JP2015031820A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus configured to generate electric power at an optimum operation point, and an image forming method.SOLUTION: The image forming apparatus includes: a power generation element 201 which generates electric power with heat generated in an image forming apparatus 100; temperature detection means which controls a fixing temperature of the image forming apparatus 100; a load 212 for consuming the power for the image forming apparatus 100; a switching circuit 211 which selects shared power generated by the image forming apparatus 100 from an AC power supply 206 or power from a storage battery 209 for supplying the electric power generated in the power generation element 201 to the load 212; and a control unit 204 which controls an output voltage of the power generation element 201 in response to the fixing temperature used by the image forming apparatus 100.

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus and an image forming method for making it possible to generate power at an optimum operating point using exhaust heat from a fixing device.

  In recent years, electrophotographic image forming apparatuses have high power saving needs. In order to meet these needs, not only power supply from commercial power sources but also power generation (power generation) is performed in the apparatus. A technique for using the generated power more efficiently has been considered.

  Japanese Patent Laid-Open No. 2012-124991 (Patent Document 1) discloses that an image forming apparatus provided with a solar cell can always generate power by storing the solar cell with optimum efficiency in order to increase the power generation efficiency. A configuration is disclosed in which an MPPT circuit capable of following the voltage at the optimum operating point at which the output of the solar cell is maximum is provided between the solar cell and the storage battery, and output control of the power generation element is performed.

  However, in Patent Document 1 in which power generation is performed using a solar cell, adjustment is performed by feedback control of the MPPT circuit so that the output of the solar cell that fluctuates with the amount of solar radiation and temperature is maximized. For this reason, in the control of the MPPT circuit, it takes time to search for the optimum operating point, and there is a problem that the responsiveness to weather changes is poor. Further, there is a problem that even if the control of the MPPT circuit used in the solar cell is used as it is, even if it is applied to an image forming apparatus whose power consumption changes according to the user setting, the power cannot be used with optimum efficiency.

  The present invention has been made in view of the above-described prior art, and the present invention creates electricity using exhaust heat from the fixing device and instantaneously determines the voltage at the optimum operating point of the power generating element. An object of the present invention is to provide an image forming apparatus capable of using electric power with optimum efficiency.

In the present invention, there is provided an image forming apparatus capable of generating power at an optimum operating point by controlling the output voltage of a power generating element in accordance with a fixing set temperature that varies depending on printing conditions such as monochrome, color, thick paper, and thin paper.
That is, according to the present invention, a power generation element that generates power using heat generated by the image forming apparatus,
Load means for consuming power for the image forming apparatus;
Switching means for switching between shared power generated by the image forming apparatus from an AC power supply and power from a secondary battery means for providing the power generated by the power generation element to the load means;
There is provided an image forming apparatus including a control unit that controls an output voltage of the power generation element in response to a fixing temperature used by the image forming apparatus.

1 is a schematic diagram of an image forming apparatus 100 of the present embodiment. The block diagram of the functional module of the power supply system in a digital compound machine. FIG. 10 is a block diagram of another embodiment of a functional module of a power supply system in the image forming apparatus 100 of the present embodiment. The flowchart of the control processing which the control part 304 performs when utilizing the electric power generation of the electric power generation element 301. FIG. The figure which shows the voltage-current characteristic in the case of using a thermoelectric element as an electric power generation element in this embodiment. The figure explaining operation | movement of MPPT control used in solar power generation.

  FIG. 1 is a schematic diagram of an image forming apparatus 100 of the present embodiment. The image forming apparatus 100 is configured as a digital multi-function peripheral and can provide a copy function, a printer function, a facsimile function, and the like. The plurality of functions can be selected by sequentially switching a copy function, a printer function, and a facsimile function by using an application switching key of an operation unit such as a so-called operation panel. By function switching, the copy mode is selected when the copy function is selected, the printer mode is selected when the printer function is selected, and the facsimile mode is functioned when the facsimile mode is selected.

  Hereinafter, the functional units of the image forming apparatus 100 will be briefly described with reference to FIG. 1, taking the operation of the image forming apparatus 100 in the copy mode as a specific example.

  In the copy mode, the document bundle is sequentially fed to the image reading device 120 by the ADF 110, and the image information is read by the image reading device 120. The read image information is converted into optical information by the writing unit 130 as writing means via the image processing means. The photosensitive drum 142 is uniformly charged by a charger (not shown) and then exposed with optical information from the writing unit 130, and an electrostatic latent image is formed on the surface of the photosensitive drum 142.

  The electrostatic latent image on the photosensitive drum 142 is developed by the developing device 141 to be visualized as a toner image. The toner image is transferred onto the transfer paper by the transfer belt 143. The transfer belt 143 conveys the transfer paper carrying the toner image to the fixing device 144, fixes the toner image on the transfer paper by the fixing device 144, and discharges it to the outside as a printed matter having a solid toner image. ing.

  FIG. 2 is a block diagram of functional modules of the power supply system in the digital multifunction peripheral. The power generating element 201 is installed adjacent to the pressure roller of the fixing device 203 and converts the heat energy discharged from the fixing device 144 into electric energy.

  The control unit 204 stores the fixing temperature transition state under printing conditions such as color / monochrome, transfer paper type, and number of printed sheets in a storage unit 205 such as NVRAM or EEPROM. The control unit 204 determines in advance the output voltage setting value of the power generation element for the printing conditions from the history of the storage unit 205, and sets the output voltage of the power generation element according to the printing conditions during printing. With this output voltage setting, the control unit 204 switches the output voltage of the power generation element 201. The output voltage setting value can be set in advance in firmware or the like in consideration of the generated power characteristics of the power generation element 201 with respect to the temperature condition. As the power generation element 201, a Peltier element that functions in an appropriate temperature range can be used, but the invention is not limited thereto.

  The electric energy generated from the power generation element 201 charges the storage battery 209 configured by a secondary battery via the DDC 208 that functions as a charger. As the storage battery, any known secondary battery such as a nickel cadmium battery or a lithium ion battery can be used.

  The electrical energy stored in the storage battery 209 is supplied to the load 212 via the DDC 210 that functions as a discharger and the switching circuit 211. Here, the DDC 208, the DDC 210, and the switching circuit 211 require power to operate, but a common power line of the image forming apparatus 100 is also connected to each module. The switching circuit 211 functions to switch the shared power generated from the AC power source 206 and the power generated by the power generation element 201 and supplied from the storage battery 209 and the DDC 210 according to control by the control unit 204 and supply the load to the load. To do.

  The control unit 204 controls the entire image forming apparatus 100 and operates each load sequentially according to each operation mode.

  FIG. 3 is a block diagram of another embodiment of a power supply function module in the image forming apparatus 100 of the present embodiment. The power generation element 301 is installed adjacent to the pressure roller of the fixing device 303 and converts the heat energy discharged from the fixing device 144 into electric energy. The control unit 304 sets the fixing set temperature according to the printing conditions, and sets the output voltage of the power generation element 301 in response to the temperature detected by the environmental temperature detection unit 313. The control unit 304 performs control so as to switch the output voltage of the power generation element 301 when setting the output voltage. The output voltage setting value can be set in advance in the firmware of the control unit 304 in consideration of the power characteristics of the power generation element 301 with respect to the temperature condition.

  The electrical energy generated by the power generation element 301 is stored in the storage battery 309 via the DDC 308 that functions as a charger. The stored electrical energy is supplied to the load 312 via the DDC 310 functioning as a discharger and the switching circuit 311. Here, the DDC 308, the DDC 310, and the switching circuit 311 require power to operate, and this power can use a common power supply line of the image forming apparatus 100.

  The switching circuit 311 controls the shared power generated based on the AC power supplied from the AC power source 306 and the power generated by the power generation element 301 and supplied via the storage battery 309 and the DDC 310 by the control unit 304. The switches are switched to each other and supplied to the load 312. The control unit 304 controls the entire image forming apparatus 100 and operates each load sequentially according to each operation mode.

  In the present embodiment, it is possible to provide time measuring means for measuring the elapsed time of the process so as not to perform temperature control and switching control each time continuous printing is performed. This timing means saves the previous set value for the time between sheets in continuous printing, and if it is determined to be continuous printing, the printing process can be performed without changing the setting at the previous printing. . In this embodiment, it is possible to eliminate the redundancy that a control process for temperature setting and voltage setting must be performed each time when printing is performed continuously.

  In yet another embodiment, the timed time can be used to determine the temperature rise rate of the fixing device 144. In the present embodiment, the control unit 304 predicts the final fixing temperature by associating the temperature increase rate with the process time, and performs voltage control so that optimum power generation is performed in association with the temperature increase state. At the same time, switching control can be performed. Information used for this purpose can also be stored in the storage means 205, 305. A program for that purpose can be stored in the control unit 304 itself or the storage unit 305 as firmware of the control unit 304.

  FIG. 4 shows a flowchart of a control process performed by the control unit 304 when the power generation of the power generation element 301 is used. The process of FIG. 4 starts when the image forming apparatus 100 is powered on in step S400. Thereafter, in step S401, a color / monochrome printing selection command is received from the user or a default color designation is acquired, and a transfer paper selection command designated thereafter is detected in step S402. At this stage, the control unit determines the fixing temperature in step S403 with reference to a lookup table or the like for the transfer sheet specified in the specified color mode.

  Thereafter, it is determined whether or not the determined fixing temperature is equal to or lower than the threshold value 1. If the determined fixing temperature is equal to or lower than the threshold value 1 (yes), the output voltage of the power generation element is set to xV in step S406, and the charging circuit is set in step S410. turn on. If the set fixing temperature exceeds the threshold value 1 (no), it is determined in step S405 whether the fixing setting temperature is equal to or lower than the threshold value 2. If the set fixing temperature is equal to or lower than the threshold value 2 (yes), the output voltage of the power generation element is set to yV in step S407, and the charging circuit is turned on in step S411.

  On the other hand, if the set fixing temperature exceeds the threshold value 2 (no), the output voltage of the power generating element is set to zV in step S408, and the charging circuit is turned on in step S409. The threshold values 1 and 2 described in steps S404 and S405 are optimum set temperatures determined by monochrome printing, color printing, transfer paper, and the like. For example, the threshold value 1 can be a fixing temperature set in the case of high-quality paper in monochrome printing, and the threshold value 2 can be a set temperature in the case of printing on plain paper in full-color printing. In addition to this, as the threshold value, a set temperature when a full-color image is fixed on a plastic sheet can be used.

  The control unit of the present embodiment switches the output voltage of the power generation element according to the threshold value and performs power generation with optimum efficiency according to the temperature condition, thereby efficiently reusing and reusing heat energy as electric energy. Make it possible.

  FIG. 5 shows voltage-current characteristics when a thermoelectric element is used as a power generation element in the present embodiment. The horizontal axis is the output voltage, and the vertical axis is the output current. Thermoelectric elements have the characteristic that the operating voltage that provides optimum efficiency varies with the operating temperature. For this reason, it is necessary to set the operating voltage that gives the optimum efficiency depending on the operating temperature.

  FIG. 6 illustrates the MPPT control operation of the present embodiment. Looking at the voltage-current characteristics of FIG. 5, the thermoelectric element 630 has a characteristic that when the output current is increased, the output voltage is decreased, and when the output current is decreased, the output voltage is increased. When control is performed to increase the output voltage of the DDC 620 that functions as a charger, the potential difference from the storage battery 610 increases. For this reason, the charging current to the storage battery 610 increases. For this reason, in view of the characteristics of the thermoelectric element, the input voltage to the DDC decreases. On the other hand, the reverse relationship also holds. Therefore, by controlling the output voltage of the DDC, the current that can be extracted from the thermoelectric element can be maximized, and the charging power can be increased.

  At this time, since the operating temperature of the thermoelectric element becomes a temperature to be set in the fixing device, the control unit controls the output voltage of the DDC so that the maximum power can be generated at the set fixing temperature.

  As described above, according to the present invention, it is possible to generate electric energy regeneratively from the heat energy generated by the fixing device and use it as a power source for operating various loads of the image forming apparatus. An image forming apparatus with improved energy efficiency can be provided.

  The present invention has been described with the embodiment. However, the present invention is not limited to the embodiment, and other embodiments, additions, modifications, deletions, and the like can be conceived by those skilled in the art. Any of the embodiments is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

100: Image forming apparatus 110: ADF
120: image reading device 130: writing unit 140: printer unit 141: developing device 142: photosensitive drum 143: transfer belt 144, 203, 303: fixing device 150: capacitor unit 201, 301: power generation element 202, 302: temperature detection Elements 204 and 304: Control units 205 and 305: Storage means 206 and 306: AC power supply 207 and 307: PSU
208, 210, 308, 310: DDC
209, 309: storage batteries 211, 311: switching circuit 212, 312: load 313: environmental temperature detection means

JP 2012-124991 A

Claims (6)

A power generation element that generates electricity using heat generated by the image forming apparatus;
Load means for consuming power for the image forming apparatus;
Switching means for switching between shared power generated by the image forming apparatus from an AC power supply and power from a secondary battery means for providing the power generated by the power generation element to the load means;
An image forming apparatus comprising: control means for controlling an output voltage of the power generating element in response to a fixing temperature used by the image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit controls the output voltage so that the power generating element generates electric power with an optimum electric power according to the fixing temperature. Temperature detecting means for detecting the fixing temperature;
In order for the control means to control the output voltage of the power generating element, the control means comprises storage means for storing information in which the output voltage of the power generating element and output current are associated with each other, and the control means comprises the detected fixing temperature 3. The image forming apparatus according to claim 1, wherein information on an output voltage to be set is acquired from the storage unit in response to the control to control the output voltage.   The image forming apparatus includes a time measuring unit that measures a time from the previous fixing to the next fixing, and predicts an output voltage of the control unit according to a time elapsed from the previous fixing. The image forming apparatus according to any one of the above.   5. The image forming apparatus according to claim 1, wherein the image forming apparatus detects a temperature rise state of the fixing temperature, and controls the output voltage and the switching unit by the control unit. 5. Image forming apparatus. Generating power by a power generation element using heat generated by the image forming apparatus;
Detecting a fixing temperature of the image forming apparatus;
Switching between shared power generated by the image forming apparatus from an AC power source and power from secondary battery means for providing the power generated by the power generation element;
Supplying the switched power to load means that consumes power for the image forming apparatus;
Controlling the output voltage of the power generating element in response to the fixing temperature used by the image forming apparatus.