JP5161140B2 - Fixing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, and more specifically, a fixing device that fixes an unfixed image formed on a recording paper by means of laser light irradiation means, and the same The present invention relates to an image forming apparatus including

  An electrophotographic image forming apparatus (for example, a printer) includes a fixing device that fixes a toner image formed on a recording member (recording paper or paper) onto the paper by heat melting. As an example of this fixing device, as disclosed in Patent Document 1, a roller-pair type fixing device including a fixing roller and a pressure roller is known.

The fixing roller is a roller member in which an elastic layer is formed on the surface of a hollow metal core made of metal such as aluminum, and a halogen lamp is arranged as a heat source inside the core metal. Then, the temperature control device controls the temperature of the fixing roller surface by controlling the halogen lamp on / off based on a signal output from a temperature sensor provided on the surface of the fixing roller.
The pressure roller is a roller member in which a heat-resistant elastic layer such as silicon rubber is provided as a coating layer on a cored bar. The pressure roller is pressed against the peripheral surface of the fixing roller, and a nip region is formed between the fixing roller and the pressure roller by elastic deformation of the elastic layer of the pressure roller.
In the above configuration, the fixing device sandwiches the paper on which the unfixed toner image is formed in the nip region between the fixing roller and the pressure roller, and conveys the paper by rotating both the rollers, The toner image on the sheet is melted and fixed on the sheet by the heat of the peripheral surface of the fixing roller.

  However, in the conventional roller pair system, immediately after the power is turned on in the morning, the fixing roller and the pressure roller are at room temperature. Further, in the standby state in which the copying operation is not performed, the roller surface needs to be maintained at a predetermined temperature. Therefore, the heating must always be performed even when the copying operation is not performed. In addition to these copying operations, useless energy is consumed.

  Accordingly, as a method for efficiently fixing only toner without consuming wasteful energy, a fixing device for fixing toner using laser power as disclosed in Patent Document 2 has been proposed. According to Patent Document 2, the toner is heated by using a plurality of lasers, so that the fixing ability is insufficient by using only one weak laser, and the fixing ability is improved by using a plurality of lasers. It is described that this makes it possible to use a low-power and inexpensive laser, so that the entire apparatus can be simplified.

Japanese Patent Laid-Open No. 11-38802 JP-A-7-191560

  However, in the fixing device of Patent Document 2, even if a plurality of lasers are used, the light energy conversion efficiency of the laser element (the ratio of the power that can be output as laser light to the power input to the laser element) is low. The usually used laser element has a light conversion efficiency of 50% or less. That is, 50% or more of the input power is conversion loss, and the conversion loss becomes heat generated from the laser light source, and means for cooling the heat generation is required. In addition, since separate power is required for cooling, the total energy conversion efficiency (light irradiation for all the input power required to operate the laser including the power input to the laser element and the input power required for cooling, etc.) The proportion of electric power that can be produced is worse.

  The present invention has been made in view of the above problems, and by using the heat of the laser light source unit for fixing, the light energy required for fixing an unfixed toner image is reduced, and at the same time, the paper is passed. An object of the present invention is to provide a fixing device that realizes low power consumption by reducing recording power by using recording paper as a cooling means of a laser light source unit, and an image forming apparatus including the fixing device.

The present invention relates to a fixing device for fixing an unfixed toner image by irradiating a laser beam.
A laser light source and a laser irradiation unit are separated and connected by an optical fiber, and a recording paper transport belt and a recording paper are heated by heat generated by the laser light source, and an unfixed toner image transported by the recording paper transport belt is formed. Preheating the recorded recording paper, irradiating the laser beam to the preheated recording paper to fix an unfixed toner image, and the laser light source is provided on the inner peripheral surface side of the recording paper transport belt, It is in contact with the upper and lower surfaces of the inner circumference of the recording paper transport belt and is heated by the heat generated by the laser light source .

  As a result, the waste heat generated by the laser light source can be reused and the recording paper on which the unfixed toner image is recorded can be preheated, so the light energy of the laser beam required for fixing the recording paper can be reduced and consumed. Fixing can be performed while suppressing electric power. Further, since the recording paper cools the laser light source, it is not necessary to provide a cooling device for the laser light source, and electric power necessary for cooling becomes unnecessary.

Further , by disposing the laser light source on the inner peripheral surface side of the recording paper conveyance belt, useless space is not required. Also, if the recording paper transport belt is arranged on the inner peripheral surface side, the recording paper transport belt is present at least above and below the laser light source and heat is more easily transferred than the outside, so that the recording paper transport belt can be efficiently heated. As a result, the recording paper can be efficiently preheated.
Further, since the laser light source is in contact with the recording paper conveyance belt, heat can be directly supplied to the recording paper conveyance belt, and efficient preheating can be performed.

Further, the laser light source of the present invention is in contact with the recording paper conveyance belt through a high thermal conductive material .

Thus, when brought into contact with the recording paper conveying belt through a high thermally conductive material, it becomes possible to enlarge the contact area in contact with the recording paper conveying belt, it can be more efficiently preheated.

In addition, the conveyance belt of the present invention is stretched around two rollers, and the high heat conductive material has a side surface portion in a columnar shape and abuts against the conveyance belt to serve as one roller. To do.

As a result, the high thermal conductivity material can contact the recording paper conveyance belt in addition to the top and bottom surfaces by sliding the stretched recording paper conveyance belt, compared to the high thermal conductivity material. Thus, a wide area can be contacted, and heat transfer can be improved.

  The fixing treatment of the present invention further includes a temperature sensor for detecting the temperature of the recording paper conveyance belt, and has laser irradiation control means for controlling the irradiation amount of the laser light source based on the detection result detected by the temperature sensor. It is characterized by that.

  Accordingly, since the recording paper is preheated by the recording paper conveyance belt, the temperature of the recording paper depends on the temperature of the recording paper conveyance belt. Therefore, by controlling the light energy (power consumption) output from the laser light source according to the temperature of the recording paper transport belt, the light energy of the laser light can be controlled efficiently without irradiating the recording paper with unnecessary light energy. And a fixing device with low power consumption can be obtained.

  The laser irradiation control means of the present invention controls the light irradiation timing of the laser light source based on the printing position information on the recording paper.

  As a result, the unfixed toner image is based on the print position information on the recording paper from the image information input to the image forming apparatus (refers to a signal indicating which position is printed for each page with respect to the print job). Since the laser beam is irradiated only at the timing necessary for fixing the laser beam, unnecessary laser beam irradiation can be eliminated and low power consumption can be achieved. Further, since the recording paper transport belt is not directly irradiated with laser, thermal deterioration of the recording paper transport belt can be suppressed.

  The fixing device according to the present invention is characterized in that a bias voltage is applied to the recording paper conveyance belt. The fixing device of the present invention is characterized in that the recording paper transport belt is made of a conductive material.

  Thereby, by applying a bias voltage to the recording paper transport belt, the recording paper is electrostatically adsorbed to the recording paper transport belt, and the adhesion between the recording paper transport belt and the recording paper is improved. It is possible to uniformly preheat the entire recording paper while suppressing the floating of the recording paper. Further, since the unfixed toner image can be uniformly irradiated with the light energy of the laser beam, it can be fixed efficiently.

  A plurality of the laser irradiation sections of the present invention are arranged in a direction perpendicular to the conveyance direction of the recording paper conveyance belt.

Thus, for example, when the entire surface of the paper is irradiated with a single laser beam irradiation means, it is necessary to scan the laser beam in a direction perpendicular to the paper conveyance direction in addition to the paper conveyance direction, and thus fixing takes time. Accordingly, when the recording paper conveyance speed of a high-speed machine or the like is increased, fixing becomes insufficient.
In addition, scanning the laser increases the complexity and cost of the apparatus.
Therefore, by arranging the laser irradiation units in the direction perpendicular to the paper conveyance direction (width direction), it is not necessary to scan the laser light, and a laser light source compatible with a high-speed machine can be obtained. In addition, since the parts to be scanned are unnecessary, the space for the parts to be scanned becomes unnecessary, and a compact laser fixing device can be obtained.

  The present invention also provides a photosensitive drum on which an electrostatic latent image is formed, a charging device that charges the surface of the photosensitive drum, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, and a photosensitive member. A developing device for supplying toner to the electrostatic latent image on the drum surface to form a toner image, a transfer device for transferring the toner image on the surface of the photosensitive drum to a recording medium, and fixing the transferred toner image on the recording medium An image forming apparatus for forming an image using toner by an electrophotographic method includes the above-described fixing device of the present invention as the fixing device.

  As a result, the warm-up time of the image forming apparatus can be shortened, and power consumption during standby is not necessary, so that an image forming apparatus with low power consumption can be obtained.

  According to the present invention, the waste heat generated by the laser light source can be reused, and the recording paper on which the unfixed toner image is recorded can be preheated, thereby reducing the light energy of the laser beam necessary for fixing the recording paper. And can be fixed while suppressing power consumption. Further, since the recording paper cools the laser light source, it is not necessary to provide a cooling device for the laser light source, and electric power necessary for cooling becomes unnecessary.

1 is a schematic view of an image forming apparatus including a laser fixing device according to the present invention. 1 is a schematic view showing an embodiment of a laser fixing device according to the present invention. It is the schematic which shows other embodiment of the laser fixing apparatus which concerns on this invention. It is the schematic which shows other embodiment of the laser fixing apparatus which concerns on this invention. It is the schematic which shows other embodiment of the laser fixing apparatus which concerns on this invention. It is a figure when it sees in the orthogonal | vertical direction with respect to the paper conveyance direction of a laser beam irradiation apparatus. It is a figure which shows the structure and initial condition of the recording paper in a laser fixing, and a recording paper conveyance belt. It is a figure which shows the relationship between the temperature and preheating time in case the initial temperature of a recording paper conveyance belt is 30 degreeC. It is a figure which shows the relationship between the temperature and preheating time in case the initial temperature of a recording paper conveyance belt is 40 degreeC. It is a figure which shows the result of fixing quality determination at the time of changing the output of a laser element with respect to preheating temperature. FIG. 3 is a control block diagram of the image forming apparatus according to the present invention. 3 is a flowchart illustrating a copy operation procedure of the image forming apparatus according to the present invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

An embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows the internal structure of a dry electrophotographic color image forming apparatus. The image forming apparatus forms a multi-color or single-color image on a predetermined recording sheet based on, for example, image data transmitted from each terminal device on the network.

The image forming apparatus includes a visible image forming unit 50 (50Y, 50M, 50C, and 50B), a recording paper transport unit 30, a fixing device 40, and a supply tray 20.
In the image forming apparatus, four visible image forming units 50Y, 50M, 50C, and 50B are arranged in parallel corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (B). ing. That is, the visible image forming unit 50Y forms an image using yellow (Y) toner, and the visible image forming unit 50M forms an image using magenta (M) toner to form a visible image. The unit 50C forms an image using cyan (C) toner, and the visible image forming unit 50B forms an image using black (B) toner. A specific arrangement is a so-called tandem type in which four sets of visible image forming units 50 are arranged along a recording paper conveyance path connecting the supply tray 20 of the recording paper P and the fixing device 40.

  Each of the visible image forming units 50 has substantially the same configuration, that is, the photosensitive drum 51, the charger 52, and the laser beam irradiation means 53 (here, a latent image is written on the photosensitive drum). A developing device 54, a transfer roller 55, and a cleaner unit 56, and each color toner is transferred onto the conveyed recording paper P in a multiple transfer manner.

  Here, the photosensitive drum 51 carries an image to be formed. The charger 52 charges the surface of the photosensitive drum 51 uniformly to a predetermined potential. The laser beam irradiation unit 53 exposes the surface of the photosensitive drum 51 charged by the charger 5 according to the image data input to the image forming apparatus, and forms an electrostatic latent image on the surface of the photosensitive drum 51. . The developing unit 54 visualizes the electrostatic latent image formed on the surface of the photosensitive drum 51 with toner of each color. The transfer roller 55 is applied with a bias having a polarity opposite to that of the toner, and transfers the formed toner image onto the recording paper P conveyed by the recording paper conveying means 30 described later. The drum cleaner unit 56 removes and collects the toner remaining on the surface of the photosensitive drum 51 after the development processing in the developing unit 54 and the transfer of the image formed on the photosensitive drum 51. The transfer of the toner image onto the recording paper P as described above is repeated four times for four colors.

  The recording paper conveying means 30 includes a driving roller 31, an idling roller 32, and a conveying belt 33, and conveys the recording paper P so that a toner image is formed on the recording paper P by the visible image forming unit 50. It is. The drive roller 31 and the idling roller 32 stretch the endless transport belt 33. The drive roller 31 is rotated by being controlled at a predetermined peripheral speed, thereby rotating the endless transport belt 33. Yes. The transport belt 33 generates static electricity on the outer surface, and transports the recording paper P while electrostatically attracting the recording paper P.

  In this way, the recording paper P is transferred to the conveying belt 33 while the toner image is transferred thereto, and then peeled off from the conveying belt 33 by the curvature of the driving roller 31 and conveyed to the fixing device 40. The fixing device 40 applies an appropriate amount of heat to the recording paper P, dissolves the toner, and fixes it to the recording paper, thereby forming a robust image.

Here, the fixing device will be described in detail with reference to FIG.
The fixing device 40 a includes a laser light source 104, a laser irradiation unit 105, an optical fiber 106 that connects the laser light source 104 and the laser irradiation unit 105, and a recording paper conveyance device 107 that conveys the recording paper P.

  The recording paper transport device 107 includes two tension rollers 101 and 102 and a recording paper transport belt 103 having a heat-resistant endless belt. The tension roller 101 and the tension roller 102 stretch the recording paper conveyance belt 103. A driving means (not shown) is connected to the tension roller 101 and is rotated by the driving means. The recording paper P having an unfixed toner image (toner 110) is transported on the recording paper transport belt 103.

  The laser light source 104 is a semiconductor laser. Semiconductor lasers have the advantage of being cheaper and smaller than other lasers such as carbon dioxide lasers. In addition, laser light having a wide range of wavelengths can be generated arbitrarily in the region of 400 nm to 1000 nm depending on the composition of the semiconductor element and the material composition. The laser light source 104 is installed on the inner peripheral surface side of the recording paper conveyance belt 103, and the entire laser light source 104 is covered with a columnar high thermal conductive material 108a. The two upper and lower surfaces of the high thermal conductive material 108 a are in contact with the recording paper conveyance belt 103.

  As the high thermal conductive material 108a, a material having a high thermal conductivity such as aluminum, silver, or copper is used. The surface of the high thermal conductive material 108a is made of a non-conductive material (not shown). The non-conductive material is thinly coated with PFA (about 10 μm), and the frictional resistance at the contact surface with the recording paper conveyance belt 103 is reduced as much as possible. Further, it also has a role of maintaining insulation on the contact surface with the recording paper conveyance belt 103. Materials other than the above PFA may be used such as PTFE and FEP. That is, the coating material is not limited to this as long as the coating material has insulating properties and low frictional resistance.

  The heat generated by the laser light source 104 is transferred to the recording paper conveyance belt 103 through the high thermal conductive material 108a. In FIG. 2, the high thermal conductive material 108 a is in contact with the recording paper transport belt 103 on two upper and lower surfaces, but can efficiently transfer the heat generated by the laser light source 104 to the recording paper transport belt 103 (less heat loss). Further, although the heat generated from the laser light source 104 is transferred to the recording paper conveyance belt 103 through the high thermal conductive material 108 a, the laser light source 104 may be directly brought into contact with the recording paper conveyance belt 103 to transfer heat. However, when the laser light source 104 is small, a sufficient contact area with the recording paper conveyance belt 103 cannot be ensured, and thus heat radiation of the laser light source 104 may be insufficient. Therefore, it is preferable to increase the contact area with the recording paper conveyance belt 103 with the high thermal conductive material 108a or the like.

  The recording paper transport belt 103 uses two tension rollers 101 and 102, but is not limited thereto. For example, in the fixing device 40b shown in FIG. 3, one side surface portion of the columnar high thermal conductive material 108b is formed in a cylindrical shape so that the recording paper conveyance belt 103 can be stretched instead of the tension roller 102. In this way, the high thermal conductivity material 108b can make the cylindrical portion of the side surface in addition to the upper and lower surfaces abut against the recording paper conveyance belt 103 by sliding the stretched recording paper conveyance belt 103. Compared with 108a, a large area can be contacted, and heat conductivity can be improved.

Further, as shown in the fixing device 40c of FIG. 4, the laser light source 104 is disposed on the surface (outer peripheral surface) side of the recording paper conveyance belt 103, the laser light source 104 is covered with a columnar high thermal conductive material 108c, and the high thermal conductive material 108c. Alternatively, the laser light source 104 may be in contact with the surface of the recording paper conveyance belt 103 via the gap. The high thermal conductive material 108 c covers the surface of the laser light source 104 on the recording paper conveyance belt 103 side and the side surface in the direction extending along the recording paper conveyance belt 103 in order to increase the contact area. Note that the high thermal conductive material 108c may be a plate-like material that comes into contact with the surface of the laser light source 104 on the recording paper conveyance belt 103 side as shown in FIG.
For the high thermal conductivity material, its shape, how to cover the laser light source, and the contact area with the recording paper transport belt are determined in consideration of the preheating state and the cooling state of the laser light source.

  Further, as shown in the fixing device 108d of FIG. 5, the high heat conductive material does not cover the laser light source, and the lower surface of the laser light source 104 may be brought into contact with the upper surface of the columnar high heat conductive material 108c. In this case, the surface of the high thermal conductive material 108 c (the lower surface where the laser light source 104 is not in contact) is disposed in the vicinity (non-contact) of the recording paper at a position before being conveyed to the laser irradiation unit 105. Thus, the recording paper surface having an unfixed toner image is brought close to the recording paper surface in a non-contact manner, and heat is transferred to the recording paper P. Naturally, the direct laser irradiation unit 105 may be disposed near the surface of the recording paper without using the high thermal conductive material 108. Further, the periphery of the laser irradiation unit 105 may be covered with a high thermal conductive material 108.

  Such a non-contact type is not heated as compared with the contact type and thus preheats the recording paper itself, but may be used for preheating the recording paper conveyance belt. Further, the shape, the method of covering the laser light source, and the contact area with the recording paper conveyance belt of the high heat conductive material are determined in consideration of the preheating state and the laser light source cooling state.

  2 to 5 are examples of the present embodiment, and any other arrangement may be used as long as the recording paper P can be preheated by the heat generated from the laser light source 104.

  With the above configuration, the laser light source 104 self-heats due to energy conversion loss, but radiates heat (cools with the recording paper) to the recording paper via the recording paper conveyance belt 103, so the temperature of the laser light source 104 The rise can be suppressed.

  The laser light output from the laser light source 104 is emitted from the laser irradiation unit 105 through the optical fiber 106. The laser irradiation unit 105 performs laser irradiation on the surface of the recording paper having the unfixed toner image.

  As shown in FIG. 2, the recording paper conveyance belt 103 is made of a material in which a conductive member such as carbon is dispersed in a resin such as polycarbonate, vinylidene fluoride, polyamideimide, or polyimide (PI). The surface (outer peripheral surface) of the recording paper transport belt 103 is configured to electrostatically attract the recording paper P by applying a bias voltage by a power source 111 connected to the inner surface of the transport belt 103. By electrostatically adsorbing the recording paper P to the recording paper transport belt 103, the recording paper transport belt 103 and the recording paper P are brought into close contact with each other, and the heat on the recording paper transport belt can be efficiently transferred to the recording paper P. .

FIG. 6 shows a view of the laser light irradiation apparatus in FIG. 2 when viewed from the direction perpendicular to the paper conveyance direction.
In FIG. 6, a plurality of laser light sources 104 and laser irradiation units 105 are arranged in a direction perpendicular to the paper conveyance direction (width direction of the recording paper conveyance belt 103). For example, when the entire surface of the recording paper is irradiated with a single laser irradiation unit, it is necessary to scan the laser beam in a direction perpendicular to the recording paper conveyance direction (width direction of the recording paper conveyance belt 103) in addition to the recording paper P conveyance direction. Since the fixing process takes time, fixing failure may occur when the fixing speed of a high-speed machine or the like is high. Further, scanning with laser light increases the complexity and cost of the fixing device. On the other hand, in this embodiment, it is necessary to scan the laser in the direction perpendicular to the paper conveyance direction by arranging the laser irradiation units 105 in a line in the direction perpendicular to the paper conveyance direction (width direction of the recording paper conveyance belt 103). Therefore, the fixing device can be configured with the minimum necessary space, and further, fixing can be performed at high speed.

  As shown in FIG. 2, a thermistor 109 is installed on the inner peripheral surface side of the recording paper conveyance belt 103 as temperature detection means (temperature sensor) for detecting the temperature of the recording paper conveyance belt 103. Based on the temperature detected by the thermistor 109, the laser irradiation unit 105 controls the amount of light irradiation (controlled by a fixing control unit 602 in FIG. 11 described later). The thermistor 109 is not limited to this position as long as the temperature of the recording paper conveyance belt 103 or the temperature of the recording paper P is a temperature detecting temperature appropriately. Further, temperature detecting means other than the thermistor 109 may be used.

  When the recording paper P having an unfixed toner image is preheated by heat generated from the laser light source 104, the recording paper P and the toner 110 are heated before the laser irradiation unit 105 irradiates the laser light. Therefore, when the toner 110 is heated and fixed with the laser light emitted by the laser irradiation unit 105, the laser irradiation amount of the laser irradiation unit 105 can be suppressed.

  For example, when a conventional laser fixing device performs a fixing operation immediately after warming up at room temperature (20 ° C.), the back surface of the recording paper P is not heated because the laser light source 104 hardly generates heat. Therefore, the toner 110 present on the surface of the recording paper P is also at about room temperature, and the energy required to fix the toner 110 is a theoretical value of 0.000795 J / mm 2. Specifically, for example, a case where a general polyester toner is used will be described. Toner 110 specific heat 1.42 J / g · ° C., specific gravity 0.000817 g / mm 3, toner thickness 0.016 mm, toner 110 filling rate 0.476 (volume of toner per unit volume), room temperature (20 ° C. ) Is melted at 110 ° C. (toner temperature necessary for melting the toner), the light irradiation energy necessary for fixing is 0.000795 J / mm 2 (= specific heat × specific gravity × filling rate × (110 ° C.). −20 ° C.).

  On the other hand, in the laser fixing apparatus of this embodiment shown in FIG. 2, the recording paper P is continuously passed, and the heat generated by the energy conversion loss by the laser light source 104 is transferred to the recording paper conveyance belt 103 through the high thermal conductive material 108. When the thermistor detection temperature is preheated to 40 ° C. (the unfixed toner image is 40 ° C. at this time), the light irradiation energy required to melt the toner 110 is 0.000618 J / mm 2 (= specific heat × specific gravity × The filling rate × (110 ° C.-40 ° C.), and a light irradiation amount of 78% (= 0.000593 / 0.000795) with respect to room temperature is sufficient.

  By the way, the relationship between the thermistor detection temperature and the temperature of the unfixed toner image (here, the interface temperature between the lowermost toner layer and the paper) is, for example, the configuration shown in FIG. 7 (FIG. 7A) and the initial condition ( A one-dimensional thermal analysis is performed in FIG. 7B, and the relationship between the thermistor detection temperature and the toner temperature can be predicted in advance from the results (FIGS. 8 and 9). For example, in FIGS. 8 and 9, the relationship between the temperature detected by the thermistor (that is, the initial temperature of the recording paper transport belt is 30 ° C. or 40 ° C.) and the toner temperature is as follows. The recording paper on which the unfixed image is placed becomes substantially the same in the time from the time when the recording paper comes into contact with the recording paper conveyance belt to the time when the recording paper reaches the laser irradiation section, and thus the thermistor detection temperature may be regarded as the toner temperature. On the other hand, when the contact time between the high thermal conductivity material 108 and the recording paper conveyance belt 103 is short, the heat of the high thermal conductivity material 108 may not be sufficiently transferred to the recording paper conveyance belt 103. The temperature of the toner 110 may be different. In that case, an appropriate temperature conversion table in consideration of the temperature difference may be created from the calculation results described above (FIGS. 8 and 9).

  Based on the above theoretical values, a temperature conversion table that calculates the relationship of the light irradiation amount of the laser irradiation unit 105 to the detection temperature of the thermistor 109 is created, and the temperature is calculated based on the detection temperature of the thermistor 109 using this table. If the conversion table is read and the light irradiation amount is determined, fixing can be performed with the minimum necessary light irradiation amount. The temperature conversion table is stored in the storage unit 609 in FIG.

  The above-described temperature conversion table obtained by calculation is only an example, and the temperature conversion table may be created by another method. For example, a temperature conversion table in which optimum fixing conditions are determined by changing the detected temperature of the thermistor 109 and the amount of light irradiation by experiment may be used. Specifically, a toner fixing experiment by laser light irradiation with respect to the temperature detected by the thermistor was performed under the following experimental conditions, and the energy required for fixing the toner was calculated. The calculation method of energy required by experiment is to calculate the energy density per unit area from the laser output necessary for obtaining sufficient fixing strength for the image pattern.

  For example, when the paper conveyance speed is V (mm / s), the image area width is L (mm), and the necessary laser output is P (W), the required energy density E (J / mm 2) is E = P / (V · L). The experimental conditions are: thermistor detection temperatures of 20 ° C., 30 ° C., 40 ° C., paper conveyance speed of 200 mm / s, semiconductor laser of 780 nm, laser spot diameter of 0.3 mm in one laser element, and laser elements at intervals of 0.3 mm. Individual arrangement (that is, an image area width of 300 mm). The output of one laser element was changed by 0.02 W from 0.16 W to 0.26 W, and the minimum output to be applied to the laser element necessary for fixing was measured. The result is shown in FIG.

From the results shown in FIG. 10, it was confirmed that fixing can be performed with an output of 0.24 W or more at a detected temperature of 20 ° C. as an output per element. The energy required to fix the toner at room temperature was calculated by the above experiment and found to be 0.004 J / mm 2. (The difference between the calculated value from the above experiment and the above theoretical value 0.000795 J / mm 2 is that the theoretical value is calculated when only the toner is heated. Actually, the ambient air is heated while the toner is heated. In the experiment, since the heat escapes to paper or the like, the toner itself does not absorb 100% of the laser light, and an energy absorption loss due to reflection or the like occurs, the value becomes larger than the theoretical value in the experiment. Since fixing is possible at 0.22 W at 0.2 ° C. and 0.20 W at 40 ° C., a table for controlling the laser output with respect to each thermistor detection temperature may be created based on these values.
By the way, the above example is only an example, and the value varies depending on the configuration of the member to be used, the thickness, and the like. Therefore, the optimum experimental condition may be calculated as appropriate.

FIG. 11 is a control block diagram of the image forming apparatus according to the present embodiment.
The image forming apparatus 1 is, for example, a multifunction machine including a scanner, a printer, and peripheral devices, a reading unit 605 that reads a document image, and an image that generates image data by converting the read document image into an appropriate electrical signal. A processing unit 606, an image forming unit 607 that prints out the generated image data, a fixing control unit (laser irradiation control means) 602 that controls laser light irradiation of a fixing unit (not shown), and detects a process speed and a paper conveyance start signal. A storage unit 609 that stores the arrival time of the recording member from the actuator start signal to the laser irradiation unit in the fixing device, and peripheral devices such as finishers and sorters that are post-processing devices A peripheral device control unit 608 to be controlled, an input unit 603 that is an operation unit of the image forming apparatus 1, and a display unit 604 are provided.

  The control unit 601 stores in advance in the storage unit 609 based on the print position information of the image information received from the image processing unit 606 (refers to a signal indicating at which position each page is printed for a print job). The received data is collated, and the laser light output value calculated by the temperature conversion table based on the print position information and the thermistor detection temperature information is transmitted to the fixing control unit 602. The fixing control unit 602 receives the received print Based on the position information and the calculated output value of the laser beam, the recording paper conveying belt 103 is driven to control to irradiate the laser beam.

  Further, the fixing control unit 602 monitors a signal of an actuator (not shown) that detects the conveyance of the recording paper P, and performs control to apply a bias voltage to the recording paper conveyance belt 103 based on this signal.

FIG. 12 shows a flowchart relating to a copy operation of the image forming apparatus according to the present invention.
Note that it is needless to say that the control based on this flowchart can be applied based on the print instruction signal of the user even when the user issues a print instruction from the printer driver screen (not shown) of the image forming apparatus 1.

  When the user presses a copy button (not shown) of the input unit 603, the control unit 601 receives a signal (a document that the user wants to copy has been placed on the scanner or placed on the document table). When a print instruction signal) is received, for example, a document image is read by the reading unit 605 of the scanner, the image processing unit 606 performs image processing on the read signal, and receives the above-described print position information.

  The control unit 601 first determines whether or not print position information is included based on the print position information received from the image processing unit (step S1). If the print position information is included (step S1). S1; Yes), the control unit 601 collates the data with the storage unit 609 and determines at what timing the print start time should be output (step S2). The control unit 601 receives the temperature detected by the thermistor 109 (step S3). Next, the detected temperature from the thermistor 109 received is collated with the temperature conversion table created in advance as described above (step S4). Next, the output value of the laser irradiation amount corresponding to the detected temperature data is determined in the temperature conversion table (step S5). Next, the laser output signal and output value of the laser light source 104 are transmitted to the fixing controller 602 (step S6).

  The fixing control unit 602 performs control to apply a bias voltage from the power source 111 to the recording paper conveyance belt 103 (step S7), and performs irradiation by the laser irradiation unit 105 by controlling the laser light source 104 (step S8). When the print job is completed (print position information is completed) (step S9), the fixing control unit 602 stops the output of the laser beam to the laser irradiation unit 105 (step S10), and then outputs to the recording paper conveyance belt 103. The application of the bias voltage is also stopped (step S11).

  The fixing control unit 602 monitors a signal of an actuator that detects conveyance of the recording paper P (not shown), and recognizes that the paper has been conveyed based on this signal, the laser irradiation unit 105 and the bias voltage. You may control. For example, the travel time of the recording paper P is measured from the time when the recording paper P is fed from a supply roller (not shown) from the supply tray 20, and the arrival time to the laser light source 104 is calculated to calculate the laser irradiation unit 105 and the recording. The paper conveyance belt 103 and bias voltage application and stop may be controlled.

  As described above, the recording paper P having an unfixed toner image conveyed by the recording paper conveyance belt 103 (FIG. 2) is in close contact with the recording paper conveyance belt 103 and emits laser light based on the print position information. Irradiation and laser light irradiation is performed based on the print position information obtained from the image information during the paper passing operation, so that the fixing device and the image forming device are warmed up other than the paper passing operation of the image forming device. At the time and during standby, no power is required, and a low power consumption fixing device and image forming apparatus can be realized.

  In the flowchart of FIG. 12, the fixing control unit 602 controls the control for stopping the irradiation of the laser light source 104. However, even if the fixing control unit 602 does not control the laser light source from the control unit 601. The irradiation of the laser light source 104 may be controlled based on only the instruction signal for irradiating 104.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Charger 20 Supply tray 30 Recording paper conveyance means 31 Drive roller 32 Idling roller 33 Conveyor belt 40 (40a, 40b, 40c, 40d) Fixing device 50 (50B, 50C, 50M, 50Y) Visible image formation Unit 51 Photosensitive drum 52 Charger 53 Laser light irradiation means 54 Developer 55 Transfer roller 56 Cleaner unit 101 Tension roller 102 Tension roller 103 Recording paper conveyance belt 104 Laser light source 105 Laser irradiation unit 106 Optical fiber 107 Recording paper conveyance device 108 (108a) 108b, 108c, 108d) High thermal conductivity material 109 Thermistor 110 Toner 111 Power supply 601 Control unit 602 Fixing control unit 603 Input unit 604 Display unit 605 Reading unit 606 Image processing unit 607 Image forming unit 608 Peripheral device Control unit 609 storage unit

Claims (9)

In a fixing device that fixes an unfixed toner image by irradiating a laser beam,
A laser light source and a laser irradiation unit are separated and connected by an optical fiber, and a recording paper transport belt and a recording paper are heated by heat generated by the laser light source, and an unfixed toner image transported by the recording paper transport belt is formed. Preheating the recorded recording paper, irradiating the preheated recording paper with the laser beam to fix an unfixed toner image ;
The laser light source is
A fixing device , which is provided on an inner peripheral surface side of the recording paper transport belt, contacts the upper and lower surfaces of the inner periphery of the recording paper transport belt, and is heated by heat generated by the laser light source . The fixing device according to claim 1, wherein the laser light source is in contact with the recording paper conveyance belt via a high thermal conductive material . The conveyor belt is stretched around two rollers,
The fixing device according to claim 2, wherein the high thermal conductive material has a side surface portion in a columnar shape and is brought into contact with the conveyance belt to serve as one roller . 2. A laser irradiation control unit that includes a temperature sensor that detects a temperature of the recording paper conveyance belt, and that controls an irradiation amount of the laser light source based on a detection result detected by the temperature sensor. 4. The fixing device according to any one of items 1 to 3 . The fixing device according to claim 4 , wherein the laser irradiation control unit controls light irradiation timing of the laser light source based on print position information on the recording paper. The fixing device according to any one of claims 1 to 5, characterized in that a bias voltage is applied to the recording sheet conveying belt. The fixing device according to any one of claims 1 to 6, characterized in that it constitutes the recording paper conveying belt with a conductive material. The laser irradiation unit, a fixing device according to any one of claims 1 to 7, characterized in that are arranged more perpendicularly to the conveying direction of the recording paper conveying belt. A photosensitive drum on which an electrostatic latent image is formed, a charging device for charging the surface of the photosensitive drum, an exposure device for forming an electrostatic latent image on the surface of the photosensitive drum, and an electrostatic latent image on the surface of the photosensitive drum A developing device that supplies toner to the image to form a toner image, a transfer device that transfers the toner image on the surface of the photosensitive drum to a recording medium, and a fixing device that fixes the transferred toner image to the recording medium. In an image forming apparatus for forming an image using toner by electrophotography,
Examples fixing device, an image forming apparatus comprising the fixing device according to any one of claims 1 to 8.

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