JP2010054961A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, achieving energy saving and eliminating trouble due to overheating in the apparatus. <P>SOLUTION: When a control unit 105 determines that the interior of the apparatus needs cooling, power is supplied from a storage battery 101 and a thermoelectric transducer 102 to thereby cause high-speed rotary drive of a fan 100. Alternatively, the power supply to the fan 100 is stopped to charge the storage battery 101 with the thermoelectric transducer 102. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for effectively using waste heat of a fixing device.

An electrophotographic image forming apparatus includes a fixing device that melts and presses a toner image transferred onto a recording sheet. If the heat generated by the fixing device is trapped in the image forming apparatus, there is a risk that equipment around the fixing device will be overheated, causing problems or toner welding in the toner bottle. For this reason, it is common to provide a cooling fan to exhaust heat outside the machine.
Exhaust heat to the outside of the machine, for example, needs to continue even after the main power supply is interrupted due to a sudden power failure, so a technology has been developed that uses the residual heat of the fuser to supply power to the fan using a thermoelectric conversion element. ing. According to this technique, if the power generation amount of the thermoelectric conversion element is reduced as the temperature of the fixing device is lowered, there is a possibility that sufficient electric power cannot be supplied to the fan.

In order to solve such a problem, for example, there is a technique in which output power of a thermoelectric conversion element is stored in a secondary battery in advance, and when the temperature of the fixing device is lowered, power is supplied from the secondary battery to drive a fan. It has been proposed (see Patent Document 1). Thereby, even if the temperature of the fixing device is lowered, it is possible to prevent the occurrence of a malfunction due to the fan stop.
JP 2006-171481 A

In recent years, there has been a strong demand for image forming apparatuses to increase the number of prints per unit time. For this reason, for example, the fixing time per recording sheet has been shortened by increasing the fixing temperature and melting the toner faster.
However, when the fixing temperature is raised, the inside of the image forming apparatus may be overheated to cause a problem. For example, when an IC (Integrated Circuit) that controls the fan is thermally destroyed, the fan cannot be driven, and the interior of the apparatus is further overheated.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that realizes energy saving and elimination of problems caused by overheating in the apparatus.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a fixing device that thermally fixes a toner image to a recording sheet, a thermoelectric conversion element that generates power using heat from the fixing device, a storage battery, If the temperature inside the machine is lower than the required cooling temperature, power supply from the thermoelectric conversion element and storage battery to the fan is stopped, the storage battery is charged by the thermoelectric conversion element, and the temperature inside the machine If the temperature is higher than the cooling temperature, a power supply control means for supplying power to the fan from the thermoelectric conversion element and the storage battery is provided.

  In this way, if the in-machine temperature is lower than a predetermined required cooling temperature, the electric power generated by the thermoelectric conversion element is stored in the storage battery without driving the fan unnecessarily, so that energy saving can be achieved. Further, if the in-machine temperature is higher than the required cooling temperature, electric power is supplied from both the thermoelectric conversion element and the storage battery to the fan and the fan is driven to rotate at a higher speed.

In this case, it is preferable that a temperature sensor for measuring the in-machine temperature is provided, and that the power supply control means determine whether the in-machine temperature is equal to or lower than a predetermined required cooling temperature based on the measurement result of the temperature sensor.
In addition, a voltmeter for measuring the electromotive voltage of the thermoelectric conversion element is provided, and the power supply control means has a predetermined internal cooling temperature if the electromotive voltage measured by the voltmeter is lower than a predetermined cooling voltage. It may be determined that the temperature is lower than the temperature.

Furthermore, the image forming apparatus according to the present invention includes a charge control unit that stops power supply from the thermoelectric conversion element to the storage battery when the electromotive voltage of the thermoelectric conversion element is lower than a predetermined charge stop voltage. .
Further, if the in-machine temperature measured by the temperature sensor is lower than a predetermined charge stop temperature, a charge control means for stopping power supply from the thermoelectric conversion element to the storage battery may be provided.

  Furthermore, it is preferable to provide an overcharge prevention means for stopping power supply from the thermoelectric conversion element to the storage battery when the storage amount of the storage battery exceeds a predetermined amount.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the present embodiment will be described.
FIG. 1 is a diagram illustrating a main configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes a fan 100, a storage battery 101, a thermoelectric conversion element 102, a heat radiation fin 103, a temperature sensor 104, a control unit 105, imaging units 110Y to 110K, an exposure unit 111, and an intermediate transfer belt. 112, a secondary transfer roller 113, a paper feed cassette 114, a pickup roller 115, a fixing device 116, a cleaner 117, a paper discharge roller 119, and a paper discharge tray 120, and toner bottles 118Y to 118K are mounted.

The imaging units 110Y to 110K develop the electrostatic latent image formed by the exposure device 111 to form yellow (Y), magenta (M), cyan (C), and black (K) toner images. Primary transfer is performed on the transfer belt 112. Residual toner on the intermediate transfer belt 112 is removed by a cleaner 117.
The paper feed cassette 114 stores the recording sheet P therein. The recording sheets P are taken out one by one by the pickup roller 115 and sent out to the conveyance path. The secondary transfer roller 113 electrostatically transfers the toner image on the intermediate transfer belt 112 onto the recording sheet.

The fixing device 116 melts the toner image and presses the toner image on the recording sheet. Thereafter, the recording sheet is discharged onto the discharge tray 120 by the discharge roller 119.
The control unit 105 monitors the internal temperature with the temperature sensor 104 and supervises the overall operation of the image forming apparatus 1. In addition, the toner bottles 118Y to 118K are detachably mounted, and supply toner of each color to the imaging units 110Y to 110K, respectively.

The thermoelectric conversion element 102 generates electric power by utilizing a temperature difference generated when one side surface is heated by radiant heat from the fixing device 116 and the other side surface is cooled by the heat radiating fins 103.
The electric power generated by the thermoelectric conversion element 102 is supplied to the fan 100 and the storage battery 101. The storage battery 101 supplies power to the fan 100 under the control of the control unit 105. The fan 100 is driven at a higher number of times as the applied voltage is higher, and the rotational speed is reduced when the applied voltage is lowered.

The fan 100 discharges warm air in the apparatus heated and heated by the fixing device 116 to the outside. Then, since outside air is taken into the image forming apparatus 1 from an air inlet (not shown), the temperature inside the apparatus is lowered, and various parts in the apparatus are cooled. Thereby, thermal failure of each component constituting the image forming apparatus 1 is prevented.
[2] Power Supply System of Fan 100 Next, a power supply system for supplying power to the fan 100 will be described.

FIG. 2 is a diagram illustrating a configuration of the power feeding system. As shown in FIG. 2, the power feeding system 2 includes a storage battery 101, a thermoelectric conversion element 102, a heat radiation fin 103, a temperature sensor 104, a control unit 105, a switch 201, and a sheet metal part 202.
The sheet metal part 202 isolates the fixing device 116 and the toner bottles 118Y to 118K. As a result, the amount of heat transferred from the fixing device 116 to the toner bottles 118Y to 118K is reduced, and the toner in the toner bottles 118Y to 118K is prevented from being overheated and fused.

The thermoelectric conversion element 102 is formed by alternately connecting P-type semiconductor pieces and N-type semiconductor pieces. The phenomenon that holes (holes) move in the P-type semiconductor and electrons move in the N-type semiconductor from the high temperature side to the low temperature side is called the Seebeck effect. The semiconductor moves so that the movement directions of the holes and electrons are opposite to each other. By connecting the pieces, the temperature difference can be converted into a potential difference.
Note that the high temperature side of the thermoelectric conversion element 102 is closely attached and fixed to the sheet metal part 202 with an insulating adhesive. Moreover, the radiation fin 103 is being fixed to the low temperature side. Thereby, a larger temperature difference can be given to the thermoelectric conversion element 102 to improve the power generation efficiency.

The electric power generated by the thermoelectric conversion element 102 is supplied to the fan 100 via the switch 201. The switch 201 connects or disconnects the storage battery 101 to / from a circuit including the fan 100 under the control of the control unit 105.
FIG. 3 is a circuit diagram illustrating a main configuration of the power feeding system 2. As shown in FIG. 3, the switch 201 includes two switches 201 a and 201 b, both of which are under the control of the control unit 105. Further, the control unit 105 measures the electromotive voltage of the thermoelectric conversion element 102 with the voltmeter 301.

  Fan 100 receives power from a power supply circuit in which storage battery 101 and thermoelectric conversion element 102 are connected in parallel. The control unit 105 switches the switch 201a in accordance with the in-machine temperature measured by the temperature sensor 104, and controls power supply from the storage battery 101 and the thermoelectric conversion element 102 to the fan 100. In addition, the control unit 105 switches the switch 201b according to the electromotive voltage of the thermoelectric conversion element 102 measured by the voltmeter 301, and connects or disconnects the storage battery 101 to the thermoelectric conversion element 102.

[3] Configuration of Control Unit 105 Next, the configuration of the control unit 105 will be described. The control unit 105 is a so-called computer, and as shown in FIG. 4, a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, and an I / O interface (Input / Input). Output Interface) 404 is connected by an internal bus 405.

The control unit 105 controls the sheet cassette 114, the imaging units 110Y to 110K, the switches 201a and 201b, and the like via the I / O interface 404, and monitors the internal temperature with the temperature sensor 104.
[4] Operation of Control Unit 105 Next, the operation of the control unit 105 will be described.

  FIG. 5 is a flowchart illustrating an operation performed by the control unit 105 to control the power feeding system 2. As shown in FIG. 5, the control unit 105 refers to the in-machine temperature t with the temperature sensor 104 (S501), and switches the switch 201a when the in-machine temperature t exceeds the required cooling temperature T (S502: Yes). Then, the fan 100 is connected to the power source, that is, the storage battery 101 and the thermoelectric conversion element 102 (S503). As a result, the interior of the machine is cooled.

The required cooling temperature T means that if the in-machine temperature t is equal to or lower than the required cooling temperature T, there is no need to cool the inside of the apparatus by the fan 100, and if the in-machine temperature t exceeds the required cooling temperature T, This is the temperature that must be cooled.
If the in-machine temperature t is equal to or lower than the required cooling temperature T (S502: Yes), the switch 201a is switched to disconnect the fan 100 from the power supply (S504). As a result, the inside of the apparatus is not unnecessarily cooled by the fan 100, and power can be saved.

  Furthermore, if the electromotive voltage v of the thermoelectric conversion element exceeds the predetermined voltage V (S505: Yes), the storage battery 101 is connected to the thermoelectric conversion element 102 (S506). In this case, the storage battery 101 supplies power to the fan 100 if the fan 100 is connected to the circuit, and the storage battery 101 is charged by the thermoelectric conversion element 102 if the fan 100 is disconnected from the circuit.

The predetermined voltage V is a voltage at which the storage battery 101 cannot be charged by the thermoelectric conversion element if the electromotive voltage v is equal to or lower than the predetermined voltage V.
Moreover, if the electromotive voltage v is below the predetermined voltage V (S505: No), the storage battery 101 will be cut off from the thermoelectric conversion element 102 (S507).
In this way, when the inside of the apparatus is at a high temperature, current is output from both the storage battery 101 and the thermoelectric conversion element 102, so that a high voltage is applied to the fan 100. Then, since the fan 100 rotates at higher speed, the inside of the apparatus can be cooled more quickly.

Further, since the storage battery is charged without rotating the fan 100 until the inside of the machine is sufficiently cooled and further cooling is not necessary, wasteful power consumption can be reduced.
Further, when the in-machine temperature is lowered and the electromotive force of the thermoelectric conversion element 102 is lowered, the storage battery is disconnected from the circuit, so that wasteful discharge from the storage battery can be prevented.
[5] Modifications As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .

(1) In the above embodiment, the case where the temperature sensor 104 and the voltmeter 301 are used to control the switch 201 has been described, but it goes without saying that the present invention is not limited to this. It may be as follows.
For example, instead of measuring the in-machine temperature with the thermometer 301, the switch 201a may be controlled according to the level of the electromotive voltage of the thermoelectric conversion element 102 measured with the voltmeter 301. This is because the level of the electromotive voltage of the thermoelectric conversion element 102 changes according to the level of the in-machine temperature, and therefore the in-machine temperature can be estimated by measuring the electromotive voltage.

Conversely, the switch 201b may be controlled according to the temperature inside the machine. This is because, as described above, the electromotive voltage of the thermoelectric conversion element 102 changes according to the level of the in-machine temperature, so that the in-machine temperature can be estimated from the electromotive voltage of the thermoelectric conversion element 102.
(2) In the above embodiment, the case where the switch is controlled with reference to the in-machine temperature has been described. Needless to say, the present invention is not limited to this, and the following may be performed.

That is, the control unit 105 measures the temperature of the recording sheet on the paper discharge tray 120 in addition to the internal temperature, and if either the internal temperature or the recording sheet temperature is higher than a predetermined cooling temperature, the fan 100 And the fan 100 may be stopped if both are lower than the required cooling temperature.
In order to increase the speed of the image forming apparatus, a toner having a high fixing temperature or a low melting temperature is used. As a result of the difference between the fixing temperature and the melting temperature of the toner as described above, if the recording sheet is discharged without solidifying the toner, there is a possibility that the overlapping recording sheets are stuck on the discharge tray.

On the other hand, according to this modification, the recording sheet is reliably cooled by using the thermoelectric conversion element 102 together with the storage battery 101 and rotating the fan 100 at a higher speed, so that tacking can be eliminated.
In this case, if the wind generated by the exhaust of the fan 100 is sent to the discharge tray, the recording sheet on the discharge tray can be cooled more efficiently.

(3) Although not particularly mentioned in the above embodiment, generally, overcharging the storage battery may cause inconveniences such as shortening the life of the storage battery, so an overcharge prevention circuit may be added. desirable.
For example, when the voltage of the storage battery 101 rises to a predetermined value V1, charging of the storage battery 101 may be stopped. In this way, since the storage battery 101 is not overcharged, problems due to overcharge can be prevented.

In general, when the storage battery stops charging, the amount of stored electricity gradually decreases. Therefore, a very small amount of power may be supplied to the storage battery 101 while the charging is stopped. In this way, sufficient electric power can be supplied from the storage battery 101 when the fan is driven to rotate.
Furthermore, it is desirable to maintain the charge stop state of the storage battery 101 until the voltage of the storage battery 101 drops to a voltage V2 lower than the predetermined value V1. In this way, charging is not resumed immediately even if the voltage of the storage battery 101 decreases due to the natural gradual decrease in the amount of stored electricity, so that frequent stopping and resuming of charging can be prevented.

  Needless to say, when power is supplied from the storage battery 101 to the fan 100, the storage battery 101 is connected to a circuit regardless of the voltage of the storage battery 101.

  The image forming apparatus according to the present invention is useful as a technique for effectively using the waste heat of the fixing device.

1 is a diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of a power supply system for supplying power to a fan 100. FIG. 1 is a diagram illustrating a main circuit configuration of a power feeding system 2. FIG. FIG. 2 is a diagram illustrating a main configuration of a control unit 105. 4 is a flowchart illustrating an operation performed by a control unit to control the power feeding system 2.

Explanation of symbols

1 ……………………… Image forming apparatus 2 ……………………… Power supply system 100 …………………… Fan 101 ………………… Storage battery 102 ……………… ... thermoelectric conversion element 103 ......... radiating fin 104 ............... temperature sensor 105 ............... control unit 110Y to 110K ... imaging unit 111 ............... exposure device 112... ...... Intermediate transfer belt 113... ...... Secondary transfer roller 114... …… Fixer 117 …………………… Cleaner 118Y to 118K… Toner bottle 119 …………………… Discharge roller 120 ………………… Discharge tray 201 …………… Switch 201a, 201b ... switch 202 ............... Gold 301 ..................... voltmeter 401 ..................... CPU
402 …………… ROM
403 …………… RAM
404 ... I / O interface 405 ... Internal bus P ... Recording sheet

Claims (6)

A fixing device for thermally fixing a toner image to a recording sheet;
A thermoelectric conversion element that generates heat using heat from the fixing device;
A storage battery,
A fan that cools the inside of the aircraft,
If the in-machine temperature is lower than the required cooling temperature, power supply to the fan from the thermoelectric conversion element and the storage battery is stopped, and the storage battery is charged with the thermoelectric conversion element,
An image forming apparatus comprising: a thermoelectric conversion element and a power supply control unit configured to supply power from the storage battery to the fan if the in-machine temperature is higher than a predetermined cooling temperature. It has a temperature sensor that measures the temperature inside the machine,
The image forming apparatus according to claim 1, wherein the power supply control unit determines whether the in-machine temperature is equal to or lower than a predetermined required cooling temperature based on a measurement result of the temperature sensor. It has a voltmeter that measures the electromotive voltage of the thermoelectric conversion element,
The power feeding control means determines that the in-machine temperature is lower than a predetermined required cooling temperature if the electromotive voltage measured by the voltmeter is lower than the predetermined required cooling voltage. Image forming apparatus. The image according to claim 1 or 3, further comprising charge control means for stopping power supply from the thermoelectric conversion element to the storage battery if the electromotive voltage of the thermoelectric conversion element is lower than a predetermined charge stop voltage. Forming equipment. 2. The image forming apparatus according to claim 1, further comprising a charge control unit that stops power supply from the thermoelectric conversion element to the storage battery when the in-machine temperature measured by the temperature sensor is lower than a predetermined charge stop temperature. The image forming apparatus according to claim 1, further comprising an overcharge prevention unit that stops power supply from the thermoelectric conversion element to the storage battery when a storage amount of the storage battery exceeds a predetermined amount.

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