JP6972925B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile.

Conventionally, image forming devices such as copiers, printers, and facsimiles using an electrophotographic method have been charged with a photoconductor drum as an image carrier, a charging device for charging the photoconductor drum to a predetermined polarity and potential, and a charging device. An exposure device that forms an electrostatic latent image on a photoconductor drum, a developing device that visualizes the electrostatic latent image as a toner image with toner, a transfer device that transfers the toner image to a recording medium, and a toner image recording. It is equipped with a fixing device for fixing on a medium.

The fixing device used in such an electrophotographic image forming apparatus includes a fixing member and a pressure member, and the pressure member presses against the fixing member to form a nip portion. A belt heating type fixing device is used in which a toner image formed on a recording medium is heated and melted and fixed by sandwiching a recording medium conveyed to the nip portion and heating and pressurizing the toner image.

Japanese Patent Application Laid-Open No. 2015-1561 (Patent Document 1) is a fixing device having a nip forming member that abuts on an endless band-shaped fixing belt heated by a heating member, and pressurizes the nip forming member by pressure contact. Those having a pressing member for pressing the member are disclosed.

Japanese Unexamined Patent Publication No. 2015-1561

However, in the width direction of the recording medium in the fixing device, one end side may be the transport reference end. Here, when a recording medium having a particularly small width is conveyed, a difference occurs in the nip pressure of the pressurizing member between the nip region in which the recording medium is nipped and the non-nip region in which the recording medium is not nip. As a result, a stable nip pressure cannot be obtained within the width of the recording medium, and the recording medium may be loosened or twisted.

FIG. 27 is an explanatory diagram showing a nip state in a conventional fixing device. As shown in the figure, the fixing pad 502 and the pressure pad 505 may nip the recording medium m1 having the recording medium width w1 on one end side (right half in the figure) in the width direction of the recording medium m1. When the recording medium thickness t is thick, a difference occurs in the left and right pressures in the lateral width direction of the recording medium m1 in the nip region where the recording medium m1 is nipped and the non-nip region where the recording medium m1 is not nipped.
The left and right pressures in the paper passing region of the recording medium width w1 are strong pressure Ps at the left end side m1L of the recording medium width w1, and weak pressure Pw at the right end side m1R of the recording medium width w1. As a result, there is a problem that a difference occurs in the transport amount of the recording medium m1 between the left and right sides, and the medium is slackened or twisted.

The present invention has been made by paying attention to such a problem, and enables stable transfer of a recording medium even when a recording medium having a small width is conveyed with one end side as a transfer reference end. It is an object of the present invention to provide a fixing device.

In order to solve the above-mentioned problems, the present invention is a fixing device for fixing an image on the recording medium by heating and pressurizing while transporting the recording medium in a predetermined direction, comprising a first belt, and said first. A fixing member provided so as to face one surface of the recording medium via the belt 1 and a second belt are provided and provided so as to face the other surface of the recording medium via the second belt. is, has a pressing member for pressing the recording medium by pressing the fixing member through said recording medium, further, the pressure member through the first belt and the second belt has a first elastic member made of silicone rubber member pressed against the fixing member Te, furthermore, the first elastic member is formed to be inclined in two left and right direction with respect to the transport direction of the recording medium It is characterized by having a plurality of first groove portions and a plurality of first island portions divided by the plurality of first groove portions.

According to the present invention, since the first elastic member provided on the pressurizing member has the first groove portion formed at an angle with respect to the transport direction of the recording medium, the first elastic member is the first elastic member. A plurality of islands will be divided and formed in the portion surrounded by the groove. As a result, the plurality of divided islands are individually pressed against the fixing member, so that the pressing force becomes uniform. Therefore, in the paper passing region, the pressure difference between the left and right sides disappears, and a uniform nip pressure can be obtained. As a result, in the fixing device, even when a recording medium having a small width is conveyed with one end side as a transfer reference end, it is possible to stably transfer the recording medium.

It is a relationship diagram of the fixing pad, the pressure pad, and the recording medium of the fixing device which concerns on 1st Embodiment. It is a side view which shows the structure of the image forming apparatus which concerns on 1st Embodiment. It is a perspective view which shows the fixing device which concerns on 1st Embodiment. It is a front view which shows the fixing device which concerns on 1st Embodiment. It is a side view which shows the fixing device which concerns on 1st Embodiment. It is explanatory drawing which shows the internal structure of the fixing device which concerns on 1st Embodiment. It is a perspective view which shows the state which the fixing device which concerns on 1st Embodiment is separated into the upper fixed unit, the lower movable unit and the base unit. It is a front view of the base unit of the fixing device which concerns on 1st Embodiment. It is a perspective view (1) which shows the lower movable unit of the fixing device which concerns on 1st Embodiment. It is a perspective view (2) which shows the lower movable unit of the fixing device which concerns on 1st Embodiment. It is a relationship diagram (1) of the fixing pad and the pressure pad which concerns on 1st Embodiment. It is a relationship diagram (2) of a fixing pad and a pressure pad which concerns on 1st Embodiment. It is explanatory drawing which shows the positional relationship of the cam and the cam gear which concerns on 1st Embodiment. It is a perspective view of the fixing pad which concerns on 1st Embodiment. It is a perspective view of the pressure pad which concerns on 1st Embodiment. It is a top view of the pressure pad which concerns on 1st Embodiment. It is a front view which shows the correspondence relationship of the fixing pad and the pressure pad which concerns on 1st Embodiment. It is explanatory drawing which shows the positional relationship of the pressure pad, the pressure pad holding arm, and the pressure pad bearing which concerns on 1st Embodiment. It is explanatory drawing which shows the positional relationship of the pressure pad and the pressure roller holding arm which concerns on 1st Embodiment. It is a control block diagram of the image forming apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows the nip state of the fixing pad and the pressure pad which concerns on 1st Embodiment. It is a perspective view of the pressure pad which concerns on the modification of 1st Embodiment. It is a top view of the pressure pad which concerns on the modification of 1st Embodiment. It is a perspective view of the fixing pad which concerns on 2nd Embodiment. It is a top view of the fixing pad which concerns on 2nd Embodiment. It is a front view which shows the correspondence relationship of the fixing pad and the pressure pad which concerns on 2nd Embodiment. It is a conceptual diagram which shows the correspondence relationship of the fixing pad elastic member and the pressure pad elastic member which concerns on 2nd Embodiment. It is explanatory drawing which shows the nip state in the conventional fixing apparatus.

(First Embodiment)
Hereinafter, the first embodiment will be described with reference to the drawings. FIG. 2 is a side view showing the configuration of the image forming apparatus according to the first embodiment. The image forming apparatus 1 prints an image on the recording medium M. Therefore, the image forming apparatus 1 includes the fixing apparatus 40 and has the following parts and functions.

Inside the image forming apparatus 1, there are transfer rollers 11K, 11Y, 11M and 11C as transfer rollers corresponding to the image forming units 2K, 2Y, 2M and 2C. Further, a medium cassette 12 for accommodating a plurality of recording media M in a stacked state is arranged at the lower part. A paper feed roller 13 for taking out the recording media M one by one from the medium cassette 12 by a separation means (not shown) is provided. By driving the paper feed roller 13, the recording medium M is fed out to the transport path 130.

In the transport path 130, an inlet sensor 14, a writing sensor 15, and transport rollers 16 and 17 are arranged at predetermined positions. A belt driven roller 18 is provided on the upstream side of the transfer rollers 11K, 11Y, 11M and 11C, and a belt drive roller 19 is arranged on the downstream side. Between the belt driven roller 18 and the belt driving roller 19, there is a transport belt 20 which is an endless belt-shaped belt to which a constant tension is applied. The recording medium M is transported on the transport belt 20.
The belt blade 21 is arranged on the contact surface side of the transport belt 20 with the recording medium M at a position that does not interfere with the transport. The belt blade 21 is made of an elastic member such as urethane rubber and cleans the surface of the conveyor belt 20. Below the belt blade 21, a belt waste toner box 22 for collecting scraped dust, specifically paper dust and toner is provided.

A fixing device 40 is arranged on the downstream side of the belt drive roller 19. The fixing device 40 is composed of a fixing unit 41 as a fixing member for heating and a pressure unit 42 as a pressure member for pressurizing. The fixing unit 41 is provided facing one surface of the recording medium M, and the pressurizing unit 42 is provided facing the other surface. The fixing device 40 has a function of heating and pressurizing the developer on the recording medium M to fix the image on the recording medium M while transporting the recording medium M in the medium transport direction indicated by the arrow F. The fixing unit 41 as a fixing member is composed of a fixing roller 28, a fixing belt 43 as a first belt, fixing heaters 50a and 50b, a fixing pad 51 and the like, and the pressure unit 42 as a pressure member is a pressure roller. 29, a pressure belt 44 as a second belt, a pressure heater 55, a pressure pad 52, and the like. The details of the fixing device 40 will be described later.

The image forming units 2K, 2Y, 2M and 2C have LED heads 3K, 3Y, 3M and 3C as K, Y, M and C heads for printing black, yellow, magenta and cyan, respectively. Further, there are photoconductor blades 10K, 10Y, 10M and 10C made of an elastic body such as urethane rubber that abuts on the photoconductor drums 4K, 4Y, 4M and 4C and cleans the surface thereof.
As shown in the figure, the image forming units 2K, 2Y, 2M and 2C include charging rollers 5K, 5Y, 5M and 5C as K, Y, M and C charging rollers. Further, there are developing rollers 6K, 6Y, 6M and 6C and toner tanks 7K, 7Y, 7M and 7C as K, Y, M and C developing rollers. In addition, it has developing blades 8K, 8Y, 8M and 8C and toner supply sponge rollers 9K, 9Y, 9M and 9C.

When the image forming units 2K, 2Y, 2M and 2C and the LED heads 3K, 3Y, 3M and 3C are described in an integrated manner, they are referred to as an image forming unit 2 or an LED head 3. Also, the photoconductor drums 4K to 4C, charging rollers 5K to 5C, developing rollers 6K to 6C, toner tanks 7K to 7C, developing blades 8K to 8C, toner supply sponge rollers 9K to 9C, and photoconductor blades 10K to 10C. The same is true. Since the detailed structure and function of the image forming unit 2 are well-known techniques, the description thereof will be omitted.

The transport path 130 is substantially S-shaped as shown in the figure. The media cassettes 12 arranged at the bottom are separated one by one by the paper feed roller 13 and fed out in the direction of arrow F. The recording medium M fed to the transport path 130 is guided upward in the drawing and further conveyed in the left direction in the drawing. After the image is formed by the image forming unit 2, it passes through the fixing device 40. The recording medium M on which the toner is fixed by the fixing device 40 is subsequently guided to the transport path 130 on the downstream side.
The transport path 130 on the downstream side of the fixing device 40 has a discharge sensor 23 for monitoring the transport jam and detecting the length of the recording medium. The transport path 130 at this site is substantially C-shaped, and there are discharge rollers 24 and 25 at the end. On the downstream side of the discharge rollers 24 and 25, there is a stacker 26 that receives the image-formed recording medium M. The stacker 26 is provided on the exterior cover.

The image forming apparatus 1 described above is provided with motors and solenoids for rotating rollers such as the paper feed roller 13 and the transfer rollers 16 and 17, and sensors for transfer monitoring (see FIG. 19). A transport roller, a position detection sensor, and the like are arranged in the transport path 130 in order to properly transport the recording medium M to be used. The image formation control unit 700 controls these various actuators.

As the motors of the transport system, as shown later in FIG. 19, the feed motor 811 mainly for rotating the paper feed roller 13, the transport rollers 16 and 17, and the transport motor 812 for rotating the discharge rollers 24 and 25 are included. be. Further, there is a conveyor belt motor 801 for rotating the belt drive roller 19. Further, there is a fixing motor 793 for rotating the fixing belt 43 arranged in the fixing unit 41 and rotating the pressure belt 44 arranged in the pressure unit 42. In addition, it has four independent K motors 781, Y motors 782, M motors 783 and C motors 784 for driving the image forming unit 2. The details of these will be described later with reference to the control block diagram shown in FIG.

Next, the fixing device 40 will be described. FIG. 3 is a perspective view showing a fixing device according to the first embodiment. FIG. 3A is a view seen from the upstream side in the medium transport direction indicated by the arrow F, and FIG. 3B is a view seen from the downstream side in the medium transport direction as well. The fixing device 40 is roughly divided into an upper fixed unit 45 having a fixing unit 41 described later, a lower movable unit 46 having a pressurizing unit 42 described later at the lower part thereof, and a cam mechanism 120 described later at the lowermost part. It is composed of a base unit 47.

The upper fixing unit 45 includes an upper chassis 59. Both end faces of the upper chassis 59 in the medium width direction are provided with vertical wall surfaces 59a and 59b facing each other. The rotating shaft 60 of the fixing roller 28 and the rotating shaft 61b of the fixing guide rollers 48a and 48b (see FIG. 6), which will be described later, are rotatably supported on the vertical wall surfaces 59a and 59b. Further, when the fixing roller drive gear 58 fixed to the end of the fixing roller 28 is rotationally driven in the direction of the arrow G, the fixing roller 28 is configured to rotate.
Each component is stacked on the lower movable unit 46 and the base unit 47 with the lower chassis 65 and the base chassis 86 as a structure (chassis), respectively. The recording medium M is conveyed in the direction of arrow F.

FIG. 4 is a front view showing a fixing device according to the first embodiment. This figure is a view of the fixing device 40 viewed from the upstream side in the transport direction of the recording medium M, and the fixing device 40 has an upper chassis 59, a lower chassis 65, and a base chassis 86 as described above. Further, a fixing roller drive gear 58 is provided on the right side surface shown in the drawing.

FIG. 5 is a side view showing a fixing device according to the first embodiment. 5 (a) is a left side view as an arrow view of AA shown in FIG. 4, and FIG. 5 (b) is a right side view as a view of arrow BB shown in FIG. The engagement posts 95a and 95b planted in the upper fixing unit 45 are positioned by the first slits 91a and 91b formed in the lower chassis 65 of the lower movable unit 46.

FIG. 6 is an explanatory diagram showing an internal configuration of the fixing device according to the first embodiment. This figure corresponds to the CC arrow view in FIG. The fixing unit 41 as a fixing member extends in a region exceeding the width of the recording medium M to be passed, that is, extending beyond the width of the recording medium M. The fixing unit 41 has a fixing belt 43 formed in an endless band shape and a fixing roller 28 inscribed on the inner surface side of the endless band-shaped fixing belt 43. Further, the fixing unit 41 has two fixing guide rollers 48a and 48b inscribed in the fixing belt 28 and a fixing pad 51.

Further, a pair of fixing belt guide members 49 that are inscribed in the fixing belt 43 and guide the inner peripheral surface of the fixing belt 43 are provided so as to substantially face each other. When the fixing roller 28 rotates in the direction of arrow H, the fixing belt 43 can be rotated in the direction of arrow H by the fixing guide rollers 48a and 48b and the fixing belt guide member 49.
In the inner space of the endless band-shaped fixing belt 43, two fixing heaters 50a and 50b are provided as a first heating member for heating the fixing belt 43. In the present embodiment, there are two fixing heaters 50a and 50b, but in the case of integrated explanation, the fixing heater 50 will be described.

In the fixing unit 41 as a fixing member, the fixing pad 51 according to the present embodiment is arranged below the fixing heater 50 as the first heating member. The fixing pad 51 is composed of a fixing pad base member 101, a fixing pad elastic member 102 as a second elastic member, and a sheet material 103, and a detailed description thereof will be described later. In the separated space between the fixing heater 50 and the fixing pad 51, a fixing reflector 62 that reflects the heat generated by the fixing heater 50 in a predetermined direction on the inner peripheral surface of the fixing belt 43 is provided.
The fixing pad 51 is obtained by fixing a fixing pad elastic member 102 made of silicone rubber or the like to a fixing pad base member 101 made of a highly rigid material such as aluminum or synthetic resin by adhesion or the like. Further, the surface is covered with a sheet material 103 having slidability.

The pressurizing unit 42 as a pressurizing member extends in the lateral width direction of the recording medium M in a region exceeding the lateral width of the recording medium M to be passed. The pressure unit 42 has a pressure belt 44 formed in an endless band shape and a pressure roller 29 inscribed on the inner surface side of the pressure belt 44. The pressure roller 29 is driven by pressure contact with the fixing roller 28 and can rotate in the arrow K direction.
The pressurizing unit 42 is provided with a pressurizing roller 29 and a pressurizing guide rollers 53a and 53b that are rotationally driven. Further, a pair of pressure belt guide members 54 for guiding the inner peripheral surface of the pressure belt 44 are provided so as to substantially face each other. When the pressure roller 29 rotates in the direction of arrow K, the pressure belt 44 can be rotated in the direction of arrow K by the pressure guide rollers 53a and 53b and the pressure belt guide member 54.

In the pressurizing unit 42 as a pressurizing member, in the inner space of the endless band-shaped pressurizing belt 44, there is a pressurizing heater 55 as a second heating member for heating the pressurizing belt 44. A pressure pad 52 according to the present embodiment is arranged above the pressure heater 55. The pressure pad 52 is composed of a pressure pad base member 204, a pressure pad elastic member 205 as a first elastic member, and a sheet material 206, which will be described in detail later. A pressure reflector 57 that reflects the heat generated by the pressure heater 55 in a predetermined direction on the inner peripheral surface of the pressure belt 44 is provided in the space between the pressure heater 55 and the pressure pad 52 as the second heating member. ing.

The pressure pad 52 is formed by adhering a pressure pad elastic member 205 made of silicone rubber or the like to a pressure pad base member 204 made of a highly rigid material such as aluminum or synthetic resin by adhesion or the like. Further, the surface is covered with a sheet material 206 having slidability.
The pressurizing unit 42 as a pressurizing member can be moved in the vertical direction so as to be in contact with and detachable from the fixing unit 41 as a fixing member by means described later. When the fixing roller 28 and the pressure roller 29 are in the nip position forming the nip portion, the pressure pad 52 is pressed against the fixing pad 51 via the fixing belt 43 and the pressure belt 44.

The fixing roller 28 and the pressure roller 29, and the fixing pad 51 and the pressure pad 52 continuously and simultaneously sandwich the fixing belt 43 and the pressure belt 44 to form a linear transport path. In this state, the fixing roller drive gear 58 fixed to the end of the fixing roller 28 is rotated in the arrow G direction (see FIG. 3) by obtaining the driving force from the fixing motor 793 (see FIG. 19). As a result, the fixing belt 43 is rotationally driven in the arrow H direction and the pressure belt 44 is rotationally driven in the arrow K direction together with the pressurizing roller 29 that is driven by the rotation of the fixing roller 28. A cam mechanism 120, which will be described later, is provided below the pressurizing unit 42, and details will be described later.

Next, the detailed configuration of the fixing device 40 will be described. FIG. 7A is a perspective view showing a state in which the fixing device according to the first embodiment is separated into an upper fixed unit, a lower movable unit, and a base unit. 7A (a) shows the upper fixed unit 45, FIG. 7A (b) shows the lower movable unit 46, and FIG. 7A (c) shows the base unit 47. FIG. 7B is a front view of the base unit of the fixing device according to the first embodiment. FIG. 8 is a perspective view (1) showing a lower movable unit of the fixing device according to the first embodiment. 8 (a) shows a state in which the pressure belt 44 of the lower movable unit 46 shown in FIG. 7A (b) is not shown, and FIG. 8 (b) shows the addition of the lower movable unit 46 shown in FIG. 8 (a). A state in which the pressure guide roller 53, the pressure roller spring 74, and the pressure pad spring 78 are not shown is shown.

As shown in FIG. 7A (a), the upper fixing unit 45 holds the fixing belt 43 in the internal space formed by the upper chassis 59 and the elevation walls 59a and 59b. Further, it has rotating shafts 61a and 61b for rotating the fixing guide rollers 48a and 48b (see FIG. 6). As described above, the fixing roller 28 (see FIG. 6) is rotated by the fixing roller drive gear 58 fixed to the rotating shaft 60.

The fixing pad 51 (see FIG. 6) extends in substantially the same region as the fixing belt 43 and in the lateral width direction of the recording medium M of the entire fixing unit 41. The fixing pad ends 63a and 63b (see FIG. 10), which are both ends of the recording medium M of the fixing pad 51 in the horizontal direction, are fitted into holding holes provided in the fixing pad holding sheet metal 64b (on the left side in the medium horizontal direction). The fixing pad holding sheet metal fitted to the fixing pad end 63a is not shown), and the fixing pad 51 is supported on the upper fixing unit 45 in a horizontal state. The fixing pad holding sheet metal 64 is fixed to the elevation walls 59a and 59b of the upper chassis 59, respectively.
As described above, the engaging posts 95a and 95b (see FIG. 5) planted on the elevation walls 59a and 59b correspond to the first slits 91a and 91b of the lower movable unit 46. Further, a part (leg portion) of the elevation walls 59a and 59b extends downward and is fixed to the base chassis 86.

Next, in FIG. 7A (b), the lower movable unit 46 provided with the pressurizing unit 42 shown in FIG. 6 includes a lower chassis 65. Both sides of the lower chassis 65 in the medium width direction form upwardly bent vertical walls 65a and 65b. Rotating shafts 66a and 66b (see FIG. 8A) of the pressure guide rollers 53a and 53b shown in FIG. 6 are rotatably supported on the vertical walls 65a and 65b.
A rotating shaft 72b is planted on the vertical wall surface 65b on the right side in the lateral width direction of the medium, and a pressure roller holding arm 68b rotatably supported is provided. On the other hand, a rotating shaft (not shown) is similarly planted on the vertical wall surface 65a on the left side in the lateral width direction of the medium, and a pressure roller holding arm 68a rotatably supported is provided.

The pair of pressure roller holding arms 68a and 68b rotate around rotation shafts 72a and 72b provided at one end (see FIG. 17 for 72a), and stopper portions 73a and 73b are provided at the other ends. .. The pressure roller holding arms 68a and 68b are provided with pressure roller rotary bearing portions 76a and 76b (see FIG. 18) between the rotation shaft 72 and the stopper portions 73a and 73b to provide the pressure roller 29. Holds freely.
The rotating shaft 72 further rotatably supports a pair of pressure pad holding arms 70a and 70b. Therefore, the rotating shaft 72 holds both ends of the pressure pad 52 in the medium width direction via the pressure pad holding arms 70a and 70b.

The pressure roller holding arms 68a and 68b and the pressure pad holding arms 70a and 70b are fitted to the rotating shafts 72 planted on the vertical wall surfaces 65a and 65b of the lower chassis 65, respectively, and are rotatably held. .. Further, the pressure roller holding arms 68a and 68b are provided with stopper portions 73a and 73b for regulating their own rotation amount as described above.
On the other hand, side brackets 67a and 67b having spring locking portions facing substantially parallel to the stopper portions 73a and 73b are also arranged on the lower chassis 65 side. A pressure roller spring 74 as an urging member is installed between the side brackets 67a, 67b and the stopper portions 73a or 73b. The pressure roller spring 74 is a compression type coil spring, and the stopper portion 73a or 73b is locked on the upper end side thereof, and the side brackets 67a and 67b are locked on the lower end side.

The lower chassis locking portions 75a and 75b are bent outward from each of the vertical wall surfaces 65a and 65b of the lower chassis 65 and are provided so as to project. The amount of rotation of the pressure roller holding arms 68a and 68b is regulated by the stopper portions 73a and 73b coming into contact with the lower chassis locking portions 75a and 75b. Therefore, the pressure roller holding arms 68a and 68b are always urged upward in the drawing.

The pressure pad holding arms 70a and 70b are provided with pressure pad spring fixing portions 77a and 77b (see FIGS. 8b and 9) at positions away from the rotation shaft 72 as a rotation fulcrum in the pressure pad 52. There is. The pressure pad spring fixing portions 77a and 77b are provided with a pressure pad spring 78 as a urging member for urging the pressure pad holding arms 70a and 70b upward. The pressure pad spring 78 is also a compression type coil spring, and is provided between the side brackets 67a and 67b. As a result, the pressure pad holding arms 70a and 70b are constantly urged upward in the drawing around the rotation shaft 72.

The pressure pad holding arms 70a and 70b are between the rotation shaft 72 and the pressure pad spring fixing portions 77a and 77b, and the pressure pad rotation shafts 79a and 79b as rotation fulcrums in the pressure pad 52 (see FIG. 17 for 79a). Is arranged. As a result, the pressure pad holding arms 70a and 70b rotatably hold the pressure pad 52 via the pressure pad bearings 80a and 80b (see FIG. 17 for 80a). Below the vertical walls 65a and 65b, second slits 92a and 92b and third slits 93a and 93b, which are substantially U-shaped sliding grooves, are formed from the lower end. These will be described later with reference to FIGS. 8 and 9.

Next, as shown in FIGS. 7A (c) and 7B, the base unit 47 has a cam mechanism 120 on the base chassis 86 as described above. In the base chassis 86, the first cam shaft 87 is arranged on the upstream side in the transport direction of the recording medium M, and the second cam shaft 89 is arranged on the downstream side as well. The base chassis 86 is provided with a pair of first cam support portions 88a and 88b for rotatably holding the first cam shaft 87 at both ends of the recording medium M in the lateral width direction. Further, a pair of second cam support portions 90a and 90b for rotatably holding the first cam shaft 87 and the second cam shaft 89 arranged adjacent to each other in parallel are formed.

The first cam 121 and the cam gear 122 are coaxially fixed to one end of the recording medium M of the first camshaft 87 as the left side in the lateral width direction on the upstream side in the transport direction. A first cam 123 (see FIG. 12B) and a cam gear 124 are coaxially fixed to the other end of the first cam shaft 87 as the right side in the medium width direction on the upstream side in the transport direction.
A second cam 125 and a cam gear 126 are coaxially fixed to one end of the second cam shaft 89 as the left side in the medium width direction on the downstream side in the transport direction. A second cam 127 (see FIG. 12B) and a cam gear 128 are coaxially fixed to the other end of the second cam shaft 89 as the right side in the medium width direction on the downstream side in the transport direction.

The cam gear 122 and the cam gear 126 are arranged so as to mesh with each other, and the cam gear 124 and the cam gear 128 are also arranged so as to mesh with each other. Further, the first cam 121 and the second cam 125 are in a line-symmetrical positional relationship with each other, and the first cam 123 and the second cam 127 are also in a line-symmetrical positional relationship with each other (see FIG. 12). Details will be described later in FIG. Although the cam 121 and the cam gear 122, the cam 123 and the cam gear 124, the cam 125 and the cam gear 126, and the cam 127 and the cam gear 128 are coaxially fixed, they can be integrally molded.

If the pressure belt 44 shown in FIG. 7A (b) is omitted as shown in FIG. 8 (a), the arrangement of the pressure rollers 29, the pressure guide rollers 53a and 53b, and the pressure pad 52 becomes clear. Will be. That is, the pressure pad 52 is positioned between the pressure roller 29 arranged on the downstream side in the medium transport direction and the pressure guide roller 53a arranged on the upstream side. The pressure roller 29 is rotatably supported by the rotary shaft 69, and the pressure guide rollers 53a, 53b are rotatably supported by the rotary shafts 66a, 66b on the vertical wall surfaces 65a, 65b.

In FIG. 8B, the description of the pressure roller 29 and the pressure guide rollers 53a and 53b is omitted as compared with FIG. 8A, and further, a pair of pressure roller springs 74 in the lateral width direction of the recording medium M. And the pressure pad spring 78 are omitted. As shown in the figure, the pressure pad spring fixing portion 77b provided on the pressure pad holding arm 70b has a protruding shape and engages with the coil inner wall portion of the pressure pad spring 78.

As shown in FIG. 8B, below the vertical wall surfaces 65a and 65b, second slits 92a and 92b are provided on the upstream side in the medium transport direction, and third slits 93a and 93b are provided on the downstream side. A first contact protrusion plate 97a, 97b and a second contact protrusion plate 98a, 98b are formed above the substantially width center line of the second slits 92a, 92b and the third slits 93a, 93b. .. The first contact protrusion plates 97a and 97b and the second contact protrusion plates 98a and 98b come into contact with the first cams 121 and 123 and the second cams 125 and 127 described above (FIG. 12). reference).

FIG. 9 is a perspective view (2) showing a lower movable unit of the fixing device according to the first embodiment. Note that FIG. 9 corresponds to FIG. 8 (b) described above, and FIG. 8 (b) is a view seen from the upstream side in the medium transport direction, while FIG. 9 is a view seen from the downstream side in the medium transport direction. Is. The description of each part has already been described in FIGS. 7A, 7B and 8, and will be omitted.
The cross section of the pressure pad 52 is substantially square as shown in FIG. 6, but the lower half of the surface on the downstream side in the medium transport direction is a vertical surface, and the upper half is continuously downstream from the vertical surface. It becomes a slope that slopes like an overhang like an eaves. The sheet material 206 is fixed using the vertical surface on the downstream side. Details will be described with reference to FIGS. 10 and 11.

Here, returning to FIGS. 7A, 7B and 8, the attachment relationship between the upper fixed unit 45, the lower movable unit 46 and the base unit 47 of the fixing device 40 will be described together with FIG. 9. When the lower movable unit 46 is mounted on the base unit 47, the second slits 92a and 92b formed on the vertical walls 65a and 65b of the lower chassis 65 are fitted to the first camshaft 87 of the base unit 47. Similarly, the third slits 93a and 93b are fitted to the second camshaft 89 of the base unit 47.

The first cams 121 and 123 of the first cam shaft 87 are brought into contact with the first contact protrusion plates 97a and 97b formed on the upper portions of the second slits 92a and 92b. The second cams 125 and 127 of the second cam shaft 89 are brought into contact with the second contact protrusion plates 98a and 98b formed on the upper portions of the third slits 93a and 93b.
In this way, with the lower movable unit 46 mounted on the base unit 47, the upper fixing unit 45 and the base unit 47 are fixed by screws or the like (not shown). At this time, the engaging posts 95a and 95b arranged in the upper chassis 59 of the upper fixing unit 45 are fitted into the first slits 91a and 91b formed in the lower chassis 65 of the lower movable unit 46.

With the above configuration, the lower movable unit 46 is engaged with the first cam shaft 87 and the second cam shaft 89 of the base unit 47, and the second slits 92a and 92b and the third slits 93a and 93b, respectively. Further, it is guided by the engagement of the engagement posts 95a and 95b of the upper fixing unit 45 and the first slits 91a and 91b of the lower movable unit 46, and is held in a state where it can move in the vertical direction. The lower movable unit 46 moves in the vertical direction with the rotation of the four cams 121, 123, 125, 127.

FIG. 10 is a relationship diagram (1) of a fixing pad and a pressure pad in the fixing device according to the first embodiment. FIG. 11 is a relationship diagram (2) of the fixing pad and the pressure pad in the fixing device also according to the first embodiment. FIG. 10 is a perspective view seen from the upstream side in the medium transport direction, and FIG. 11 is a perspective view seen from the downstream side in the medium transport direction. In both figures, the fixing pad 51 is covered with the sheet material 103, and the fixing pad ends 63a and 63b at both ends in the medium width direction are fitted to the fixing pad holding sheet metal 64 (see FIG. 7A (a) for 64b). The width Z of the fixing pad 51 as the length in the medium transport direction is substantially the same as the width Y of the pressure pad.

The pressure pad 52 is also covered with the sheet material 206, and the pressure pad ends 81a and 81b of the pressure pad receiving portions 84a and 84b are the pressure pad bearings 80a and 80b of the pressure pad holding arms 70a and 70b described above. (See FIG. 7A (b)).
The fixing pad 51 is fixed to the upper fixing unit 45, while the pressure pad 52 is fixed to the lower movable unit 46. The lower movable unit 46 can be raised and lowered by the cam mechanism 120.

As shown in FIG. 11, the sheet material 103 that covers the surface of the fixing pad base member 101 is fixed with fixing screws 111 so that distortion does not occur during mounting. At this time, the fixing pad base member 101 is provided with a circular protrusion 112 for positioning in the longitudinal direction (media lateral width direction) and a plurality of rectangular protrusions 113 for positioning in the lateral direction (medium transport direction).
On the other hand, it goes without saying that the sheet material 103 is provided with mounting holes (not shown) corresponding to the fixing screws 111, the circular protrusions 112, and the rectangular protrusions 113. Further, in order to fix the sheet material 103 to the fixing pad base member 101, a sheet metal 114 for sandwiching and fixing the sheet material 103 is provided. Even if the pressure pad 52 side is attached, the sheet material 206 is fixed in the same manner as the fixing pad 51.

As described above, the cross section of the pressure pad 52 is substantially square, but the lower half of the surface on the downstream side in the medium transport direction is a vertical surface, and the upper half is like an eaves continuing from the vertical surface toward the downstream. It becomes a slope that slopes like an overhang. The upper surface of the square becomes the pressure pad pressure contact surface 210 as the first pressure contact surface of the pressure pad 52.
On the other hand, the cross section of the fixing pad 51 is also substantially square, but is vertically symmetrical with the cross section of the pressure pad 52. That is, the lower half of the surface on the downstream side in the medium transport direction is a vertical surface, and the lower half is a slope that inclines so as to continue downward from the vertical surface. Then, the lower surface of the square becomes the fixing pad pressure contact surface 110 as the second pressure contact surface of the fixing pad 51, and is in pressure contact with the pressure pad pressure contact surface 210 of the pressure pad 52 as described later (see FIG. 1). ).

FIG. 12 is an explanatory diagram showing the positional relationship between the cam and the cam gear according to the first embodiment. 12 (a) is a view taken along the line DD in FIG. 7B as the left end portion in the width direction of the medium, and FIG. 12 (b) is an arrow view taken along the line EE in FIG. 7B as the right end portion in the width direction of the medium. It is a figure.
As described above, the first cam 121 and the cam gear 122 are coaxially fixed to the left end portion of the first cam shaft 87 (see FIG. 7A (c)) on the upstream side in the medium transport direction in the medium width direction. The first cam 123 and the cam gear 124 are coaxially fixed to the right end portion in the lateral width direction of the medium. A second cam 125 and a cam gear 126 are coaxially fixed to the left end portion of the second cam shaft 89 (see FIG. 7A (c)) on the downstream side in the transport direction in the medium width direction, and the medium width is A second cam 127 and a cam gear 128 are coaxially fixed to the right end in the direction.

As shown in FIG. 12A, the cam 121 and the cam 125 are arranged in a shape that is axisymmetric with respect to the center line S described between the first cam shaft 87 and the second cam shaft 89. Further, as shown in FIG. 12B, the cam 123 and the cam 127 are arranged in a shape that is axisymmetric with respect to the center line S described between the first cam shaft 87 and the second cam shaft 89. be. The cam 121 is fixed to the first camshaft 87 or the second camshaft 89 at the same shape and angle as the cam 127, and the cam 125 has the same shape and angle as the cam 123 and the first camshaft 87 or the second cam. It is fixed to the shaft 89. The cam 121 and the cam 125 form two different types of cam surfaces with respect to the center of the first cam shaft 87 and the center of the second cam shaft 89, respectively.

That is, the cam surfaces 121a, 123a, 125a and 127a have a concentric arc shape with respect to the first camshaft 87 and the second camshaft 89 only in the angle range indicated by the broken line, and the first camshaft 87 and the second camshaft 87 and the second camshaft 89. An equal arc portion having a radius of the distance R farthest from the center of the cam shaft 89 is formed. The cam surfaces 121b, 123b, 125b and 127b have an arc shape concentrically with respect to the first cam shaft 87 and the second cam shaft 89, and a constant amount from the center of the first cam shaft 87 and the second cam shaft 89. The equi-arc portion is formed with the distance Q as the radius. The distance Q, which is the minimum diameter, is set to be approximately 6 mm smaller than the distance R, which is the maximum diameter.

A drive gear (not shown) meshes with the cam gear 124, and the cam gear 122 is rotated by a coaxial first cam shaft 87. Since the cam gear 126 meshes with the cam gear 122, the cam gear 128 rotates via the second cam shaft 89. Since the cam gear 128 meshes with the cam gear 124, a driving force acts from both of the second cam shaft 89.
The first contact protrusion plates 97a, 97b and the second contact protrusion plates 98a, 98b provided on the vertical wall surfaces 65a, 65b are in contact with the cam surfaces 121a, 123a, 125a, and 127a, respectively (as described above). See FIG. 8 (b)). In the standby state, the contact is made at the position of the distance Q, which is the minimum diameter, and the stop position is rotationally driven and controlled by the detection information of the cam position sensor (not shown).

FIG. 13 is a perspective view of the fixing pad according to the first embodiment. FIG. 13 is a view seen from slightly below upstream in the medium transport direction. As described above, the fixing pad 51 has the fixing pad elastic member 102 as a second elastic member fixed to the fixing pad base member 101 by adhesion or the like. The fixing pad elastic member 102 has a fixing pad pressure contact surface 110 as a second pressure contact surface. The fixing pad ends 63a and 63b at both ends in the width direction of the medium are portions held by the fixing pad holding sheet metal 64 (see FIG. 7A (a) for 64b). The recording medium M is conveyed from the direction of the arrow F in the figure, and the pressure pad pressure contact surface 210 of the pressure pad 52 described below is pressed against the fixing pad pressure contact surface 110 of the fixing pad 51 from the direction of the arrow P as the downward direction. Will be done.

FIG. 14 is a perspective view of the pressure pad according to the first embodiment. Further, FIG. 15 is a plan view of the pressure pad according to the first embodiment. As described above, the pressure pad 52 has the pressure pad elastic member 205 fixed to the pressure pad base member 204 by adhesion or the like. The pressure pad 52 is provided on the lower movable unit 46, and is pressure-welded to the recording medium M by pressure-contacting with the fixing pad 51 provided on the upper fixing unit 45.

The pressure pad elastic member 205 as the first elastic member constituting the pressure pad 52 according to the first embodiment is the pressure pad pressure contact surface 210 as the first pressure contact surface to be in pressure contact with the fixing pad 51. In, a plurality of groove portions 207 as the first groove portions are formed. The groove portion 207 is composed of a plurality of linear grooves formed at angles in two directions, left and right, with respect to the transport direction (arrow F direction) of the recording medium M. That is, it is composed of a plurality of linear groove portions 207-1 formed at predetermined intervals in the diagonally right direction and a plurality of linear groove portions 207-2 formed at predetermined intervals in the diagonal direction to the left. The angle θ of the groove portion 207 with respect to the transport direction is in the range of ± 10 degrees to ± 80 degrees. At = 45 degrees, both are crossed at a right angle to form a mesh.

The groove width 207w of the groove portion 207 is in the range of 0.5 mm to 1.5 mm, and is set to 1.0 mm or less in the first embodiment. Further, the island portion width 208w in the lateral width direction of the recording medium M of the island portion 208 as the first island portion surrounded by the groove portion 207 is set to 4 mm to 10 mm. The recording medium M that can be used in the fixing device 40 according to the present embodiment is assumed to have a paper width of three or more consecutive island widths 208w in the medium width direction.
The depth of the groove portion 207 is appropriately determined by the inclination angle θ, the groove portion width 207w, the thickness of the pressure pad elastic member 205, the rubber hardness, the pressure contact force with the fixing pad 51, and the like. It is necessary to prevent the island portion 208 from being deformed by at least the pressure contact force and the groove portion 207 from disappearing. As described above, the pressure pad 52 is supported by the pressure pad end portions 81a, 81b provided on the pressure pad receiving portions 84a, 84b.

FIG. 16 is a front view showing the correspondence between the fixing pad and the pressure pad according to the first embodiment. As described above, the fixing pad 51 is obtained by fixing the fixing pad elastic member 102 as a second elastic member to the fixing pad base member 101 by adhesion or the like. Further, as described above, in the pressure pad 52, the pressure pad elastic member 205 is fixed to the pressure pad base member 204 by adhesion or the like.

A plurality of island portions 208 are formed on the pressure pad pressure contact surface 210 as the first pressure contact surface of the pressure pad elastic member 205 by providing a plurality of groove portions 207 at predetermined intervals. The recording medium M is sandwiched between the pressure pad pressure contact surface 210 of the pressure pad 52 having the groove portion 207 and the fixing pad pressure contact surface 110 as the second pressure contact surface of the fixing pad 51 having a surface corresponding to the pressure contact surface 210. Become. The holding relationship between the fixing pad 51 and the pressure pad 52 is as described above (for example, FIG. 10).

FIG. 17 is an explanatory diagram showing the positional relationship between the pressure pad, the pressure pad holding arm, and the pressure pad bearing according to the first embodiment, and FIG. 18 shows the pressure pad and the pressure pad according to the first embodiment. It is explanatory drawing which shows the positional relationship of a pressure roller holding arm.
The pressure pad 52 extends in the lateral width direction of the recording medium M of the pressure unit 42 (see FIG. 6) in substantially the same region as the pressure belt 44. The pressure pad ends 81a and 81b, which are both ends in the width direction of the medium, are fitted to the pressure pad bearings 80a and 80b of the pressure pad holding arms 70a and 70b as shown in FIG. 7A (b). .. Further, the pressure pad 52 is rotatably held by the pressure pad holding arms 70a and 70b via the pressure pad rotation shafts 79a and 79b (see FIG. 17 for 79a). The pressure pad holding arms 70a and 70b themselves are rotatably supported by a rotating shaft 72 planted on the vertical wall surface 65a and 65b (see FIG. 7A (b)).

Regarding the positional relationship between the width Y as the length of the pressure pad 52 in the medium transport direction and the pressure pad bearings 80a and 80b, the midpoint of the width Y substantially coincides with the center of the pressure pad bearings 80a and 80b (Y, Z). / 2) It is arranged so as to do.
Further, as shown in FIG. 18, the pressure pad receiving portions 84a and 84b on the left and right sides of the pressure pad 52 in the medium width direction are loosened in the insertion holes 83a and 83b formed in the pressure roller holding arms 68a and 68b. It is inserted and simultaneously held by the pressure pad holding arms 70a and 70b. As described above, the lower chassis locking portions 75a and 75b regulate the amount of rotation when the stopper portions 73a and 73b at the tips of the pressure roller holding arms 68a and 68b come into contact with each other.

When the recording medium M is at the nip position of the nip portion formed by the fixing roller 28 and the pressurizing roller 29, the pressurizing pad receiving portions 84a and 84b and the insertion holes 83a and 83b of the pressurizing pad 52 form a predetermined gap. do. In this state, the pressure pad 52 is pressed against the fixing pad 51 via the pressure belt 44 and the fixing belt 43. In this state, the positional relationship between the width Y of the pressure pad 52 and the width Z of the fixing pad 51 is such that the centers of the width Y and the width Z are substantially the same, and the nip width is formed by the width Y and the width Z. ..

FIG. 1 is a relationship diagram of a fixing pad, a pressure pad, and a recording medium of a fixing device according to the first embodiment. As shown in the figure, a fixing pad pressure contact surface 110 as a second pressure contact surface is provided below the fixing pad 51, and a pressure pad pressure contact surface 210 as a first pressure contact surface is provided above the pressure pad 52. .. The storage medium M is conveyed between the fixing pad 51 and the pressure pad 52 in the direction of arrow F as the medium conveying direction. The pressure pad 52 is configured by fixing the pressure pad elastic member 205 as the first elastic member to the pressure pad base member 204.

The pressure pad pressure contact surface 210 of the pressure pad elastic member 205 is provided with a groove portion 207 as a first groove portion formed linearly at a predetermined angle with respect to the medium transport direction. A plurality of the groove portions 207 are provided in a mesh pattern by crossing a plurality of the groove portions 207, and a plurality of island portions 208 as the first island portion surrounded by the groove portions 207 are divided and provided. When the front surface side of the recording medium M is the printed surface Mx and the back surface side is the non-printed surface My, the divided island portions 208 are transferred to the back surface side of the recording medium M, that is, the toner image of the recording medium M. It abuts on the non-printing surface side My (direction of arrow P) as the non-printed surface. Therefore, the pressure pad pressure contact surface 210 is pressed from the non-printing surface side My of the recording medium M toward the fixing pad pressure contact surface 110 as the second pressure contact surface of the fixing pad 51.

FIG. 19 is a control block diagram of the image forming apparatus according to the first embodiment. The image forming apparatus 1 is composed of each part described below, and its operation is controlled according to a control program (not shown).
The image formation control unit 700 is composed of a microprocessor, a ROM, a RAM, an input / output port, and the like. Specifically, it receives print data and control commands from a higher-level device (not shown), controls the sequence of each part as a whole, and performs an image forming operation. Inside the image formation control unit 700, there is a print medium setting unit 700a that sets the recording medium M as various media (various characteristics, etc.).

The I / F control unit 710 is a part that communicates with the host device, transmits the status information of the image forming device 1 to the host device, analyzes the control command input from the host device, and receives it from the host device. Process print data, etc. The reception memory 720 is a memory that stores the data received from the host device for each color based on the control of the I / F control unit 710.
The image data editing memory 730 edits the input data input from the host device via the I / F control unit 710 as image data. The image data editing memory 730 stores the image data edited for receiving the print data temporarily stored in the receiving memory 720 and transmitting the print data to the LED head.

The operation unit 701 is a portion provided with an LED for displaying the state of the image forming apparatus 1 and switches for operating and inputting the operation of the image forming apparatus 1. The various sensors 702 are sensors for detecting the transport position of the recording medium M, specifically, the above-mentioned inlet sensor 14, write sensor 15, and discharge sensor 23, and in addition, detect the temperature inside the image forming apparatus 1. It is composed of a temperature sensor 30 for measuring the temperature and a concentration sensor 31 for measuring the concentration. The outputs from these various sensors 702 are input to the image formation control unit 700.

The charging voltage control unit 740 applies a voltage to the charging roller 5 according to the instruction of the image forming control unit 700 to charge the surface of the photoconductor drum 4. The head control unit 750 controls to irradiate and expose the surface of the photoconductor drum 4 charged by the LED head 3 for printing according to the image data stored in the image data editing memory 730. ..
The developing voltage control unit 760 controls to apply a voltage to the developing roller 6 in order to attach toner to the electrostatic latent image generated by the LED head 3 on the surface of the photoconductor drum 4. The transfer voltage control unit 770 controls the voltage applied to the transfer roller 11 in response to instructions from the image formation control unit 700 in order to transfer the toner image generated on the surface of the photoconductor drum 4 to the recording medium M.

The image formation drive control unit 780 is for rotationally driving the photoconductor drum 4, charging roller 5, and developing roller 6, and is directed by the image forming control unit 700 to drive the K motor 781, the Y motor 782, and the M motor 738. The rotation of the C motor 784 is controlled.
A K motor 781, a Y motor 782, an M motor 783, and a C motor 784 were used for each of the image forming units 2K, 2Y, 2M, and 2C. However, it may be configured to be driven by a single motor.

The fixing control unit 790 is for fixing the toner image transferred to the recording medium M, and the fixing heaters 50a, 50b and the fixing heaters 50a and 50b as the first heating member in the fixing device 40 are instructed by the image forming control unit 700. Control is performed to apply a voltage to the pressurizing heater 55 as the second heating member. In this control block diagram, the fixing heaters 50a and 50b and the pressurizing heater 55 are described as a heater 791 as a heating member including both.

Further, the temperature detected from the thermistor 792 for measuring the temperature in the fixing device 40 is received, and the voltage application to the heater 791 as a heating member is controlled to be turned on / off. In addition, the fixing control unit 790 controls the rotation of the fixing motor 793 for rotationally driving the fixing roller 28 and the cam motor 794 for controlling the rotation of the cam mechanism 120.
The transport belt drive control unit 800 drives and controls the transport belt 20 for transporting the recording medium M, and controls the rotation of the transport belt motor 801 according to the instructions of the image formation control unit 700. The paper feed / transfer drive control unit 810 feeds and conveys the recording medium M to the position corresponding to the transfer roller 11, and therefore controls the rotation of the paper feed motor 811 and the transfer motor 812 according to the instructions of the image formation control unit 700. ..

(Operation explanation)
Next, the operation of the image forming apparatus 1 will be described. The image formation control unit 700 of the image formation device 1 receives control commands and print data transmitted from the host device via the I / F control unit 710. Upon receiving a print instruction from the host device, the image formation control unit 700 instructs the paper feed / transfer drive control unit 810 to perform a predetermined transfer operation, and rotates the paper feed roller 13.

The paper feed roller 13 sends only one recording medium M from the medium cassette 12 to the transport path 130. When the paper is transported to the transport rollers 16 and 17 arranged in the transport path 130 and detected by the inlet sensor 14, the image forming control unit 700 determines that the paper feed roller 13 has normally fed. If the inlet sensor 14 does not detect within a predetermined time, the image formation control unit 700 determines that the paper feeding could not be performed normally, and performs the paper feeding operation again.

The recording medium M conveyed to the transfer rollers 16 and 17 is conveyed to the image forming unit 2. The image forming unit 2 starts rotating the rollers almost at the same time as the start of feeding. At this time, a negative voltage (about −1000 V) instructed by the image formation control unit 700 to the charge voltage control unit 740 is applied to the charging roller 5 to charge the surface of the photoconductor drum 4.
Toner used for printing is supplied from the toner tank 7 to the developing roller 6 via the toner supply sponge roller 9. The toner on the developing roller 6 is triboelectrically charged by the developing blade 8. Further, when the belt drive roller 19 is rotated with the start of rotation of the photoconductor drum 4, the transport belt 20 also starts to move at the same speed.

On the other hand, the recording medium M continues to be conveyed by the conveying rollers 16 and 17, and when it passes through the writing sensor 15 (ON detection), the tip of the recording medium M is detected. After a certain period of time from the detection of the tip of the recording medium M here, the LED head 3 starts exposure, and an electrostatic image is formed on the photoconductor drum 4.
When the recording medium M reaches the toner image between the transfer roller 11 and the transfer roller 11, a positive voltage (about +3000 V) is applied to the transfer roller 11 to draw the toner toward the recording medium M and transfer the toner image to the recording medium M. Transcription is performed. These operations perform exposure and transfer of each color based on the analysis result of the print data.

When the transfer to the recording medium M is completed, the recording medium M is heated and pressurized between the fixing unit 41 as the fixing member and the pressure unit 42 as the pressure member, and the toner is fixed to the recording medium M. After fixing, the tip of the recording medium M is discharged to the stacker 26 by the discharge rollers 24 and 25 after the discharge sensor 23 for jam monitoring and fixing of the recording medium length after fixing detects (ON) the passage. ..

The operation of the fixing device 40 will be described. In the fixing device 40, the fixing roller 28 and the pressure roller 29 are usually separated from each other when there is no printing instruction from the host device. Further, the fixing pad 51 and the pressure pad 52 (see FIG. 6 and the like) are also on standby in a separated state. When there is a predetermined printing instruction from the host device, the fixing roller 28 and the pressure roller 29 are pressure-welded, and the fixing pad 51 and the pressure pad 52 are also pressure-welded to form a nip portion.

Upon receiving a print instruction from the host device, the fixing control unit 790 drives the cam motor 794, and a gear (not shown) rotates the cam gear 124 (see FIG. 7 (c)). The rotation of the cam gear 124 is transmitted to the cam gear 122 and the cam gear 126 via the cam gear 128 and the first cam shaft 87 and the second cam shaft 89. A cam position sensor (not shown) causes the cam gear 124 to stop at the position shown in FIG.

The lower movable unit 46 is constantly urged downward due to its own weight. Further, the first cam shaft 87 and the second cam shaft 89 of the base unit 47, and the second slits 92a and 92b and the third slits 93a and 93b (see FIG. 8B) are engaged with each other. Further, the engaging posts 95a and 95b arranged on the upper fixing unit 45 and the first slits 91a and 91b are urged downward while being guided by the engagement.

The cams 121 and 123 pivotally supported by the first cam shaft 87 correspond to the first contact protrusion plates 97a and 97b, and the cams 125 and 127 pivotally supported by the second cam shaft 89 correspond to the second hit. The contact protrusion plates 98a and 98b correspond to each other (see FIG. 12).
Since the distance R from each camshaft of the cam surfaces 121a, 123a, 125a, 127a is set to the maximum value, the lower movable unit 46 is pushed up to the highest position in the vertical direction. At this time, the pressure roller holding arms 68a and 68b are urged upward about the rotation shaft 72 by the urging force of the pressure roller spring 74. Therefore, the pressure roller 29 is pressed against the fixing roller 28 via the pressure belt 44 and the fixing belt 43.

The pressure pad holding arms 70a and 70b are urged upward about the rotation shaft 72 by the urging force of the pressure pad spring 78. Therefore, the pressure pad 52 is pressed against the fixing pad 51 via the pressure belt 44 and the fixing belt 43 (see FIG. 17). At this time, the insertion holes 83a and 83b formed in the pressure roller holding arms 68a and 68b and the pressure pad receiving portions 84a and 84b provided in the pressure pad 52 are in a state where a predetermined gap is secured (see FIG. 18). The pressure pad 52 is in pressure contact with the fixing pad 51.

In the pressure pad 52, the pressure pad bearings 80a and 80b rotate together around the pressure pad rotation shafts 79a and 79b (see FIG. 17 for 79a) (see FIG. 7B). At this time, since the center of the width Y of the pressure pad 52 and the center of the pressure pad bearings 80a and 80b are arranged so as to substantially coincide with each other in the transport direction of the recording medium M, the width Y of the pressure pad 52 is fixed. It is easy to follow along the width Z of the pad 51 (see FIG. 17). That is, since the pressure pad 52 swings with respect to the fixing pad 51, stable pressure of the nip portion can be obtained without one-sided contact.
In this state, the corresponding positions of the width Y of the pressure pad 52 and the width Z of the fixing pad 51 are substantially the same, so that the nip width is formed by the width Y and the width Z.

FIG. 20 is an explanatory diagram of a nip state of the fixing pad and the pressure pad according to the first embodiment. FIG. 20A shows a case where the recording medium m1 having the medium width w1 conveys the recording medium m1 having a small medium width with one end side as the transfer reference end. The recording medium m1 may be nipped to one side (right side in the drawing) of the fixing pad 51 and the pressure pad 52 in the medium width direction. In this case, the pressure pad elastic member 205 of the pressure pad 52 is formed with an island portion 208 as a first island portion divided by a plurality of linear groove portions 207 as the first groove portion. Therefore, since the plurality of island portions 208 are individually pressed against the fixing pad elastic member 102, the pressure Pc at this time becomes uniform.
The groove portion 207 does not necessarily have to be a continuous groove. That is, the groove portion 207 can be applied even if the groove and the non-groove portion are formed alternately and continuously as shown by the broken line.

As a result, the entire paper-passing region of the recording medium width w1 of the recording medium m1 becomes a nipped region, and the non-nip region that is not nipped does not exist. Even if the recording medium thickness t1 is large, there is no pressure difference between the left and right in the medium width direction in the paper-passing region of the recording medium m1, and therefore a stable nip pressure that is not affected by the recording medium thickness t1 can be obtained. .. As shown in FIG. 20A, even if the recording medium m1 has a small width, there is no pressure difference between the right end side m1R and the left end side m1L.

On the other hand, as shown in FIG. 20B, the case of a recording medium having a large width will be described. In the figure, the recording medium m2 has a medium width w2, and shows a case where the recording medium m2 is conveyed closer to the center than the recording medium m1.
As described above, since the island portion 208 as the first island portion divided by the plurality of groove portions 207 is formed in the pressure pad elastic member 205, the pressure Pc by each island portion 208 becomes uniform and the recording medium m2. A stable nip pressure can be obtained within the nip area of.

If the groove portion 207 is formed parallel to the transport direction of the recording medium M, a pressure-free region is generated by the groove portion 207, so that the fixing property may be deteriorated. Since the plurality of groove portions 207 provided in the pressure pad elastic member 205 according to the present embodiment are slanted with respect to the medium transport direction (inclination angle θ shown in FIG. 15), the pressure-free region becomes an extremely trace region, and the fixability The effect on can be eliminated. In the illustration, the fixing belt 43 and the pressure belt 44 are not shown for the sake of simplicity, and the recording media m1 and m2, the groove portion 207, and the island portion 208 are exaggerated.

(Modified example of the first embodiment)
FIG. 21 is a perspective view of the pressure pad according to the modified example of the first embodiment. FIG. 22 is a plan view of the pressure pad according to the modified example of the first embodiment. In the first embodiment described above, the pressure pad pressure contact surface 210 as the first pressure contact surface of the pressure pad elastic member 205 is first diagonally diagonal to the transport direction (arrow F) of the recording medium M. A plurality of groove portions 207 are provided as the groove portions of the above, and the portion surrounded by the groove portions 207 is used as the island portion 208 as the divided first island portion. On the other hand, in the modified example of the first embodiment, the grooveless region 257 that does not form the groove portion 207 is provided on the pressure pad pressure contact surface 210 in a band shape in the lateral width direction of the medium.

As shown in the figure, the pressure pad pressure contact surface 210 of the pressure pad elastic member 205 of the pressure pad 152 according to this modification has a plurality of groove portions 207 as first groove portions and a first island surrounded by the groove portions 207. The island part 208 as a part is formed. Then, on the upstream side of the pressure pad pressure contact surface 210 of the recording medium M in the transport direction (arrow F direction), a grooveless region 257 of the elastic member that does not form the groove portion 207 is formed in a band shape toward the medium width direction. By forming the grooveless region 257 of the elastic member indicated by the band-shaped width N, when the recording medium M invades the nip portion of the fixing pad 51 and the pressure pad 152, the unfixed toner can be fixed more stably. ..

In the figure, the grooveless region 257 (width N) is provided only on the upstream side in the medium transport direction, but it can be provided in a strip shape on the downstream side or the intermediate portion in the medium transport direction (arrow F) toward the medium width direction. .. Further, the width N of the grooveless region 257 is shown to be narrower than the region of the groove portion 207, but the width N is not limited to this.

(Second embodiment)
FIG. 23 is a perspective view of the fixing pad according to the second embodiment. FIG. 24 is a plan view of the fixing pad according to the second embodiment. The difference from the first embodiment is that a groove portion and an island portion are also provided on the fixing pad side.
In the first embodiment, the groove portion 207 and the island portion 208 are provided on the pressure pad pressure contact surface 210 of the pressure pad elastic member 205 constituting the pressure pad 52. In the second embodiment, the fixing pad pressure contact surface 310 as the third pressure contact surface of the fixing pad elastic member 302 constituting the fixing pad 351 is also plurality in a direction oblique to the transport direction of the recording medium M. The groove portion 307 as the second groove portion of the above is formed. Therefore, the island portion 308 as a plurality of second island portions is formed in the portion surrounded by the groove portion 307. That is, the fixing pad pressure contact surface 310 of the fixing pad elastic member 302 is formed with an island portion 308 divided by the groove portion 307.

The fixing pad base member 101 of the fixing pad 351 is the same as the content described in the first embodiment. The groove width 307w, the island width 308w, and the inclination angle θ of the groove portion 307 shown in FIG. 24 have the same dimensions as the pressure pad 52 described above.

FIG. 25 is a front view showing the correspondence between the fixing pad and the pressure pad according to the second embodiment. As shown in the figure, the pressure pad 52 is positioned below the fixing pad 351 facing the upper fixing pad 351. At this time, the groove portion 307 provided on the fixing pad pressure contact surface 310 as the third pressure contact surface of the fixing pad elastic member 302 and the groove portion 207 provided on the pressure pad pressure contact surface 210 of the pressure pad elastic member 205 are substantially 2 It is configured so that the positional relationship is shifted in the lateral direction by a factor of 1. The correspondence, configuration, and operation of the fixing pad 351 and the pressure pad 52 are the same as those described in the first embodiment.

FIG. 26 is a conceptual diagram showing the correspondence between the groove portion of the fixing pad elastic member and the groove portion of the pressure pad elastic member according to the second embodiment. As shown in the figure, the positions of the groove portion 207 and the groove portion 307 are laterally shifted by approximately half the pitch from each other, so that the intersecting portions of the groove portions do not come into pressure contact with each other and secure stable fixing property. can.
In the figure, the solid line shows the groove portion 207 provided on the pressure pad pressure contact surface 210 of the pressure pad elastic member 205, and the broken line shows the groove portion 307 provided on the fixing pad pressure contact surface 310 of the fixing pad elastic member 302.

In the embodiment described above, the widths Y and Z (see FIG. 17) as the lengths of the pressure pad 52 and the fixing pad 51 in the medium transport direction are the same dimensions, but the dimensions are not limited to this. No. Further, the positional relationship between the width Y of the pressure pad 52 and the pressure pad bearing 80 in the medium transport direction has been described as the center (Y / 2) of the width Y, but the present invention is not limited to this. Further, although the configuration in which the pad members are arranged above and below the fixing pad 51 and the pressure pad 52 has been described, a combination of the fixing roller 28 and the pressure pad 52 may be used.

As described above, the groove portion 207 is formed in a mesh shape on the pressure pad elastic member 205 of the pressure pad 52 in a direction oblique to the transport direction of the recording medium M. Since the island portion 208 divided by the groove portion 207 is individually pressed against the fixing pad 51, the pressure difference in the paper passing region is eliminated. Therefore, a uniform nip pressure can be obtained, and a stable recording medium can be conveyed in the fixing device 40.

In the present embodiment, the image forming apparatus provided with the image forming unit of four colors has been described, but it is an image forming apparatus of a single color such as black color or an image forming apparatus for printing a roll-shaped recording medium. Is also good. Further, although the LED head is used for the exposure unit, it may be a laser exposure unit composed of a small laser and a polygon mirror. Further, it can also be used for an image forming apparatus that employs an intermediate transfer belt.

1 Image forming device 40 Fixing device 41 Fixing unit (fixing member) 42 Pressurizing unit (pressurizing member)
45 Upper fixed unit 46 Lower movable unit 51 Fixing pad 52 Pressurizing pad
110, 310 Fixing pad pressure contact surface
210 Pressurized pad pressure contact surface 102, 302 Fixing pad elastic member (second elastic member)
205 Pressurized pad elastic member (first elastic member)
207 Groove (1st groove)
208 Shimabe (1st island)
307 groove (second groove)
308 Shimabe (second island)

Claims (15)

A fixing device that fixes an image on a recording medium by heating and pressurizing while transporting the recording medium in a predetermined direction.
A fixing member provided with a first belt and provided facing one surface of the recording medium via the first belt.
A second belt is provided, which is provided facing the other surface of the recording medium via the second belt, and pressurizes the recording medium by pressing against the fixing member via the recording medium. has a member,
Furthermore, the pressing member has a first elastic member made of silicone rubber member pressed against the fixing member via said first belt and said second belt,
Furthermore, the first elastic member includes a plurality of first grooves formed inclined in the two left and right direction with respect to the conveying direction of the recording medium,
A fixing device having a plurality of first island portions divided by the plurality of first groove portions. Further, claim 1 is characterized in that when the recording medium is pressure-welded by the fixing member and the pressurizing member, the pressures of the plurality of first islands in the nip region of the recording medium become equal. The fixing device described. Further, the fixing member has a second elastic member for pressing said first elastic member through said first belt provided in contact Rutotomoni said first belt and said second belt ,
The fixing device according to claim 2, wherein the nip region is formed by pressure contact between the first elastic member and the second elastic member. The first pressure contact surface on which the plurality of first grooves of the first elastic member are formed, and
The fixing device according to claim 3, further comprising a second pressure contact surface that is in pressure contact with the first pressure contact surface of the second elastic member. The fixing device according to claim 4, wherein the first pressure contact surface is in contact with a non-printing surface of the recording medium. The first elastic member includes
The fixing device according to claim 2, further comprising a region on the upstream side in the transport direction of the recording medium, which does not form the plurality of first grooves in a strip shape toward the width direction of the medium. The fixing device according to claim 2, wherein the plurality of first groove portions are formed in a linear shape. The fixing device according to claim 7, wherein the plurality of first groove portions are formed with an inclination angle of ± 10 degrees to ± 80 degrees to the left and right with respect to the transport direction of the recording medium. The fixing device according to claim 7, wherein the groove width of the plurality of first groove portions is formed in the range of 0.5 mm to 1.5 mm. The fixing device according to claim 7, wherein the length of each of the plurality of first island portions of the recording medium in the lateral width direction is formed in the range of 4 mm to 10 mm. The number of the plurality of first island portion, the lateral width direction of the recording medium having a minimum medium width, fixing device according to claim 7, wherein a is 3 or more. Further, the fixing member may have a first belt in contact provided Rutotomoni, the first belt and the second elastic member for pressing said first elastic member through the second belt death,
The fixing device according to claim 2, wherein the second elastic member has a plurality of second grooves formed so as to be inclined in two directions to the left and right with respect to the transport direction of the recording medium. Wherein the second elastic member, fixing device according to claim 12, wherein the second island of the plurality of divided is formed by the plurality of second groove portions. Wherein the plurality of first groove portions and the fixing device according to claim 13, characterized in that disposed in a predetermined amount shifted positions in the width direction of the plurality of second groove said recording medium. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 14, wherein the image is formed on the recording medium by transporting the recording medium on which the image is transferred to the fixing apparatus. ..

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