JP7468147B2 - Image forming device - Google Patents

Description

The present disclosure relates to a technology for determining the connection state of the power cord of the power supply unit of a first load unit including a control unit and a second load unit including a control target of the control unit in an image forming device, when the power supply units are independent.

In a typical facility in Japan, the maximum power supplied from a power outlet is 100V, 15A, or 1,500W, and there are only a limited number of facilities equipped with outlets capable of supplying special 100V, 20A, or 200V, etc.

For this reason, it is stipulated that power cords for general electrical appliances must also be rated at 100V 15A (Electrical Appliance and Material Safety Act).

However, electrophotographic printers, fax machines, and other image forming devices, such as these multifunction machines, require a fixing heater, and many of them consume a lot of power, with some large, high-speed machines consuming more than 1,500 W of power in total.

For models with such high power consumption, a configuration has been proposed in which, for example, two power cords rated at 100V 15A are provided, and the load of supplying power is shared by each power cord, thereby suppressing the current flowing through each power cord to below the above-mentioned standard value (for example, Patent Document 1).

In image forming devices like the one above, general users may not realize that one image forming device has multiple power cords and may inadvertently forget to plug one of the power cords into the outlet.

If you forget to plug in the power cord that supplies power to the control unit, the image forming device will not start even if you turn on the power switch, so you will immediately notice that you have forgotten to plug it in.However, if you forget to plug in the power cord that supplies power to an AC load such as a fixing heater, the display on the operation panel will light up and the image forming device will start up and appear to be operating normally without any problems, so it will be difficult to realize that the power cord for the AC load is not connected.

Therefore, image forming devices have been proposed that include a separate AC power detection circuit to determine whether or not the power cord is connected (for example, Patent Documents 2 and 3).

JP 2003-244359 A JP 2007-316245 A JP 2005-121681 A

However, when a special AC power detection circuit is provided to detect whether the power cord is connected, as in Patent Documents 2 and 3, in addition to the component costs of the circuit, changes to the design of the control board are required, which increases manufacturing costs and also hinders space saving.

The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide an image forming device that, when there are multiple power supply units that supply power, can determine whether or not a specific power supply unit is supplying power from the power cord without increasing manufacturing costs and without affecting the space-saving design of the device.

In order to achieve the above-mentioned object, an image forming apparatus according to one embodiment of the present disclosure comprises a first power supply unit that supplies power to a first load unit including a control unit, a second power supply unit that supplies power to a second load unit that includes a control object of the control unit, and a status detection unit that detects the status of the control object, wherein the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the status detection unit does not detect a change in the status of the control object even after a predetermined time has elapsed , even though the control unit has issued an instruction to the control object to change its status, and the control object is a fixing heater that heats a fixing rotor in a fixing unit that fixes an unfixed image onto a recording sheet, and the status detection unit is a temperature sensor that detects the temperature of the fixing rotor .

Here, the "predetermined time" refers to a preset time that is equal to or longer than the time (response time) required for the state of the controlled object to change in response to an instruction from the control unit when power is normally supplied to the controlled object by the second power supply unit.

Here, the temperature sensor may be a thermistor or a thermopile.

In addition, an image forming apparatus according to another aspect of the present disclosure includes a first power supply unit that supplies power to a first load unit including a control unit, a second power supply unit that supplies power to a second load unit that includes a control object of the control unit, and a status detection unit that detects a status of the control object, wherein the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when, despite issuing an instruction to the control object to change its status, no change in the status of the control object is detected by the status detection unit even after a predetermined time has elapsed, and the control object is a dehumidifying heater that dehumidifies recording sheets.

In another aspect of the present disclosure, the state detection unit is a humidity sensor that detects the humidity in the storage unit that stores the recording sheets.

In another aspect of the present disclosure, the state detection unit is a temperature sensor that detects the temperature of the storage unit that stores the recording sheets.

In another aspect of the present disclosure, a power switch is provided, and the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the state detection unit detects that the state of the controlled object has not changed even after a predetermined time has elapsed after the power switch is turned on.
According to yet another aspect of the present disclosure, an image forming apparatus includes a first power supply unit that supplies power to a first load unit including a control unit, a second power supply unit that supplies power to a second load unit that includes a control object of the control unit, a status detection unit that detects a status of the control object, a transport roller that transports a sheet on which an image is formed, or an intermediate transfer belt onto which a toner image formed in an image creating unit is primarily transferred and which secondarily transfers the primarily transferred toner image to a sheet being transported at a secondary transfer position, and a drive motor that drives the transport roller or the intermediate transfer belt, wherein the control object is the drive motor, the status detection unit is an encoder for controlling the rotation of the drive motor, and the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the detection value detected by the encoder does not change despite issuing a drive instruction to the drive motor.

In another aspect of the present disclosure, the first power supply unit is characterized by having another power cord different from the power cord of the second power supply unit, and a power conversion unit that converts AC power supplied from the other power cord into DC power.

In another aspect of the present disclosure, the first power supply unit is a secondary battery that receives power in advance from the power cord of the second power supply unit and stores the power.

In another aspect of the present disclosure, the device is characterized in that it includes a warning unit that warns the user when the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted.

In another aspect of the present disclosure, the first load unit includes an image forming unit that forms an unfixed image on a recording sheet and the warning unit.

An image forming apparatus according to another aspect of the present disclosure is an image forming apparatus that supplies power to a first load unit including a control unit and a warning unit via a first power cord, and supplies power to a second load unit including a fixing heater of a fixing unit via a second power cord, and is characterized in that the control unit determines that the second power cord is not connected to a power outlet when the temperature of the fixing rotor of the fixing unit does not increase even after a predetermined time has elapsed, even though the apparatus has been started and warm-up control of the fixing unit has begun, and causes the warning unit to warn the user to insert the second power cord into the power outlet.

In another aspect of the present disclosure, the device includes a plurality of temperature sensors that detect the temperature of the fixing rotor of the fixing unit, and the control unit determines that the second power cord is not connected to a power outlet when the detected temperatures of all of the plurality of temperature sensors do not increase even after a predetermined time has elapsed despite the start of the warm-up control.

According to the above configuration, the connection state of the power cord of the power supply unit that supplies power to the second load unit including the control object can be determined by using the detection result by the state detection unit for controlling the state of the control object that is originally provided in the image forming device, so there is no need to provide a new circuit for detecting AC power, and there is no unnecessary increase in cost or hindrance to space saving.

FIG. 1 is a diagram illustrating a configuration of a printer according to an embodiment of the present disclosure. 4 is a block diagram showing the configuration of a power supply system in the printer. FIG. 10 is a flowchart for determining the connection state of the power cord in the control unit by utilizing the detection result of the temperature sensor of the fixing unit. 13A and 13B are diagrams illustrating an example of a warning message that is displayed on the display unit of the operation panel when the control unit determines that the power cord is not connected. 10 is a flowchart for determining the connection state of the power cord in the control unit by utilizing the detection result of the humidity sensor in the paper feed unit. FIG. 13 is a diagram illustrating a configuration example in which a secondary battery is used as a power supply unit for a load including a control unit.

<Embodiment>
Hereinafter, an embodiment of an image forming apparatus according to the present disclosure will be described taking as an example a case where the image forming apparatus is applied to a tandem type color digital printer (hereinafter simply referred to as a "printer").

(1) Overall Configuration of the Printer FIG. 1 is a schematic diagram showing the overall configuration of a printer 10.

As shown in the figure, the printer 10 is equipped with an image forming unit 11, a paper feed unit 12, a fixing unit 14, a control unit 15, and an operation panel 100. It is connected to a network such as a LAN, and when it receives an instruction to execute a print job from an external terminal (not shown), it forms toner images of yellow, magenta, cyan, and black based on the image data included in the print job, and then transfers these images in multiple layers to form a color image.

The image forming unit 11 includes imaging units 20Y, 20M, 20C, and 20K, which correspond to the colors yellow (Y), magenta (M), cyan (C), and black (K), respectively, and an intermediate transfer belt 21.

The imaging units 20Y to 20K are arranged in a row at a predetermined interval along the intermediate transfer belt 21. The imaging unit 20Y comprises a photoconductor drum 1, around which are arranged a charger 2, an exposure unit 3, a development unit 4, a cleaner 6 for cleaning the surface of the photoconductor drum 1, and a primary transfer roller 5 disposed opposite the photoconductor drum 1 across the intermediate transfer belt 21, and forms a Y-color toner image on the peripheral surface of the photoconductor drum 1.

The other image forming units 20M to 20K are basically configured the same as image forming unit 20Y, and form toner images of the corresponding colors. Reference numerals are omitted in the figure.

The intermediate transfer belt 21 is an endless belt that is stretched around a drive roller 22 and a driven roller 23 and driven to rotate in the direction of the arrow in the figure.

The image-making operation for each developing color is performed with different timing so that the toner images of each color formed in each image-making unit 20Y to 20K are superimposed and primarily transferred to the same position on the intermediate transfer belt 21. The color toner images formed on the intermediate transfer belt 21 move toward the secondary transfer position 37.

Meanwhile, the paper feed unit 12 uses a feed roller 32 to feed a number of recording sheets S stored in a paper feed cassette 31 in a storage space (storage unit) 19 below the device, one by one, to a sheet transport path 38, and transports the sheets further up to a registration roller 34 by an intermediate roller 33. The registration roller 34 feeds the recording sheets S toward a secondary transfer position 37 in accordance with the movement of the toner image on the intermediate transfer belt 21, and the toner image on the intermediate transfer belt 21 is secondarily transferred all at once onto the recording sheets S by a secondary transfer roller 35.

After passing through the secondary transfer position 37, the recording sheet S is transported to the fixing unit 14.

The fixing unit 14 forms a fixing nip 145 between a fixing roller (fixing rotor) 141 and a pressure roller 142. The fixing roller 141 is hollow and has a fixing heater 143 built in. A temperature detection unit 144 is disposed near the circumferential surface of the fixing roller 141, and the amount of electricity supplied to the fixing heater 143 is controlled by the control unit 15 based on the detected temperature, so that the surface temperature of the fixing roller 141 is maintained at a target temperature.

In this embodiment, as shown in FIG. 2, the fixing heater 143 is, for example, a halogen heater, and includes a central heater 143a that heats the central portion in the direction of the rotation axis of the fixing roller 141, and end heaters 143b and 143c that heat both ends of the central heater 143a. The amount of electricity supplied to each heater is adjusted according to the size of the recording sheet S passing through the center.

For example, when fixing a relatively small size recording sheet S, only the center heater 143a is energized, whereas when fixing a large size recording sheet S or when warming up quickly, the center heater 143a and the end heaters 143b and 143c are energized.

In response to this, the temperature detection unit 144 also includes a central temperature sensor 144a that detects the temperature of the central portion of the fixing roller 141, and an end temperature sensor 144b that detects the temperature of one end portion of the fixing roller 141, and the control unit 15 controls the surface temperature of each portion of the fixing roller 141 based on the detection results of each temperature sensor.

A thermistor or thermopile can be used as the central temperature sensor 144a and the end temperature sensor 144b.

As the recording sheet S passes through the fixing nip 145 of the fixing section 14, the toner image (unfixed image) on the recording sheet S is heated and pressurized to be fixed to the recording sheet S, and then the recording sheet S is discharged onto the discharge tray 39 via the discharge rollers 36.

An operation panel 100 is installed on the upper front of the printer 10 in a position that is easy for the user to operate. The operation panel 100 has multiple input keys and a display unit 110. The display unit 110 is made of a liquid crystal display panel with a touch panel laminated on its surface. Instructions from the user are accepted through touch input from the touch panel or key input from the input keys, and notified to the control unit 15. Also, based on instructions from the control unit 15, a specified message is displayed on the display unit 110 to attract the user's attention.

In addition, if the recording sheet S is left in the paper feed cassette 31 for a long time, it will absorb moisture from the air and the moisture content will increase. This can cause transfer problems, for example, when the toner image on the intermediate transfer belt 21 is transferred to the recording sheet S, or the sheet may curl and cause transport problems when the toner image is thermally fixed.

Therefore, in this embodiment, a plate-shaped dehumidifying heater 310 is provided on the bottom surface of the paper feed cassette 31 to heat and dehumidify the recording sheets S and the paper feed cassette 31.

In addition, a humidity sensor 311 is provided to detect the humidity (relative humidity) in the storage space 19 in which the paper feed cassette 31 is arranged, and the control unit 15 controls the operation of the dehumidifying heater 310 based on the detection result of the humidity sensor 311.

Two power cords 41 and 42 extend from the main body of the printer 10 and are connected to power outlets (not shown) to supply power to two loads within the printer 10.

(2) Power Supply System FIG. 2 is a diagram illustrating a schematic of the main components of the power supply system in the printer 10 according to this embodiment.

Plug 41a of power cord 41 and plug 42a of power cord 42 are each inserted into a 100V AC power outlet connected to a different breaker.

The power cord 41 is connected to a low-voltage power supply unit (power conversion unit) 43 via a power switch 41b. The low-voltage power supply unit 43 rectifies 100V AC, converts it to a specified low-voltage DC voltage, and supplies power to each component of the first load unit 210 in the printer 10 (first power supply unit).

In this embodiment, the first load unit 210 includes DC loads such as the control unit 15, the image forming unit 11, and the operation panel 100.

The power cord 42 supplies 100V AC power to the second load section 220 via the power switch 42b (second power supply section).

The second load section 220 mainly includes AC loads that consume large amounts of power, in particular the central heater 143a, the end heaters 143b and 143c, and the dehumidification heater 310 of the fixing section 14, as well as a heater driving section 44 that supplies the necessary power to each of these heaters in response to instructions from the control section 15 to drive them.

In this embodiment, power switch 41b and power switch 42b are designed to operate in conjunction with each other as a main body power switch.

The control unit 15 included in the first load unit 210 includes a CPU (Central Processing Unit), a communication interface that receives print jobs and the like from an external terminal, ROM (Read Only Memory), and RAM (Random Access Memory). When the printer 10 is powered on, the CPU reads the necessary programs from the ROM and starts up the device, and is configured to use the RAM as a work area to comprehensively control the image forming unit 11, paper feed unit 12, and fixing unit 14 to smoothly execute print jobs.

In addition, the control unit 15 determines whether the power cord 42 is connected to a power outlet based on the detection result of the temperature detection unit 144 (hereinafter referred to as the "cord connection determination process").

(3) Cord Connection Determination Process FIG. 3 is a flowchart showing the operation of the cord connection determination process performed by the control unit 15.

First, the control unit 15 determines whether it is time to start control (warm-up) to quickly raise the temperature of the fixing roller 141 of the fixing unit 14 to a target temperature at which fixing is possible (step S11).

When the printer 10 is turned on, or when the power supply to the fixing unit 14 is stopped (or maintained at a predetermined temperature lower than the fixing temperature) (sleep state) and the control unit 15 receives a user operation on the operation panel 100 or a print job from an external terminal, the control unit 15 determines that it is time to start warming up (Yes in step S11), and drives the pressure roller 142 to rotate, thereby rotating the fixing roller 141, and instructs the heater drive unit 44 to supply power to the center heater 143a and the end heaters 143b and 143c, thereby starting the warming up of the fixing unit 14 (step S12).

When this warm-up starts, the control unit 15 starts sampling the temperatures detected by the center temperature sensor 144a and the end temperature sensor 144b and stores them in the internal RAM (step S13).

The control unit 15 keeps track of time using an internal counter and determines whether a predetermined time, ta seconds, has elapsed since the start of warm-up (step S14).

The "predetermined time" here is set to a time equal to or longer than the time (response time) required for the fixing roller 141 to heat up in response to an instruction from the control unit 15 when the power cord 42 is connected to a power outlet and power is being normally supplied to the controlled objects of the second load unit 220 (the central heater 143a, the end heaters 143b, 143c).

In this embodiment, the time is set to an appropriate value (e.g., 20 seconds) that allows a margin so that a temperature rise can be reliably detected when power is being supplied normally, and does not delay too much the determination of whether the power cord is connected.

If ta seconds have passed (Yes in step S14), the temperatures detected by the central temperature sensor 144a and the end temperature sensor 144b at that time are compared with the detected temperatures sampled when warm-up began to determine whether the detected temperatures have risen by or above T°C (the temperature that is reliably raised to after ta seconds when the power supply is normal (set to 10°C in this embodiment)) (step S15).

If the temperatures detected by both the central temperature sensor 144a and the end temperature sensor 144b have not risen by T°C or more (Yes in step S15), it is determined that the power cord 42 is not connected to an outlet and therefore power is not being supplied to the second load unit 220 including the fixing unit 14. Therefore, the control unit 15 causes the display unit 110 of the operation panel 100 to display a message requesting confirmation that the power cord 42 is connected (step S16).

In this case, since temperature control of the fixing unit 14 is not possible, the control unit 15 stops the fixing temperature control (step S17) and ends the process. If the control unit 15 is also controlling other loads belonging to the second load unit 220, it may stop controlling those loads as well.

Figure 4 shows a specific example of a message that is displayed on the display unit 110 in step S16, indicating that there is a "power cord connection error" and encouraging the user to "turn off the main unit power, insert the power cord into the outlet, and then turn the main unit power on."

In addition to or instead of displaying the warning message on the display unit 110, audio data may be stored in the internal ROM of the control unit 15, and an audio message with the same content as the above may be output from the speaker unit 120. Alternatively, a specific warning sound may be emitted. This will further attract the user's attention.

The higher-level concept of the configuration in which the control unit 15 displays a warning message on the display unit 110 or outputs voice or warning sounds to alert the user is referred to as the "warning unit."

On the other hand, if the determination in step S15 is "No," this includes cases where only the temperature detected by one of the central temperature sensor 144a and the end temperature sensor 144b has not risen by T°C or more, and cases where the temperatures detected by both temperature sensors have risen by T°C or more.

First, in step S18, it is determined whether the temperature detected by only one of the temperature sensors has risen by T°C or more. If this determination is positive (Yes in step S18), it is determined that power is being supplied to the second load unit 220, but the temperature sensor and/or fixing heater at that detection point is malfunctioning. Therefore, the display unit 110 of the operation panel 100 displays a message stating that "The temperature sensor or fixing heater is abnormal" (step S19), and fixing temperature control is stopped (step S17). In this case, the user contacts a serviceman with a maintenance contract for the device and requests an inspection.

If the result of step S18 is No, it means that the temperatures detected by both temperature sensors have risen by T°C or more, so it is determined that the power cord 42 is connected and that both the fixing heater and the temperature sensor are operating normally. Therefore, normal fixing temperature control continues (step S20), and the cord connection determination process ends.

Here, normal fixing temperature control includes, for example, a control to warm up the fixing roller 141 to a temperature (fixing temperature) required for fixing a toner image to the recording sheet S, and then maintain that fixing temperature while a print job is being executed, and a control to lower the temperature of the fixing roller 141 and transition to a sleep mode to save power if a predetermined time has passed since the previous print job was executed without executing the next print job.

(Modification)
Although the embodiments of the present disclosure have been described above, it goes without saying that the present invention is not limited to the above-described embodiments, and the following modified examples can be implemented.

(1) In the above embodiment, whether the power cord 42 is connected or not is determined based on whether there is a change in the temperature detected by the temperature detection unit 144 of the fixing unit 14. In this modified example, however, whether the power cord 42 is connected or not is determined based on a change in the humidity detected by the humidity sensor 311 for controlling the operation of the dehumidifying heater 310.

Figure 5 is a flowchart showing the procedure for the code connection determination process executed by the control unit 15 in such a case.

First, the control unit 15 determines whether it is time to start dehumidification control using the dehumidification heater 310 (step S21).

The control unit 15 determines that it is time to start dehumidification control when the printer 10 is turned on or when the humidity (relative humidity) detected by the humidity sensor 311 exceeds a predetermined value (for example, a relative humidity of 60%).

If it is determined that it is time to start dehumidification control (Yes in step S21), power is started to be supplied to the dehumidification heater 310 via the heater drive unit 44 (step S22), and sampling of the detected humidity of the humidity sensor 311 is started and the value is stored in the internal RAM (step S23).

The control unit 15 determines whether a predetermined time, tb seconds, has elapsed since the start of power supply to the dehumidifying heater 310 (the predetermined time in this case is determined in advance by referring to the response time of the dehumidifying heater 310 when the power supply is normal, as in the case of Figure 3 above. In this example, it is set to, for example, 3600 seconds (1 hour)) (step S24).

If tb seconds have passed (Yes in step S24), the humidity detected by the humidity sensor 311 at that time is compared with the humidity sampled when power was first applied to the dehumidifying heater 310 to determine whether or not both have decreased by a predetermined amount (e.g., 5% or more) (step S25).

If the detected humidity has not decreased by the predetermined amount (No in step S25), it is determined that the power cord 42 is not connected to the outlet, and the control unit 15 causes the display unit 110 of the operation panel 100 to display a message confirming the connection of the power cord 42, as in FIG. 4 (step S26). At this time, a voice message may be output, as in the above embodiment.

If power is not being supplied to the second load unit 220 via the power cord 42, humidity control by the dehumidifying heater 310 is not possible, so the control unit 15 stops the constant humidity control (step S27) and ends the cord connection determination process. If the control unit 15 is also controlling other loads belonging to the second load unit 220, it also stops controlling those loads.

On the other hand, if the answer in step S25 is "Yes," power is being normally supplied to the second load unit 220 via the power cord 42, so normal humidity control continues (step S28) and the cord connection determination process ends.

Normal humidity control refers to control in which heating by the dehumidifying heater 310 continues until the humidity detected by the humidity sensor 311 falls to, for example, 50% or less.

In addition, to detect the operating state of the dehumidifying heater 310, a temperature sensor that detects the temperature inside the storage space 19 may be used instead of the humidity sensor 311.

When the temperature of the storage space 19 reaches a predetermined temperature or higher (e.g., 35°C or higher) due to heating by the dehumidifying heater 310, it is understood that the recording sheet S has also been dehumidified to a degree that does not affect the image quality due to heating.

In this case, the cord connection determination process is such that the "humidity sensor" in step S23 in the flowchart of FIG. 5 is changed to a "temperature sensor," and the determination content in step S25 is replaced with "Is the temperature inside the storage space above a predetermined value?"

Some printer models are equipped with an environmental sensor that detects the temperature and/or humidity near the image forming unit 11, and based on the results of the detection by the environmental sensor, the printer may perform control functions to maintain image quality, such as driving a fan device (not shown) to suppress temperature rise inside the printer or optimizing the charging potential of the photosensitive drum and the transfer voltages of the primary and secondary transfer rollers. In such cases, the environmental sensor may also be used as a humidity or temperature sensor to detect the operating state of the dehumidifying heater 310.

(2) In the above embodiment, the load on the printer 10 is divided into a first load unit 210 including the control unit, image forming unit, and paper feed unit, which are mainly DC loads, and a second load unit 220 including the fixing heater 143 of the fixing unit 14 and the dehumidifying heater 310, which are controlled by the control unit (control target), and a power cord 41 and a power cord 42 dedicated to each power supply unit are provided.

However, in large, high-speed printers, the power consumption of the fixing heater and the output of the drive motor for the sheet transport system also increase. Power consumption also increases in printers that are integrated with post-processing devices.

In these cases, the power consumption of the printer 10 as a whole will increase further, and three or more power cords may be required. Even in such cases, as long as power is supplied to the control unit and the load including the warning unit such as the operation panel, the loads supplied with power through other power cords are generally controlled objects that are subject to the control of the control unit, and are controlled based on the detection results of the detection means (state detection unit) that detects their operating states. Therefore, based on the detection results of the detection means, it is possible to determine through control whether or not power is being supplied to the loads including those controlled objects, and ultimately whether or not the power cords are connected, and the result of this determination can be warned by the warning unit.

(3) In the above embodiment, the fixing heater 143 (central heater 143a, end heaters 143b, 143c) of the fixing unit 14 and the dehumidifying heater 310 are given as examples of the load to be controlled, and the temperature detection unit 144 (central temperature sensor 144a, end temperature sensor 144b) and the humidity sensor 311 are given as examples of their status detection units. However, for example, when driving a sheet transport roller or an intermediate transfer belt drive motor, if the rotation speed, etc. is controlled by an encoder or the number of drive pulses, the drive motor becomes the "control target" and the encoder, etc. can become the "status detection unit."

In these cases, when a specific drive motor should be driven by control ("when the state of the controlled object should change"), if the drive motor is not rotating as intended and the detection value by the state detection unit does not change, the control unit can determine that the power cord of the power supply unit for the load unit including the drive motor is not connected.

(4) In the above embodiment, two heaters, a central heater 143a and end heaters 143b and 143c, are used as the fixing heater 143, and two temperature sensors, a central temperature sensor 144a and an end temperature sensor 144b, are installed accordingly.

However, even if the fixing heater 143 is a single heater that heats the entire longitudinal direction of the fixing roller 141, it is preferable to provide two or more temperature sensors.

If there is only one temperature sensor in the fixing unit 14, if there is no change in the detected temperature during warm-up control, this may be because the power cord 42 is not connected to an outlet, or the temperature sensor itself is broken.

However, if there are multiple temperature sensors, it is unlikely that all of them will be out of order at the same time. If none of the temperature sensors detect a change in temperature of the fixing roller 141 during warm-up, it can be immediately determined that the power cord 42 is not connected to a power outlet. Also, if even just one of the multiple temperature sensors detects a change in temperature, it can be determined that the power cord 42 is connected (see steps S15 and onward in the flowchart in Figure 3).

(5) In the above embodiment, a power cord 41 is provided to supply power to the first load unit 210 including the control unit 15. However, the first load unit 210, which is mainly a DC load, does not consume much power compared to the fixing heater 143 and the like, and the functionality of secondary batteries has been greatly improved recently. Therefore, in this modified example, a secondary battery is used as the power supply unit for the first load unit 210.

Figure 6 is a block diagram showing an example of the main parts of a power supply system for a printer according to this modified example. In this figure, the same reference numerals as in Figure 2 indicate the same components, and therefore their description will be omitted.

As shown in FIG. 6, this modified example has only a power cord 42, and the power cord 41 is omitted. The power cord 42 is selectively connected to the heater drive unit 44 and the low-voltage power supply unit 43 via a changeover switch 45.

The changeover switch 45 is linked to, for example, the power switches 41b and 42b. When the power switches 41b and 42b are turned OFF, the power cord 42 is connected to the contact a1, DC power is supplied via the low-voltage power supply unit 43, and the secondary battery 46 is charged.

When the power switches 41b and 42b are turned ON, the changeover switch 45 is switched so that the power cord 42 is connected to the contact a2, and AC power is supplied to the heater drive unit 44.

As a result, the first load unit 210 including the control unit 15 operates by receiving DC power from the secondary battery 46 (first power supply unit), and the second load unit 220 including the heater drive unit 44 can receive AC power via the power cord 42 (second power supply unit).

For example, if the power cord 42 is unplugged from the power outlet and the printer 10 is moved, and then the power switches 41b and 42b are turned ON while forgetting to plug the power cord 42 into the power outlet at the new location, the cord connection determination process described with reference to Figures 3 and 5 can be executed to warn the user that the power cord 42 has been forgotten to be plugged in.

(6) In the above embodiment, a halogen heater is used as the fixing heater, but this is not limited to this and a resistive film heater or an electromagnetic induction heater (IH heater) may also be used. Also, it is not limited to an AC (alternating current) drive type, and a DC (direct current) drive type may also be used.

(7) In the above embodiment, a tandem type color printer has been described, but the present invention is not limited to this. The image forming device may be a fax machine, copier, or multifunction device as long as the total power consumption exceeds the rated value specified for a single power cord. Also, the printer may be a monochrome printer instead of a color printer.

<Additional Information>
Although the image forming apparatus according to the present invention has been described above based on the embodiment and the modified examples, the present invention is not limited to the above embodiment and the modified examples. The present invention also includes forms obtained by applying various modifications to the above embodiment and the modified examples that a person skilled in the art can think of, and forms realized by arbitrarily combining the components and functions of the embodiment and the modified examples within the scope of the present invention.

The present invention is suitable as a technology for determining the connection state of the power cord in the power supply system to a second load unit, such as a fixing heater, when the power supply system to a first load unit including a control unit is different from the power supply system to a second load unit that is the subject of control by the control unit.

REFERENCE SIGNS LIST 10 printer 11 image forming section 12 paper feed section 14 fixing section 15 control section 41, 42 power cord 41b, 41b power switch 43 low voltage power supply section 44 heater driving section 45 changeover switch 46 secondary battery 100 operation panel 110 display section 141 fixing roller 143 fixing heater 143a central heater 143b, 143c edge heater 144 temperature detection section 144a central temperature sensor 144b edge temperature sensor 310 dehumidification heater 311 humidity sensor

Claims (13)

a first power supply unit that supplies power to a first load unit including a control unit;
A second power supply unit that supplies power to a second load unit including a control target of the control unit;
A state detection unit that detects a state of the controlled object;
Equipped with
the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the state detection unit does not detect a change in the state of the control target even after a predetermined time has elapsed despite the control unit having issued an instruction to change the state of the control target,
the control target is a fixing heater that heats a fixing rotor in a fixing unit that fixes an unfixed image onto a recording sheet;
The image forming apparatus according to claim 1, wherein the state detection unit is a temperature sensor that detects a temperature of the fixing rotator. 2. The image forming apparatus according to claim 1 , wherein the temperature sensor is a thermistor or a thermopile. a first power supply unit that supplies power to a first load unit including a control unit;
A second power supply unit that supplies power to a second load unit including a control target of the control unit;
A state detection unit that detects a state of the controlled object;
Equipped with
the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the state detection unit does not detect a change in the state of the control target even after a predetermined time has elapsed despite the control unit having issued an instruction to change the state of the control target,
The image forming apparatus according to claim 1, wherein the object to be controlled is a dehumidifying heater for dehumidifying a recording sheet. 4. The image forming apparatus according to claim 3 , wherein the state detection section is a humidity sensor that detects humidity in a storage section that stores the recording sheets. 4. The image forming apparatus according to claim 3 , wherein the state detection section is a temperature sensor that detects the temperature of a storage section that stores the recording sheets. Equipped with a power switch,
The image forming apparatus according to any one of claims 1 to 5, characterized in that the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted when the state detection unit detects that the state of the controlled object has not changed even after a predetermined time has elapsed after the power switch is turned on. a first power supply unit that supplies power to a first load unit including a control unit;
A second power supply unit that supplies power to a second load unit including a control target of the control unit;
A state detection unit that detects a state of the controlled object;
a conveying roller for conveying a sheet on which an image is to be formed, or an intermediate transfer belt for primarily transferring a toner image formed in an image forming unit and secondarily transferring the primarily transferred toner image at a secondary transfer position onto a sheet being conveyed;
a drive motor that drives the transport roller or the intermediate transfer belt;
Equipped with
the control target is the drive motor,
the state detection unit is an encoder for controlling rotation of the drive motor,
The control unit determines that the power supply from the power cord of the second power supply unit has been cut off when the detected value by the encoder does not change even though the control unit issues a drive command to the drive motor.
1. An image forming apparatus comprising: The first power supply unit is
Another power cord different from the power cord of the second power supply unit;
a power conversion unit that converts AC power supplied from the other power cord into DC power;
The image forming apparatus according to claim 1 , further comprising: The first power supply unit is
8. The image forming apparatus according to claim 1 , wherein the second power supply unit is a secondary battery that receives power in advance from a power cord and stores the power. 10. The image forming apparatus according to claim 1, further comprising a warning unit that warns the user when the control unit determines that the power supply from the power cord of the second power supply unit has been interrupted. 11. The image forming apparatus according to claim 10 , wherein the first load section includes an image forming section that forms an unfixed image on a recording sheet and the warning section. An image forming apparatus that supplies power to a first load unit including a control unit and a warning unit via a first power cord, and supplies power to a second load unit including a fixing heater of a fixing unit via a second power cord,
The control unit determines that the second power cord is not connected to a power outlet when the temperature of the fixing rotor of the fixing unit does not increase even after a predetermined time has elapsed, even though the device has started up and started warm-up control of the fixing unit, and causes the warning unit to warn the user to insert the second power cord into the power outlet. a plurality of temperature sensors for detecting the temperature of the fixing rotor of the fixing unit;
The image forming apparatus according to claim 12, wherein the control unit determines that the second power cord is not connected to a power outlet when the detected temperatures of all of the plurality of temperature sensors do not increase even after a predetermined time has elapsed despite the start of the warm-up control.

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