JP4170849B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

  Japanese Patent Application Laid-Open No. 2004-133830 discloses a paper gap adjusting unit capable of changing a paper gap distance from the trailing edge of a recording material to the leading edge of the succeeding recording material in a conveyance direction during continuous fixing processing of a plurality of recording materials, and switching. The power capacity of the commercial power supply is controlled by controlling the paper gap adjusting means so that the temperature detected by the temperature detecting means is maintained at a predetermined temperature that can be fixed when the means is in a conduction state of power supplied from the power supply to the heating means. In this range, a fixing device capable of maintaining the maximum image forming speed without significantly reducing the image forming speed and an image forming apparatus including the fixing device are described.

  In Patent Document 2, a power input unit connected to a commercial power source and a plurality of power output units connected to a power supply unit of the device are provided, and between each of the different power output units and the power input unit A power supply change control means having a plurality of open / close sections that alternately open and close, and a time limit setting section that sets the switching timing of these open / close sections, and when the time set in the time limit setting section has been reached A power supply control device is described in which the voltage applied to the power supply input unit is alternately output to the plurality of different power supply output units by operating the opening / closing unit.

Japanese Patent Application Laid-Open No. 2002-229381

Japanese Patent Laid-Open No. 7-194002

  Image forming apparatuses such as copying machines and printers are required to increase the image forming speed and shorten the warm-up time. Particularly in recent years, image forming apparatuses are required to save energy, and it is desirable to eliminate power consumption by the fixing heater during standby. However, in the image forming apparatus, when the energization to the fixing heater is cut off during standby, if the time from the resumption of energization to the completion of warming up is long, the work efficiency is remarkably lowered. Therefore, shortening the warming up time is very important.

  However, when an image forming apparatus such as a copying machine or a printer tries to increase the image forming speed, the image forming apparatus is not limited to 1500 W, although the power capacity of a general commercial power source in Japan is limited. The electric power necessary for speeding up the operation of the apparatus increases, and the electric power distributed to the fixing device becomes more severe.

The higher the speed of the fixing device, the greater the number of recording papers passed per unit time and the more heat is taken away, and the roller temperature required for fixing cannot be maintained even if the heater is continuously turned on. The actual situation is that the number of image forming sheets of the image forming apparatus is determined by how many recording sheets can be fixed per minute.
In addition, since the image forming apparatus does not consume power of the exposure lamp and the motor at the time of warming up immediately after the power is turned on, it is possible to divide the power of several hundred watts to the fixing device. The time can be shortened.

  An object of the present invention is to provide an image forming apparatus capable of maintaining the maximum image forming speed without limiting the image forming speed due to insufficient heat quantity of the fixing device.

In order to achieve the above object, an invention according to claim 1 is directed to an image forming apparatus that includes a thermal fixing device that is heated by the supply of electric power from a commercial power source , and forms an image using the thermal fixing device. A plurality of plugs to which a first commercial power source and a second commercial power source constituting a plurality of commercial power sources having different capacities are respectively connected, and the rollers of the heat fixing device are respectively supplied by supplying power from the plurality of commercial power sources. Two heaters for heating independently, a power supply number designation switch for designating the number of commercial power supplies connected to the plurality of plugs, and an image forming speed according to the number of commercial power supplies connected to the plugs A control circuit for controlling the power supply, and the control circuit receives a signal from a power supply number designation switch to determine the number of commercial power supplies capable of supplying power, and to provide a power supply capable of supplying power to the heater. When only the first commercial power source is connected to the plug, an image forming operation is performed at a low speed, and the first commercial power source and the second commercial power source can be used to supply power to the heater. When a power source is connected to the plug, a high-speed image forming operation is performed .

  According to the present invention, the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat quantity of the fixing device.

FIG. 2 shows a first reference embodiment of the present invention. The first reference embodiment, a first reference embodiment of a digital copying machine as an image forming apparatus, an image forming system for reproducing a connexion image reading an original document. The document M is placed on the transparent plate 2a of the document table and fixed by the document mat 2b. In the optical system, the illumination lamp 41a emits light, the light is reflected by the reflecting mirror 41b, and the light from the illumination lamp 41a and the light from the reflecting mirror 41b are combined and applied to the document M.

  Image light, which is reflected light from the original M, moves with a moving reflection mirror 41c that moves integrally with the illumination lamp 41a, and a moving reflection mirror 42d that moves in the same direction at a half moving speed of the moving reflection mirror 41c. , And 42e, while passing through the lens 43a while scanning the document M while maintaining the optical path length, the light is received by the solid-state imaging device 43b.

  The output signal of the solid-state imaging device 43b is subjected to signal processing such as shading correction, gradation correction by γ conversion, and halftone reproduction by multi-value processing in an image processing unit (not shown), and then input to the laser driver unit 5a. The The laser driver unit 5a modulates and drives the semiconductor laser 5b with the image data from the image processing unit, and the laser beam modulated with the image data is output from the semiconductor laser 5b to the polygon mirror 5c.

  The polygon mirror 5c is rotated by the scanner motor 5d to deflect the laser light from the semiconductor laser 5b, and the laser light from the polygon mirror 5c is applied to the photosensitive drum 6 as an image carrier and is rotated with respect to the rotation direction of the photosensitive drum 6. Scan vertically. A photo sensor 5e is provided at a position 11 mm before the position at which scanning with the laser beam on the photosensitive drum 6 is started. Is generated. This BD signal determines the writing timing of one line by the semiconductor laser, and the output timing for one line of the image data of the line memory (timing for starting the modulation driving of the semiconductor laser 5b by the image data for one line). ). Here, the laser driver unit 5a, the semiconductor laser 5b, the polygon mirror 5c, and the scanner motor 5d constitute an exposure means for exposing the photosensitive drum 6.

  The photosensitive drum 6 is driven by a drive unit (not shown) and rotates in the direction of the arrow, and an image forming process is executed. That is, the photosensitive drum 6 is negatively and uniformly charged by a charger 7 to which a negative high voltage current is supplied from a high voltage power source (not shown) immediately before the laser beam is irradiated, and the photosensitive drum 6 is irradiated with the laser beam from the polygon mirror 5c. An electrostatic latent image is formed by scanning. The electrostatic latent image is developed by the developing device 8 and visualized into a toner image. Thereafter, the photosensitive drum 6 is irradiated with light by a charge eliminating lamp 9 for erasing the electrostatic latent image, and the negatively charged electrostatic latent image is erased.

  Next, the recording paper as the recording material sent from the paper feed cassette 13a by the rotation of the paper feed roller 13b is temporarily stopped while being abutted against the registration roller 13 when detected by the registration sensor 13c. When the registration roller 13 rotates in synchronization with the toner image on the upper side, the registration roller 13c feeds the toner image and reaches the transfer position below the photosensitive drum 6.

  The toner image on the thermal drum 6 is transferred to a recording sheet by a transfer electrode 10 as a transfer means to which a positive high voltage current is supplied from a high voltage generator (not shown), and then an AC high voltage current is supplied from the high voltage generator (not shown). Is removed from the photosensitive drum 6 by the separation electrode 11 supplied with the toner. After the toner image has been transferred, the photosensitive drum 6 passes through a static elimination lamp QL12 for eliminating the remaining charge, and the residual charge is removed. It is scraped off to be beautiful and finishes preparation for the next image formation. Here, the thermal drum 6, the charger 7, the exposure unit, the developing unit 8, the static elimination lamp QL12, the transfer electrode 10, the separation electrode 11, and the cleaning device 13 are image forming units for forming a toner image on the recording paper. It is composed.

  On the other hand, the recording paper on which the toner image separated from the photosensitive drum 6 is fed is conveyed by the conveyor belt 14 and passes between the upper roller 15a and the lower roller 15b of the heat fixing device 15 to be pressed and heated. The toner image is fixed to become a fixed image, and the fixed image is not disturbed even if it is blown or rubbed.

By the way, a general commercial power source in Japan is 100V15A, but there are also commercial power sources of other voltage / current, though the number is very small. In some countries, the voltage of the commercial power supply is generally 200V, 220V or 240V. In the first reference form, as shown in FIG. 6, a plurality of plugs 21 and 22 connected to a plurality of commercial power sources are provided, and the plugs 21 and 22 are selectively connected to a plurality of commercial power sources having different power capacities. Connected.

  The switching power supply 23 is connected to the plug 21 via a power switch 24 and a fuse 25, and is supplied with electric power from a commercial power supply via the plug 21, fuse 25 and power switch 24 to generate a predetermined DC voltage. The voltage is supplied to a control circuit 26 as a control means, a motor, a clutch, and the like. The fixing device 15 has a plurality of fixing heaters 27, 28. The fixing heaters 27, 28 are respectively connected to relays 29 a, 29 b, 29 c, triacs 30, 31 as switches, a power switch 24, and a fuse 25. Are connected to the plugs 21 and 22.

  The fixing heaters 27 and 28 are supplied with electric power from commercial power sources through plugs 21 and 22, fuse 25, power switch 24, triacs 30 and 31, and contacts 29 a, 29 b and 29 c of the relay 29, respectively, and generate heat, as shown in FIG. As shown, it is installed in a roller 15a of the fixing device 15 and heats the roller 15a. A diode 32 and resistors 33 and 34 are connected in series between two power lines to which the plug 21 is connected via a fuse 25 and a power switch 24, and a capacitor 55 is connected in parallel with the resistor 34. The connection point 33, 34 is connected to the A / D input 2 (terminal) of the control circuit 26.

  A diode 35 and resistors 36 and 37 are connected in series between two power lines to which the plug 22 is connected via the fuse 25 and the power switch 24, and a capacitor 38 is connected in parallel with the resistor 37. A connection point of 36 and 37 is connected to the A / D input 2 (terminal) of the control circuit 26. As shown in FIG. 5, the thermistor 39 is a temperature detecting element that detects the surface temperature of the upper roller 15a in the fixing device 15. The thermistor 39 is connected to the + 5V terminal of the switching power supply 23 and the A / D input 1 (terminal) of the control circuit 26. Connected between.

  The coil of the relay 29 is connected between the + 5V terminal of the switching power supply 23 and the output 3 (terminal) of the control circuit 26. The contact 29a of the relay 29 is a contact that opens and closes between the heater 27 and the triac 30, the contact 29b of the relay 29 is a contact that switches the heater 27 to the triacs 30 and 31, and the contact 29c of the relay 29 is the heater 27. Is a contact for switching connection between the heater 27 and the triac 31. The outputs 1 and 2 (terminals) of the control circuit 26 are connected to the gate sides of the triacs 30 and 31 via solid state relays (SSR) 51 and 52, respectively.

  The AC voltage input from the commercial power supply via the plug 21, fuse 25, and power switch 24 is rectified by the diode 32, divided by the resistors 33 and 34, smoothed by the capacitor 55, and A / D of the control circuit 26. The control circuit 26 determines whether the voltage of the commercial power source connected to the plug 21 is 100V or 200V from the input voltage and whether there is power supply from the plug 21 based on the commercial power source. To do. The AC voltage input from the commercial power supply via the plug 22, fuse 25, and power switch 24 is rectified by the diode 35, divided by the resistors 36 and 37, smoothed by the capacitor 38, and A / D of the control circuit 26. The control circuit 26 determines whether the voltage of the commercial power source connected to the plug 22 is 100V or 200V from the input voltage and whether there is power supply from the plug 22 based on the commercial power source. To do.

When the voltage of the commercial power source connected to the plug 21 is 100 V and power is supplied from the plug 22 by the commercial power source, the control circuit 26 controls the relay 29 to turn on both the heaters 27 and 28. The control of the first reference mode is performed so that the high-speed continuous image formation is performed by turning on the light. In addition, the control circuit 26 cannot turn on the heater 28 when the voltage of the commercial power source connected to the plug 21 is 100 V and no power is supplied from the plug 22 by the commercial power source. The control of the first reference mode is performed so that low-speed continuous image formation is performed by lighting.

Further, when the voltage of the commercial power source connected to the plug 21 is 200 V, the control circuit 26 controls the relay 29 to connect the heaters 27 and 28 having the same W number as shown in FIG. Control of the first reference form is performed such that high-speed continuous image formation is performed by turning on the heaters 27 and 28 for 100 V at 200 V by connecting in series to the commercial power supply via the power switch 24, the fuse 25, and the plug 22. I do.

  The control circuit 26 performs on / off control of the triacs 30 and 31 via the SSRs 51 and 52 based on the temperature detection signal from the thermistor 39, thereby setting the surface temperature (fixing temperature) of the upper roller 15a of the fixing device 15 to the set temperature. To control. Since power is supplied to the control circuit 26 other than the heaters 27 and 28, the motor, the clutch, and the like from the switching power supply 23, if the switching power supply 23 shared with 100V and 200V is used, the voltage of the commercial power supply is 100V. Operation is possible even at 200V.

According to the first reference embodiment, since the power from different commercial power source the power supply capacity and can be supplied, it is possible to supply power in the range of each power capacity from a plurality of the commercial power source, fixing the image formation speed The maximum image forming speed can be maintained without being limited by the shortage of heat in the apparatus.

In addition, according to the first reference embodiment, since the thermal fixing device 15 that can supply power from commercial power sources having different power capacities is provided, power is supplied from a plurality of commercial power sources within the range of the respective power capacities. The maximum image forming speed can be maintained without restricting the image forming speed due to insufficient heat amount of the fixing device.

In one embodiment of the present invention, in the first reference embodiment, as shown in FIG. 1, the fixing heaters 27 and 28 are independently connected via the triacs 30 and 31, the power switch 24, the fuse 25, and the plugs 21 and 22. It is connected to two different commercial power sources. The fixing heaters 27 and 28 are supplied with electric power from two different commercial power sources via the plugs 21 and 22, the fuse 25, the power switch 24, and the triacs 30 and 31, and generate heat to heat the roller 15 a of the fixing device 15. .

In the present embodiment, the minimum necessary apparatus (component) as an image forming apparatus is configured to supply power from a common commercial power source (commercial power source connected to the plug 21). Since power is supplied from a commercial power source (commercial power source connected to the plug 22), image formation is possible even if the plug 22 is disconnected from the outlet (not connected to the commercial power source).

  The control circuit 26 supplies power to the heaters 27 and 28 by checking a signal from a power supply number designation switch 53 provided on the operation panel for designating the number of commercial power supplies connected to the plugs 21 and 22. The number of commercial power sources (commercial power sources connected to the plugs 21 and 22) that can be used is determined, and as a result, there is a surplus in the amount of heat of the fixing device 15 (commercial power sources that can supply power to the heaters 27 and 28). The number of power supplies to the heaters 27 and 28 is sufficient), a full-speed image forming operation is performed, and the number of commercial power sources that can supply power to the heaters 27 and 28 is one. In this case, the control of the present embodiment is performed so as to slow down the image forming speed (reducing recording paper passing through the fixing device 15 per unit time) by using another control program prepared in advance.

  Specifically, the control circuit 26 determines the number of commercial power sources that can supply power to the heaters 27 and 28 by checking a signal from the power number designation switch 53 provided on the operation panel. When the heat amount of the fixing device 15 is sufficient (the number of commercial power sources that can supply power to the heaters 27 and 28 is two and the power supplied to the heaters 27 and 28 is sufficient), full-speed image formation is performed. When the number of commercial power sources that can be operated and can supply power to the heaters 27 and 28 is one, the process speed is decreased (per unit time) by another control program prepared in advance. The control of this embodiment is performed so as to reduce the image forming speed (by reducing the number of recording sheets passing through the fixing device 15).

Further, the control circuit 26 determines the number of commercial power sources that can supply power to the heaters 27 and 28 by checking a signal from a power source number designation switch 53 provided on the operation panel, and as a result, the fixing device. When there is a surplus in the amount of heat of 15 (the number of commercial power sources that can supply power to the heaters 27 and 28 is two and there is a surplus in power supply to the heaters 27 and 28), a full-speed image forming operation is performed. When the number of commercial power sources that can supply power to the heaters 27 and 28 is one, the interval between the recording sheets is widened by another control program prepared in advance (per unit time). The control of this embodiment may be performed so as to reduce the image forming speed (by reducing the number of recording sheets passing through the fixing device 15). In this embodiment, the relay 29, the diodes 32 and 35, the resistors 33, 34, 36, and 37 and the capacitors 38 and 55 in the first reference embodiment are omitted.

According to this embodiment, since the heat fixing device 15 having the plurality of loads 27 and 28 that are electrically connected to each other and supplied with electric power from the plurality of commercial power sources is provided, the plurality of commercial power sources respectively The power can be supplied within the range of the power capacity, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat quantity of the fixing device.

According to this embodiment, since power can be supplied from a plurality of commercial power sources, it is also possible to operate with a single commercial power source. Therefore, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities. The maximum image forming speed can be maintained without restricting the image forming speed due to insufficient heat amount of the fixing device.

According to this embodiment, power can be supplied from a plurality of commercial power sources, but it can also be operated by a single commercial power source, and the number of images to be formed per unit time is changed depending on the number of commercial power sources. Power can be supplied from the commercial power source within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat amount of the fixing device.

According to this embodiment, while it is possible to supply power from a plurality of commercial power sources, it is also possible to operate with a single commercial power source, and by changing the process speed according to the number of commercial power sources, The power can be supplied within the range of the power capacity, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat quantity of the fixing device.

According to this embodiment, power can be supplied from a plurality of commercial power sources, but it can also be operated by a single commercial power source, and the interval of paper as a recording material to be conveyed is changed depending on the number of commercial power sources. Thus, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat amount of the fixing device.

According to this embodiment, power can be supplied from a plurality of commercial power supplies, and power can be supplied to a load that operates according to a command from the control circuit 26 as control means that operates with power from the first commercial power supply. By performing from the second commercial power source, power can be supplied from the plurality of commercial power sources within the range of the respective power capacities, and the maximum image formation can be performed without limiting the image forming speed due to insufficient heat amount of the fixing device. The speed can be maintained.

According to this embodiment, power can be supplied from a plurality of commercial power sources, and the fixing device 15 that is turned on / off by a command from the control circuit 26 as a control unit that operates with power from the first commercial power source. By supplying power from the second commercial power source, it is possible to supply power from a plurality of commercial power sources within the range of the respective power capacities, and without restricting the image forming speed due to insufficient heat quantity of the fixing device, The maximum image forming speed can be maintained.

According to this embodiment, a fixing heater 27 that can be supplied with power from a plurality of commercial power supplies and is turned on / off in response to a command from a control circuit 26 as a control means that operates with power from the first commercial power supply. By supplying power from the second commercial power source to the power source 28, power can be supplied from the plurality of commercial power sources within the range of the respective power capacities, and the image forming speed is limited by insufficient heat amount of the fixing device. And the maximum image forming speed can be maintained.

According to this embodiment, the heaters 27 and 28 that can be supplied with power from a plurality of commercial power supplies and are turned on / off in response to a command from the control circuit 26 as control means that operates with the power from the first commercial power supply. Power is supplied from the second commercial power source, and the heater 28 that receives power supply from the first commercial power source is provided, so that power is supplied from the plurality of commercial power sources within the range of the respective power capacities. The maximum image forming speed can be maintained without restricting the image forming speed due to insufficient heat amount of the fixing device.

In the second reference embodiment of the present invention, in the above embodiment, as shown in FIG. 3, the photoisolate (photoisolator) 54 has two power supplies in which the plug 22 is connected via the fuse 25 and the power switch 24. The line is connected between the input 2 (terminal) of the control circuit 26 and the ground point GND. The control circuit 26 checks the number of commercial power sources that can supply power to the heaters 27 and 28 by checking the signal that the plug 22 inputs from the commercial power source through the fuse 25, the power switch 24, and the photoisolate 54. As a result, there is a surplus in the amount of heat of the fixing device 15 (the number of commercial power sources that can supply power to the heaters 27 and 28 is two and there is a surplus in the power supplied to the heaters 27 and 28). Allows a full-speed image forming operation to be performed. When the number of commercial power sources capable of supplying power to the heaters 27 and 28 is one, the image forming speed can be controlled by another control program prepared in advance. The control according to the second embodiment is performed so as to be delayed (the number of recording sheets passing through the fixing device 15 per unit time is reduced).

Specifically, the control circuit 26 determines the number of commercial power sources that can supply power to the heaters 27 and 28 by checking a signal from the photoisolate 54, and as a result, determines the amount of heat of the fixing device 15. When there is a margin (the number of commercial power sources that can supply power to the heaters 27 and 28 is two and there is a margin for the power supplied to the heaters 27 and 28), a full-speed image forming operation is performed, and the heater When the number of commercial power sources capable of supplying power to 27 and 28 is one, the process speed is slowed down (passes the fixing device 15 per unit time) by another control program prepared in advance. to reduce the recording paper) performs control according to this reference embodiment to slow imaging speed.

Further, the control circuit 26 determines the number of commercial power sources that can supply power to the heaters 27 and 28 by checking a signal from the photoisolate 54, and as a result, there is a margin in the amount of heat of the fixing device 15. When the number of commercial power sources that can supply power to the heaters 27 and 28 is two and the power supplied to the heaters 27 and 28 is sufficient, a full-speed image forming operation is performed, and the heaters 27 and 28 are operated. When the number of commercial power sources capable of supplying power to the recording medium is one, the interval between the recording sheets is widened (recording passing through the fixing device 15 per unit time) by another control program prepared in advance. paper less to) may be performed in control of this preferred embodiment to slow imaging speed.

According to the second reference embodiment, while it is possible to supply power from a plurality of commercial power sources, it is possible to operate with a single commercial power source, and the number of image formations per unit time is automatically changed according to the number of commercial power sources. Accordingly, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat amount of the fixing device. .

According to the second reference embodiment, while it is possible to supply power from a plurality of commercial power sources, it is possible to operate with a single commercial power source, and by automatically changing the process speed according to the number of commercial power sources, Electric power can be supplied from the commercial power source within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat quantity of the fixing device.

According to the second reference embodiment, while it is possible to supply power from a plurality of commercial power sources, it is possible to operate with a single commercial power source, and the interval of paper as a recording material to be conveyed is automatically set according to the number of commercial power sources. By changing to, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat amount of the fixing device. be able to.

According to the second reference embodiment, power can be supplied from a plurality of commercial power supplies, and the number of connected commercial power supplies is inserted into the line connected to each commercial power supply (of the photoisolate 54). By determining from the number of light emitting elements), it is possible to supply power from a plurality of commercial power sources within the range of the respective power capacities, and without limiting the image forming speed due to insufficient heat amount of the fixing device. The maximum image forming speed can be maintained.

According to the second reference embodiment, power can be supplied from a plurality of commercial power supplies, and power is supplied to a load that operates according to a command from the control circuit 26 as a control means that operates with power from the first commercial power supply. By using the second commercial power supply, power can be supplied from a plurality of commercial power supplies within the respective power capacity ranges, and the maximum image can be obtained without limiting the image forming speed due to insufficient heat amount of the fixing device. The formation speed can be maintained.

According to the second reference embodiment, the fixing device 15 that can supply power from a plurality of commercial power sources and is turned on / off by a command from the control circuit 26 as a control unit that operates with the power from the first commercial power source. By supplying power to the printer from the second commercial power source, it is possible to supply power from the plurality of commercial power sources within the range of the respective power capacities, and without limiting the image forming speed due to insufficient heat quantity of the fixing device. The maximum image forming speed can be maintained.

According to the second reference embodiment, the fixing heater 27 that can supply power from a plurality of commercial power supplies and is turned on / off in response to a command from the control circuit 26 as a control means that operates with the power from the first commercial power supply. , 28 from the second commercial power supply, power can be supplied from a plurality of commercial power supplies within the range of the respective power capacities, and the image forming speed is limited due to insufficient heat amount of the fixing device. And the maximum image forming speed can be maintained.

In the third reference embodiment of the present invention, in the second reference embodiment, as shown in FIG. 4, the photoisolate 54 is omitted, and the plug 22 is connected via the fuse 25 and the power switch 24. A diode 35 and resistors 36 and 37 are connected in series between the power supply lines, a capacitor 38 is connected in parallel with the resistor 37, and a connection point of the resistors 36 and 37 is connected to an input 2 (terminal) of the control circuit 26. The

  The AC voltage input from the commercial power supply via the plug 22, fuse 25, and power switch 24 is rectified by the diode 35, divided by the resistors 36 and 37, smoothed by the capacitor 38, and A / D of the control circuit 26. The control circuit 26 determines whether the voltage of the commercial power source connected to the plug 22 is 100V or 200V from the input voltage and whether there is power supply from the plug 22 based on the commercial power source. To do.

According to the third reference embodiment, power can be supplied from a plurality of commercial power sources, and the number of connected commercial power sources is divided by resistors 36 and 37 inserted into the lines to which the commercial power sources are connected. Since it is determined from the number of generated voltages, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities, and the maximum image forming speed can be achieved without being limited by insufficient heat amount of the fixing device. The image forming speed can be maintained.

Since the control circuit 26 cannot operate when the power supply from the commercial power source A connected to the plug 21 is cut off, the power is supplied from the commercial power source B connected to the plug 22 to the load in this state. Very dangerous. Therefore, in the second reference embodiment, when the power supply from the commercial power source A is cut off, the light-emitting diode of the SSR 52 cannot shine, so the power supply from the commercial power source B to the heater 28 is surely performed. Can be prohibited.

As described above, according to the second reference embodiment, power can be supplied from a plurality of commercial power supplies, and the load to the load operated by the command from the control circuit 26 as the control means that operates with the power from the first commercial power supply. The power supply is performed from the second commercial power supply, and when the power supply from the first commercial power supply is cut off, the power supply to the load supplied with the power from the second commercial power supply is prohibited. Therefore, when the power supply from the first commercial power source is cut off, the power supply to the load supplied with the power from the second commercial power source can be reliably prohibited.

Usually, the control circuit 26 and the SSR 51 or SSR 52 are not located on the same substrate, but are installed at separate locations and connected between them by a conductor and a connector. Even if the connector is disconnected or the conductor is cut and no command is sent from the control circuit 26 to the SSR 51 or SSR 52, the light emitting diodes of the SSR 51 and SSR 52 cannot shine in the second reference embodiment, so that the commercial power The power supply from B to the heater 28 can be prohibited.

As described above, according to the second reference embodiment, power can be supplied from a plurality of commercial power supplies, and the load to the load operated by the command from the control circuit 26 as the control means that operates with the power from the first commercial power supply. When power is supplied from the second commercial power source and the command is not sent, the power supply to the load supplied with power from the second commercial power source is prohibited, so the command is not sent The power supply to the load supplied with power from the second commercial power source can be prohibited.

In the fourth reference embodiment of the present invention, in the second reference embodiment, the thermistor 39 contacts the surface of the upper roller 15a of the fixing device 15, and the control circuit 26 detects the temperature input from the thermistor 39 to the A / D input terminal. The surface temperature of the upper roller 15a is measured from the signal. The control circuit 26 outputs an L (low level) signal from the output 1 and output 2 (terminal) when the surface temperature of the upper roller 15a is relatively close to room temperature (sufficiently lower than the set temperature) just after the power is turned on. As a result, the triacs 30 and 31 are turned on to turn on both the heaters 27 and 28, and the temperature of the upper roller 15a is rapidly increased.

  The control circuit 26 controls the triacs 30 and 31 to turn on only one of the heater 27 and the heater 28 when the surface temperature of the upper roller 15a reaches a predetermined temperature close to the preset set temperature. This prevents overshooting of the temperature of the fixing device 15. When the surface temperature of the upper roller 15a reaches a predetermined temperature further than the predetermined temperature and reaches a predetermined temperature, the control circuit 26 controls the triacs 30 and 31 to determine which of the heater 27 and the heater 28 is used. Only one of them is lit intermittently to further prevent overshooting of the temperature of the fixing device 15.

  When the surface temperature of the upper roller 15a reaches the set temperature or when the number of images formed from the same document is small, the control circuit 26 does not take much heat from the fixing device 15, so the triacs 30, 31 Is controlled so that only one of the heater 27 and the heater 28 is turned on to reduce the temperature ripple of the fixing device 15. At this time, although only one of the heater 27 and the heater 28 is lit, there is no problem in temperature, but considering that the life of the heaters 27 and 28 and the inrush current are reduced, the control circuit 26 causes the heaters 27 and 28 to be reduced. It is desirable to alternately turn on the lamps alternately and intermittently with a period that the filament turns red.

According to the fourth embodiment, power can be supplied from a plurality of commercial power sources, and the first on / off operation is performed in response to a command from the control circuit 26 serving as control means that operates with power from the first commercial power source. Electric power is supplied to the heater 27 from the second commercial power source, and both the second heater 28 and the first heater 27 that are supplied with electric power from the first commercial power source are turned on when the temperature is lower than a predetermined temperature. Therefore, power can be supplied from a plurality of commercial power sources within the range of the respective power capacities, and the maximum image forming speed can be maintained without limiting the image forming speed due to insufficient heat quantity of the fixing device. Furthermore, the temperature of the fixing device can be rapidly increased when the temperature of the fixing device is low.

According to the fourth embodiment, power can be supplied from a plurality of commercial power sources, and the first on / off operation is performed in response to a command from the control circuit 26 serving as control means that operates with power from the first commercial power source. Electric power is supplied to the heater 27 from the second commercial power source, and the second heater 28 and the first heater 27 that receive power supply from the first commercial power source are only one when the temperature is equal to or higher than a predetermined temperature. By turning on, overshooting of the temperature of the fixing device can be prevented.

According to the fourth embodiment, power can be supplied from a plurality of commercial power sources, and the first on / off operation is performed in response to a command from the control circuit 26 serving as control means that operates with power from the first commercial power source. Electric power is supplied to the heater 27 from the second commercial power source, and the second heater 28 and the first heater 27, which receive power from the first commercial power source, are alternately set to 1 when the temperature is equal to or higher than a predetermined temperature. By turning on only one of them, the life of the heater and the inrush current can be reduced.

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

It is a circuit diagram showing one embodiment of the present invention. It is sectional drawing which shows the 1st reference form of this invention. It is a circuit diagram which shows the 2nd reference form of this invention. It is a circuit diagram which shows the 3rd reference form of this invention. It is sectional drawing which shows the fixing device of the said embodiment . It is a circuit diagram which shows one operation state of the said embodiment . It is a circuit diagram which shows the other operation state of the said embodiment .

Explanation of symbols

15 Fixing device 21, 22 Plug 23 Switching power supply 26 Control circuit 27, 28 Fixing heater 29 Relay 30, 31 Triac 32, 35 Diode 33, 34, 36, 37 Resistance 38 Capacitor 39 Thermistor 51, 52 SSR
53 Power supply number switch 54 Photoisolate

Claims (1)

A thermal fixing device that is heated by the supply of electric power from a commercial power source;
In an image forming apparatus that forms an image using the thermal fixing device,
A plurality of plugs to which a first commercial power source and a second commercial power source constituting a plurality of commercial power sources having different power capacity are respectively connected;
Two heaters for independently heating the rollers of the thermal fixing device by supplying power from the plurality of commercial power sources;
A power supply number designating switch for designating the number of commercial power supplies connected to the plurality of plugs;
A control circuit that controls the image forming speed in accordance with the number of commercial power supplies connected to the plug,
The control circuit determines the number of commercial power supplies that can supply power in response to a signal from a power supply number designation switch,
When only the first commercial power source is connected to the plug as a power source capable of supplying power to the heater, the image forming operation is performed at a low speed.
Image forming operation characterized in that when a first commercial power source and a second commercial power source are connected to the plug as a power source capable of supplying power to the heater, an image forming operation is performed at a high speed. apparatus.

Images