Patent Application
20250026140
The present invention relates to a sheet thermocompression apparatus, and a post-processing apparatus including a sheet thermocompression apparatus.
Conventionally, in regard to a plurality of sheets that have been subjected to image forming processing by an image forming apparatus, a method for pressing a sheet by a sheet thermocompression apparatus and melting an adhesion layer (adhesion toner) on the sheet again to perform adhesion processing and make a booklet has been known. Examples of the adhesion method for a booklet by sheet thermocompression include corner adhesion where one of four corners of a sheet is used for adhesion and line adhesion where the entire edge portion along one side of a sheet is used for adhesion.
Japanese Patent Application Publication No. 2000-255881 discloses a configuration of a sheet thermocompression apparatus in which a thermocompression unit (refixing means) is used to heat and press a bundle of sheets having adhesion toner formed thereon to perform adhesion processing. The above-mentioned sheet thermocompression apparatus is capable of executing adhesion processing by corner adhesion and line adhesion for a bundle of sheets by using a plurality of thermocompression units in different ways or moving a thermocompression unit.
However, in the configuration including a plurality of thermocompression units, the thermocompression units are independently driven, and hence operation control of the thermocompression units may be complicated and the ease of maintenance of the thermocompression units may be low. On the other hand, in a configuration in which a single thermocompression unit is moved to execute adhesion processing, only a corner portion of a sheet is pressed during adhesion processing for corner adhesion, and hence a booklet is made while a part of sheets are displaced during thermocompression operation, which may decrease the quality of the booklet.
In view of the above-mentioned problem, it is an object of the present invention to provide a sheet thermocompression apparatus capable of executing stable thermocompression operation.
In order to achieve the above-mentioned object, a sheet thermocompression apparatus according to the present disclosure is a sheet thermocompression apparatus for bonding a plurality of sheets to one another, the sheet thermocompression apparatus comprising:
According to the present invention, the sheet thermocompression apparatus capable of executing stable thermocompression operation can be provided.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, a description will be given, with reference to the drawings, of embodiments (examples) of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments. In addition, not all features described in the following embodiments are essential to solutions provided by the invention.
A sheet thermocompression apparatus of the present invention is particularly suitable for a sheet thermocompression apparatus for making a booklet in which a plurality of sheets bonded to one another. Hereinafter, as an example of a sheet thermocompression apparatus to which the present invention is applied, a sheet thermocompression apparatus provided to a post-processing apparatus which is connected to an image forming apparatus for forming an image on a sheet and to which the sheet is conveyed from the image forming apparatus is described.
As illustrated in
In Example 1, the maximum size of a sheet P on which an image can be formed by the image forming apparatus 1 is an A4 size (vertical 297 mm×horizontal 210 mm). The image forming apparatus 1 can perform image formation by conveying a sheet P of A4 size in a vertical direction (longitudinal direction is parallel to conveyance direction). The sheet conveyance speed in the image forming apparatus 1 in this case is 300 mm/sec.
The cassette 8 is inserted at a lower part of the image forming apparatus 1 so as to be withdrawable from the casing 19 of the image forming apparatus 1, and is capable of storing a large number of sheets P therein. A sheet P stored in the cassette 8 is fed from the cassette 8 by a feeding roller 8a as a feeding portion, and conveyed by a conveyance roller pair 8b. The image forming apparatus 1 further includes a multi tray 20, and can feed sheets P set in the multi tray 20 one by one.
The image forming unit 1e is a tandem electrophotographic unit including four process cartridges 7n, 7y, 7m, and 7c, a scanner unit 2, and a transfer unit 3. Hereinafter, the process cartridges 7n, 7y, 7m, and 7c are generically referred to as “process cartridge 7” unless otherwise distinguished. The same applies to members provided in the process cartridge 7 such as a photosensitive drum D.
The process cartridge 7 is a unit of a plurality of parts for an image forming process that can be replaced. Each of the process cartridges 7n, 7y, 7m, and 7c includes a photosensitive drum D (Dn, Dy, Dm, and Dc) as an image bearing member, a charging roller for charging the photosensitive drum D, and a toner storage portion for storing toner therein and supplying the toner to the photosensitive drum D.
Of the four process cartridges 7, three process cartridges 7y, 7m, and 7c on the right side in
In Example 1, in the case of printing a black image such as a text, the image is expressed by process black obtained by superimposing toners of yellow, magenta, and cyan. However, for example, the fifth process cartridge that uses black image toner may be added to the image forming unit 1e such that a black image can be expressed by black image toner. Without being limited thereto, the type and number of image toner can be changed depending on the purpose of the image forming apparatus 1.
In the present invention, conventionally and publicly known image toners can be used. Of those, image toner in which a thermoplastic resin is used as a binder resin is preferred. Resins that can be used for the thermoplastic resin are not particularly limited, and resins that are conventionally used for image toner, such as a polyester resin, a vinyl resin, an acrylic resin, and a styrene acrylic resin, can be used. Furthermore, the image toner may contain a plurality of the resins. The image toner is formed while containing a colorant, a magnetic substance, a charge control agent, a wax, or an external additive.
In the present invention, adhesion toner containing a thermoplastic resin can be used. Resins that can be used for the thermoplastic resin are not particularly limited, and examples thereof include a polyester resin, a vinyl resin, an acrylic resin, and a styrene acrylic resin similarly to the image toner. Furthermore, the adhesion toner may contain a plurality of the resins. Similarly to the image toner, the adhesion toner may be formed while containing a colorant, a magnetic substance, a charge control agent, a wax, or an external additive. Furthermore, the image toner may be used as the adhesion toner as long as the image toner satisfies adhesion properties.
The scanner unit 2 is exposure means for irradiating photosensitive drums Dn, Dy, Dm, and Dc of the process cartridges 7n, 7y, 7m, and 7c with laser light to form electrostatic latent images. Note that the exposure means in the image forming apparatus 1 of an electrophotographic system is not limited to the above-mentioned configuration.
The transfer unit 3 includes an endless transfer belt 3a as an intermediate transfer member (secondary image bearing member), and an opposing roller 3b and a drive roller 3c that are located on the inner circumferential side of the transfer belt 3a. The transfer belt 3a is a belt member stretched over the opposing roller 3b and the drive roller 3c, and an outer circumferential surface thereof is opposed to the photosensitive drums Dn, Dy, Dm, and Dc. On the inner circumferential side of the transfer belt 3a, primary transfer rollers Fn, Fy, Fm, and Fc are disposed at positions corresponding to the photosensitive drums Dn, Dy, Dm, and Dc, respectively.
Furthermore, a secondary transfer roller 5 as transfer means is disposed at a position opposed to the opposing roller 3b through the transfer belt 3a. A transfer nip 5n formed between the secondary transfer roller 5 and the transfer belt 3a is a transfer portion (secondary transfer portion) for transferring a toner image from the transfer belt 3a to the sheet P.
The fixing unit 6 is a fixing portion for heating, melting, and pressing a toner image formed on a sheet P such that the toner image is fixed on the sheet P as a permanent image. The fixing unit 6 is a fixing unit of a thermal fixing system including a halogen heater 6a as a heat source, a heat roller 6b as a fixing member that includes the halogen heater 6a and is heated by the halogen heater 6a, and a pressure roller 6c as a pressing member.
Heating of the heat roller 6b may be implemented by a ceramic heater as a heating source or a heat generation mechanism of an induction heating system. The heat roller 6b may be used as a polyimide resin or a polyamide imide resin as a high heat resistant resin or a film on which or metal such as stainless steel is formed into a thin film.
The heat roller 6b is driven by drive means (not shown), and is pressed to the pressure roller 6c by biasing means such as a spring. Due to a pressing force of the pressure roller 6c, a fixing nip 6n is formed between the heat roller 6b and the pressure roller 6c. In the heat roller 6b, power input to the halogen heater 6a is adjusted by a control unit (not shown) such that a detection temperature of a thermistor (not shown) as a temperature detection element that contacts the surface of the halogen heater 6a becomes a predetermined value.
Next, an image forming operation of the image forming apparatus 1 is described. When a printing instruction with image data to be printed is input to the image forming apparatus 1, the control unit in the image forming apparatus 1 starts a series of operations for conveying a sheet P and forming an image on the sheet P (conveyance operations by conveyance means and image forming operation). In
In the image forming operation, first, sheets P are fed from the cassette 8 one by one and conveyed toward the transfer nip 5n through the conveyance roller pair 8b. In parallel to the feeding of the sheets P, the process cartridges 7 are sequentially driven, and the photosensitive drums D are rotationally driven. The surface of the rotationally driven photosensitive drum D is applied with uniform charge by a charging roller (not shown). Furthermore, the scanner unit 2 irradiates the photosensitive drum D with laser light modulated on the basis of image data, thereby forming an electrostatic latent image on the surface of each photosensitive drum D. Then, the electrostatic latent image on the photosensitive drum D is developed as a toner image by toner carried by a developing roller in a toner storing portion in each process cartridge 7.
Note that an adhesion toner image Ti to be formed on the photosensitive drum Dn by adhesion toner is different from a toner image (normal toner image) of image toner for printing an image such as a text and a figure on a sheet P because the adhesion toner image Ti is not intended to communicate visual information. However, in the following description, the adhesion toner image Ti developed by an electrophotographic process in order to form the adhesion toner image Ti on a sheet P with a predetermined pattern is also treated as one type of “toner image”.
A toner image formed by each process cartridge 7 is transferred (primarily transferred) onto the transfer belt 3a from each photosensitive drum D by an electric field formed between the photosensitive drum D and the primary transfer roller F. In this case, the transfer belt 3a rotates in the counterclockwise direction (arrow direction) in
The toner image carried on the transfer belt 3a and arrived at the transfer nip 5n is transferred (secondarily transferred) to a sheet P fed and conveyed from the cassette 8 by an electric field formed between the secondary transfer roller 5 and the opposing roller 3b.
After that, the sheet P is conveyed to the fixing unit 6 and subjected to thermal fixing processing. When the sheet P passes through the fixing nip 6n, the toner image on the sheet P is heated and pressed such that image toner (yellow, magenta, and cyan) and adhesion toner are melted and then fixed. Then, the toner image is fixed on the sheet P as a permanent image.
On the downstream side of the fixing nip 6n in the conveyance direction of the sheet P, an inversion flapper 21 as a guide member for switching the conveyance direction of the sheet P is installed. Owing to the inversion flapper 21, the conveyance direction of the sheet P is switched in accordance with a printing mode selected from a single-sided printing mode for forming an image on only one side of the sheet P and a both-sided printing mode for forming images on both sides of the sheet P.
In the single-sided printing mode, the inversion flapper 21 guides a sheet P toward the discharge roller pair 22. The sheet P guided by the inversion flapper 21 toward the discharge roller pair 22 is arrived at the post-processing apparatus 4 through an intermediate conveyance unit 26 having conveyance roller pairs 24 and 25, and a series of image forming operation by the image forming apparatus 1 is finished.
In the both-sided printing mode, the inversion flapper 21 conveys a sheet P having an image formed on one side thereof toward a switch-back roller pair 23. The switch-back roller pair 23 changes its rotation direction to a reverse direction after the sheet P is delivered until a trailing end, thereby conveying the sheet P toward a both-sided conveyance path 27 for both-sided printing.
The sheet P conveyed to the both-sided conveyance path 27 passes again through the secondary transfer portion and the fixing unit 6. Through this process, an image is formed on a surface of the sheet P on which no image has been formed, so that images are formed on both sides of the sheet P.
The sheet P having images formed on both sides thereof is conveyed by the inversion flapper 21 toward the discharge roller pair 22. Through the operation described above, a series of image forming operation by the image forming apparatus 1 is finished, and the sheet P is conveyed to the post-processing apparatus 4 through the intermediate conveyance unit 26.
The post-processing apparatus 4 in Example 1 has a floor standing type configuration. The post-processing apparatus 4 includes a conveyance mechanism for conveying a sheet P, a sheet alignment portion (alignment mechanism) provided at a lower part of the apparatus, and a booklet making apparatus 50 having a thermocompression unit 60 for heating and pressing a bundle of aligned sheets for a predetermined time. The booklet making apparatus 50 is a sheet thermocompression apparatus for heating and pressing a bundle of aligned sheets such that a plurality of sheets bonded to one another.
Post-Processing Apparatus Subsequently, operation of the post-processing apparatus 4 is described. In the post-processing apparatus 4, a discharge upper tray 33 and a discharge lower tray 34 located below the discharge upper tray 33 are provided as delivery destinations of sheets P.
When the delivery destination of a sheet P is the discharge upper tray 33, the sheet P conveyed from the intermediate conveyance unit 26 passes through a discharge roller pair 32 through a conveyance roller pair 30 and a conveyance roller pair 31 in the post-processing apparatus 4, and is discharged to the discharge upper tray 33.
When the delivery destination of a sheet P is the discharge lower tray 34, the inversion flapper 35 is switched at a timing at which a sheet trailing end (trailing end of sheet P in conveyance direction) has passed the inversion flapper 35, and at the same time, the rotation of the discharge roller pair 32 is stopped. After that, the discharge roller pair 32 is reversely rotated, and the sheet P is switched back and conveyed to a conveyance roller pair 36.
The sheet P conveyed from the conveyance roller pair 36 is conveyed to a conveyance roller pair 38 through an intermediate conveyance roller pair 37. At a predetermined timing after a trailing end of the sheet P has passed the intermediate conveyance roller pair 37, the conveyance roller pair 38 is stopped and reversely rotated such that the sheet P is conveyed to a booklet discharge roller pair 39 and discharged to the discharge lower tray 34.
Subsequently, the booklet making apparatus 50 is described. Sheets P that constitute a booklet are conveyed to the conveyance roller pair 38 through the intermediate conveyance roller pair 37, and conveyed to an intermediate loading portion 51 in the booklet making apparatus 50.
A vertical alignment reference plate 52 is disposed at the most downstream part of the intermediate loading portion 51. When end portions of the sheets P are brought into contact with the vertical alignment reference plate 52, the plurality of sheets P are aligned as a bundle.
An alignment method for sheets P is described with reference to
Through the operation described above, a bundle of sheets (plurality of sheets P) that have been accurately aligned with reference to the vertical alignment reference plate 52 and the horizontal alignment reference plate 55 are placed in the intermediate loading portion 51. The bundle of aligned sheets are subjected to a thermocompression step involving heating and pressing by the thermocompression unit 60, and become a single booklet in which the sheets P bonded to one another with the adhesion toner images Ti as adhesive. In this manner, the booklet making apparatus 50 functions as a sheet thermocompression apparatus for causing a plurality of sheets P to bonded to one another by the thermocompression unit 60. Note that the alignment mechanism for aligning the sheets P loaded in the intermediate loading portion 51 is not limited to the above-mentioned configuration, and a publicly known alignment mechanism can be employed.
The thermocompression unit 60 is described.
The ceramic heater 70 is a heating source in which a heat generating element 72 as a first heat generating element and a heat generating element 73 as a second heat generating element are provided on a surface of a substrate 71 made of ceramic with a thickness of 1.0 mm. Note that the substrate 71 in the ceramic heater 70 may be a rigid member such as metal, in addition to ceramic. The first pressure plate 62 is in close contact with a downward surface of the ceramic heater 70, and the ceramic heater 70 heats the first pressure plate 62.
The first pressure plate 62 is a pressing member for heating and pressing a bundle of sheets loaded in the intermediate loading portion 51. The first pressure plate 62 in Example 1 is made of aluminum with a thickness of 1.5 mm. For the first pressure plate 62, a material having small heat capacity and high heat conductivity in order to efficiently transmit heat from the ceramic heater 70 and having an elastic modulus of 1,000 Pa or more so as not to be deformed by a pressing force during thermocompression is preferred. More preferably, a highly elastic material with an elastic modulus of 10,000 Pa or more is used for the first pressure plate 62. By using a member with low heat capacity for the constituent member of the thermocompression unit 60 such as the first pressure plate 62, power consumption during the operation of thermocompression is reduced.
A heater support member 63 supports the ceramic heater 70 from the above. The heater support member 63 can be formed of, for example, a material such as a liquid crystal polymer, which is one of high heat resistant functional resins. The heater support member 63 is provided with a thermistor 64 as a temperature measurement sensor, and temperatures of the ceramic heater 70 and the first pressure plate 62 are measured through the heater support member 63.
By controlling the amounts of heat generation of the heat generating elements 72 and 73 such that temperatures of the heat generating elements 72 and 73 become a target thermocompression control temperature on the basis of a temperature detected by the thermistor 64, a surface temperature of the first pressure plate 62 is controlled by the ceramic heater 70 to a temperature with which thermocompression can be executed. In the booklet making apparatus 50, a control unit 90 for controlling the amounts of heat generation of the heat generating elements 72 and 73 on the basis of a measurement result of the thermistor 64 is provided. The control unit 90 may be capable of executing only the control of the thermocompression unit 60, or may be capable of controlling operations of the rollers in the post-processing apparatus 4 as well.
The heating unit 61 configured by the heater support member 63, the ceramic heater 70, and the first pressure plate 62 is integrally pressed toward a bundle of sheets by the pressure lever 65. The above-mentioned members are electrically connected to one another and arranged in the order of the first pressure plate 62, the ceramic heater 70, and the heater support member 63 from the sheet P.
The pressure lever 65 is a movement mechanism located above the heating unit 61 and configured to receive power from a drive source (not shown) to press the heating unit 61 toward sheets P (sheet loading surface of intermediate loading portion 51) in the −Z direction (downward direction in
A metal stay 66 as a rigid member is provided on a surface of the heater support member 63 on a side opposite to its connection surface for the ceramic heater 70. The pressing force of the pressure lever 65 is transmitted to the first pressure plate 62 through the metal stay 66.
Furthermore, a second pressure plate 67 is provided at a position overlapping the first pressure plate 62 in the Z direction and below a bundle of sheets. When the pressure lever 65 is operated by a drive source (not shown), the first pressure plate 62 contacts a bundle of sheets conveyed between the first pressure plate 62 and the second pressure plate 67, and the bundle of sheets are sandwiched and pressed by the first pressure plate 62 and the second pressure plate 67.
The second pressure plate 67 is a plate-shaped member formed of silicon rubber with a thickness of 2.0 mm, and is a member for stably transmitting a pressing force from the pressure lever 65 to a bundle of sheets. For the second pressure plate 67, a heat resistant material having an elastic modulus of 1,000 Pa or less with some degree of deformability and having resistance to repeated stress can be used as a member for stably transmitting a pressing force to a bundle of sheets, without being limited to silicon rubber.
It is desired that the number of sheets P to be thermally compressed be set as appropriate in consideration of a time necessary for the thermocompression step and producibility of booklet making. In Example 1, the thermocompression unit 60 is controlled to thermally compress a bundle of 5 sheets P loaded and aligned. In Example 1, in the state in which the temperature of the first pressure plate 62 is set to a target temperature for thermocompression, the first pressure plate 62 presses the bundle of sheets for 2 seconds and is thereafter separated from the sheets P, so that the booklet making by thermocompression is finished. Note that, in the case of thermally compressing a bundle of 5 sheets or less, thermocompression is executed for that number of sheets.
For example, a booklet with 18 sheets P is made in the following process. First, as the first thermocompression, thermocompression operation is performed in the state in which the first to fifth sheets P are loaded in the intermediate loading portion 51. In the first thermocompression, a booklet with 5 sheets P is made.
Subsequently, as the second thermocompression, thermocompression operation is executed in the state in which the sixth to tenth sheets P are loaded on a booklet of 5 sheets P. In the second thermocompression operation, a booklet with 10 sheets P is made.
Subsequently, as the third thermocompression, thermocompression operation is executed in the state in which the eleventh to fifteenth sheets P are loaded on a booklet of 10 sheets P. In the third thermocompression operation, a booklet with 15 sheets P is made.
Finally, as the fourth thermocompression, thermocompression operation is executed in the state in which the sixteenth to eighteenth sheets P are loaded on a booklet of 15 sheets P. In the fourth thermocompression operation, a booklet with 18 sheets P is made. Through the four thermocompression operations described above, a booklet with 18 sheets P is completed.
A positional relation between sheets P aligned by the vertical alignment reference plate 52 and the ceramic heater 70 is described with reference to
The size of sheets P for a booklet is freely selected by a user, and there are various sizes.
In Example 1, the alignment positions of the sheets P to be thermally compressed are the same position regardless of the size. A reference position in the ceramic heater 70 is determined with reference to the arrangement positions of the vertical alignment reference plate 52 and the horizontal alignment reference plate 55. Sheets P loaded in the intermediate loading portion 51 are positioned by the vertical alignment reference plate 52 and the horizontal alignment reference plate 55, and hence the sheets P are accurately positioned with respect to the ceramic heater 70 regardless of the sizes of the sheets P.
In Example 1, the length of the first pressure plate 62 in the longitudinal direction is larger than the length of an A4 sheet, which is the maximum size, in the longitudinal direction. When viewed in the loading direction (Z direction) of sheets P, the alignment mechanism aligns the sheets P such that the first pressure plate 62 overlaps from one end portion to the other end portion of the sheet P and covers the entire region of an edge portion of the sheet P in the longitudinal direction. Similarly, the longitudinal lengths of the heat generating element 72 and the heat generating element 73 are determined such that the entire longitudinal region of an edge portion of the sheet P is covered by the heat generating element 72 and the heat generating element 73. In this manner, the first pressure plate 62 is capable of pressing the sheet P from one end portion to the other end portion in the longitudinal direction, and hence the displacement of the sheet P during the thermocompression operation is suppressed such that stable thermocompression operation is executed, and the quality of a booklet made is improved.
The booklet making apparatus 50 in the first embodiment is capable of executing at least corner adhesion and line adhesion as adhesion forms of sheets P. The corner adhesion is a method for making a booklet by controlling a plurality of sheets P to bonded to one another at one corner of four corners of the sheets P. The line adhesion is a method for making a booklet by controlling a plurality of sheets P to bonded to one another at an edge portion along one side of the sheet P. The control unit 90 in the first embodiment can execute, on the basis of input information from a user, a first mode for executing the thermocompression operation under adhesion conditions for corner adhesion and a second mode for executing the thermocompression operation under adhesion conditions for line adhesion in a switching manner.
The adhesion toner image Ti formed on a sheet P is described.
For example, in the case of making a booklet with n pages, adhesion toner images Ti are formed on sheets P until the n-th page except for the first page as a front page. Then, in the state in which the sheets P are loaded with five sheets each, the thermocompression operation is executed to complete a booklet. Note that, in
Whether to form the adhesion toner image Ti on only one side of the sheet P or on both sides of the sheet P may be selected in consideration of the types of the booklet making apparatus 50, adhesion toner, and sheets P and functions required for a booklet. For example, adhesion toner images Ti may be formed on both sides in order to obtain reliable adhesiveness in the case where a booklet is used as a collector's edition or in the case where thick paper or a special sheet P is used as a front page of a booklet. For a simple booklet for temporal use, an adhesion toner image Ti may be formed on only one side.
A booklet completed by repeating the thermocompression step described above is pushed from the booklet delivery port 40 to the outside of the post-processing apparatus 4 as illustrated in
The booklet delivery port 40 is provided with a booklet discharge roller pair 39, and at a timing at which a leading end of a completed booklet is beyond the booklet discharge roller pair 39, the bundle delivery guide is stopped and returns to the standby position. The booklet discharge roller pair 39 that has received the completed booklet from the bundle delivery guide delivers the booklet from the post-processing apparatus 4 to the discharge lower tray 34, and a series of booklet making operations is finished.
A detailed configuration of the ceramic heater 70 as a heating source for the thermocompression unit 60 is described with reference to
The heat generating elements 72 and 73 are arranged side by side in the longitudinal direction of the ceramic heater 70 and are controlled to generate heat independently. In other words, heat generating means in the ceramic heater 70 is configured by the heat generating elements 72 and 73 of two systems. Owing to such a configuration, the booklet making apparatus 50 can thermally compress the sheets P by the heating unit 61 while changing the amounts of heat generation of the heat generating elements 72 and 73 in accordance with the adhesion form (corner adhesion or line adhesion) for making a booklet and adhesion conditions such as the type of sheet. In the following description, a longitudinal direction end portion of the ceramic heater 70 on a side where the heat generating element 72 is located is referred to as “first end portion 70a”, and a longitudinal direction end portion of the ceramic heater 70 on a side opposite to the first end portion 70a is referred to as “second end portion 70b”.
In
The heat generating element 72 is formed as a heat generating element used for adhesion in the case of corner adhesion, and is disposed at a position corresponding to a corner adhesion part of the sheet P. The heat generating element 72 is formed such that the length in the longitudinal direction is smaller than that of the heat generating element 73.
In the case of corner adhesion, only the heat generating element 72 generates heat, and as illustrated in
The heat generating element 73 is formed as a heat generating element used for adhesion in the case of line adhesion by being controlled to generate heat together with the heat generating element 72. In the case of line adhesion, both the heat generating elements 72 and 73 generate heat, and as illustrated in
Furthermore, in Example 1, in the case of corner adhesion, the heat generating element 72 generates heat to partly heat a bundle of sheets, and the enter region of an edge part of the bundle of sheets is pressed by the first pressure plate 62. With such a configuration, the displacement of the sheet P during the thermocompression operation is suppressed, and the thermocompression operation is stably executed. Then, a plurality of sheets P bonded to one another while the positions of end faces of the sheets P are aligned, and a booklet with high quality having the end faces of the sheets P aligned is obtained.
Furthermore, in Example 1, in the case of corner adhesion, only the heat generating element 72 generates heat to mainly heat a corner part of the sheet P where the adhesion toner image Ti is formed. With such a configuration, power consumed for corner adhesion is reduced as compared to, for example, a configuration in which heat generating means of the heating source is configured by a single heat generating element and the amount of heat generation of the heating source is always uniform in the longitudinal direction.
Next, Example 2 according to the present invention is described. Hereinafter, only a configuration in Example 2 different from the configuration in Example 1 is described. In the configuration in Example 2, the same parts in the image forming apparatus 1 and the post-processing apparatus 4 as those in the configuration in Example 1 are denoted by the same reference symbols, and descriptions thereof are omitted.
In Example 1, the entire edge part of sheets P is pressed by the heating unit 61 to align end faces of the sheets P constituting a booklet, thereby improving the quality of a finished product of a booklet. However, the quality required for a booklet is not limited to the alignment of the sheet P. Example 2 is different from Example 1 in that the adhesiveness of sheets P is improved to further improve the quality of a booklet.
Peeling of sheets P bonded as a booklet is not desirable, and rigid adhesiveness that less causes peeling of sheets P is required for thermocompression. As means for enhancing the adhesiveness, some methods such as a method for extending a period of the thermocompression step and a method for increasing the amount or adhesion area of adhesion toner are conceivable. However, although the method for extending a period of the thermocompression step is advantageous for adhesion, the producibility of booklet making decreases. Furthermore, the method for increasing the amount of adhesion toner or increasing the area thereof is advantageous for adhesiveness, but the amount of use of adhesion toner increases to affect the cost of booklet making.
In order to obtain adhesiveness necessary for a booklet, the following facts have been found from earnest studies by the inventors of the present application. First, adhesion peels from an edge portion of an adhesion toner image Ti. In particular, peeling of a booklet by line adhesion is more likely to occur from both longitudinal end portions of the adhesion toner image Ti formed for line adhesion, and is less likely to occur from a longitudinal center portion. Furthermore, in the case of corner adhesion, the area of an adhesion toner image Ti is smaller than that in the case of line adhesion, and hence adhesiveness is low as compared to line adhesion, and it is difficult to obtain sufficient adhesiveness. In this manner, in both adhesion forms of line adhesion and corner adhesion, it is desired that sheets P firmly bonded at longitudinal direction end portions thereof.
As a result of studying factors of peeling of an adhesion toner image Ti from an end portion, the following facts have been found.
As described above, when the escape of heat that impairs the melting of the adhesion toner image Ti occurs to decrease the temperatures of both end portions of the thermocompression unit 60 in the longitudinal direction, the thermal flows from the heat generating elements 72 and 73 to a bundle of sheets P reduce to decrease the adhesiveness. As illustrated in
Furthermore, the degree of the escape of heat that causes the decrease in adhesiveness may change depending on conditions and environments where thermocompression is executed. For example, in the state in which the entire thermocompression unit 60 is cooled, a temperature difference between the heat generating elements 72 and 73 that increase their temperatures for thermocompression and other members in the thermocompression unit 60 is large, and hence the amount of the escape of heat is large. On the other hand, in the case where the thermocompression operation is repeatedly executed and the entire thermocompression unit 60 is warmed, a temperature difference between the heat generating elements 72 and 73 and the other members is small, and the amount of the escape of heat is small.
Furthermore, the amount of the escape of heat also changes depending on an environment temperature where the thermocompression unit 60 is placed. As compared to the case where the thermocompression operation is executed under an environment where temperature is high, in the case where the thermocompression operation is executed under an environment where temperature is relatively low, the amount of the escape of heat increases to decrease the adhesiveness.
In Example 2, the decrease in adhesiveness of sheets P due to the escape of heat can be suppressed in consideration of the above-mentioned phenomenon. Next, a detailed configuration of a ceramic heater 70 as a heating source in Example 2 is described with reference to
In
In the configuration in which the end portion heat generating elements 74 and the center portion heat generating element 75 are independently controlled, the amounts of heat generation therefrom can be freely changed. Thus, Example 2 employs a configuration in which the end portion heat generating elements 74 are controlled to generate heat at a temperature higher than that of the center portion heat generating element 75 in order to compensate for the escape of heat from the end portions, which decrease the adhesiveness. Owing to such a configuration, temperatures at both end portions of the thermocompression unit 60 in the longitudinal direction are secured to obtain reliable adhesiveness at the end portions.
A specific example of heat generation control of the ceramic heater 70 during thermocompression operation by the thermocompression unit 60 according to Example 2 is described. In Example 2, a control temperature T1 for thermocompression operation of the end portion heat generating element 74 in the case of line adhesion is set to be higher than a control temperature T2 for thermocompression operation of the center portion heat generating element 75, specifically, higher by 10° C. Then, in Example 2, the control temperature T1 of the end portion heat generating element 74 is adjusted depending on the warming state of the thermocompression unit 60 and the environment temperature. Hereinafter, a method for adjusting the control temperature T1 is described on the basis of a control example in which a temperature higher than the control temperature T2 of the center portion heat generating element 75 by 10° C. is set as the reference control temperature TO of the end portion heat generating element 74.
First, the adjustment of heat generation of the end portion heat generating element 74 depending on the warming state of the thermocompression unit 60 is described. The case where the thermocompression unit 60 is warmed is the case where the thermocompression step is repeated. Thus, in Example 2, the control temperature T1 of the end portion heat generating element 74 is adjusted as described below depending on the number of repetitions of the thermocompression step that is continuously repeated. Here, the number of repetitions of the thermocompression step refers to the number of repetitions of the thermocompression step within a single job (instruction), but when a plurality of jobs are continuously executed, the number of repetitions of the thermocompression step in the jobs may be added.
Subsequently, the adjustment of heat generation of the end portion heat generating element 74 depending on the environment temperature where the thermocompression unit 60 is placed is described. The environment temperature is detected by an environment detection thermistor (not shown) for detecting the environment temperature that is provided to the image forming apparatus 1 or the post-processing apparatus 4. Then, the control unit 90 controls the control temperature T1 of the end portion heat generating element 74 in accordance with the detection temperature.
In Example 2, 25° C. is set as a reference environment temperature E0 where the thermocompression unit 60 is placed, and the control temperature T1 of the end portion heat generating element 74 is adjusted depending on a difference amount of the environment temperature with respect to the reference environment temperature E0. Specifically, when the environment temperature is larger than the reference environment temperature E0, the control temperature T1 of the end portion heat generating element 74 is adjusted to be low, and when the environment temperature is smaller than the reference environment temperature E0, the control temperature T1 of the end portion heat generating element 74 is adjusted to be large. In Example 2, the control temperature T1 of the end portion heat generating element 74 is increased or decreased by 2° C. in accordance with the increase or decrease of the environment temperature by 1° C.
When the thermocompression control temperature of the end portion heat generating element 74 is adjusted as described above, for example, if the thermocompression step is continuously repeated 15 times under an atmosphere temperature of 23° C., the control temperature T1 of the end portion heat generating element 74 is determined as follows.
First, the number of repetitions of the thermocompression step is 15, and hence, as described above, in consideration of the warming state of the thermocompression unit 60, the control temperature T1 is adjusted to be lower than the reference control temperature T0 by 5° C.
On the other hand, the environment temperature is 23° C., which is lower than the reference environment temperature E0 (25° C.) by 2° C., and hence the control temperature T1 is adjusted to be higher than the reference control temperature T0 by 2° C.×2=4° C.
A value obtained by adding the adjustment amount in consideration of the warming state of the thermocompression unit 60 and the adjustment amount in consideration of the environment temperature is set as a final adjustment amount of the control temperature T1 of the end portion heat generating element 74. In the above-mentioned operation example, the adjustment amount is −5° C.+4° C.=−1° C., and the control temperature T1 is set to a temperature lower than the reference control temperature T0 by 1° C.
As described above, the reference control temperature T0 is higher than the control temperature T2 of the center portion heat generating element 75 by 10° C. Thus, the control temperature T1 of the end portion heat generating element 74 is controlled to be a temperature higher than the control temperature T2 by 10° C.−1° C.=9° C.
As described above, with the configuration in Example 2, the heat generating elements that can be controlled independently from each other are disposed at the center portion and both end portions in the longitudinal direction, and the end portions and the center portion of the first pressure plate 62 in the longitudinal direction can be heated to different temperatures. Thus, the amounts of heat generation can be controlled so as to compensate for the escape of heat from both end portions of the thermocompression unit 60 in the longitudinal direction, and hence stable adhesiveness can be obtained to suppress the decrease in quality of a booklet. Note that the control method for the control temperature T1 and the relations among various temperatures described above are merely examples, and can be changed as appropriate depending on adhesion conditions such as the type of sheet.
Furthermore, in
Furthermore, in the configuration in Example 2, in the case of corner adhesion, the center portion heat generating element 75 at the center can be controlled to generate heat at a temperature lower than the control temperature necessary for melting adhesion toner, thereby suppressing the escape of heat. Also in the case of such control, power consumed for corner adhesion is reduced as compared to, for example, a configuration in which heat generating means of the heating source is configured by a single heat generating element and the amount of heat generation of the heating source is always uniform in the longitudinal direction.
Note that, in Example 2, the plurality of heat generating elements are provided such that temperatures at the center portion and the end portions of the ceramic heater 70 in the longitudinal direction are controlled to different temperatures, but the temperatures at the center portion and the end portions may be controlled to different temperatures by a single heat generating element. Next, a first modification of Example 2 in which a heat generating element of a single system is employed is described.
In
The amount of heat generation generated by a resistive heat generating element such as the heat generating element 76 is equivalent to power determined by a product of the square of a value of a current flowing through the resistive heat generating element and a resistance value of the resistive heat generating element. Thus, when the resistance value is large, the amount of heat generation is large, and when the resistance value is small, the amount of heat generation is also small.
The value of a current flowing through the heat generating element 76 of a single system as illustrated in
As described above, with the configuration in the first modification, the ceramic heater 70 that can be simply configured by the resistive heat generating element of a single system can be used to heat the end portions and the center portions of the first pressure plate 62 in the longitudinal direction to different temperatures. In addition, the amounts of heat generation can be controlled so as to compensate for the escape of heat from both end portions of the thermocompression unit 60 in the longitudinal direction, thereby obtaining stable adhesiveness to suppress the decrease in quality of a booklet.
Note that, in the first modification, the widths of the end portion 76c and the center portion 76d in the lateral direction are uniform in the longitudinal direction, but the resistive heat generating element may be formed by a tapered shape in which the width gradually changes in the longitudinal direction. Also in such a configuration, the end portions and the center portion of the first pressure plate 62 in the longitudinal direction can be heated to different temperatures, and the amounts of heat generation can be controlled so as to compensate for the escape of heat from both end portions of the thermocompression unit 60 in the longitudinal direction, thereby suppressing the decrease in quality of a booklet.
The present modification cannot implement control such that only an end portion in the longitudinal direction generates heat, and is thus suitable for, for example, the booklet making apparatus 50 that executes only line adhesion. In this manner, which of the configurations in Example 1, Example 2, and the modifications thereof is employed may be selected as appropriate depending on specifications of a booklet making apparatus.
Next, Example 3 according to the present invention is described. Hereinafter, only a configuration in Example 3 different from the configuration in Example 2 is described. In the configuration in Example 3, the same parts in the image forming apparatus 1 and the post-processing apparatus 4 as those in the configurations in Example 1 and Example 2 are denoted by the same reference symbols, and descriptions thereof are omitted.
In Example 2, the escape of heat from both end portions of the thermocompression unit 60 is compensated for by increasing the amounts of heat generation of the end portion heat generating elements 74 that can be independently controlled, so that reliable adhesiveness at end portions is obtained. With such a configuration, there may be a case where a thermocompression step is executed in a state in which a temperature difference occurs between the end portion heat generating element 74 and the center portion heat generating element 75. The end portion heat generating element 74 and the center portion heat generating element 75 each thermally expand, and hence due to a difference in expansion caused by a difference in temperature between the heat generating elements, thermal stress may occur at a boundary between the end portion heat generating element 74 and the center portion heat generating element 75.
The ceramic heater 70 is created by coating and baking of a resistive heat generating element on the surface of the substrate 71, and is configured to generate heat when voltage is applied to the resistive heat generating element. It is necessary for the resistive heat generating element to secure electrical insulation because voltage is applied thereto. Thus, in the ceramic heater 70, insulating glass with thermal resistance is formed as an insulating protective layer (insulating glass layer) with a thickness of 50 m.
A difference in thermal stress caused by thermal expansion is received by the substrate 71 and the insulating glass layer. The substrate 71 has a thickness of 1 mm and has high rigidity, and is thus less likely to be broken by thermal stress. On the other hand, the insulating glass layer is a thin film of 50 μm, and hence when the insulating glass layer repeatedly receives thermal stress, very small microcracks may occur. Such microcracks may cause a problem in securing electrical insulation.
Thus, Example 3 employs a configuration in which a ceramic heater 70 is configured by a plurality of resistive heat generating elements such that the amounts of heat generation can be controlled so as to compensate for the escape of heat from both end portions of the thermocompression unit 60 in the longitudinal direction while suppressing microcracks in the insulating glass layer and the like. In the ceramic heater 70 according to Example 3, one heat generating element 77 and two heat generating elements 78 are provided.
As illustrated in
In
The heat generating element 77 is formed into a tapered shape in which the width in the lateral direction gradually changes such that the width becomes maximum at a center portion in the longitudinal direction and becomes minimum at end portions. Thus, a resistance value of the heat generating element 77 is the lowest at the center portion in the longitudinal direction, and becomes gradually higher as being closer to the end portions. As described above, the amount of heat generation of a resistive heat generating element is equivalent to power determined by a product of the square of a value of current flowing through the resistive heat generating element and a resistance value thereof. Thus, the amount of heat generation of the heat generating element 77 becomes gradually larger as being closer to the end portions from the center portion in the longitudinal direction.
On the other hand, the heat generating element 78 is formed into a tapered shape in which the width in the lateral direction gradually changes such that the width becomes maximum at the center portion in the longitudinal direction and becomes minimum at the end portions. Thus, a resistance value of the heat generating element 78 is the highest at the center portion in the longitudinal direction, and becomes gradually lower as being closer to the end portions. Thus, the amount of heat generation of the heat generating element 78 becomes gradually smaller as being closer to the end portions from the center portion in the longitudinal direction.
The heat generating elements 77 and 78 are each formed to extend from the first end portion 70a to the second end portion 70b of the ceramic heater 70 in the longitudinal direction, and formed continuously in the longitudinal direction. Furthermore, the heat generating element 77 and the heat generating elements 78 are disposed with gaps in the lateral direction. Such a configuration can prevent the occurrence of thermal stress caused by a difference in amount of heat generation of adjacent heat generating elements, and suppress the breakage of an insulating glass layer.
Furthermore, the amounts of heat generation of the heat generating elements 77 and 78 have a complementary relation as illustrated in
In Example 3, in the case of corner adhesion, by energizing only the heat generating element 77, the amount of heat necessary for a thermocompression step can be secured at a position corresponding to a corner portion of a sheet P where an adhesion toner image Ti is formed. Furthermore, substantially the entire region of an edge portion of a sheet P is pressed while being sandwiched by the first pressure plate 62 and the second pressure plate 67. Thus, the configuration in Example 3 can reduce the amount of power consumption as compared to a configuration in which the amount of heat generation is controlled to be uniform in the longitudinal direction, while suppressing the displacement of the sheet P.
Furthermore, in Example 3, in the case of line adhesion, by energizing both the heat generating element 77 and the heat generating elements 78, the entire thermocompression unit 60 in the longitudinal direction is controlled to generate heat such that the amount of heat necessary for a thermocompression step can be secured at a position corresponding to an edge portion of a sheet P where an adhesion toner image Ti is formed. Then, by controlling the amount of heat generation of the heat generating element 77 to be high, the amounts of heat generation at both end portions of the ceramic heater 70 in the longitudinal direction can be increased to suppress the escape of heat. In addition, according to Example 3, stable adhesiveness can be obtained to suppress the decrease in quality of a booklet.
In Example 3, the control unit 90 controls the energization to the heat generating elements 77 and 78 such that detection temperatures of the plurality of thermistors 64 become a thermocompression control temperature, and hence the amount of heat generation of the heating unit 61 is controlled in accordance with adhesion forms and adhesion conditions. Also in Example 3, similarly to Example 2, the control temperatures of the heat generating elements 77 and 78 can be adjusted as appropriate in accordance with the warming state of the thermocompression unit 60 and the environment temperature.
As described above, with the configuration in Example 3, the plurality of heat generating elements each having a tapered shape in which the width gradually changes in the longitudinal direction can be controlled independently from each other, and hence the end portions and the center portion of the first pressure plate 62 in the longitudinal direction can be heated to different temperatures. Thus, the amounts of heat generation can be controlled so as to compensate for the escape of heat from both end portions of the thermocompression unit 60 in the longitudinal direction while suppressing the occurrence of thermal stress, and hence the thermocompression operation can be stably executed and the decrease in quality of a booklet can be suppressed.
Furthermore, the amounts of heat generation of the heat generating elements in Example 3 have a complementary relation, and hence longitudinal temperature profiles of the heat generating elements 77 and 78 can be freely changed through control of changing the ratio of energization to the heat generating elements in accordance with the detection temperatures of the plurality of thermistors 64. In other words, the configuration in Example 3 enables complicated heat generation control with a higher degree of freedom as compared to the configuration in Example 2.
In Examples 2 and 3, the resistive heat generating element is formed to have a shape symmetric in the longitudinal direction. However, the resistive heat generating element is not necessarily required to be formed into a shape symmetric in the longitudinal direction. For example, when an adhesion position for corner adhesion (position at which adhesion toner image Ti is disposed) is fixed, the resistive heat generating element may be configured such that the amount of heat generation at a longitudinal direction end portion corresponding to the adhesion position is larger than the amount of heat generation at an end portion on the opposite side. Next, a second modification of Example 3 that employs a resistive heat generating element formed into a shape asymmetric in the longitudinal direction is described.
In the second modification, similarly to Example 3, one heat generating element 79 and two heat generating elements 80 that extend from the first end portion 70a to the second end portion 70b in the longitudinal direction are provided. The second modification is different from Example 3 in that the width in the lateral direction of the end portion of the heat generating element 79 on the second end portion 70b side is smaller than the width in the lateral direction of the end portion on the first end portion 70a side.
The second modification is configured on the assumption that sheets P are aligned such that a corner portion at which an adhesion toner image Ti is formed is located near the second end portion 70b of the ceramic heater 70 during thermocompression operation for corner adhesion. By configuring the heat generating element 79 as described above, as illustrated in
Furthermore, the heat generating element whose amounts of heat generation in the longitudinal direction are asymmetric as in the second modification is suitable for a configuration in which thermal flows in the ceramic heater 70 are asymmetric in the longitudinal direction due to the configuration of the thermocompression unit 60. The thermal flows in the ceramic heater 70 may be asymmetric in the longitudinal direction depending on a support configuration in the ceramic heater 70 and the presence/absence of an electric contact for energization to the resistive heat generating element. Thus, the configuration in the second modification is suitable for the case where thermal flows need to be uniform in the longitudinal direction depending on configurations of peripheral members of the ceramic heater 70 by changing the amount of heat generation in the longitudinal direction.
Note that, in the above-mentioned examples, temperature control of the thermocompression unit 60 is performed on the basis of a detection temperature of the thermistor 64 contacting the ceramic heater 70, but the present invention is not limited to such a configuration. For example, the temperature of the first pressure plate 62 may be detected by another temperature detection means, and temperature control of the thermocompression unit 60 may be performed on the basis of a detection temperature thereof.
Furthermore, the thermocompression unit 60 is configured by the first pressure plate 62 made of metal and the second pressure plate 67 made of silicon rubber, but the present invention is not limited to such a configuration. For example, a unit including a pressure plate made of silicon rubber may be pressed toward a sheet P by the pressure lever 65, and the position of a pressure plate made of metal to be heated may be fixed.
Furthermore, in the first modification and Example 3, the width of the resistive heat generating element in the lateral direction is changed to change the resistance value of the resistive heat generating element in the longitudinal direction such that the amount of heat generation of the thermocompression unit 60 is changed in the longitudinal direction, but the present invention is not limited to such a configuration. For example, by changing the resistance value of the resistive heat generating element in the longitudinal direction by another method, such as a method of changing the thickness of the resistive heat generating element in the longitudinal direction, the amount of heat generation of the thermocompression unit 60 may be changed in the longitudinal direction.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2023-119406, filed on Jul. 21, 2023, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-119406 | Jul 2023 | JP | national |
