JP2012163869A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an apparatus for fixing a toner image on a sheet by irradiation of a light source and appropriately heating a sheet passing range.
An image forming apparatus having a fixing unit for fixing a toner image onto a sheet, wherein the fixing unit converts a light source and light of a light source incident from a side surface into linear light orthogonal to the incident direction and a bottom surface. This is solved by a light guide member that is irradiated from above and an adjustment unit that adjusts the width of the linear light.
[Selection] Figure 2

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that melts and fixes a toner image formed on a sheet by radiant heat from a light source such as an infrared LED.

  As a fixing device for fixing a toner image on a sheet, a fixing device using a heat roller is widely used. In this fixing device using a heat roller, a heat source is provided in at least one of the rollers in pressure contact with each other, and when the sheet is sandwiched and moved by a pair of rollers controlled to a predetermined temperature, heat and pressure are used. The toner melts and fixes.

  On the other hand, a non-contact fixing device that melts and fixes a toner image formed on a sheet by radiant heat of a light source is known.

  Patent Document 1 describes a non-contact fixing device shown in FIG. The fixing device includes an LED array 101 and a cylindrical lens 102. The LED array 101 includes LEDs 111 arranged in a row in a direction orthogonal to the paper conveyance direction, and the length of the LED array 101 is set to be longer than the direction orthogonal to the conveyance direction of the paper 103 being conveyed. . The cylindrical lens 102 is provided along the LED array 101 so as to collect the light from the LED array 101 including infrared light on the paper 103, and the light from the LED array 101 is orthogonal to the arrangement direction of the LEDs 111. It has a refractive power in the plane where the light is emitted and does not have a refractive power in a plane parallel to the arrangement direction of the LEDs 111 for the light from the LED array 101.

  Further, in Patent Document 1, as shown in FIG. 8A, in order to reduce unevenness in the amount of light reaching the paper 103 even when there is a variation in the light emission amount of each LED 111, the paper 103 It is disclosed that the light of a plurality of LEDs reaches the arbitrary point above.

JP-A-6-301304

  FIG. 8B shows an aspect of the light amount distribution in the direction orthogonal to the paper conveyance direction irradiated by the LED array of Patent Document 1.

  As shown in FIG. 8B, in the fixing device disclosed in Patent Document 1, a sheet for fixing toner has an effective range RA in which a predetermined number of LEDs reach and a prescribed amount of light is stably maintained. The paper passing range is set to pass. However, the light from the LED array irradiates the irradiation range RL that the light from the LEDs at both ends reaches. Irradiation in a range wider than the sheet passing range adversely affects processing for fixing the toner, for example, excessively heating the transport mechanism member around the sheet passing range to cause wrinkles on the sheet.

  Furthermore, since the light from the LED array cannot be used around the paper passing range, the utilization efficiency of the light emitted from the LED array becomes poor.

  Further, the LED array that can generate heat at a high temperature requires a cooling mechanism, but it is difficult to form a space for cooling at the top in terms of downsizing the fixing device in the height direction.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize an apparatus for fixing a toner image onto a sheet by irradiation of a light source, and appropriately heating the sheet passing range. is there.

  The image forming apparatus of the present invention is an image forming apparatus having a fixing unit that fixes a toner image onto a sheet, and the fixing unit is a linear light source and light of a light source incident from a side surface that is orthogonal to the incident direction. A light guide member that emits light from the bottom surface and an adjustment unit that adjusts the width of the linear light are provided.

  Preferably, there is provided a detecting means for detecting the width of the paper and a control means for adjusting the width of the linear light according to the width of the paper detected by the detecting means.

  Preferably, the control means adjusts the light amount of the light source in accordance with the width of the paper detected by the detection means.

  Preferably, the adjustment unit adjusts the width of the linear light by transmitting or reflecting incident light.

  Preferably, the adjustment unit is an electrochromic material.

  In the image forming apparatus of the present invention, the width of the linear light can be adjusted so that the light from the light source does not reach the outside of the sheet passing range through which the sheet passes. It is possible to reduce factors that adversely affect toner fixing, such as excessive heating.

1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus 1 according to the present invention. It is a figure which shows schematic structure of the light fixing unit 40 of this invention which reflected the reflective part 421 in the OFF state. It is a figure which shows schematic structure of the light fixing unit 40 of this invention which reflected the reflective part 421 in the ON state. It is a figure which shows the aspect by which the light of the light source 41 is guided. 5 is a flowchart showing a processing procedure of a control means 49. 4 is a table showing a relationship between a paper size and driving power of a light source 41. It is a figure which shows schematic structure of the conventional non-contact fixing apparatus. It is a figure which shows the aspect of the light quantity distribution of the direction orthogonal to the paper conveyance direction of the conventional non-contact fixing device.

  FIG. 1 shows an example of the overall configuration of an image forming apparatus 1 according to an embodiment of the present invention.

  The image forming apparatus 1 includes a paper feed tray 10 that holds the paper 90 to be transported, and image forming units 30Y and 30M for sequentially forming yellow, magenta, cyan, and black toner images on the transported paper 90. , 30C, 30B (hereinafter collectively referred to as the image forming unit 30), a light fixing unit 40 for melting and fixing the toner image formed on the paper 90 by the image forming unit 30, and a light fixing The paper discharge tray 20 that holds the paper 90 carried out from the unit 40 and various transport mechanisms for sequentially transporting and transporting the paper 90 downstream.

  Here, each of the image forming units 30 electrostatically charges the photosensitive member 31, a charger 32 for charging the photosensitive member 31 to a predetermined potential, and the photosensitive member 21 charged to the predetermined potential based on image information. The image forming apparatus includes an exposure unit 33 that forms a latent image, a developing unit 34 that develops an electrostatic latent image to form a toner image, and a transfer unit 35 that transfers the toner image onto a sheet 90.

  2 and 3 show a schematic configuration of the light fixing unit 40 of the present invention. Here, FIG. 2 is a schematic view when the reflecting portion 421 is not driven (hereinafter referred to as an OFF state), and FIG. 3 is a schematic view when the reflecting portion 421 is driven (hereinafter referred to as an ON state). ing.

  The light fixing unit 40 guides the light source 41 typified by an infrared LED and the light of the light source 41 to linear light having a uniform predetermined width and irradiates the surface of the paper 90 on which the toner image is formed. In order to control the state of the light body 42 and the reflection unit 421, the sensor 43 for detecting the size of the conveyed paper 90, the drive circuit 45 for adjusting the amount of light emitted from the light source 41, and the reflection unit 421. Drive circuit 46 and a control means 49 for inputting the signal from the sensor 43 and controlling the drive circuit 45 and the drive circuit 46.

  Here, the sensor 43 may be provided in the vicinity of the paper feed tray 10, for example, without being part of the configuration of the light fixing unit 40.

  Further, the control means 49 does not constitute a part of the optical fixing unit 40, but controls each part of the image forming unit 30 and various parts of the image forming apparatus 1 including various transport mechanisms for transporting and transporting the paper 90. It doesn't matter.

  As the light source 41, for example, 60 infrared LED elements having a wavelength of 850 nm and an optical output of 4 W are arranged at the incident end of the light guide 42. Each of these LED elements is connected to a drive circuit 45 that is driven individually or in series. By controlling the amount of power of each LED element and the number of LED elements to be driven via the drive circuit 45, the light source It is possible to adjust the amount of power of light emitted from 41.

  The light guide 42 has a substantially rectangular parallelepiped shape, and guides and irradiates the light of the light source 41 incident from the side surface in the short direction toward the bottom surface where the paper 90 is located. Further, the light guide 42 is arranged so that the longitudinal direction thereof is orthogonal to the paper 90.

  That is, the light guide 42 is configured to irradiate the surface of the paper 90 on which the toner image is formed with an irradiation width that maximizes the length of the long side in the longitudinal direction of the light guide 42. Specifically, for example, a light guide 42 having an irradiation width direction of 220 mm, a paper carry-out direction of 4 mm, and a height direction of 10 mm is used in order to enable 21 cm width fixing with A4 vertical feeding.

  In addition, for the reflecting portion 421, electrochromic glass using an electrochromic material is used. The drive circuit 46 that controls energization of the electrochromic glass can be driven and controlled to an OFF state in which light from the light source 41 is transmitted and an ON state in which light is reflected.

  That is, when the reflecting portion 421 is controlled to be in the OFF state, the light from the light source 41 is guided to the linear light having the irradiation width W1 that is substantially the same as the long side of the longitudinal side surface of the light guide 42. And then irradiate.

  On the other hand, when the reflecting part 421 is controlled to be in the ON state, the light source 41 is converted into the linear light having the irradiation width W2 obtained by subtracting the adjustment width W3 of the range reflected by the reflecting part 421 from the irradiation width W1. The light is guided and irradiated.

  FIG. 4 is a conceptual diagram showing an aspect in which the light from the light source 41 is guided, and showing changes due to the state of the reflecting portion 421. Here, among the lights L1 to Ln of the light source 41, the lights L1 to L4 indicate light to be irradiated from the point where the reflecting portion 421 is located.

  FIG. 4A shows an aspect when the reflecting portion 421 is in the OFF state. At this time, the lights L <b> 1 to L <b> 4 of the light source 41 are transmitted through the reflecting portion 421. That is, all the lights L1 to Ln of the light source 41 are uniformly reflected on the upper layer surface of the light guide 42 and guided to the bottom surface of the light guide 42 from the reflected point. Thus, the light guide 42 uniformly guides and irradiates the light from the light source 41 to the irradiation range A1.

  FIG. 4B shows a state when the reflecting portion 421 is in the ON state. At this time, the light L1 to L4 of the light source 41 is uniformly reflected by the reflecting portion 421, and the reflected light is also uniformly reflected by the upper layer surface of the light guide 42, and from the reflected point of the light guide 42. Guided to the bottom. Therefore, the lights L1 to L4 in the adjustment range A3 are uniformly enlarged and guided to the irradiation range A2.

  On the other hand, the lights L5 to Ln of the light source 41 are also uniformly reflected on the upper layer surface of the light guide 42, guided from the reflected point to the bottom surface of the light guide 42, and irradiated to the irradiation range A2.

  Here, the reflection unit 421 includes a plurality of blocks depending on the type of paper size to be supported. Specifically, when the supported paper sizes are five types of “A3 vertical feed”, “B5 horizontal feed”, “A4 vertical feed”, “B5 vertical feed”, and “postcard vertical feed”, they are controlled to ON state and OFF state. It is composed of four blocks that can be used.

  FIG. 5 shows a processing procedure of the control means 49 and will be described below.

  The control means 49 determines whether or not the maximum paper size supported by the image forming apparatus 1 based on a signal output from the sensor 43 when the paper on which the toner image is formed is conveyed to the optical fixing unit 40. (S001: S represents a step, and so on).

  If it is determined in the above determination that the sheet size is the maximum, the signal for controlling the reflecting section 421 to be turned off is output to the drive circuit 46 (S002).

  Then, a signal for maximizing the driving power of the light source 41 is output to the driving circuit 45 (S003).

  On the other hand, if it is determined in the above determination that the paper size is not the maximum, a signal for controlling the reflecting section 421 to be turned on according to the paper size is output to the drive circuit 46 (S004).

  Then, a signal for setting the driving power of the light source 41 to the amount of power matching the transported paper size is output to the driving circuit 45 (S005).

  Here, the driving power of the light source 41 with respect to the paper size will be described below.

  FIG. 6 shows the relationship between the paper size and the driving power of the light source 41. Here, the driving power is shown as a ratio based on the driving power of the light source 41 at the time of “A3 vertical feed”.

  Through the processing from S001 to S003 described above, all the light from the light source 41 is guided to the irradiation range corresponding to the conveyed paper size. Further, the minimum amount of light per unit area necessary for fixing the toner is constant. For this reason, when the paper size is not the maximum, it is not necessary to maximize the driving power of the light source 41. By driving the light source 41 with the driving power reduced according to the width of the conveyed paper, the toner can be sufficiently supplied. It can be fixed.

  Specifically, as shown in FIG. 6, for example, when “A4 vertical feed” paper is conveyed, the light source 41 is driven with a driving power of about 70% of the driving power of “A3 vertical feeding”. .

  As described above, the image forming apparatus according to the present invention can adjust the width of the linear light so that the light from the light source does not reach the outside of the sheet passing range through which the sheet passes. Factors that adversely affect toner fixing, such as excessive heating of the mechanism member, can be reduced.

  Furthermore, since the driving power of the light source is adjusted according to the paper size, an image forming apparatus with high light use efficiency of the light source can be realized.

  Further, since the light source is not located immediately above the sheet surface on which the toner is fixed, an image forming apparatus in which the heat generated by the light source does not adversely affect the toner fixing can be realized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Paper feed tray 20 Paper discharge tray 30,30Y, 30M, 30C, 30B Image formation unit 40 Light fixing unit 41 Light source 42 Light guide 421 Reflecting part 43 Sensor 45 Drive circuit (for light source)
46 Drive circuit (for reflector)
49 Control means

Claims (5)

An image forming apparatus having fixing means for fixing a toner image on a sheet,
The fixing means is
A light source;
A light guide member that irradiates light from the light source incident from the side surface into linear light orthogonal to the incident direction from the bottom surface;
An image forming apparatus comprising an adjusting unit for adjusting the width of the linear light. Detecting means for detecting the width of the paper;
The image forming apparatus according to claim 1, further comprising a control unit that adjusts a width of the linear light according to a width of the sheet detected by the detection unit. The control means includes
The image forming apparatus according to claim 2, wherein the light amount of the light source is adjusted according to the width of the sheet detected by the detection unit.   The image forming apparatus according to claim 1, wherein the adjustment unit adjusts a width of the linear light by transmitting or reflecting incident light.   The image forming apparatus according to claim 1, wherein the adjusting unit uses an electrochromic material.