Image forming apparatus

Abstract

To provide an image forming apparatus that can make transition to a power saving mode (home mode) with simple operation even in an environment under power restrictions (at home), and that can be used without reducing image quality even in the power saving mode (home mode).SOLUTION: An image forming apparatus of the present invention has: means that controls an AC current to be applied to a fixing device; means that measures the temperature of the fixing device; and means that detects the temperature and controls the AC current on the basis of the temperature.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as an electrophotographic copying machine (hereinafter abbreviated as MFP) and a laser beam printer (hereinafter abbreviated as SFP) that forms an image on a recording medium by using an electrophotographic method. [Background technology]

[0002] In recent years, the number of people working from home has increased, and electrophotographic image forming apparatuses that are generally used for business purposes are increasingly being used at home. However, there is a limit to the amount of power that can be used at home, and there is a risk of the breaker tripping when using an electrophotographic image forming apparatus in conjunction with other electrical appliances.

[0003] In Japanese households, 100V-30A is common, and changing to 100V-40A or 50A will result in an increase in the basic charge for electricity usage.

[0004] In addition, air conditioners consume a lot of electricity in the summer for cooling and in the winter for heating, so there is a high possibility that the breaker will trip in the summer or winter. In addition, the use of a microwave oven or other appliances increases the possibility of the breaker tripping at 100V-30A. This makes it difficult to introduce electrophotographic SFP / MFPs in homes, and ink-type SFP / MFPs that do not use much electricity are often introduced. However, with the increase in telecommuting, there is also a possibility that there will be an increased demand for electrophotographic printing, which is used for business purposes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-259359 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, when used for business purposes, it can operate as usual, while in environments where power restrictions are imposed, such as at home, the breaker will not trip, making it possible to provide users with a stress-free electrophotographic SFP / MFP.

[0007] The object of the present invention is to provide an image forming device that allows the use of electrophotographic SFPs and MFPs at home by gradually warming up the fixing device when used at home where the power supply is insufficient, for example for working from home, thereby preventing sudden power consumption. [Means for solving the problem]

[0008] In order to achieve the above object, the image forming apparatus of the present invention is an electrophotographic image forming apparatus having a means for controlling the AC current applied to the fixing device, a means for measuring the temperature of the fixing device, and a means for detecting the temperature and controlling the AC current based on the temperature. Effect of the Invention

[0009] According to the present invention, when used in an office or other place where there is no concern about power supply, the printer can be used in the conventional manner, and when used at home where the power supply is insufficient for working from home or other such purposes, the fixing device can be gradually heated to prevent sudden power consumption, making it possible to use electrophotographic SFPs and MFPs at home. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a configuration of an image forming apparatus. [Diagram 2] 2 is a circuit diagram showing a configuration of the fixing device in FIG. 1. [Diagram 3] 13 is a graph showing changes in power consumption when printing in a small MFP in normal use. [Figure 4] FIG. 4 is a correlation diagram between temperature transition and power transition of the fixing device. [Diagram 5]5 is a correlation diagram between temperature transition and power transition of the fixing device in the first embodiment. FIG. [Figure 6] 13 is a graph showing an estimated change in power consumption during printing of a small SFP in the first embodiment. [Figure 7] 7 is a flowchart showing the control up to printing in FIGS. 3 to 6. [Figure 8] 5 is a flowchart showing the control of the multiple printing shown in FIGS. [Figure 9] 4 is a flowchart showing control of multiple printing in the first embodiment. [Figure 10-1] FIG. 4 is a diagram showing wave number control of the fixing device. [Figure 10-2] FIG. 4 is a diagram showing phase control of the fixing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. EXAMPLES

[0012] (Overall configuration of image forming apparatus) <Configuration of Image Forming Apparatus> Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0013] <Image forming device> An image forming apparatus 100 of this embodiment will be described. FIG. 1 is a cross-sectional view of the image forming apparatus 100. As shown in FIG. 1, the image forming apparatus 100 is a monochrome copying machine in which a one-color image forming section PK is located on an intermediate transfer belt 7. The image forming apparatus 100 forms an image on a recording medium S using an electrophotographic method. The image forming apparatus 100 forms a black-and-white image. In this embodiment, a monochrome copying machine is described as an example, but the image forming apparatus 100 of the present invention is not limited to the color printed thereon. In FIG. 1, the left side is the left side of the image forming apparatus 100, and the right side is the right side of the image forming apparatus 100. The image forming apparatus 100 is controlled by an image processing control section 113.

[0014] The image forming apparatus 100 is provided with a main body cooling fan 111 that takes in outside air around the image forming apparatus 100 into the inside of the image forming apparatus and cools the inside of the main body of the image forming apparatus 100. As shown by the arrow AF in Fig. 1, the main body cooling fan 111 takes in outside air from the outside to the inside of the image forming apparatus 100 to cool the inside of the image forming apparatus 100. An image reading device 140 that reads an image of a document is provided on the upper part of the image forming apparatus 100. The image reading device 140 reads the image of the document and outputs an image signal. In addition, an operation unit 104 that is operated by a user is provided on the upper part of the image forming apparatus 100.

[0015] The image forming unit PK forms a black image using black toner. The image forming unit PK has a photosensitive drum (image carrier) 1K as a photosensitive member. The photosensitive drum 1K is rotatable in the direction indicated by the arrow R2. Around the photosensitive drum 1K, a charging device 2K, an optical scanning device 200, a developing device 80K, and a primary transfer roller 4K are arranged. An endless intermediate transfer belt (intermediate transfer body) 7 is arranged below the photosensitive drum 1K. The primary transfer roller 4K is arranged opposite the photosensitive drum 1K via the intermediate transfer belt 7, and forms a primary transfer unit T1K.

[0016] The intermediate transfer belt 7 is stretched around a driven roller 17, a tension roller 18, and a secondary transfer inner roller 8 which also serves as a drive transmission means. The intermediate transfer belt 7 rotates in the direction indicated by the arrow R1 in FIG. 1 during image formation. The primary transfer roller 4K is disposed opposite the photosensitive drum 1K via the intermediate transfer belt 7. The primary transfer roller 4K transfers the toner image on the photosensitive drum 1K to the intermediate transfer belt 7. The secondary transfer roller (secondary transfer member) 9 is disposed opposite the secondary transfer inner roller 8 via the intermediate transfer belt 7, and forms a secondary transfer portion T2 as a transfer nip portion.

[0017] A feed cassette 60 containing a recording medium S is disposed at the bottom of the image forming apparatus 100. The recording medium S is a transfer material on which an image is formed by the image forming apparatus 100, and is, for example, paper, an OHP sheet, or cloth. Hereinafter, the recording medium S is referred to as a sheet S. The sheet S is fed from the feed cassette 60 by a feed roller 61 that employs a friction separation method. The sheet S is transported to the secondary transfer section T2 by a registration roller 62. The fixing device 13 is disposed downstream of the secondary transfer roller 9 in the transport direction of the sheet S. The fixing device 13 has a pressure roller 14 and a heating roller 15 that face each other to form a fixing nip. The pressure roller 14 and the heating roller 15 heat and press the sheet S passing through the fixing nip to melt and fix the toner image on the sheet S. The fixing device 13 has a heater as a heat source, and is always controlled to an optimal temperature by the heater. The sheet S is transported from the secondary transfer roller 9 to the discharge roller 64 via the fixing device 13. The sheet S on which the image has been formed is discharged onto a discharge tray 63 by a discharge roller 64 .

[0018] (Image formation process) Next, the image forming process of the image forming apparatus 100 will be described.

[0019] The charging device 2K uniformly charges the surface of the photosensitive drum 1K. The optical scanning device 200 emits a light beam 3K modulated according to image information of a black component onto the uniformly charged surface of the photosensitive drum 1K to form an electrostatic latent image on the photosensitive drum 1K. The developing device 80K develops the electrostatic latent image with black toner (developer) to form a black toner image. The primary transfer roller 4K primarily transfers the black toner image on the photosensitive drum 1K onto the intermediate transfer belt 7.

[0020] The sheet S fed from the feed cassette 60 by the feed roller 61 passes through a conveying path and is conveyed to the registration roller 62. The skew of the sheet S is corrected by the registration roller 62. After correcting the skew of the sheet S, the registration roller 62 conveys the sheet S to the secondary transfer section T2 in synchronization with the toner image on the intermediate transfer belt 7. The four-color toner images formed on the intermediate transfer belt 7 are secondarily transferred collectively onto the sheet S by the secondary transfer roller 9. The sheet S onto which the toner images have been transferred is conveyed to the fixing device 13. The fixing device 13 applies heat and pressure to the sheet S to fix the toner image onto the sheet S. The sheet S on which the image has been formed is discharged to the discharge tray 63 by the discharge roller 64.

[0021] In the case of double-sided image formation, the sheet S is switched back by the discharge rollers 64, the conveying path is switched by the flapper 65, and the sheet S is conveyed to the reverse conveying rollers 97. The sheet S is conveyed again to the secondary transfer portion T2, an image is formed on the back side of the sheet S, and the sheet S is discharged to the discharge tray 63 by the discharge rollers 64.

[0022] Reference numeral 112 denotes an LVPS which supplies power to operate the motor 17, the main body cooling fan 111, the image reader 140, and the like, and 113 denotes a controller which controls the overall operation of this image forming apparatus.

[0023] <Fixing circuit diagram> FIG. 2 shows a circuit diagram of the fixing device 13 in FIG.

[0024] The heater 23 in FIG. 2 has a temperature detection element 25 on the back surface of the substrate 27 (the surface opposite to the nip portion N). The temperature detection element 25 is provided to detect the temperature of the heater 23. In this embodiment, a thermistor in contact with the back surface of the heater 23 is used as the temperature detection element. This thermistor 25 is configured, for example, by providing a heat insulating layer on a support (not shown), fixing a chip thermistor element on the heat insulating layer, and pressing the element against the back surface of the substrate 27 with a predetermined pressure to bring the support into contact with the back surface of the substrate 27. In this embodiment, the thermistors are provided at two locations in the longitudinal direction of the heating resistor. One of the thermistors, the thermistor 25b, is provided at a location in the longitudinal direction of the heating resistor where the recording medium always passes. The other thermistor, the thermistor 25a, is located in the longitudinal direction of the heating resistor. 31 is a thermoswitch as a safety device.

[0025] The control unit 28 obtains temperature information from 25a / b, and controls the triac 29 according to instructions from the controller 113 in FIG. 1, thereby controlling the AC current 24 supplied to the heater.

[0026] Reference numeral 22 denotes a photocoupler that detects AC voltage, and by notifying the controller 113 of the current AC point, the controller 113 can determine the current AC voltage point.

[0027] Based on the graph in Figure 3, the actual current (power) situation when printing with an electrophotographic MFP is shown.

[0028] This graph shows the power consumption when printing a 10-page document double-sided on a small 38ppm MFP at 100V / 50Hz.

[0029] The red line is the main body power, and the blue line is the power of the fixing device 13. As shown in the graph, the power of the fixing device 13 is dominant, and it can be seen that a current of about 10 A is consumed momentarily at the start of printing. In addition, the fixing device 13 is controlled so that heating is stopped between sheets, and then a current is applied all at once to heat it up again.

[0030] FIG. 4 shows a graph of the temperature applied to the fixing device 13 in FIG.

[0031] Generally, the temperature of the fixing device 13 is first raised to 100°C, power to the fixing device 13 is stopped to stop the temperature increase, and then the temperature is raised to -10°C, which is the target fixing temperature required for the paper type.

[0032] The reason for setting the fixing target temperature at -10°C is to prevent overshooting and exceeding the target temperature.

[0033] When the target fixing temperature of -10°C is reached, a current is applied so that the target fixing temperature is reached from there.

[0034] When printing is completed, the application of current to the fixing device 13 is stopped, and the temperature of the fixing device 13 gradually drops. When a print request is notified again, a current is applied to the fixing device 13 to raise the temperature.

[0035] Next, the temperature application method and the estimated power value for the fixing device 13 based on the first embodiment of the present invention are shown in Fig. 5 and Fig. 6. This control method is not the mode used for business use that is conventionally set as the default by the user through the operation unit 104 in Fig. 1, but can be switched to a second mode tentatively named "home mode" here, and allows users who have low power contracts to set it at their own discretion.

[0036] FIG. 5 shows how to apply temperature to the fixing device 13 according to the first embodiment of the present invention.

[0037] 4, the temperature of the fixing device 13 is not raised all at once to 100° C., but in this embodiment, the temperature is raised by 10° C. at a time until the target fixing temperature is reached.

[0038] The necessary power is applied until a certain temperature is reached, and if a higher temperature is required, the amount of power is increased until the target temperature is reached. Once the target temperature is reached, the power is reduced to the temperature maintenance power amount required to maintain that temperature.

[0039] 6 shows the power transition of the main body and the fixing device 13 based on the first embodiment of the present invention. Once the temperature is raised to the target fixing temperature, a current is applied, and once a certain temperature is reached, a current sufficient to maintain the target fixing temperature is continued to be applied, thereby avoiding a drop or sudden rise in power between pages.

[0040] It should be noted that, compared to the mode normally used in business, the embodiment of the present invention does not guarantee printing performance, in particular the time until the first print, called First Print Out Time (FPOT).

[0041] Next, the control method up to the start of printing according to the present invention will be described with reference to the flow chart of Fig. 7. The home mode and normal mode will also be described.

[0042] The MFP receives a print instruction in 701, and sets a fixing temperature=Y° C. suitable for the paper in 702. Here, in 703, it is determined whether the mode is the home mode or the normal mode. First, in the normal mode, the steps 734 to 745 described with reference to FIGS.

[0043] The fixing temperature is temporarily set to 100° C. in 734, and a current is applied to the fixing device 13 in 735. If the fixing temperature in 736 is determined to be 100° C., the process proceeds to 737, and if it has not yet reached 100° C., the process returns to 735 and the current is continued to be applied.

[0044] When it reaches 100°C, the fixing temperature 738 is set to the target = Y°C -10°C, i.e. Y-10°C, and a current is applied again in 739. When the fixing temperature reaches Y-10°C, the current amount is temporarily reduced in 741. If it has not yet reached that level, it returns to applying the current in 739, and continues to apply the current until it reaches Y-10°C.

[0045] When the temperature reaches Y-10°C, the fixing temperature 742 is set to Y°C, and current is continued to be applied until the temperature reaches Y°C in the same manner as before. When the temperature reaches Y°C, a current 745 is applied to the fixing device 13 to maintain the fixing temperature.

[0046] Next, the home mode of the present invention will be described.

[0047] The fixing temperature is temporarily set to 40° C. in 754, and when a current is applied to the fixing device 13 in 755 and it reaches 40° C., the current amount is temporarily reduced to an amount sufficient to maintain the temperature of the fixing device 13 in 757, and if the target temperature Y in 758 has not been reached, X=X+1 is substituted and the process returns to 755, a current is applied to the fixing device 13, and the current is continued until the temperature of the fixing device 13 reaches (40+10×X)° C. Then the process returns to Y>40+10×X in 758. 755 to 759 are repeated, and when Y=40+10×X is reached in 758, the process exits from this flowchart and the process returns to the start of printing in 704, where printing begins.

[0048] Next, a flowchart of the conventional mode for multiple printing from the start of printing will be described with reference to FIG.

[0049] 7 on the left, executes 802 which is a combination of 701 to 704 and 704 in the flowchart of FIG. 7, and when printing is completed in 803, immediately stops the power supply to the fixing device 13. If there is a next print instruction, the process returns and performs the same process, and if there is no print instruction, ends in 804.

[0050] Next, a flowchart of the home mode for printing multiple sheets of paper according to the present invention will be described with reference to FIG.

[0051] The process of 902, which combines the processes of 701 to 754 to 704 described in FIG. 7, is carried out, and printing ends at 903, and then the current for maintaining the temperature of the fixing device 13 continues to flow at 904. A timer is set at 905. Here, it is set to 20 seconds considering the case where there are consecutive print instructions, but the value is not limited to this. The timer counts down at 905, and if there is a next print instruction at 907, printing is carried out at 908, and the process returns to the end of printing at 903. If there is no print instruction, it is judged whether the counter value at 909 has passed a certain time, and if there is no print instruction after the certain time has passed, the current supply at 910 is stopped and the process ends.

[0052] In this way, when printing multiple sheets, the power is dropped between sheets as shown in FIG. 3, thereby avoiding the application of a sudden current to the fixing device again.

[0053] Finally, we will briefly explain how to control the power based on Figures 10-1 and 10-2. Since both wave number control and phase control are well-known technologies, we will only provide an overview.

[0054] Figure 10-1 shows wave number control, which is the control of how many waves of AC current are used, and in Figure 10-1, one wave is used out of two waves. Of course, it is possible to use one wave out of four or one wave out of six, and adjust the amount of power to set the appropriate temperature.

[0055] Figure 10-2 shows a control method called phase control, which allows you to control which part of the wave to use. Because AC waves have a fixed period, the current from the latter half of the wave is used, calculated from the 0 crossing point.

[0056] In the first embodiment of the present invention, the current in the latter half of the phase control is used to prevent a sudden current consumption. Also, if the power is insufficient, the wave number used in the wave number control is increased to cover the power, and the amount of power is controlled to prevent an instantaneous increase as much as possible.

[0057] Generally, the temperature of the fixing device is controlled by using both the wave number control and the phase control.

[0058] Using the above-mentioned method, it becomes possible for users to use electrophotographic SFP / MFPs at home without any stress. [Explanation of symbols]

[0059] 13 Fixing device 14 Pressure roller 15 Heating roller 60 Feeding Cassette 62 Registration roller 64 Discharge roller 100 Image forming device 104 Operation section 113 Image processing control unit 140 Image reader

Claims

1. This electrophotographic image forming apparatus has a first mode for supplying power to a fixing device, which places importance on the printing time for the first sheet, and a second mode for gradually supplying power to the fixing device without supplying abrupt power so that printing can be performed even in an environment where the power supply situation is limited, such as a home, without supplying abrupt power.

2. 2. An electrophotographic image forming apparatus according to claim 1, wherein when printing multiple sheets, the power supply is not stopped between pages, but rather the power supply is continued for a certain period of time, thereby making it possible to avoid a sudden power supply to the fixing device even after the second page.

3. 2. An electrophotographic image forming apparatus according to claim 1, wherein a user can easily change the mode from the first mode to the second mode through an operation panel or the like.

Images