JP2010128465A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of improving productivity by shortening the first print time to increase the speed of image forming processing. <P>SOLUTION: In the image forming apparatus, the invocation of image forming start operation in the image forming apparatus except a fixing device is started at the time which is at least earlier than the completion of temperature rise of the fixing device and satisfies T≤S wherein S is the time required from the start of the invocation of image forming start operation in the image forming apparatus except the fixing device to entrance of an image recording medium into a fixing member of the fixing device and T is a predicted time remaining till reach to a target temperature of the fixing member after the start of temperature rise of the fixing device, and the image recording medium is made enter the fixing device simultaneously with the completion of temperature rise of the fixing device. Consequently, not only the first print time is shortened without poor fixing to be able to improve the productivity but also the power consumption required for maintaining the temperature of the fixing device can be reduced to be able to save energy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention uses a fixing member such as a fixing roller and a fixing belt, and uses an image of a copying machine, a printer, a facsimile, or a complex machine of these having a fixing device that fixes heat onto an image recording medium using heat and pressure. The present invention relates to a forming apparatus.

In various industrial fields, image forming apparatuses such as electrophotographic copiers, printers, facsimiles, or multifunction peripherals thereof are now widely used. In these electrophotographic image forming apparatuses, a method in which a toner image is fixed onto an image recording medium with heat or pressure using a fixing member such as a fixing roller or a fixing belt is generally used. Due to the recent increase in awareness of environmental problems, energy saving is also progressing in these electrophotographic image forming apparatuses. What is most important in considering energy saving of the image forming apparatus is power saving of the fixing device. This is because the fixing device uses a large amount of electric power to raise the temperature of the fixing member and maintain the temperature. Many technologies have been developed to reduce the power consumption of the fixing device. For example, the so-called on-demand fixing method in which the fixing member is heated only when necessary by shortening the fixing temperature rise time, and heat generation for power consumption. An IH fixing method using electromagnetic induction, which is said to have high efficiency, has already been put into practical use.
In addition, although the fixing rise time is shortened, there is an increasing demand for waiting time reduction, and it is important to shorten the first print time after the print command.

  Therefore, for example, in the conventional technique described in Patent Document 1 (Japanese Patent Laid-Open No. 7-287474), an optimum ready temperature can be set, and the waste time from the arrival of the fixing temperature to the fixing start timing is minimized. In order to provide an image forming apparatus capable of performing image processing, in the image forming apparatus in which the heating body starts or enables image formation at a predetermined temperature lower than the fixing temperature, the toner image forming means cannot be interrupted. By correcting the predetermined temperature by the process processing time determining means for determining the time in advance and the correction value determining means for determining the predetermined temperature according to the expected processing time, the remaining warm temperature proportional to the process processing time is determined. The optimum ready temperature can be set so that the up time (multiple processing time) is reached. Dead time from timing to the fixing start timing is set to be so as to minimize.

  However, in the above-described prior art method, since the parameters for controlling the flow for controlling the fixing temperature are many and complicated, it is unavoidable that the actual time required to reach the fixing target temperature is not deviated from the estimated value. Absent. Further, from the viewpoint of reducing power consumption, the standby power cannot be sufficiently reduced.

JP-A-7-287474

Another method for power saving of the fixing device is to reduce energy consumption during standby. Significant power savings can be achieved by bringing the power supply to zero as much as possible when not in use or for a long standby time.
However, in the conventional fixing device configuration, if the standby power is set to zero, it takes a long time for the fixing member to warm up when it is reused, so the waiting time until the image can be output becomes longer and the usability of the user deteriorates. End up. Normally, in the conventional control, since the image forming operation is performed after the temperature increase of the fixing is completed after receiving the print command, the temperature increase time of the fixing is a full waiting time.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an image forming apparatus capable of shortening the first print time, achieving high-speed image forming processing, and improving productivity. To do.
In the present invention, in addition to the above object, the sequence of image forming timing is simple, and the control parameter for the time required to reach the fixing target temperature is determined by the configuration of the fixing device, and is input to the fixing device. It is an object of the present invention to provide an image forming apparatus that can manage only the amount of electric power and can perform highly accurate control.

In order to solve the above-described problems, the present invention employs the following solutions.
The first means of the present invention is an image forming apparatus comprising: an image forming means for forming a toner image on an image carrier and transferring the toner image to an image recording medium; and a fixing device for fixing the toner image on the image recording medium. The time taken from the start of the image forming start operation of the image forming apparatus excluding the fixing device until the image recording medium enters the fixing member of the fixing device is S, and the fixing member When the estimated remaining time until the target temperature is reached is T, at least the start of activation of the image forming apparatus excluding the fixing device is earlier than the completion of the temperature rise of the fixing device and the time T ≦ S is satisfied. The image forming apparatus image forming start operation excluding the fixing device is started, and the image recording medium enters the fixing device simultaneously with completion of the temperature increase of the fixing device.

  A second means of the present invention is the image forming apparatus of the first means, wherein the image forming means includes an optical writing means for forming a latent image on the image carrier by optical writing, and an image on the image carrier. And developing means for developing the latent image with toner into a visible image, and transfer means for transferring the toner image on the image carrier to the image recording medium.

  The third means of the present invention is the image forming apparatus of the first means, wherein the image forming means forms a latent image on the image carrier by scanning laser light via a rotating optical deflector. Optical writing means; developing means for developing the latent image on the image carrier with toner to make it visible; and transfer means for transferring the toner image on the image carrier to the image recording medium. The time taken from the start of the image forming apparatus image forming start operation excluding the optical deflector and the fixing device to the entry of the image recording medium into the fixing member of the fixing device is S, and the temperature of the fixing device is increased. When the estimated remaining time until the fixing member reaches the target temperature after the start is T, at least the start of the image forming apparatus excluding the fixing device is started after the rotation of the optical deflector is in a steady state. , Faster than completion of temperature increase of the fixing device, and T ≦ S. It starts the activation of the image forming apparatus image forming start operation except for the fixing device from the point, at the same time the image recording medium and complete heating of the fixing device is characterized in that entering into the fixing device.

  A fourth means of the present invention is the image forming apparatus of the first means, wherein the image forming means forms an intermediate image receiving member as the image carrier and a toner image on the intermediate image receiving member. And at least one print station and transfer means for transferring the toner image on the intermediate image receiving member to the image recording medium.

According to a fifth means of the present invention, in the image forming apparatus of any one of the first to fourth means, the start of the image forming apparatus image forming start operation excluding the fixing device is started from the time when T = S. The image recording medium enters the fixing device simultaneously with completion of the temperature increase of the fixing device.
According to a sixth means of the present invention, in the image forming apparatus of any one of the first to fifth means, an estimated remaining time T until the fixing member reaches a target temperature after the temperature rise of the fixing device is started. Is predicted based on temperature information from a temperature monitoring device provided in the fixing device.

  According to a seventh aspect of the present invention, in the image forming apparatus of any one of the first to sixth aspects, the image forming apparatus includes a power detection unit that monitors input power to the fixing device, and is attached to the image forming apparatus. When the power supplied to the fixing device decreases due to the operation of the peripheral device or the operation of the document reading unit, until the fixing member reaches the target temperature after the heating start of the fixing device according to the input power The estimated remaining time T is predicted in advance.

  According to an eighth means of the present invention, in the image forming apparatus of any one of the first to sixth means, when the voltage input to the power supply unit that supplies power to the image forming apparatus decreases. According to the input voltage, a predicted remaining time T until the fixing member reaches a target temperature after the start of temperature raising of the fixing device is predicted in advance.

  According to a ninth means of the present invention, in the image forming apparatus of any one of the first to sixth means, the image forming apparatus has a temperature detecting means for monitoring an outside temperature, and the fixing device is configured to detect the outside temperature. The estimated remaining time T until the fixing member reaches the target temperature after the start of temperature increase is predicted in advance.

  According to a tenth means of the present invention, in the image forming apparatus of any one of the first to sixth means, the temperature of the fixing device is increased according to the type and thickness of the image recording medium to be used. A predicted remaining time T until the fixing member reaches a target temperature is predicted in advance.

  In the image forming apparatuses of the first to fourth means, the image forming start operation is started earlier than the fixing temperature raising completion, which is the start condition of the conventional image forming starting operation, and the fixing temperature raising is completed with certainty. Since the image recording medium enters the fixing device, the first print time can be shortened and productivity can be improved without accompanying fixing failure, and at the same time, the power consumption required to maintain the temperature of the fixing device can be reduced. Energy saving can be achieved.

  In the image forming apparatus of the fifth means, the image recording medium enters the fixing device at the timing of completion of the fixing temperature rise, that is, the timing of starting the conventional image forming start operation. The first print time can be shortened and productivity can be improved, and at the same time, wasteful power consumption can be reduced to the maximum and energy saving can be achieved.

  In the image forming apparatus of the sixth means, the fixing temperature, which is a key for calculating the estimated remaining time T until the fixing member reaches the target temperature, is directly monitored and the current temperature is compared with the target temperature. Can be calculated more accurately, reducing the first print time without improper fixing and improving productivity, and at the same time reducing the power consumption required to maintain the temperature of the fixing device. Can be achieved.

  In the image forming apparatus of the seventh means, the power input to the fixing device is reduced by monitoring the power input to the fixing device, for example, due to the operation of the peripheral device attached or the operation of the document reading unit. Since the estimated remaining time T can be corrected and calculated according to the input power at that time, even if any operation accompanied by power consumption is performed in parallel with the fixing temperature rise, T As a result, the first print time can be shortened and productivity can be improved without improper fixing, and at the same time the power consumption required to maintain the temperature of the fixing device can be reduced. Can be achieved.

  In the image forming apparatus of the eighth means, the input voltage from the power supply unit to the image forming apparatus is monitored as needed, and when the input voltage decreases, the estimated remaining time T is corrected and calculated accordingly. Therefore, even if the input voltage from the power supply unit is reduced, T can always be calculated accurately, thereby shortening the first print time and improving productivity without causing fixing failure. At the same time, power consumption required for maintaining the temperature of the fixing device can be reduced, so that energy saving can be achieved.

  In the image forming apparatus of the ninth means, the estimated remaining time T can be corrected and calculated by monitoring the outside temperature, so that T can always be calculated accurately under any temperature condition. As a result, the first print time can be shortened and productivity can be improved without accompanying fixing failure, and at the same time, the power consumption required for maintaining the temperature of the fixing device can be reduced, so that energy saving can be achieved.

  In the image forming apparatus of the tenth means, since the estimated remaining time T can be calculated with respect to the fixing temperature increase target temperature for each type and thickness of the image recording medium to be used, any image recording medium is used. However, T can always be calculated accurately, thereby reducing the first print time without improper fixing and improving productivity, and at the same time reducing the power consumption required to maintain the temperature of the fixing device. This can save energy.

  Specific examples of the configuration, operation, and effects of the image forming apparatus according to the present invention are shown below.

First, an electrophotographic image forming apparatus using a light emitting diode (LED) array as an optical writing means (optical writing unit) of an image forming means will be described as a first embodiment.
FIG. 1 is a schematic configuration diagram showing an electrophotographic printer which is an example of an electrophotographic image forming apparatus.
In FIG. 1, reference numeral 1 denotes a photoconductive photosensitive drum as an example of an image carrier, and a charging unit 2, an optical writing unit 3, a developing unit are disposed around the photosensitive drum 1 that can rotate in the direction of arrow A. The unit 4, the transfer unit 5, and the cleaning unit 6 are respectively arranged at predetermined positions. The optical writing unit 3 as an optical writing means collects the light emitted from the LED array 7 as a light source, the substrate 8 on which the LED array 7 is mounted, and the light emitted from the LED array 7 to form an image on the photosensitive drum 1. SELFOC lens (registered trademark, hereinafter referred to as a lens) 9. The distance B from the LED array 7 to the optical writing unit 1 a of the photosensitive drum 1 is a constant value determined by the type of the lens 9.

  Next, the printing process of the conventional electrophotographic printer having the above structure will be described with reference to FIG. The charging unit 2 uniformly charges the periphery of the photosensitive drum 1 and forms an electrostatic latent image on the photosensitive drum 1 by light irradiation of the LED array 7. Then, the developing unit 4 follows the electrostatic latent image on the photosensitive drum 1. The toner is adsorbed and developed. The transfer unit 5 transfers the toner adsorbed on the photosensitive drum 1 onto a sheet P that is an image recording medium, and the sheet P is sent to a fixing device (hereinafter referred to as a fixing unit) 10, and the fixing unit 10 transfers the transferred toner. Is heated and fixed on the paper P. On the other hand, excess toner remaining on the photosensitive drum 1 is scraped off by the cleaning unit 6 and the photosensitive drum 1 is cleaned. Printing is performed by repeating the above process.

  As shown in FIG. 1, the optical writing unit 3 that is an optical writing means includes a substrate 8 that is a plate-like member and a lens 9. As shown in FIG. 2, the substrate 8 is mounted with an LED array 7 and a driver IC 15 that drives the LED array 7. On the LED array 7, a plurality of light emitting elements 7a are arranged in a line as shown in FIG. 2, and these light emitting elements 7a emit light, and light irradiation by the LED array 7 is performed. . By the way, the light emitting element 7a emits light not only in the vertical direction but also in a wide range from the entire portion where the light emitting element 7a is exposed from the LED array 7. The light irradiated vertically from the LED array 7 is the strongest.

  Further, as shown in FIG. 3, the optical writing unit 3 can be provided with an angle θ with respect to the tangential plane 17 of the photosensitive drum 1 with the LED array 7 as the rotation center. This angle θ is an appropriate angle set so that the lens 9 can be sufficiently condensed on the photosensitive drum 1 so that the light emitted from the LED array 7 does not affect the printing accuracy.

  Next, the optical writing operation will be described. When the driver IC 15 is driven to selectively emit light from the light emitting elements 7a of the LED array 7, light 18 emitted from each light emitting element 7a passes through the lens 9 and is charged with a photosensitive drum. An image is formed on one optical writing unit 1a. As described above, the print data (electrostatic latent image) is written on the photosensitive drum 1.

Next, a general fixing device using a heater roller (hereinafter referred to as a fixing roller) including a heating member as a fixing member will be described in detail.
As shown in FIG. 4, the fixing device 10 includes a fixing roller 18 and a pressure roller 19 pressed against the fixing roller 18 by a biasing force of a spring (not shown). The fixing roller 18 is attached to the fixing side plates 50 and 50 via heat insulating bushes 51 and 51 and bearings 52 and 52, and is rotationally driven by a gear 53 engaged with a driving source (not shown). A radiant heater 23 is provided inside the fixing roller 18, and an end of the radiant heater 23 is held by a heater holding member 24.

A temperature sensor 60 as a temperature monitoring device is brought into contact with the surface of the fixing roller 18, and a signal detected by the temperature sensor 60 is taken into a central processing unit (CPU) 63 through an input circuit 61 of the control unit 37. The CPU 63 is configured to control energization to the radiation heater 23 via the driver 62 based on the temperature of the fixing roller 18 detected by the temperature sensor 60.
Normally, when the power of the image forming apparatus is turned on, a current flows to the radiation heater 23 via the driver 62, and the fixing roller 18 is rapidly raised to a predetermined set temperature of about 180 ° C.

As shown in FIG. 5, the fixing roller 18 often has a thin aluminum pipe 27 made of metal as a base. A fluorine-based surface release layer 26 is preferably formed on the outer surface of the fixing roller 18 in order to improve the separation of the paper P after fixing.
The pressure roller 19 includes a cored bar 40 and a foamed silicon rubber layer 42 as an elastic material.

  The radiation heater 23 is configured to cover the tungsten filament 29 with a glass tube 28, and at least an inert gas is sealed in the glass tube 28, and nitrogen that prevents oxidation of the tungsten filament 29 as necessary. In addition, halogen substances containing iodine, bromine, chlorine, etc. are enclosed.

  The CPU 63 of the control unit 37 shown in FIG. 4 includes a microcomputer, memories (ROM, RAM, nonvolatile memory, etc.) for storing various control programs and control data, an input / output device, a clock, a timer, and the like. , Based on input signals from the temperature sensor 60 and various detection means (electric energy monitor, input voltage monitor, external temperature sensor, etc.), input information from the operation unit, etc. A function of correcting and calculating control data such as “remaining time T” is provided. Further, the CPU 63 has a function of controlling operations of the fixing device 10 and other parts of the apparatus based on the corrected data.

Next, the fixing temperature rise curve will be described.
An example of the relationship data between the power supply time to the fixing device 10 and the temperature of the fixing roller 18 is shown in FIG. In FIG. 6, when the supply power supplied from the external power source to the radiation heater 23 via the driver 62 is constant, the horizontal axis represents the power supply time from the external power supply to the radiation heater 23, and the vertical axis represents the fixing roller temperature. FIG. 6 is a conceptual diagram showing how the temperature of the fixing roller 18 increases with power supply when the power is supplied. The rising gradient of the fixing roller temperature with respect to the power supply time varies depending on the configuration and conditions of the fixing member. The fixing member configuration and conditions here include the diameter and material of the fixing roller 18 and the pressure roller 19, the thickness of the roller, the presence or absence of a surface coat layer, the fixing nip width, the nip pressure, the offset amount, the roller linear velocity, and the like. . This temperature rise curve has a characteristic of drawing a temperature rise curve with the same gradient no matter how many times the fixing member configuration and conditions are the same. Therefore for each of the fixing members configurations, conditions, be previously extracted reference temperature T _S corresponding to the time t ₁ in response to the amount of power supplied to the fixing device 10, the power supply time to the radiant heaters 23 It is possible to predict how many times the fixing roller temperature becomes with respect to the length.

  Of course, this temperature rise curve is limited to the case where the power supply to the radiant heater 23 is constant, but when the fixing device starts up, the radiant heater 23 is usually supplied with full power and heated. As shown in FIG. 7, the relationship between the power supply time and the temperature of the fixing roller 18, that is, the temperature rising curve is uniform. For example, the temperature increase gradient ΔT / Δt at a certain point in the temperature increase curve and the required time t until reaching the reload temperature (for example, 185 ° C.) are constant.

Next, the fixing temperature control will be described in detail.
In order to shorten the temperature raising time of the fixing roller 18, it is effective to increase the input energy per unit time, that is, the rated power. In fact, some high-speed machines with a high printing speed are compatible with a power supply voltage of 200V. However, in general offices in Japan, the upper limit of the power supply is generally 100V / 15A (1500W), and in order to support the power supply voltage of 200V, it is necessary to carry out special work related to the power supply at the installation site. Is not a general solution. For this reason, even if it is attempted to raise the temperature of the fixing roller 18 in a short time, the upper limit of the input energy cannot be raised.

Next, an image forming sequence will be described.
Here, the image forming apparatus (electrophotographic printer) including the general fixing device 10 using the heater roller (fixing roller) 18 having the photosensitive drum 1 as described above and including a heating member as a fixing member. An example is shown. 8 and 9 schematically show the timing sequence of the fixing heating operation of the image forming apparatus and the image forming system operation including the photosensitive drum motor and the like.
FIG. 8 shows a normal (conventional) printing operation. When printing preparation is started, the fixing heating operation is started. The fixing device 10 transitions to a temperature rise completion state after a certain time after the start of the heating operation. The image forming system operation starts when the temperature rise is completed. That is, if the time taken from the start of the image forming apparatus excluding the fixing device 10 to the image recording medium (paper) P entering the fixing member (fixing roller) 18 of the fixing device 10 is S, the fixing device 10 is moved up. The image recording medium (paper) P enters the fixing device 10 after S (sec) has elapsed from the temperature completion state. This indicates that S (sec) elapses from the time when the fixing device 10 transitions to the temperature rise completion state until the image recording medium (paper) P enters the fixing device 10, and productivity including the first print time. It can be seen that this is disadvantageous in terms of energy saving.

  On the other hand, FIG. 9 shows the printing operation of this embodiment. When the estimated remaining time until the fixing member (fixing roller) 18 reaches the target temperature after the temperature rise of the fixing device is T, the start timing of the image forming system operation is earlier than the completion of the temperature rise of the fixing and T ≦ S. When the time is reached ((1) in FIG. 9), the image forming system starts to operate at a timing earlier than before and the temperature rise is completed before the image recording medium (paper) P enters the fixing device 10. Therefore ((2) in FIG. 9), the first print time can be shortened without the toner being fixed onto the image recording medium (paper) P inadequately. Further, at this time, by making the operation start timing of the image forming system earlier by T (sec) than the conventional timing shown in FIG. 8, the fixing device 10 shifts to the temperature rising completion state and at the same time to the fixing device 10. The image recording medium (paper) P can be entered. In other words, compared to the conventional sequence shown in FIG. 8, the first print time can be shortened by S (sec) in the sequence of the present embodiment shown in FIG. 9 ((3) in FIG. 9), and energy saving. Has also been shown to be achieved.

  When the control of this embodiment is performed, if the fixing device 10 is provided with a device (temperature sensor) 60 for monitoring the temperature, the temperature of the fixing device and the target temperature for completion of temperature increase are determined as needed from the start of the temperature increase of the fixing device 10. By comparing, the remaining time T required for completion of the temperature rise can be calculated with higher accuracy. Further, if the temperature sensor 60 signal (temperature data) detected in the nonvolatile memory or the like is temporarily stored, the remaining time T until the completion of the temperature rise can be corrected and calculated based on the data. . Therefore, according to the present invention, it is possible to allow the image recording medium to enter the fixing device without generating a useless temperature increase waiting time and within a range where the temperature increase is not insufficient.

  The remaining time T required to complete the temperature increase can be determined using the above-described temperature increase curve (FIGS. 6 and 7) prepared based on experimental data in advance, and the temperature sensor 60. The remaining time T until the completion of the temperature rise may vary depending on the operating state of the image forming apparatus, the environment, etc., and will be described later in this embodiment. It is assumed that T is corrected in accordance with various conditions, and real-time control is performed, for example, Feed Forward control. Specific examples are shown below.

  For example, when copying is performed in the image forming apparatus, the document reading unit may be operating at the same time as the temperature of fixing is increased. When a peripheral device that performs stapling or punching is mounted on the image forming apparatus, the initial operation of the peripheral device may be performed at the same time as the temperature of fixing is increased. As described above, when various power consumption operations are performed simultaneously with the temperature rise of the fixing device 10, the electric power supplied to the fixing device 10 for the temperature rise temporarily decreases, and the actual temperature rise Completion will be delayed than expected. However, in the image forming apparatus that can monitor the amount of power supplied to the fixing device 10, the temperature rises from the amount of power actually supplied to the fixing device at any time even when the aforementioned power reduction occurs. The remaining time T until completion can be corrected and calculated.

  The reason why the input power to the fixing device 10 decreases is not limited to the above. For example, the voltage itself input from the power supply unit to the image forming apparatus may be low. In this case, the time required to complete the temperature rise actually takes longer than expected, but in an image forming apparatus that can monitor the input voltage from the power supply unit to the image forming apparatus at any time, even in such a case, The remaining time T until the completion of the temperature rise can be corrected and calculated according to the input voltage.

  In addition, the time required for completing the temperature increase of the fixing device 10 also varies depending on the outside temperature. Specifically, when the outside temperature is low, the remaining time T until the temperature rise is completed becomes long, and conversely, when the outside temperature is high, the remaining time T becomes short. Therefore, in an image forming apparatus that has temperature detection means (temperature sensor) for monitoring the temperature outside the machine and can monitor the temperature outside the machine at any time, even from such fluctuation, T can be corrected and calculated.

  Further, even when the target temperature itself for completion of temperature rise is different, the time required for completion of temperature rise naturally varies. That is, the target temperature at which the temperature increase is completed usually varies depending on the thickness and type of the image recording medium (paper) P to be used. On the other hand, the remaining time T until the temperature increase is completed is corrected for each target temperature. In an image forming apparatus having a calculating means, T can be calculated more accurately regardless of the image recording medium used.

Next, as a second embodiment, an electron using an optical writing unit comprising a laser diode (LD), an optical deflector (polygon mirror, etc.) and a scanning imaging optical system as an optical writing unit of the image forming unit. A photographic image forming apparatus will be described.
Here, as an example, a general tandem type color image forming apparatus having a laser scanning type optical writing unit as shown in FIG. 10 will be described.
In FIG. 10, reference numeral 100 denotes an apparatus body of a tandem type color copying machine as an image forming apparatus, 30 denotes an optical writing unit that emits laser light based on input image information, and 81 conveys a document D to a document reading unit 82. A document conveying unit 82 is a document reading unit that reads image information of the document D.
Reference numerals 1Y, 1M, 1C, and 1K denote photoconductive photosensitive drums that are image carriers on which toner images of respective colors (yellow (Y), magenta (M), cyan (C), and black (K)) are formed. 2Y, 2M, 2C, and 2K are charging units for charging the photosensitive drums 1Y, 1M, 1C, and 1K, and 4Y, 4M, 4C, and 4K are formed on the photosensitive drums 1Y, 1M, 1C, and 1K. The developing units 5Y, 5M, 5C, and 5K that develop the electrostatic latent images are transfer biases that transfer the toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K in an overlapping manner on the image recording medium P. Rollers 6Y, 6M, 6C, and 6K indicate cleaning units that collect untransferred toner on the photosensitive drums 1Y, 1M, 1C, and 1K, respectively. Reference numeral 70 denotes a paper feeding unit that accommodates an image recording medium P such as transfer paper, 71 denotes a paper feeding roller, 72 denotes a registration roller that adjusts the conveyance timing of the image recording medium P, and 73 denotes a plurality of color toner images. A transfer belt that conveys the image recording medium P so as to be carried on the image recording medium P, 74 is a transfer belt cleaning unit that cleans the transfer belt 73, and 75 is a separation that separates the image recording medium P from the transfer belt 73. Chargers 10 are fixing devices for fixing a toner image (unfixed image) on the image recording medium P, respectively.

Hereinafter, an operation during normal color image formation in the image forming apparatus having the configuration shown in FIG. 10 will be described.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport roller of the document transport unit 81 and placed on the contact glass 83 of the document reading unit 82. Then, the document reading unit 82 optically reads the image information of the document D placed on the contact glass 83.

Specifically, the document reading unit 82 scans the image of the document D on the contact glass 83 while irradiating light emitted from the illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.
Then, image information of each color of yellow, magenta, cyan, and black is transmitted to the optical writing unit 30. Then, laser light (exposure light) based on the image information of each color is emitted from the optical writing unit 30 toward the corresponding photosensitive drums 1Y, 1M, 1C, and 1BK.

  On the other hand, the four photosensitive drums 1Y, 1M, 1C, and 1K rotate in the clockwise direction in FIG. First, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K are uniformly charged at the facing portions of the charging portions 2Y, 2M, 2C, and 2K (charging process). Thus, a charged potential is formed on the photosensitive drums 1Y, 1M, 1C, and 1K. Thereafter, the surfaces of the charged photosensitive drums 1Y, 1M, 1C, and 1K reach the irradiation positions of the respective laser beams.

In the optical writing unit 30, laser light corresponding to the image signal is emitted from four light sources (LD) (not shown) corresponding to each color. Each laser beam passes through a different optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).
For example, a laser beam corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 1Y from the left side of the drawing through an optical deflector (not shown) and a scanning imaging optical system. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 1Y by an optical deflector (for example, a polygon mirror that rotates at high speed by a polygon motor). Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 1Y charged by the charging unit 2Y.

  Similarly, a laser beam corresponding to the magenta component is irradiated to the surface of the second photosensitive drum 1M from the left side of the drawing through an optical deflector (not shown) and a scanning imaging optical system, and an electrostatic latent image corresponding to the magenta component is emitted. An image is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 1C from the left side of the drawing through an optical deflector and a scanning imaging optical system (not shown) to form an electrostatic latent image of cyan component. The black component laser light is applied to the surface of the fourth photosensitive drum 1K from the left side of the drawing through an optical deflector (not shown) and a scanning imaging optical system, and a black component electrostatic latent image is formed.

  Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K on which the electrostatic latent images of the respective colors are formed reach positions facing the developing units 4Y, 4M, 4C, and 4K, which are developing units, respectively. Then, the respective color toners are supplied from the developing units 4Y, 4M, 4C, and 4K onto the photosensitive drums 1Y, 1M, 1C, and 1K, and the latent images on the photosensitive drums 1Y, 1M, 1C, and 1K are developed. (Development process).

  Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the development process reach the facing portions of the transfer belt 73, respectively. Here, transfer bias rollers 5 </ b> Y, 5 </ b> M, 5 </ b> C, and 5 </ b> K are installed at the respective opposed portions so as to contact the inner peripheral surface of the transfer belt 73. The toner images of the respective colors formed on the photosensitive drums 1Y, 1M, 1C, and 1K are sequentially superimposed on the image recording medium P on the transfer belt 73 at the positions of the transfer bias rollers 5Y, 5M, 5C, and 5K. Is transferred (this is a transfer process).

Then, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer process reach positions facing the cleaning units 6Y, 6M, 6C, and 6K, respectively. Then, untransferred toner remaining on the photosensitive drums 1Y, 1M, 1C, and 1K is collected by the cleaning units 6Y, 6M, 6C, and 6K (this is a cleaning process).
Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K pass through a static elimination unit (not shown), and a series of image forming processes on the photosensitive drums 1Y, 1M, 1C, and 1K is completed.

On the other hand, the image recording medium P onto which the toners of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are transferred (carrying) is run in the direction of the arrow in the figure, and is at a position facing the separation charger 75. Reach. Then, the charge accumulated in the image recording medium P is neutralized at a position facing the separation charger 75, and the image recording medium P is separated from the transfer belt 73 without causing toner dust or the like.
Thereafter, the surface of the transfer belt 73 reaches the position of the transfer belt cleaning unit 74. Then, the deposit adhered on the transfer belt 73 is collected by the transfer belt cleaning unit 74.

Here, the image recording medium P transported on the transfer belt 73 is transported from the paper feeding unit 70 via the registration roller 72 and the like.
Specifically, the image recording medium P fed by the paper feeding roller 71 from the paper feeding unit 70 that stores the image recording medium P passes through a conveyance guide (not shown) and is then guided to the registration roller 72. The image recording medium P that has reached the registration roller 72 is conveyed toward the position of the transfer belt 73 in time.

Then, the image recording medium P on which the full-color image is transferred is guided to the fixing device 10 after being separated from the transfer belt 73. In the fixing device 10, a color image (toner image) is fixed on the image recording medium P at the nip between the fixing roller and the pressure roller.
Then, the image recording medium P after the fixing process is discharged as an output image by a paper discharge roller (not shown) to a paper discharge tray and a post-processing device (a device that performs stapling, punching, sorting, and the like) outside the apparatus main body. A series of image forming processes is completed.

Next, the configuration of the fixing device 10 using the heater roller (fixing roller) 18 including a heating member as the fixing member is the same as that shown in FIGS. 4 and 5 and is as described in the first embodiment.
That is, as shown in FIG. 4, the fixing device 10 includes a fixing roller 18 and a pressure roller 19 pressed against the fixing roller 18 by a biasing force of a spring (not shown). The fixing roller 18 is attached to the fixing side plates 50 and 50 via heat insulating bushes 51 and 51 and bearings 52 and 52, and is rotationally driven by a gear 53 engaged with a driving source (not shown). A radiant heater 23 is provided inside the fixing roller 18, and an end of the radiant heater 23 is held by a heater holding member 24.

A temperature sensor 60 as a temperature monitoring device is brought into contact with the surface of the fixing roller 18, and a signal detected by the temperature sensor 60 is taken into the CPU 63 through the input circuit 61 of the control unit 37. The CPU 63 is configured to control energization to the radiation heater 23 via the driver 62 based on the temperature of the fixing roller 18 detected by the temperature sensor 60.
Normally, when the power of the image forming apparatus is turned on, a current flows to the radiation heater 23 via the driver 62, and the fixing roller 18 is rapidly raised to a predetermined set temperature of about 180 ° C.
Since the configuration of the fixing roller 18 and the pressure roller 19 has been described in the first embodiment, the description thereof is omitted here.

The fixing temperature rise curve is the same as that in the first embodiment, and an example of the relational data between the power supply time to the fixing device 10 and the temperature of the fixing roller 18 is as shown in FIG.
That is, in FIG. 6, when the supply power supplied from the external power source to the radiation heater 23 through the driver 62 is constant, the horizontal axis indicates the power supply time from the external power supply to the radiation heater 23, and the vertical axis indicates the fixing roller. FIG. 6 is a conceptual diagram showing how the temperature of the fixing roller 18 increases with power supply when the temperature is set, and the rising gradient of the fixing roller temperature with respect to the power supply time varies depending on the configuration and conditions of the fixing member. The fixing member configuration and conditions here include the diameter and material of the fixing roller 18 and the pressure roller 19, the thickness of the roller, the presence or absence of a surface coat layer, the fixing nip width, the nip pressure, the offset amount, the roller linear velocity, and the like. . This temperature rise curve has a characteristic of drawing a temperature rise curve with the same gradient no matter how many times the fixing member configuration and conditions are the same. Therefore for each of the fixing members configurations, conditions, be previously extracted reference temperature T _S corresponding to the time t ₁ in response to the amount of power supplied to the fixing device 10, the power supply time to the radiant heaters 23 It is possible to predict how many times the fixing roller temperature becomes with respect to the length.

  Of course, this temperature rise curve is limited to the case where the power supply to the radiant heater 23 is constant, but when the fixing device starts up, the radiant heater 23 is usually supplied with full power and heated. As shown in FIG. 7, the relationship between the power supply time and the temperature of the fixing roller 18, that is, the temperature rising curve is uniform. For example, the temperature increase gradient ΔT / Δt at a certain point in the temperature increase curve and the required time t until reaching the reload temperature (for example, 185 ° C.) are constant.

  The fixing temperature control is also as described in the first embodiment. In order to shorten the heating time of the fixing roller 18, it is effective to increase the input energy per unit time, that is, the rated power. In fact, some high-speed machines with a high printing speed are compatible with a power supply voltage of 200V. However, in general offices in Japan, the upper limit of the power supply is generally 100V / 15A (1500W), and in order to support the power supply voltage of 200V, it is necessary to carry out special work related to the power supply at the installation site. Is not a general solution. For this reason, even if it is attempted to raise the temperature of the fixing roller 18 in a short time, the upper limit of the input energy cannot be raised.

Next, an image forming sequence will be described.
Here, as described above, the image forming apparatus includes the general fixing device 10 having the photosensitive drums 1Y, 1M, 1C, and 1K and using the heater roller (fixing roller) 18 including a heating member as a fixing member. An example is shown. 11 and 12 schematically show the timing sequence of the image forming system operation including the polygon motor operation, the fixing heating operation, and the photosensitive drum motor of the image forming apparatus.

  FIG. 11 shows a normal (conventional) printing operation. When printing preparation is started, polygon motor operation and fixing heating operation are started. The polygon motor of the optical writing unit 30 transitions to a steady state (polygon motor lock) at a certain time after the operation starts, and the fixing device 10 also transitions to a temperature increase completion state at a time after the heating operation starts. The image forming system operation is started when the polygon motor lock and the temperature rise are completed. That is, if the time taken from the start of the image forming apparatus excluding the fixing device 10 until the image recording medium P enters the fixing member (fixing roller) 18 is S, S (sec) from the temperature rising completion state of the fixing device. After that, the image recording medium (paper) P enters the fixing device 10. This indicates that S (sec) elapses after the fixing device 10 transitions to the temperature rise completion state and the image recording medium enters the fixing device. From the viewpoints of productivity and energy saving including the first print time. It turns out that it is disadvantageous.

  On the other hand, FIG. 12 shows the printing operation of this embodiment. When the estimated remaining time until the fixing member (fixing roller) 18 reaches the target temperature after the temperature rise of the fixing device 10 is T, the start timing of the image forming system operation is earlier than the completion of the temperature rise of the fixing and T When ≦ S is reached ((1) in FIG. 12), the temperature rise is completed before the image forming system starts operating at a timing earlier than before and the image recording medium P enters the fixing device 10. Therefore ((2) in FIG. 12), the first print time can be shortened without the toner being fixed onto the image recording medium P inadequately. Further, at this time, the operation start timing of the image forming system is made T (sec) earlier than the conventional timing shown in FIG. At the same time, the image recording medium P can enter the fixing device 10. In other words, compared with the conventional sequence shown in FIG. 11, in the sequence of this embodiment shown in FIG. 12, the first print time can be shortened by S (sec) ((3) in FIG. 12) and energy saving. Has also been shown to be achieved.

  When the control of this embodiment is performed, if the fixing device 10 is provided with a device (temperature sensor) 60 for monitoring the temperature, the temperature of the fixing device and the target temperature for completion of temperature increase are determined as needed from the start of the temperature increase of the fixing device 10. By comparing, the remaining time T required for completion of the temperature rise can be calculated with higher accuracy. Further, if the temperature sensor 60 signal (temperature data) detected in the nonvolatile memory or the like is temporarily stored, the remaining time T until the completion of the temperature rise can be corrected and calculated based on the data. . Therefore, according to the present invention, it is possible to allow the image recording medium to enter the fixing device without generating a useless temperature increase waiting time and within a range where the temperature increase is not insufficient.

  The remaining time T required to complete the temperature increase can be determined using the above-described temperature increase curve (FIGS. 6 and 7) prepared based on experimental data in advance, and the temperature sensor 60. The remaining time T until the completion of the temperature rise may vary depending on the operating state of the image forming apparatus, the environment, etc., and will be described later in this embodiment. It is assumed that T is corrected in accordance with various conditions, and real-time control is performed, for example, Feed Forward control. Specific examples are shown below.

  For example, when copying is performed in the image forming apparatus, the document reading unit 82 as shown in FIG. When a peripheral device that performs stapling or punching is mounted on the image forming apparatus, the initial operation of the peripheral device may be performed at the same time as the temperature of fixing is increased. As described above, when various power consumption operations are performed simultaneously with the temperature rise of the fixing device 10, the electric power supplied to the fixing device 10 for the temperature rise temporarily decreases, and the actual temperature rise Completion will be delayed than expected. However, in the image forming apparatus that can monitor the amount of power supplied to the fixing device 10, the temperature rises from the amount of power actually supplied to the fixing device at any time even when the aforementioned power reduction occurs. The remaining time T until completion can be corrected and calculated.

  The reason why the input power to the fixing device 10 decreases is not limited to the above. For example, the voltage itself input from the power supply unit to the image forming apparatus may be low. In this case, the time required to complete the temperature rise actually takes longer than expected, but in an image forming apparatus that can monitor the input voltage from the power supply unit to the image forming apparatus at any time, even in such a case, The remaining time T until the completion of the temperature rise can be corrected and calculated according to the input voltage.

  In addition, the time required to complete the temperature increase of the fixing device varies depending on the outside temperature. Specifically, when the outside temperature is low, the remaining time T until the temperature rise is completed becomes long, and conversely, when the outside temperature is high, the remaining time T becomes short. Therefore, in an image forming apparatus that has temperature detection means (temperature sensor) for monitoring the temperature outside the machine and can monitor the temperature outside the machine at any time, even from such fluctuation, It is possible to calculate by correcting T.

  Further, even when the target temperature itself for completion of temperature rise is different, the time required for completion of temperature rise naturally varies. In other words, the target temperature at which the temperature increase is completed usually varies depending on the thickness and type of the image recording medium P to be used. On the other hand, the remaining time T until the temperature increase is corrected for each target temperature. In the image forming apparatus having the means, T can be calculated more accurately regardless of the image recording medium P to be used.

Next, a direct printing type image forming apparatus will be described as a third embodiment.
As shown in FIG. 13, the image forming apparatus according to this embodiment includes at least one print station 203 (preferably four print stations 203Y, 203M, 203C, and 203K as in the illustrated example) and an image carrier. An intermediate image receiving member 201, which is a body, a driving roller 210, at least one supporting roller 211, and preferably several variable holding elements 212 are provided. The four print stations 203Y, 203M, 203C, and 203K are arranged in a predetermined relationship with respect to the intermediate image receiving member 201 that is an image carrier. The intermediate image receiving member 201 is preferably an intermediate transfer belt, and the intermediate transfer belt 201 is provided on a driving roller 210 and a plurality of support rollers. The at least one support roller 211 is provided with a mechanism that maintains the intermediate transfer belt 201 at a constant tension and prevents movement of the intermediate transfer belt 201 in the width direction. A variable holding element 212 that also serves as a support roller is used to accurately position the intermediate transfer belt 201 with respect to the print stations 203Y, 203M, 203C, and 203K.

The drive roller 210 is preferably a cylindrical metal sleeve, and the rotation shaft extending perpendicular to the moving direction of the intermediate transfer belt 201 and the intermediate transfer belt 201 at a speed capable of addressing one dot position per printing cycle. It has a rotational speed adjusted to convey and performs line-by-line scanning printing. The variable holding element 212 is arranged so that the belt surface can be maintained at a predetermined interval from each print station 203Y, 203M, 203C, 203K. The variable holding element 212 is preferably a cylindrical sleeve and is arranged in an arch form perpendicular to the direction of belt movement, and at least each print station 203Y, in combination with the belt tension to create a stabilizing force component. The intermediate transfer belt 201 is slightly bent in the vicinity of 203M, 203C, and 203K. This stabilizing force component is in the opposite direction to the electrostatic attractive force component acting on the intermediate transfer belt 201 due to the interaction with different potentials applied to the corresponding print stations 203Y, 203M, 203C, 203K, preferably electrostatic Greater than the attractive component.
The variable holding element 212 includes a conductive surface that connects to a power source that generates a back surface electric field. Therefore, the variable holding element 212 serves as a back electrode for the adjacent print stations 203Y, 203M, 203C, and 203K.

  The intermediate transfer belt 201 is preferably an endless belt containing a composite material as a main material. The composite material of the intermediate transfer belt 201 preferably has a uniform concentration of a filler such as carbon, which makes the conductivity uniform over the entire surface of the intermediate transfer belt 201. The outer surface of the intermediate transfer belt 201 is preferably coated with a coating layer made of a conductive polymer material having appropriate conductivity, heat resistance, adhesion, peelability, and surface smoothness.

  The intermediate transfer belt 201 is transported through four different print stations 203Y, 203M, 203C, and 203K, but the toner particles are deposited on the outer surface of the intermediate transfer belt 201 and overlapped to form a four-color toner image. Form. Next, the toner image is preferably conveyed through a fixing unit (fixing device) 213 provided with a fixing holder 214 arranged in the width direction and in direct contact with the inner surface of the intermediate transfer belt 201. The fixed holder 214 includes a heating member 215, and the heating member 215 is maintained in contact with the inner surface of the intermediate transfer belt 201. When current flows through the heating member 215, the fixed holder 214 reaches a temperature necessary for melting the toner particles adhering to the outer surface of the intermediate transfer belt 201. The fixing unit 213 further includes a pressure roller 216 disposed across the width direction of the intermediate transfer belt 201 and facing the fixed holder 214. An information carrier (image recording medium) 202, which is an unprocessed plain paper (various standard papers), cardboard, postcards, OHP sheets, and other media suitable for a direct printing apparatus, is supplied from the paper supply unit 221 and pressurized. It is conveyed between the roller 216 and the intermediate transfer belt 201. The pressure roller 216 is rotated by the pressure applied to the heated surface of the fixed holder 214, and melted toner particles are fused on the information carrier (image recording medium) 202 to form a final image. After passing through the fixing unit 213, the intermediate transfer belt 201 moves and contacts the cleaning unit 217. The cleaning unit 217 extends across the width of the intermediate transfer belt 201 and removes all toner particles that have not been transferred from the outer surface.

As shown in FIG. 14, the print station 203 of the image forming apparatus according to this embodiment includes a particle supply unit 203 that preferably includes a replaceable or refillable container 230 for holding toner particles. The container 230 has a front wall, a rear wall (not shown), a pair of side walls, and a bottom wall with an elongated opening 231 with a toner supply element 232 extending from the front wall to the rear wall. The toner particles are continuously supplied to the developing sleeve 233 via the H.234. The particle charging member 234 is preferably formed from a supply brush or roller made of or coated with a fibrous elastic material. The supply brush is mechanically applied to the outer peripheral surface of the developing sleeve 233 due to particle charging by contact charge exchange caused by frictional charging of the toner particles due to frictional interaction between the fibrous material of the supplying brush and the coating material of the developing sleeve. To touch. The developing sleeve 233 is preferably made of a metal coated with a conductive material, and is preferably substantially cylindrical and has a rotation axis extending parallel to the elongated opening 231 of the particle container 230. The charged toner particles are basically held on the surface of the developing sleeve 233 by an electrostatic force proportional to (Q / D) ² . Here, Q is the charge of the particle, and D is the distance between the charge center of the particle and the boundary of the developing sleeve 233. The charging unit may further include a power source (not shown) for charging, and this power source supplies an electric field for inducing or injecting electric charges into the toner particles. Although it is preferred to charge the particles by contact charge exchange, there is no problem using other suitable charging devices such as conventional charge injection devices, charge induction devices, corona charging devices.

  The metering unit 235 is installed in the vicinity of the developing sleeve 233 and adjusts the toner particle concentration on the outer peripheral surface of the developing sleeve 233 to form a relatively thin and uniform particle layer. The metering section 235 may be formed of a flexible or rigid insulator or metal blade, or roller, or other member suitable for supplying a uniform particle layer. The metering unit 235 may also be connected to a metering power source (not shown). The power supply for metering affects the triboelectric charging of the particle layer and makes the particle charge density on the surface of the developing sleeve uniform.

  As shown in FIG. 15, the developing sleeve 233 is disposed in a positional relationship with a positioning device 240 that accurately supports and maintains the print head structure 205 at a predetermined position with respect to the outer peripheral surface of the developing sleeve 233. . The positioning device 240 is formed from a frame 241 having two side rulers 242 and 243 extending in the front, rear and width directions, and the side rulers 242 and 243 rotate on both sides of the developing sleeve 233, respectively. It is installed parallel to the axis. The first side ruler 242 is located upstream from the rotational direction of the developing sleeve 233, and is a clamp that fixes the printhead structure 205 along a widthwise clamping axis that extends across the entire width of the printhead structure 205. Attaching means 244 is provided. The second side ruler 243 is positioned on the downstream side of the developing sleeve 233 and includes a support portion 245 or a pivot for supporting the print head structure 205 at a predetermined position with respect to the outer peripheral surface of the developing sleeve 233. . The support 245 and the clamping shaft are positioned relative to each other to maintain the printhead structure 205 in an arcuate shape with at least a portion extending in the longitudinal direction. The radius of curvature of this arch shape is determined by the relative position of the support portion 245 and the fastening shaft, and is a large size necessary to maintain the print head structure 205 at the corresponding portion of the outer peripheral surface of the developing sleeve 233. I will be. The support 245 is disposed in contact with the print head structure 205 at a predetermined support position on the longitudinal axis of the print head structure 205, and the position of the print head structure 205 is slightly increased from the predetermined support position in the longitudinal direction and the width direction. Allow displacement. This is for adapting to the case where the developing sleeve 233 is decentered or unexpectedly changed. That is, the support 245 is arranged so that the printhead structure 205 can rotate about a fixed point, and the printhead can be used at any time during the printing process, regardless of the unexpected mechanical failure of the developing sleeve 233. The distance between the structure 205 and the outer peripheral surface of the developing sleeve 233 is assuredly constant over the entire width direction. A fixing member 246 is provided at the front portion and the rear portion of the positioning device 240. The particle supply unit 203 is disposed at a fixed position on the fixing member 246, and the rotation axis of the developing sleeve 233 and the transverse axis of the print head structure 205. Keep a certain distance. Preferably, the fixing member 246 is disposed at the front end and the rear end of the developing sleeve 233, and the developing sleeve 233 and the variable holding element 212 of the intermediate transfer belt 201 facing the actual print station are accurately spaced. I try to put it.

  As shown in FIGS. 16A to 16C, the print head structure 205 of the image forming apparatus according to the present invention includes a substrate 250 made of a flexible and electrically insulating material such as polyimide. Yes. The substrate 250 has a predetermined thickness and is parallel to the first surface facing the developing sleeve 233, the second surface facing the intermediate transfer belt 201, and the rotation axis of the developing sleeve 233 over the entire printing range. And a plurality of holes 252 formed so as to penetrate from the first surface to the second surface of the substrate 250. The first printed circuit includes a plurality of control electrodes 253 arranged in combination with the holes 252, and a plurality of shielding electrode structures (not shown) arranged in combination with the control electrodes 253 are included in the embodiment. Some have. The first printed circuit is disposed between the substrate 250 and the first covering layer 2501. The second surface of the substrate is covered with a second covering layer 2502 made of an insulating material. The second printed circuit includes a plurality of deflection electrodes 254 and is disposed between the substrate 250 and the second covering layer 2502. The print head structure 205 further includes an antistatic material disposed on at least a portion of the second coating layer 2502 and facing the intermediate transfer belt 201. The printhead structure 205 includes a control unit (which includes a variable control power supply connected to the control electrode 253 to supply a control potential to control the amount of toner particles introduced through the corresponding hole 252 during each printing step. (Not shown). The controller further comprises a deflection power supply (not shown) connected to the deflection electrode 254 to supply deflection voltage pulses that control the convergence and trajectory of the toner particles that can pass through the corresponding holes 252. In some embodiments, the control unit also includes a shielding power source (not shown) connected to the shielding electrode so as to supply a shielding potential for electrostatically shielding the adjacent control electrode 253.

  The printhead structure 205 is preferably sized to perform 600 dpi printing in three deflection steps in each print cycle, i.e., three through each hole 252 of the printhead structure during each print cycle. The dot position is preferably addressable. Accordingly, one hole 252 is provided for every two dot positions in the width direction, that is, 200 equally spaced holes per inch are arranged in parallel to the transverse axis 251 of the printhead structure 205. Generally, the holes 252 are arranged in one or several rows, preferably two parallel rows, each row comprising 100 holes per inch. Accordingly, the pitch of the holes, in other words, the distance between the central axes of adjacent holes in the same row is 0.01 inches, that is, 254 μm. The rows of holes are preferably located on either side of the transverse axis 251 of the printhead structure 205 and are moved in the width direction relative to each other such that all holes are equally spaced in the width direction. The distance between the rows of holes is preferably selected corresponding to the total number of dot positions.

  The first printed circuit includes a control electrode 253 having an annular structure surrounding the outer periphery of the corresponding hole 252 and a connector that preferably extends in the longitudinal direction and connects the annular structure to the corresponding control power source. The control electrode 253 preferably has an annular structure, but may have various shapes that continuously or partially surround the hole 252, and preferably has a shape that is symmetrical with respect to the central axis of the hole. In some embodiments, particularly when the holes 252 are arranged in only one row, the control electrode may be formed smaller in the width direction than in the longitudinal direction.

  The second printed circuit includes a plurality of deflecting electrodes 254, and each deflecting electrode 254 has two semicircular or crescent-shaped deflecting portions arranged at predetermined positions around the corresponding hole 252 at intervals. It is divided into 2541 and 2542. The deflecting portions 2541 and 2542 are disposed symmetrically with respect to the central axis of the hole 252 on both sides of the deflection shaft 2543 that passes through the center of the hole 252 and extends with a predetermined deflection angle d in the longitudinal direction. The deflection axis 2543 is determined according to the number of deflection processes performed for each printing cycle. This is to cancel the influence of the movement of the belt during the printing cycle. As a result, dot positions arranged in the width direction on the intermediate transfer belt are obtained. For example, when using three deflection steps, the optimum deflection angle is set to arctan (1/3), ie about 18.4 °. Therefore, the first dot is deflected slightly upstream with respect to the direction of belt movement, the second dot is not deflected, and the third dot is slightly deflected downstream with respect to the direction of belt movement. A printed dot array in the width direction is obtained on the intermediate transfer belt. That is, the deflection electrode 254 has an upstream deflection unit 2541 and a downstream deflection unit 2542, all of the upstream deflection units 2541 are connected to the first deflection power source D1 (not shown), and all of the downstream deflection units 2542 are all. It is connected to a second deflection power source D2 (not shown).

  The deflection power supplies D1 and D2 are controlled by a control unit (not shown). In each printing cycle, three deflection steps (for example: D1 <D2; D1 = D2; D1> D2) can be performed, and the difference between D1 and D2 is the deflection trajectory of the toner passing through the hole 252, that is, the toner image Determine the dot position.

  FIG. 17A to FIG. 17C show examples of the shape of the control electrode at the hole edge of the print head structure according to this embodiment. These drawings are detailed cross-sectional views of the opposing surfaces of the hole 252 and the opposing end surfaces of the control electrode 253 of the printhead structure 205. In all three embodiments, the control electrode 253 has a lower surface 2532 on the substrate 250 and an upper surface 2531 covered by the first coating layer 2501. The control electrode 253 also has an end face 2533 that faces the hole 252. FIG. 17 also shows the deflection electrode 254, and both the first coating layer 2501 and the second coating layer 2502 may extend to the side surface of the hole 252. In FIG. 17, the deflection electrode 254 is located immediately below the control electrode. However, of course, the deflection electrode 254 may be positioned slightly spaced from the edge of the hole, which has a positive effect on the flow of toner particles present in the hole.

  The end face of the deflection electrode 254 is substantially linear and parallel, and the edge of the deflection electrode 254 facing the hole 252 is basically a right angle. On the other hand, the end surface of the control electrode 253 is such that the lower end of the control electrode 253 formed between the lower surface 2532 and the end surface 2533 extends further toward the hole than the upper end formed between the upper surface 2531 and the end surface 2533. It is inclined. Therefore, the area of the hole 252 on the upper surface 2531 side of the control electrode 253 is larger than the area of the hole 252 on the lower surface 2532 side. This conical shape improves toner flow in the holes 252 and significantly reduces toner scattering and toner particle deposits on the hole walls that can cause clogging of the printhead structure. Furthermore, the direct effect obtained by retracting the upper end of the control electrode is that the electric field becomes more uniform at the opening of the hole 252. In particular, the influence of the local electric field density around the upper end of the control electrode 253 is significantly reduced at the opening of the hole.

  In FIG. 17A, the end surface 2533 of the control electrode is curved or indented from the upper surface 2531 toward the lower surface 2532 inward. With this shape, the lower end formed between the lower surface 2532 and the end surface 2533 has an acute angle, while the upper end formed between the upper surface 2531 and the end surface 2533 has an angle of 90 ° or more. The lower end of the control electrode 253 is preferably 70 ° or less. As a result, the end surface 2533 of the control electrode surrounding the hole 252 forms a substantially conical funnel shape at the opening of the hole 252.

  In the embodiment shown in FIG. 17 (b), the end surface 2533 of the control electrode 253 is bent inward or partly indented so that the upper end of the control electrode is substantially square, preferably 90 ° or more. It is out. However, unlike the embodiment shown in FIG. 17A, the lower portion of the end face 2533 bends outward and intersects the lower surface 2532 of the control electrode at an angle of 90 ° or more. Also in this embodiment, the effect of the funnel shape that the flow of toner to the hole 252 is significantly improved can be obtained. Further, since the lower end of the control electrode 253 is rounded, the electric field at the lower end of the control electrode 253 becomes more uniform, and the scattering of the toner particles is further reduced by the change in the electric field density passing through the hole.

  In the embodiment shown in FIG. 17C, the upper end of the control electrode 253 formed between the upper surface 2531 and the end surface 2533 is rounded so that the end surface 2533 falls from the upper surface 2531 at an angle of approximately 90 ° or more. Yes. The remaining portion of the end face 2533, that is, the lower portion is substantially linear, and the lower end of the control electrode is preferably an acute angle of 75 ° or less. In the embodiment shown in FIG. 17 (c), the end of the control electrode 253 is rounded in addition to the improvement of the electric field shape and the funnel shape in the embodiment shown in FIGS. 17 (a) and 17 (b). This can also significantly reduce the possibility of electrical failure at the top of the control electrode.

  The funnel-shaped control electrode common to each of the embodiments shown in FIGS. 17A to 17C greatly improves the flow of toner particles entering and passing through the holes, and excessive toner is present in and around the holes. The possibility of clogging and clogging is significantly reduced.

Next, as another configuration example of the fixing unit 213 of the image forming apparatus illustrated in FIG. 13, a fixing device using a heater roller (fixing roller) including a heating member will be described.
The configuration example of the fixing device using the fixing roller is the same as that shown in FIGS. 4 and 5, as described in the first embodiment.
That is, as shown in FIG. 4, the fixing device 10 has a fixing roller 18 and a pressure roller 19 (corresponding to the pressure roller 216 in FIG. 13) pressed against the fixing roller 18 by a biasing force of a spring (not shown). is doing. The fixing roller 18 is attached to the fixing side plates 50 and 50 via heat insulating bushes 51 and 51 and bearings 52 and 52, and is rotationally driven by a gear 53 engaged with a driving source (not shown). A radiant heater 23 is provided inside the fixing roller 18, and an end of the radiant heater 23 is held by a heater holding member 24.

A temperature sensor 60 as a temperature monitoring device is brought into contact with the surface of the fixing roller 18, and a signal detected by the temperature sensor 60 is taken into the CPU 63 through the input circuit 61 of the control unit 37. The CPU 63 is configured to control energization to the radiation heater 23 via the driver 62 based on the temperature of the fixing roller 18 detected by the temperature sensor 60.
Normally, when the power of the image forming apparatus is turned on, a current flows to the radiation heater 23 via the driver 62, and the fixing roller 18 is rapidly raised to a predetermined set temperature of about 180 ° C.
Since the configuration of the fixing roller 18 and the pressure roller 19 has been described in the first embodiment, the description thereof is omitted here.

The fixing temperature rise curve is the same as that of the first embodiment, and an example of the relational data between the power supply time to the fixing device 10 and the temperature of the fixing roller 18 is as shown in FIG. The same fixing temperature increase curve is obtained even when the fixed holder 214 including the heating member 215 is used.
That is, in FIG. 6, when the supply power supplied from the external power source to the radiation heater 23 through the driver 62 is constant, the horizontal axis indicates the power supply time from the external power supply to the radiation heater 23, and the vertical axis indicates the fixing roller. FIG. 6 is a conceptual diagram showing how the temperature of the fixing roller 18 increases with power supply when the temperature is set, and the rising gradient of the fixing roller temperature with respect to the power supply time varies depending on the configuration and conditions of the fixing member. The fixing member configuration and conditions here include the diameter and material of the fixing roller 18 and the pressure roller 19, the thickness of the roller, the presence or absence of a surface coat layer, the fixing nip width, the nip pressure, the offset amount, the roller linear velocity, and the like. . This temperature rise curve has a characteristic of drawing a temperature rise curve with the same gradient no matter how many times the fixing member configuration and conditions are the same. Therefore for each of the fixing members configurations, conditions, be previously extracted reference temperature T _S corresponding to the time t ₁ in response to the amount of power supplied to the fixing device 10, the power supply time to the radiant heaters 23 It is possible to predict how many times the fixing roller temperature becomes with respect to the length.

  Of course, this temperature rise curve is limited to the case where the power supply to the radiant heater 23 is constant, but when the fixing device starts up, the radiant heater 23 is usually supplied with full power and heated. As shown in FIG. 7, the relationship between the power supply time and the temperature of the fixing roller 18, that is, the temperature rising curve is uniform. For example, the temperature increase gradient ΔT / Δt at a certain point in the temperature increase curve and the required time t until reaching the reload temperature (for example, 185 ° C.) are constant.

  The fixing temperature control is also as described in the first embodiment. In order to shorten the heating time of the fixing roller 18, it is effective to increase the input energy per unit time, that is, the rated power. In fact, some high-speed machines with a high printing speed are compatible with a power supply voltage of 200V. However, in general offices in Japan, the upper limit of the power supply is generally 100V / 15A (1500W), and in order to support the power supply voltage of 200V, it is necessary to carry out special work related to the power supply at the installation site. Is not a general solution. For this reason, even if it is attempted to raise the temperature of the fixing roller 18 in a short time, the upper limit of the input energy cannot be raised.

Next, an image forming sequence will be described.
Here, the direct printing method shown in FIG. 13 is adopted, and a heater roller (fixing roller) 18 including a heating member and a pressure roller 19 (corresponding to the pressure roller 216 in FIG. 13) are used for the fixing unit 213. An example of an image forming apparatus having a configuration including the fixing device 10 is shown. The same sequence can be achieved by using the fixing holder 214 including the heating member 215 as a fixing member in place of the fixing roller 18.
18 and 19 schematically show a timing sequence of an image forming system operation including a fixing heating operation of the fixing unit 213 of the direct printing type image forming apparatus and an image forming drive of the print station.

  FIG. 18 shows a normal (conventional) printing operation. When printing preparation is started, the fixing heating operation is started. The fixing device of the fixing unit 213 shifts to a temperature rising completion state after a certain time after the heating operation is started. The image forming system operation starts when the temperature rise is completed. That is, if the time taken from the start of the image forming apparatus excluding the fixing device to the time when the image recording medium (information carrier 202 such as paper) enters the fixing member (fixing roller) is S, the temperature rising completion state of the fixing device is assumed. After S (sec) elapses, the image recording medium enters the fixing device. This indicates that S (sec) elapses after the fixing device transitions to the temperature rise completion state and before the image recording medium enters the fixing device, which is disadvantageous in terms of productivity including first print time and energy saving. It turns out that it is.

  On the other hand, FIG. 19 shows the printing operation of this embodiment. When the estimated remaining time until the fixing member reaches the target temperature after the temperature rise of the fixing device is T, the start timing of the image forming system operation is earlier than the temperature increase completion of the fixing device and T ≦ S. When the time is reached ((1) in FIG. 19), the image forming system starts operating at a timing earlier than the conventional timing, and the temperature rise is completed before the image recording medium enters the fixing member of the fixing device (FIG. 19). 19 (2)), the first print time can be shortened without insufficient toner fixing on the image recording medium. Further, at this time, by making the operation start timing of the image forming system earlier by T (sec) than the conventional timing shown in FIG. It became possible to enter the medium. In other words, compared with the conventional sequence shown in FIG. 18, in the sequence of the present embodiment shown in FIG. 19, the first print time can be shortened by S (sec) ((3) in FIG. 19) and energy saving. Has also been shown to be achieved.

  When the control of the present embodiment is performed, when the fixing device is provided with a device (temperature sensor 60) for monitoring the temperature, the temperature of the fixing device is compared with the target temperature for completion of temperature rising from the start of the temperature rising of the fixing device 10 as needed. By doing so, the remaining time T required for completion of the temperature rise can be calculated more accurately. Further, if the temperature sensor 60 signal (temperature data) detected in the nonvolatile memory or the like is temporarily stored, the remaining time T until the completion of the temperature rise can be corrected and calculated based on the data. . Therefore, according to the present invention, it is possible to allow the image recording medium to enter the fixing device without generating a useless temperature increase waiting time and within a range where the temperature increase is not insufficient.

  The remaining time T required to complete the temperature increase can be determined using the above-described temperature increase curve (FIGS. 6 and 7) prepared based on experimental data in advance, and the temperature sensor 60. The remaining time T until the completion of the temperature rise may vary depending on the operating state of the image forming apparatus, the environment, and the like. Therefore, in the present invention, as will be described later. It is assumed that T is corrected in accordance with various conditions, and real-time control is performed, for example, Feed Forward control. Specific examples are shown below.

  For example, when copying is performed by the image forming apparatus, a document reading unit (not shown) may be operating simultaneously with the temperature rise of fixing. When a peripheral device that performs stapling or punching is mounted on the image forming apparatus, the initial operation of the peripheral device may be performed at the same time as the temperature of fixing is increased. As described above, when various power consumption operations are performed simultaneously with the temperature rise of the fixing device, the electric power supplied to the fixing device for the temperature rise temporarily decreases, and the actual temperature rise completion is not completed. It will be delayed than expected. However, in an image forming apparatus that can monitor the amount of power supplied to the fixing device, even if the power reduction described above occurs, the temperature increase is completed from the amount of power actually supplied to the fixing device as needed. The remaining time T can be corrected and calculated.

  The reason why the input power to the fixing device is reduced is not limited to the above. For example, the voltage itself input from the power supply unit to the image forming apparatus may be low. In this case, the time required to complete the temperature rise actually takes longer than expected, but in an image forming apparatus that can monitor the input voltage from the power supply unit to the image forming apparatus at any time, even in such a case, The remaining time T until the completion of the temperature rise can be corrected and calculated according to the input voltage.

  In addition, the time required to complete the temperature increase of the fixing device varies depending on the outside temperature. Specifically, when the outside temperature is low, the remaining time T until the temperature rise is completed becomes long, and conversely, when the outside temperature is high, the remaining time T becomes short. Therefore, in an image forming apparatus that has temperature detection means (temperature sensor) for monitoring the temperature outside the machine and can monitor the temperature outside the machine at any time, even from such fluctuation, It is possible to calculate by correcting T.

  Further, even when the target temperature itself for completion of temperature rise is different, the time required for completion of temperature rise naturally varies. That is, the target temperature at which the temperature increase is completed usually differs depending on the thickness and type of the image recording medium to be used. On the other hand, a means for correcting and calculating the remaining time T until the temperature increase is completed for each target temperature. In an image forming apparatus having the above, T can be calculated more accurately regardless of the image recording medium used.

  In the first to third embodiments, the fixing device having a fixing member such as a fixing roller including a heating member such as a heater has been described as an example. However, a fixing device using electromagnetic induction heating was used. In this case, the same image forming sequence can be performed, and the same effect can be obtained.

1 is a schematic configuration diagram of an image forming apparatus showing a first embodiment of the present invention. FIG. 2 is a plan view of a principal part showing a mounting state of a substrate of an optical writing unit in the image forming apparatus of FIG. 1. FIG. 2 is a configuration explanatory diagram of an optical writing unit in the image forming apparatus shown in FIG. 1. FIG. 3 is an explanatory diagram illustrating a configuration of a fixing device provided in the image forming apparatus according to the present invention. FIG. 5 is a schematic sectional view of the fixing device shown in FIG. 4. FIG. 4 is a diagram illustrating a relationship between a power supply time to a fixing device and a temperature of a fixing roller. FIG. 4 is a diagram illustrating a relationship between a power supply time to a fixing device and a temperature of a fixing roller. FIG. 6 is a timing diagram schematically illustrating a sequence of normal (conventional) printing operations. FIG. 6 is a timing diagram schematically illustrating a printing operation sequence according to the first exemplary embodiment. It is a schematic block diagram of the image forming apparatus which shows the 2nd Example of this invention. FIG. 6 is a timing diagram schematically illustrating a sequence of normal (conventional) printing operations. FIG. 10 is a timing diagram schematically illustrating a printing operation sequence according to the second embodiment. It is a schematic block diagram of the image forming apparatus which shows the 3rd Example of this invention. FIG. 14 is a schematic cross-sectional view of a print station in the image forming apparatus shown in FIG. 13. It is principal part sectional drawing for demonstrating the positioning apparatus of the print head structure provided in the print station shown in FIG. FIGS. 15A and 15B are explanatory diagrams of a configuration of a print head structure provided in the print station shown in FIG. 14, in which FIG. FIG. 2C is a partial view showing the surface of the head structure, and FIG. 2C is a sectional view taken along line II in the partial view of FIG. 1A and line II-II in the partial view of FIG. (A)-(c) is principal part detail drawing of the print head structure of FIG.16 (c), and is principal part sectional drawing which shows the shape of the control electrode in a hole edge. FIG. 6 is a timing diagram schematically illustrating a sequence of normal (conventional) printing operations. FIG. 10 is a timing diagram schematically illustrating a printing operation sequence according to the third embodiment.

Explanation of symbols

1: Photosensitive drum (image carrier)
1Y, 1M, 1C, 1K: photosensitive drum (image carrier)
2: Charging unit 2Y, 2M, 2C, 2K: Charging unit 3: Optical writing unit (optical writing means)
4: Development unit (developing means)
4Y, 4M, 4C, 4K: developing unit (developing means)
5: Transfer unit (transfer means)
5Y, 5M, 5C, 5K: transfer bias roller (transfer means)
6: Cleaning unit 6Y, 6M, 6C, 6K: Cleaning unit 7: LED array 8: Substrate 9: Lens 10: Fixing device 18: Fixing roller 19: Pressure roller 23: Radiation heater 30: Optical writing unit (optical writing) Included)
37: Control unit 60: Temperature sensor 61: Input circuit 62: Driver 63: CPU
70: paper feed unit 71: paper feed roller 72: registration roller 73: transfer belt 74: transfer belt cleaning unit 75: separation charger 81: document transport unit 82: document reading unit 201: intermediate image receiving member (intermediate transfer belt (image Carrier))
202: Information carrier (image recording medium)
203 (203Y, 203M, 203C, 203K): print station 205: print head structure 210: drive roller 211: support roller 212: variable holding element 213: fixing unit (fixing device)
214: fixed holder 215: heating member 216: pressure roller 217: cleaning unit 221: paper feeding unit 230: container 232: toner supply element 233: developing sleeve 234: particle charging member 235: metering unit 240: positioning device P: Paper (image recording medium)

Claims (10)

An image forming apparatus comprising: an image forming unit that forms a toner image on an image carrier and transfers the toner image to an image recording medium; and a fixing device that fixes the toner image on the image recording medium.
The time taken from the start of the image forming start operation of the image forming apparatus excluding the fixing device until the image recording medium enters the fixing member of the fixing device is S, and the fixing member When the estimated remaining time until reaching the target temperature is T,
At least the start of the image forming apparatus excluding the fixing device is started earlier than the completion of the temperature increase of the fixing device, and the image forming apparatus image forming start operation excluding the fixing device is started when T ≦ S. The image forming apparatus starts and the image recording medium enters the fixing device at the same time as the temperature rise of the fixing device is completed. The image forming apparatus according to claim 1,
The image forming means includes: an optical writing means for forming a latent image on the image carrier by optical writing; a developing means for developing the latent image on the image carrier with toner to make it visible; and the image carrier An image forming apparatus comprising: transfer means for transferring the toner image on the image recording medium. The image forming apparatus according to claim 1,
The image forming means includes an optical writing means for scanning a laser beam through a rotating optical deflector to form a latent image on the image carrier, and a latent image on the image carrier is developed with toner. A developing unit that forms an image, and a transfer unit that transfers the toner image on the image carrier to the image recording medium,
The time required from the start of the image forming apparatus image forming start operation excluding the optical deflector and the fixing device to the entry of the image recording medium into the fixing member of the fixing device is S, and the temperature rising of the fixing device is started. When T is an estimated remaining time until the fixing member reaches a target temperature later,
At least the start of the image forming apparatus excluding the fixing device is started earlier than when the temperature of the fixing device is increased and T ≦ S after the rotation of the optical deflector reaches a steady state. 2. An image forming apparatus comprising: starting an image forming start operation of an image forming apparatus excluding a fixing apparatus; and the image recording medium entering the fixing apparatus simultaneously with completion of temperature rise of the fixing apparatus. The image forming apparatus according to claim 1,
The image forming means includes an intermediate image receiving member as the image carrier, at least one print station for forming a toner image on the intermediate image receiving member, and a toner image on the intermediate image receiving member as the image recording unit. An image forming apparatus comprising: a transfer unit that transfers to a medium. The image forming apparatus according to claim 1, wherein:
The image forming apparatus image forming start operation excluding the fixing device is started from the time when T = S, and the image recording medium enters the fixing device simultaneously with completion of the temperature increase of the fixing device. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 5,
The estimated remaining time T until the fixing member reaches a target temperature after the temperature of the fixing device starts to be increased is predicted based on temperature information from a temperature monitoring device provided in the fixing device. apparatus. The image forming apparatus according to any one of claims 1 to 6,
A power detection unit that monitors power supplied to the fixing device, and when power supplied to the fixing device decreases due to operation of a peripheral device mounted on the image forming apparatus or operation of a document reading unit; An image forming apparatus that predicts in advance a predicted remaining time T until the fixing member reaches a target temperature after the start of temperature raising of the fixing device in accordance with the input power. The image forming apparatus according to any one of claims 1 to 6,
When the voltage input to the power supply unit that supplies power to the image forming apparatus decreases, the temperature until the fixing member reaches the target temperature after the start of temperature increase of the fixing device according to the input voltage is reached. An image forming apparatus characterized in that a predicted remaining time T is predicted in advance. The image forming apparatus according to any one of claims 1 to 6,
A temperature detecting means for monitoring the outside temperature of the machine, and a predicted remaining time T until the fixing member reaches a target temperature after the start of temperature raising of the fixing device is predicted in advance based on the detected outside temperature; An image forming apparatus. The image forming apparatus according to any one of claims 1 to 6,
Corresponding to the type and thickness of the image recording medium to be used, an estimated remaining time T until the fixing member reaches a target temperature after the start of temperature rise of the fixing device is predicted in advance. Forming equipment.

Images