JP2009128571A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can reduce energy as much as possible by turning on electricity for standby only when the possibility becomes high for an image forming process being started on heating a photoreceptor drum for standby. <P>SOLUTION: Before an image forming action, a control section controls the photoreceptor drum to a first standby temperature by controlling a drum heating means in response to one of; connection of a communication part with a prescribed network, supplying of power by a power source section or an operation input from an operation section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image by an electrophotographic image forming process method.

In an image forming apparatus using an electrophotographic image forming process, a corona charger is generally used as a charging means for uniformly charging a drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) to a predetermined polarity and potential. It has been. The corona charger is arranged in contact with the photosensitive drum in a non-contact manner, and uniformly charges the surface of the photosensitive drum to a predetermined polarity and potential by corona ions generated by corona discharge of the corona charger. .
In such a corona charger, corona products such as ozone O3 and nitrogen oxides NOx are generated during operation. In these corona products, discharge energy and atmospheric gas, moisture, etc. act on the photosensitive drum to form hydrophilic compounds such as nitrogen compounds, aldehyde groups, carboxyl groups, etc., and these compounds are applied to the photosensitive drum. As a result, the surface of the photoconductive drum is oxidized, or the adhering compound absorbs moisture in the atmosphere, so that the surface resistance of the photoconductive drum is lowered and the “image flow” phenomenon occurs. .

This type of image flow is a phenomenon in which corona products that adhere to the corona charger during image forming operations accumulate on the photosensitive drum when the main power of the image forming apparatus is OFF, and the image is lost in a band shape. , The ambient humidity is generated from about 50 to 60%.
In particular, after the completion of the image forming operation, moisture absorption of the discharge product is promoted during long-term storage (such as overnight) in an environment of the above humidity or higher. The incidence is highest. In addition, when an alternating current or a negative direct current voltage is applied to the corona charger, more image of the corona product is generated and the influence of the image flow is increased.
These image flow phenomena occur on most photoconductor drums, but especially when the surface hardness of the photoconductor drum is large, hydrophilic oxides such as ozone and NOx tend to deposit on the surface of the photoconductor drum, causing malignancy. Image flow occurs. This is presumably because the surface hardness of the photosensitive drum is large and the formed low resistance layer is difficult to be polished.

For example, it is known that an amorphous silicon photosensitive drum (such as an a-Si photosensitive drum) has a surface hardness as high as 1500 to 2000 KG / mm ² and is liable to cause an image flow phenomenon.
In addition, since the photosensitive drum with high surface hardness is naturally excellent in durability, it tends to be used in an image forming apparatus that requires high durability such as a high-speed copying machine, and the charging method is based on a corona charger. In many cases, this is considered to contribute to the probability of occurrence of the image flow phenomenon.

  Therefore, conventionally, as a countermeasure for preventing the image flow phenomenon, a heater (hereinafter referred to as a drum heater) is disposed on the inner surface of the photosensitive drum, and the surface of the photosensitive drum is heated by the heat generated by the drum heater, thereby generating ozone or NOx. Such a hydrophilic discharge product that prevents moisture absorption and suppresses a decrease in surface resistance of the photosensitive drum is known.

  For example, in Patent Document 1, the surface of the photosensitive drum is heated while the drum heater is always energized (ON) regardless of whether the main power of the image forming apparatus is ON / OFF (when the image forming operation is possible or when it is left). In addition, an image forming apparatus is disclosed in which the ambient environment is detected by a thermistor, a humidity sensor, etc., the input power ratio to the drum heater is changed according to the humidity, and the surface of the photosensitive drum is appropriately heated. Yes.

As for the surface temperature setting of the photosensitive drum, among the environmental conditions in which the image forming apparatus is used, moisture tends to adhere to the surface of the photosensitive drum when used in a humid environment. In general, the surface temperature of the photosensitive drum is set so that moisture can be removed. However, if the temperature of the developing unit close to the photosensitive drum rises, the developer may be solidified, and It is not preferable to raise the temperature more than necessary because there is a problem that toner tends to film on the surface of the body drum. For this reason, the surface temperature of the photosensitive drum is often set to about 35 to 40 ° C.
JP 2006-313266 A

By the way, in recent years, energy conservation regulations, especially power saving, have been carried out in each country due to heightened awareness of environmental protection.
In order to save power, the effect of reducing unnecessary energy consumption during standby is significant, so it is necessary to minimize the power supply when the equipment is not in use.
However, as in Patent Document 1, the drum heater is always energized (ON) regardless of whether the main power source of the image forming apparatus is ON / OFF (when the image forming operation is possible or when it is left). If the temperature of the photosensitive drum is kept constant by heating the power, power is always consumed, and power consumption during standby cannot be suppressed.

Therefore, it is conceivable to save power consumption by turning off the drum heater during standby such as when the image forming apparatus is left for a long time.
However, as a practical matter, when the drum heater is started after an image output instruction is transmitted from a device connected via a communication interface, such as a printer or facsimile, the drum temperature is rapidly increased to increase the first print speed. When the temperature is raised, the temperature is raised to the adjacent developing device due to the temperature overshoot, which causes problems such as solidification of the developer and filming of toner on the surface of the photosensitive drum.
Therefore, it is preferable that the photosensitive drum is heated and maintained at a predetermined standby temperature before the standby image forming operation is started.

However, even if the standby temperature is suppressed to a relatively low standby temperature, it is useless to maintain the standby temperature until no actual image formation is performed.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to suddenly start heating of the photosensitive drum during image formation in order to prevent an image from flowing during image formation. In order to avoid the inconvenience that the chute raises the temperature to the adjacent developing unit and the developer is not solidified or the toner is filmed on the surface of the photosensitive drum. An image forming apparatus that heats to a temperature, and when the standby photosensitive drum is heated, energizing standby power only when the possibility that an image forming process is started is high is as much as possible. It is an object of the present invention to provide an image forming apparatus capable of reducing the above.

In order to achieve the above object, the present invention provides:
A photosensitive drum on which an electrostatic latent image can be formed;
Drum heating means for heating the photosensitive drum;
Heating control means for controlling the drum heating means;
An operation unit for inputting an operation to the image forming apparatus;
A power supply for supplying power to the image forming apparatus;
A communication unit for connecting the image forming apparatus to a predetermined network;
In an image forming apparatus comprising:
The heating control means responds to whether the communication unit is connected to the predetermined network, power is supplied from the power supply unit, or an operation input is performed from the operation unit. The image forming apparatus is configured to control the drum heating unit to control the photosensitive drum to a first temperature for standby.
According to the present invention, a situation occurs in which the communication unit is connected to the predetermined network, the power is supplied from the power supply unit, or the operation input from the operation unit is performed. Since it is estimated that there is a high possibility that an image forming operation will be performed from now on, the drum heating means is controlled to control the photosensitive drum to a first temperature that is relatively low for standby. Compared with the conventional apparatus that keeps the photosensitive drum at a high temperature, it can save much power.

  In the standby state, when the communication unit receives an image output command from the network or an image output key provided on the operation unit is pressed, an image forming operation is immediately performed. Therefore, by controlling the drum heating means to control the photosensitive drum to a second temperature higher than the first temperature, the photosensitive drum can be moved only when the image forming operation is actually performed. Since the second high temperature is controlled, it is possible to achieve excellent power saving without unnecessarily prolonging the high temperature state.

In the present invention, when the second temperature is set to a temperature that is at least equal to or higher than the temperature necessary for removing moisture on the surface of the photosensitive drum, the second temperature is set on the photosensitive drum during an actual image forming operation. The problem of image flow due to the generation of moisture can be completely prevented.
An example of the input from the operation unit is that an energy saving mode release key provided on the operation unit is pressed.
Here, the drum heating unit stops heating of the photosensitive drum by the drum heating unit when the predetermined waiting time elapses without performing the image forming operation, and the image forming operation is not performed. A case where the heating of the photosensitive drum by the drum heating unit is stopped is conceivable if a predetermined waiting time has passed and the energy saving mode release key is not pressed.

  As yet another example, the drum heating means is a case where a predetermined waiting time has elapsed without performing an image forming operation, and further that the communication unit has disconnected from the predetermined network. As a premise, when the heating of the photosensitive drum by the drum heating unit is stopped, or when it is determined that the energy saving release key has been pressed when a predetermined waiting time has elapsed without performing the image forming operation. In this case, the drum heating unit may be controlled to control the photosensitive drum to the first temperature.

  The drum heating means is further configured such that when the predetermined waiting time has passed without performing an image forming operation and the communication unit determines that the connection with the predetermined network has been released, the drum heating means The photosensitive drum may be controlled to the first temperature by controlling a heating unit.

  According to the present invention, the heating control means that the communication unit is connected to the predetermined network, power is supplied by the power supply unit, or an operation input from the operation unit is performed. Accordingly, the drum heating means is controlled to control the photosensitive drum to a relatively low first temperature for standby, so that the conventional photosensitive drum is always kept at a high temperature. Compared with the device, it can save much power.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a block diagram showing a schematic configuration of the entire image forming apparatus X according to an embodiment of the present invention. FIG. 2 is a block diagram for explaining a control device mounted on the image forming apparatus X. FIG. 3 is a graph showing the relationship between the amount of water vapor in the air and the first drum set temperature, and FIG. 4 shows the procedure for setting the first and second drum set temperatures in the printer according to one embodiment of the present invention. FIG. 5 is a flowchart showing a procedure for setting the first and second drum set temperatures in the printer according to the embodiment of the present invention.

In FIG. 1, an image forming apparatus X includes a charger 8, an exposure device 9, a developing device 4, and a transfer roller 5 around an image carrier 1 (photosensitive drum) that rotates clockwise in the drawing along the rotation direction. , A temperature sensor 3, a cleaning blade 6, and a static elimination device 7 are disposed.
Further, a drum heater 2 (an example of a drum heating unit) for heating the photosensitive drum is provided inside the photosensitive drum 1, and the temperature sensor 3 detects the temperature of the photosensitive drum 1, Based on the temperature detected by the temperature sensor 3, the drum heater 2 is controlled by the heating control means shown in FIG.
The image forming apparatus X is controlled by the CPU shown in FIG. The CPU has the function of the heating control means in the present invention.

As shown in the figure, the CPU has a communication interface state monitoring unit connected to a network such as a LAN, and monitors a connection state and a non-connection state with an external device such as a personal computer connected to the network. 11 is connected. As a communication interface status monitoring method, communication interface control circuits such as a parallel interface control circuit, a serial interface control circuit, and a network interface control circuit require negotiation for the connection between the communication interface and the computer. To determine whether the connection with the computer is complete.
In addition, peripheral devices (such as USB (Universal Serial Bus) and IEEE (American Institute of Electrical Engineers) 1394) having a communication interface having a power supply line showing a potential higher than a certain value when communication is possible (such as the American Institute of Electrical Engineers). In a printer, for example, the potentials of the power lines of these communication interfaces are monitored, and it is determined whether or not the connection has been completed when the potential of the power line becomes equal to or higher than a specified value.

In addition, the CPU is supplied with various operation keys such as a numeric keypad, a print key, a standby mode cancel key, a standby mode shift key, an operation unit 13 having an input unit, and further supply of commercial power to the image forming apparatus X. A signal from the power supply unit 15 is input.
Further, the CPU is provided with a memory M for storing set value data of a first temperature and a second temperature described later.

  Next, the temperature control procedure of the photosensitive drum by the CPU (heating control means) will be described with reference to a flowchart showing a control procedure related to a printer (or facsimile) which is an example of the image forming apparatus shown in FIG. Here, S1, S2,... Are control procedure (step) numbers.

  When the image forming apparatus is in the power saving mode or in the power-off state (S1), the CPU is connected to a network to which an external device (such as a personal computer) is connected (from an unconnected state) by a signal from the communication unit 11. When a change in the connection state) is detected, or when a power supply is detected by a signal from the power supply unit 15 (S2), energization to the drum heater 2 is started (S3), and the photosensitive drum The signal which heats 1 to the 1st preset temperature for heat-retaining in standby mode is output (S4).

Since the photosensitive drum is preheated to such a relatively low temperature for standby, the developer overhang in the adjacent developing unit due to the temperature overshoot generated by suddenly raising the temperature or the surface of the photosensitive drum In addition, the problem of toner filming is suppressed.
Thereafter, when an image output command is received from the network via the communication interface (YES in S5), the photosensitive drum is heated to the second temperature (S6) and at the same time, the air supply fan is activated (S7), Ozone generated during the forming operation is discharged out of the machine.

Here, the first set temperature for keeping the temperature of the photosensitive drum is such that no dew condensation occurs even when the printer is cooled from the outside temperature: 32.5 ° C. and humidity: 80%, which are within the operating temperature conditions of the printer. The temperature, that is, the temperature necessary to remove at least the moisture on the surface of the photosensitive drum is desirable, and is set to 27.5 ° C. or higher, for example (see FIG. 3).
Further, the second temperature setting for removing water adhering to the photoconductor during the image forming operation is a temperature at which water can be sufficiently discharged in a humid environment, and the development close to the photoconductor drum. It is desirable that the developer in the apparatus is hardened or the temperature at which the toner does not film on the surface of the photosensitive drum, and is set to 35 to 40 ° C. or higher, for example.

After the completion of the image forming operation (S9), the drum heater 2 is heated to the second set temperature and the air supply fan is activated within a predetermined time (S6 to S11). This is because the moisture contained in the transfer paper is evaporated when the transfer paper is fixed by the fixing device, and the temperature and humidity in the machine are increased because the transfer paper is re-fed into the machine, especially during double-sided printing. This is to raise both. For this reason, when the drum heater 2 is in a stopped state, it is performed in order to prevent condensation from occurring due to the air that has been warmed and contains a lot of water being cooled by the photosensitive drum 1.
Thereafter, when the predetermined time has elapsed, the air supply fan is stopped (S12).
Meanwhile, as in S5, every time an image output command is received from the network, the image forming operation is started (S10).

  In addition, when the communication interface state monitoring unit is disconnected from the network to which an external device (such as a personal computer) is connected (YES in S13), the power supply to the drum heater 2 is stopped (S14). , The process returns to S2.

With the configuration as described above, in the image forming operation, without increasing the first print time, and due to a temperature overshoot that occurs when the temperature of the photosensitive drum 1 is rapidly increased, the developer in the adjacent developing device is clumped. In addition, the problem of toner filming on the surface of the photosensitive drum 1 can be suppressed, and moisture adhering to the photosensitive drum 1 can be quickly removed to prevent the occurrence of image flow.
Further, by having a relatively low first temperature setting to keep the photosensitive drum 1 warm, power consumption during standby can be suppressed.

As described above, FIG. 4 shows a case where the present invention is applied to a printer (or facsimile) as an example of an image forming apparatus. However, the present invention is not limited to this, and the same applies to a copying machine. Applied.
FIG. 5 shows an outline of a control procedure by the control means when the present invention is applied to a copying machine. The outline is the same as that of a printer, but the parts listed below have specific configurations, and only those parts will be described below.
(1) Since there is no image output command via the network in S2, instead, when the energy saving mode setting key of the operation unit 13 is pressed, the drum heater 2 is activated (S3).
(2) In S5, when the image output key provided in the operation unit 13 is pressed instead of the image output command via the network, the temperature of the photosensitive drum 1 is set to the second temperature (S6). .
(3) In S10, it is determined whether or not the image output key of the operation unit 13 has been pressed instead of the image output command reception determination.
(4) In S13, it is determined whether or not the energy saving mode setting key provided in the operation unit 13 is pressed instead of whether or not the interface connection is released.
Except for the differences (1) to (4), the control procedure is the same as that shown in FIG. 4 for the printer.

1 is a block diagram showing a schematic configuration of an entire image forming apparatus X according to an embodiment of the present invention. FIG. 3 is a block diagram for explaining a control device mounted on the image forming apparatus X according to the embodiment of the present invention. The graph which shows the relationship between the amount of water vapor | steam in air, and 1st drum preset temperature. 6 is a flowchart showing a procedure for setting first and second drum set temperatures in a printer according to an embodiment of the present invention. 6 is a flowchart showing a procedure for setting first and second drum set temperatures in a printer according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Drum heater 3 ... Temperature sensor 4 ... Developer 5 ... Transfer roller 6 ... Cleaning blade 7 ... Static elimination apparatus 8 ... Charger 9 ... Exposure apparatus 11 ... Communication part 13 ... Operation part 15 ... Power supply part M …memory

Claims (9)

A photosensitive drum on which an electrostatic latent image can be formed;
Drum heating means for heating the photosensitive drum;
Heating control means for controlling the drum heating means;
An operation unit for inputting an operation to the image forming apparatus;
A power supply for supplying power to the image forming apparatus;
A communication unit for connecting the image forming apparatus to a predetermined network;
In an image forming apparatus comprising:
The heating control means responds to whether the communication unit is connected to the predetermined network, power is supplied from the power supply unit, or an operation input is performed from the operation unit. An image forming apparatus characterized in that the drum heating means is controlled to control the photosensitive drum to a first temperature for standby.   The heating control unit further controls the drum heating unit in response to the communication unit receiving an image output command from the network or an image output key provided in the operation unit being pressed. The image forming apparatus according to claim 1, wherein the photosensitive drum is controlled to a second temperature higher than the first temperature.   The image forming apparatus according to claim 2, wherein the second temperature is a temperature that is at least a temperature necessary for removing moisture on the surface of the photosensitive drum.   The image forming apparatus according to claim 1, wherein the operation unit includes an energy saving mode release key.   5. The drum heating unit stops heating of the photosensitive drum by the drum heating unit when a predetermined waiting time elapses without performing an image forming operation. 6. Image forming apparatus.   The drum heating means is a case where a predetermined waiting time elapses without performing an image forming operation, and on the premise that the energy saving mode release key is not pressed, the photosensitive drum by the drum heating means. The image forming apparatus according to claim 3, wherein the heating is stopped.   The drum heating means is a drum heating means in a case where a predetermined waiting time has passed without performing an image forming operation, and further assuming that the communication unit has disconnected from the predetermined network. The image forming apparatus according to claim 1, wherein the heating of the photosensitive drum is stopped.   The drum heating unit controls the drum heating unit to control the drum heating unit when it is determined that the energy saving release key has been pressed when a predetermined waiting time has elapsed without performing an image forming operation. The image forming apparatus according to claim 1, wherein a drum is controlled to the first temperature.   If the predetermined heating time has passed without performing the image forming operation and the communication unit determines that the communication unit has disconnected from the predetermined network, the drum heating unit performs the drum heating. The image forming apparatus according to claim 1, wherein the photosensitive drum is controlled to the first temperature by controlling a unit.

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