, the control unit 15 adjusts the ratio of the ON time to the OFF time of the fixing heater 12 based on the input signal from the fixing thermistor 13, and sets the temperature of the fixing heater 12 to the set temperature (fixing temperature). Thus, feedback control is performed. The fixing temperature varies depending on the type of paper used (plain paper, OHP sheet, thin paper, etc.), that is, when the paper used is an OHP sheet, it is higher than that for plain paper. When the paper used is thin paper, the temperature is set lower than that of plain paper.

  When the image forming operation (copy state) is completed, the fixing control temperature is set to a temperature lower than that in the copy state (for example, a predetermined temperature between 157 ° C. and 165 ° C.), and the operation state of the image forming apparatus 1 is the standby state. It becomes. During the standby state, the control unit 15 reduces the drive power supplied to the fixing heater 12 by reducing the ratio of the on-time to the off-time of the fixing heater 12 than in the copy state, and the temperature of the fixing heater 12 is reduced. Feedback control is performed so that the set temperature (standby temperature) is reached.

  If the image forming operation is not started after a certain period of time has elapsed after entering the standby state, the fixing control temperature is lower than that in the standby state (for example, a predetermined temperature between 135 ° C. and 155 ° C.). And the operation state of the image forming apparatus 1 becomes the preheat state. During the preheating state, the control unit 15 further reduces the driving power supplied to the fixing heater 12 by reducing the ratio of the ON time to the OFF time of the fixing heater 12 as compared with that in the standby state. The feedback control is performed so that becomes the set temperature (preheat temperature).

  In the example of FIG. 3, the image forming operation is started in a standby state where the fixing control temperature is set to 165 ° C., and the fixing control temperature is changed to 170 ° C., so that the fixing temperature is about 170 ° C. during the copying state. Fixing processing is performed on three sheets of paper. When the image forming operation is finished, the fixing control temperature is set to a stand-by state at 161 ° C., and after a predetermined time has elapsed from the stand-by state, the fixing control temperature is set to a preheating state at which the fixing control temperature is set to 150 ° C. It has migrated.

As described above, during the non-image forming operation (standby state or preheat state), the driving power supplied to the fixing heater 12 is reduced, thereby reducing the power consumption of the fixing unit 9 (fixing heater 12). In addition, when the image forming operation is started, the temperature of the heating roller 10 can be raised to the fixing temperature in a short time.
FIG. 4 is a diagram for explaining the points counted by the number counter 18.

  As shown in FIG. 4, when a fixing process is performed on a certain sheet by the fixing unit 9, the sheet size corresponding to the area of the sheet (A3 size, B4 size, A4 size, B5 size, A5 size, etc.) A point obtained by multiplying the coefficient corresponding to the above and the coefficient corresponding to the type of paper (plain paper, OHP sheet, thin paper, etc.) is counted by the number counter 18.

  More specifically, with respect to the paper size, the A4 size is set as the reference size (coefficient is 1.0), and the B4 size whose area ratio to the A4 size is 1.7 has a coefficient of 1.7 for the A4 size. The A3 size with an area ratio of 2.0 has a coefficient of 2.0, the B5 size with an area ratio of 0.7 for the A4 size has a coefficient of 0.7, and the area ratio for the A4 size of 0.5. A coefficient 0.5 is associated with each A5 size. Regarding the paper type, plain paper is used as the reference type (coefficient is 1.0), and the weight ratio (or thickness) to plain paper is 1.5 for the OHP sheet, and the coefficient is 1.5 for the plain paper. A coefficient of 0.5 is associated with thin paper (for example, tracing paper) having (or thickness) of 0.5.

In the example shown in FIG. 4, the number counter 18 is obtained by counting points obtained by multiplying the coefficient according to the size and type of paper as described above for a predetermined period (for example, one week). The count value (integrated value) is 2198 points.
On the other hand, although not shown, the heater driving time counter 19 counts the time (sec) when the fixing heater 12 is turned on during the image forming operation (during the copying state) performed within a predetermined period (for example, one week). The Therefore, for example, when the fixing heater 12 is turned on for 2831 sec during the image forming operation (during copying) performed within the predetermined period, the count value (integrated value) of the heater driving time counter 19 is set. Is 2831 points.

  In this embodiment, according to the point counted by the sheet counter 18 during one week or the point counted by the heater driving time counter 19 during one week (in the standby state and preheating) In this state, the fixing control temperature is set, and the power consumption (of the fixing unit 9) during the non-image forming operation is controlled. According to such a configuration, the power consumption (of the fixing unit 9) during the image forming operation is determined based on the points counted by the number counter 18 or the points counted by the heater driving time counter 19, and the consumption When the power is high, an increase in power consumption of the entire image forming apparatus 1 can be suppressed by controlling so that the power consumption (in the fixing unit 9) during the non-image forming operation is reduced.

  If the area (size) of the paper is relatively large, the heat treatment is performed in the fixing unit 9, so that the amount of heat given to the paper increases. If the area (size) of the paper is relatively small, the heat treatment is performed in the fixing unit 9. As a result, the amount of heat applied to the paper is reduced. In addition, if the paper is of a type having a relatively large thickness (or weight ratio), the amount of heat given to the paper increases due to the heat treatment performed by the fixing unit 9, and the paper is relatively thick (or weight ratio). If the type is small, the amount of heat given to the sheet is reduced by performing the heat treatment in the fixing unit 9.

In this embodiment, the point counted by the number counter 18 is a value corresponding to the size (area) and type of the sheet on which the fixing process (heating process) is performed in the fixing unit 9, so that during the image forming operation It is possible to more accurately determine the power consumption in the fixing unit 9 (during copying).
FIG. 5 is a flowchart showing the control contents performed by the control unit 15 while the image forming apparatus 1 is powered on.

  Referring to FIG. 5, when copying is started by operation of operation unit 16 (YES in step S <b> 1), control unit 15 causes paper passing sensor 17 until copying is completed (YES in step S <b> 6). On the basis of the input signal from, it is monitored whether or not the sheet has passed through the fixing unit 9 (step S2) and whether or not the fixing heater 12 has been driven (step S4).

  When the sheet passes through the fixing unit 9 (YES in step S2), the control unit 15 multiplies a coefficient corresponding to the size and type of the sheet based on the size and type of the sheet input in advance. The points obtained by this are counted by the number counter 18 (step S3: number counting process). When the fixing heater 12 is driven (YES in step S4), the control unit 15 counts the time during which the fixing heater 12 is turned on by the heater driving time counter 19 (step S5: heater driving time counting). processing). Then, when copying is completed (YES in step S6), the control unit 15 monitors whether or not copying is started again by the operation of the operation unit 16 (step S1).

  On the other hand, when copying is not performed (NO in step S1), that is, during the non-image forming operation, the control unit 15 passes a certain time (for example, one week) based on the input signal from the timer 20. It is monitored whether or not (step S7). If the predetermined time has elapsed (YES in step S7), the control unit 15 sets the fixing control temperature in the standby state based on the count value of the number counter 18 or the count value of the heater driving time counter 19 ( (Step S8), and the fixing control temperature in the preheat state is set (corrected) (step S9). Thereafter, the control unit 15 clears the count values of the number counter 18 and the heater driving time counter 19 (step S10), starts the time measurement by the timer 20 from “0” (step S11), and again of the operation unit 16 Whether or not copying is started by the operation is monitored (step S1).

FIG. 6 is a diagram illustrating an example of the fixing control temperature set based on the count value of the number counter 18.
As shown in FIG. 6, the fixing control temperature (standby temperature) in the standby state is set to a lower temperature as the number of points counted by the number counter 18 during a certain time (for example, one week) is larger. It has become.

  In this embodiment, by operating the operation unit 16 in advance, the preheat state can be set to be executed in either the energy saving priority mode or the return time priority mode. In the return time priority mode, regardless of the count value of the sheet counter 18, the fixing control temperature (preheat temperature) in the preheat state is set to a constant value (for example, 155 ° C.), so that the image forming operation is performed during the preheat state. Even when started, the temperature of the heating roller 10 can be raised (returned) to the fixing temperature in a shorter time. On the other hand, in the energy saving priority mode, the preheat temperature is set to a lower temperature as the point counted by the number counter 18 is larger.

When the count value of the sheet counter 18 is 2198 points as shown in FIG. 4, the standby temperature is set to 161 ° C., and the preheat temperature is 145 ° C. in the energy saving priority mode and 155 in the recovery time priority mode. Set to ° C.
FIG. 7 is a diagram illustrating an example of the fixing control temperature set based on the count value of the heater driving time counter 19.

As shown in FIG. 7, the fixing control temperature (standby temperature) in the standby state is set to a lower temperature as the point counted by the heater driving time counter 19 during a certain time (for example, one week) is larger. It has become so.
In the recovery time priority mode, the fixing control temperature (preheating temperature) in the preheating state is set to a constant value (for example, 155 ° C.) regardless of the count value of the heater driving time counter 19, thereby forming an image during the preheating state. Even when the operation is started, the temperature of the heating roller 10 can be raised (returned) to the fixing temperature in a shorter time. On the other hand, in the energy saving priority mode, the preheat temperature is set to a lower temperature as the point counted by the heater driving time counter 19 is larger.

When the count value of the heater drive time counter 19 is 2831 points, for example, the standby temperature is set to 163 ° C., and the preheat temperature is set to 150 ° C. in the energy saving priority mode and 155 ° C. in the return time priority mode. The
FIG. 8 is a diagram showing the energy saving rate according to the preheat temperature and the standby temperature. FIG. 8A shows the ratio of the ON time to the OFF time of the fixing heater 12 in the preheating state according to the preheating temperature and the energy saving rate, and FIG. 8B shows the standby state according to the standby temperature. The ratio of the ON time to the OFF time of the fixing heater 12 and the energy saving rate are shown.

  As shown in FIG. 8A, when the preheat temperature is set low, the ratio of the on time to the off time of the fixing heater 12 in the preheat state is small, so that the power consumption is reduced and the energy saving rate is increased. I understand that As shown in FIG. 8B, when the standby temperature is set low, the ratio of the on time to the off time of the fixing heater 12 in the standby state is small, so that the power consumption is reduced and the energy saving rate is reduced. It can be seen that increases.

The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
For example, when the power consumption during the image forming operation (during the copying state) is large, the power consumption of the fixing unit 9 (fixing heater 12) during the non-image forming operation (during the standby state or during the preheating state) is reduced. The configuration is not limited to the configuration in which the control is performed, and the configuration in which the control is performed so that the power consumption of other portions other than the fixing unit 9 is reduced.

  The present invention is not limited to a copying machine, and can be applied to an image forming apparatus other than a copying machine such as a printer or a facsimile.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus. 6 is a time chart showing a specific example of a change in fixing control temperature. It is a figure for demonstrating the point counted in a number counter. 3 is a flowchart illustrating control contents performed by a control unit during power-on of the image forming apparatus. FIG. 6 is a diagram illustrating an example of a fixing control temperature set based on a count value of a number counter. It is a figure which shows an example of the fixing control temperature set based on the count value of a heater drive time counter. It is a figure which shows the energy-saving rate according to the preheating temperature and standby temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 9 Fixing part 12 Fixing heater 15 Control part 18 Number counter 19 Heater drive time counter

Claims (2)

An image forming apparatus capable of forming an image on a sheet by transferring a toner image to the sheet and performing heat treatment on the sheet after the toner image is transferred in a fixing unit,
Each time the sheet is heated by the fixing unit, the points obtained by multiplying the coefficient according to the area of the processed sheet and the coefficient according to the weight ratio or thickness per unit of the sheet are integrated. Integrating means;
A discriminating means for discriminating whether or not a certain period for integrating power consumption has elapsed;
Based on the lapse of a predetermined time period by the determining means is determined, based on the point value the accumulating means is accumulated, it corrects the fixing control temperature in the non-image-forming period, by integrating the integration means An image forming apparatus comprising: a power consumption control unit that clears a point value. The fixing unit includes a heater driven for heat treatment,
The image forming apparatus according to claim 1, wherein the integration unit includes a heater driving time integration unit that integrates a value corresponding to a driving time of the heater when the heating process is performed in the fixing unit.

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