Bookbinding apparatus

A bookbinding apparatus includes: a replenishing device having a pellet storing section that stores pellets of adhesive and a replenishing member that takes out the pellets in a countable manner from the pellet storing section; an adhesive reservoir that melts the pellets replenished from the replenishing member and stores the molten adhesive liquid; a coating device having a coating member that coats the adhesive scooped up from the adhesive liquid; a replenishment sensor that detects the number of pellets replenished to the adhesive reservoir; and a controller that controls the replenishing member based on an output of the replenishment sensor.

This application is based on Japanese Patent Application No. 2006-233320 filed on Aug. 30, 2006, the content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a bookbinding apparatus, and in particular, to a bookbinding apparatus that prepare booklets by bonding a plurality of sheets with adhesive.

In the field of light printing, for example, image forming systems are being used widely that prepare booklets from printing to bookbinding in one process by coupling an image forming apparatus having the ability to form images at a high speed such as an electro-photographic image forming apparatus, and a bookbinding apparatus.

Although such image forming systems have low printing speed and low bookbinding speed when compared with the conventional book manufacturing process in which the printing process and the bookbinding process are executed as separate processes, they have the advantage that it is possible to change the content of printing at any time and are on the whole high efficiency image forming systems, and are being used as POD (Print On Demand) systems.

Since a POD system has the image forming apparatus and the bookbinding apparatus coupled to each other, and is not installed in a factory for printing and bookbinding but is very often installed either within an office or in the same building as the office, it has to be small in size, and all parts constituting the system are required to be small in size.

Therefore, even as a bookbinding apparatus is used the type that prepares booklets by binding bundling sheets using adhesive bonding which is a relatively simple process.

A reduced size bookbinding apparatus has been disclosed in Unexamined Japanese Patent Application Publication No. 2000-168265 that prepares a booklet by coating the adhesive by moving the coating roller relative to the longitudinal direction of the spine of the sheet bundle by moving the sheet bundle with respect to the coating roller.

In Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457 are disclosed, in a coating apparatus suitable for small-sized bookbinding apparatus, an adhesive replenishing device that carries out replenishment of adhesive at an accurate rate in a simple manner.

In Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457 is proposed a replenishing member that transports pellets of adhesive material along an inclined transport path, and by opening or closing a threshold member provided in the transport path, supplies a fixed quantity of pellets of about a few pellets during each replenishment.

In a reduced size adhesive coating apparatus, since the level of the adhesive liquid in the adhesive reservoir varies widely because the volume of the adhesive reservoir that contains the liquid of the adhesive material is small, not only it is required to carry out replenishment of the adhesive accurately but also it is necessary to control the rate of replenishment according to the thickness of the sheet bundle, and a replenishment control that has accuracy and speed is required.

When a replenishment mechanism is used that replenishes in units of a few pellets as in Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457, although the replenishment control is carried out by controlling the number of replenishments in units of a few pellets, there was the problem that the accuracy of the replenishment in this type of replenishment control is not sufficient, and also, that the speed of control of meeting speedily the changes in the quantity of adhesive and it was difficult to carry out uniform coating over a long period.

In other words, when there is any disturbance in the unit of replenishment, because the inaccurate replenishment is carried out repeatedly, the replenishment error gets accumulated leading to the condition of excessive or insufficient quantity of adhesive in the adhesive reservoir.

SUMMARY OF THE INVENTION

One aspect of the present invention is as follows. A bookbinding apparatus provided with a replenishing device having a pellet storing section that stores pellets of adhesive and a replenishing member that takes out pellets in a countable manner from the pellet storing section, and in addition, an adhesive reservoir that melts the pellets replenished from the replenishing member and stores the molten adhesive liquid, and a coating device having a coating member that coats the adhesive scooped up from the adhesive liquid. The bookbinding apparatus further has a replenishment sensor that detects the number of pellets replenished to the adhesive reservoir, and a controller that controls the replenishing member based on the output of the replenishment sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the present invention is described here using a preferred embodiment shown in the figures, the present invention shall not be limited to the preferred embodiment.

FIG. 1is a diagram showing an entire image forming system provided with a bookbinding apparatus according to a preferred embodiment of the present invention.

The image forming system has an image forming apparatus A and a bookbinding apparatus B.

The image forming apparatus A is one that forms images on sheets using the electro-photography method, and has an image forming section A1, a document conveying device A2, and an image reading section A3.

In the image forming section A1are arranged a charging unit2, an exposure unit3, a developing unit4, a transfer unit5A, a separation unit5B, and a cleaning unit6on the periphery of a drum shaped photoreceptor1, and using these electro-photographic process devices, a toner image is formed on the photoreceptor1and the image is formed on the sheet S1after charging, exposure, developing, and transfer are carried out.

The sheets S1are stored in three sheet feeding trays7A, and one sheet at a time of the sheet S1is fed from these sheet feeding trays7A, and the toner image on the photoreceptor1is transferred onto the sheet S1by the transfer unit5A.

The toner image transferred onto the sheet S1is fixed by passing through the fixing unit8. The fixed sheet S1either is discharged by the ejection roller7C or is conveyed to the re-feeding path7E.

During face-down sheet discharge in single-sided printing, face-up sheet discharge in single-sided printing, or front surface image formation in double-sided image formation, the switching gate7D switches and guides the sheet S1. In other words, during face-up sheet discharge, the switching gate7D causes the sheet S1proceeds forward, and in face-down sheet discharge or in double-sided image formation, the switching gate7D guides the sheet S1downwards.

During face-down sheet discharge, the sheet S1, after being guided downwards, is switched back and is conveyed in the upward direction, and is then discharged by the ejection roller7C.

During double-sided image formation, the sheet S1is guided downwards, after being turned upside down by switching back, it passes through the sheet feeding path7E, fed to the transfer section in which is placed the transfer unit5A, and the image of the back surface is transferred onto it.

The document conveying device A2conveys the document one sheet at a time to the reading position. The image reading section A3reads out the image of the document conveyed by the document conveying device A2or the image of the document placed on the document table9, and generates the image signals. The communication section A4carries out communication with a network device, receives the image forming command transmitted from the network, and generates the image signals.

The bookbinding apparatus B is an apparatus that stacks a plurality of sheets that constitute a bundle and that are fed from the image forming apparatus A, and configures a bundle to be formed into a book, joins a cover sheet to that the sheet bundle, and prepares a book. In the following explanations, the sheets constituting sheets are called a sheet S1, and the cover sheet is called a cover S2, and the sheets constituting sheets to which a cover sheet has been joined is called a booklet S3.

The bookbinding apparatus B has a conveyance section10that conveys the sheets S1discharged from the image forming apparatus A either to an ejection tray20or to a sheet reverse section40, an ejection tray20, a sheet reverse section40, a stacking section50that stacks the sheets S1sent one sheet at a time or several sheets at a time, a coating device60, a cover sheet storing section80that stores the cover sheets S2, a cover sheet supporting section90that supports the cover sheet S2, and a booklet ejection section100.

The sheet S1discharged from the image forming apparatus A either is discharged to the ejection tray20via the ejection path12or is conveyed to the sheet reverse section40by the switching gate11provided in the conveyance section10. If the mode of operation is not the bookbinding mode, the sheets S1are discharged to the ejection tray20.

In the bookbinding mode, the sheets S1are conveyed to the sheet reverse section40via the conveying path13, and, after being switched back in the sheet reverse section40, they are conveyed to the stacking section50. In the stacking section50, the sheets S1are stacked until the number of sheets becomes equal to a set number, the stacking section50is rotated when the number of sheets stacked becomes equal to the set number, and the bundle of sheets S1is held in an almost vertical condition.

Adhesive is coated by the coating device60on the bottom surface of the bundle of sheets S1held in the vertical condition by the stacking section50.

A cover S2is contacted with and adhered to the bundle of sheets S1on which adhesive has been coated.

The booklet S3prepared by adhering the cover sheet S2to the bundle of sheets S1is discharged to the booking ejection section100.

FIG. 2is a diagram showing the coating process.

The coating device60is placed below the sheet bundle SS of the sheets S1, and during its forward movement driven by the motor MT2indicated by the arrow W2, the coating roller602coats the adhesive AD on the spine SA of the sheet bundle SS, and during the reverse movement indicated by the arrow W3, the coating roller coats the adhesive AD on the spine SA.

The home position of the coating device60is the left end position inFIG. 2, which is located at the deep side of the bookbinding apparatus shown inFIG. 1, and at this home position, pellets PT of the adhesive are replenished from the replenishment device61. The coating roller602is rotated in the direction indicated by the arrow W1due to the drive of the motor MT1during the forward and reverse movements thereby scooping up the adhesive from the adhesive reservoir601and coats it on the spine SA of the sheet bundle SS.

FIG. 3is a diagram showing the configuration of the coating device60.

The coating device60has an adhesive reservoir601that stores the adhesive AD, a coating roller602, two regulating members603and604, a heater605, and an adhesive quantity sensor606.

Although the pellets inside the adhesive reservoir601are heated and melted by the heater605thereby forming the coating liquid of the adhesive AD, the quantity of the adhesive AD is detected by the adhesive quantity sensor606composed of a temperature sensor, and the liquid surface is maintained constant. The part603is a regulating member having the shape of a rod with an almost circular cross-section, and the regulating member604is supported by a supporting member607having the shape of a plate, and limits the thickness of the layer of adhesive above the coating roller602using its bottom edge604B, and restricts the thickness of the adhesive layer on the spine SA of the sheet bundle SS using its top edge604A.

The adhesive reservoir601is set by rotating from the standby state indicated by dotted lines to the coating state indicated by continuous lines around the shaft601A.

The replenishment device61is explained here referring toFIG. 4toFIG. 7.FIG. 4is a cross-sectional view diagram of the replenishing device61,FIG. 5shows the important parts of the replenishing device61before the operations are started, andFIG. 6shows the important parts of the replenishing device61during replenishment.FIGS. 7(a) and7(b) show the drive system in the replenishing device61.

The replenishment device61is composed of a hopper62as the pellet storing section that stores the pellets PT of the adhesive and the replenishing pipe63through which the pellets PT drop, and the frame62A constituting the hopper62supports the different parts described below.

The replenishing device61is incorporated into the bookbinding apparatus B in the condition shown inFIG. 4, that is, in the condition in which the hopper62and the replenishing pipe63are inclined downward towards the left, and the pellets PT drop along the bottom surface of the frame62A and the bottom surface of the replenishing pipe63, and are supplied to the coating device60.

The belt663that conveys the pellets PT is entrained about the rollers664,666,667, and673in the lower part of the hopper62. The roller666is the drive roller and rotates counterclockwise by being driven by the motor MT3which is a constituent part of the replenishing member.

The belt663which is a constituent part of the replenishing member has concave-and-convex portions formed on its outer peripheral surface as is shown in the enlarge view diagram of4A, and because of this concave-and-convex surface, not only the pellets are conveyed definitely, but also the area of contact with the pellets PT is made small, thereby preventing adhesion between the pellets PT and the belt663. Because four pressure rollers670press the belt663against the frame62A using the force of springs, the spacing between the frame62A and the belt663is restricted so that it does not become larger than a prescribed limiting value, and because of this, the amount of conveying of the pellets PT by the belt663is controlled to be almost constant.

The rollers664and666are supported by the supporting plate662that can swing about the rotating shaft666A of the roller666, and the supporting plate662is pulled clockwise by a pulling type spring665. Because of this, a constant tension force is applied to the belt663by the roller664pulled by the spring665.

The rollers667and669are supported by the supporting plate671that can swing about the rotating shaft of the roller667.

The replenishing device61in the stopped state before starting operations is as shown inFIG. 5, and in this state, the roller669has narrowed the pellet discharge outlet, and the pellets PT stay in the hopper62being blocked by the belt663supported by the roller669as shown inFIG. 5.

When the replenishing device61starts operating, the roller669moves to the left as shown inFIG. 6, the belt663recedes, thereby making wide the pellet discharge outlet of the hopper62. Because of this, the pellets PT drop up to the discharge outlet, and the pellets PT that have dropped along the bottom surface of the frame62A due to the conveying action of the belt663.

During the period when the replenishing device is carrying out replenishing operation, the roller669reciprocates between the position shown inFIG. 5and the position shown inFIG. 6, and because of this reciprocating operation, the pellets PT drop in small quantities at a controlled rate and are supplied to the coating device60.

The roller669is an opening forming member that forms the narrow opening that blocks the discharge of the pellets PT and the wide opening that discharges the pellets PT due to the reciprocating movement. The drive mechanism that makes the roller669carry out reciprocating movement is explained usingFIG. 7(a) andFIG. 7(b).

A support plate675that rotates integrally with the roller666has been fixed to the shaft666A of the roller666, and a link676has been supported in a rotatable manner to the pin677provided at one end of the supporting plate675.

The shaft669A of the roller669engages with and enters the long hole676A provided in the link676.

The shaft669A of the roller669is pulled to the right inFIGS. 7(a) and7(b) by a pulling type spring668. Therefore, the roller669is maintained at the prescribed position by the tension force of the belt663and the force of the spring668.

Although the supporting plate675rotates due to the rotation of the roller666, because of the rotation of the supporting plate675, the right end position of the link676moves in the left and right directions inFIGS. 7(a) and7(b), and because of this movement, the position of the roller669moves in the left and right directions, and hence the pellet discharge outlet of the hopper62contracts and expands as is shown in the state inFIG. 5and the state inFIG. 6.

This contraction and expansion are repeated during the replenishment operation, and the pellets PT are supplied to the coating device60in small quantities at a controlled rate.

Returning toFIG. 4, FS is a replenishment sensor that detects the pellets PT falling from the hopper62, and is composed of a light emitting device FS1and a light receiving device FS2. The number of pellets PT supplied to the coating device60is detected by the replenishment sensor FS. The count of the number of pellets PT by the replenishment sensor FS is proportional to the number of pellets PT replenished.

FIG. 8is a block diagram of the control system that carries out replenishment control, andFIG. 9is a flow chart of the replenishment control carried out by the controller CR.

In STEP1inFIG. 9, the output of the adhesive quantity sensor606which is at the home position is monitored, and, based on the liquid surface reduction detection signal of the adhesive quantity sensor606, in STEP2, the motor MT3is started, and the replenishment of pellets is carried out.

In STEP3, the count value of the replenishment sensor SF is monitored, and when the count value reaches a prescribed value, in STEP4, the motor MT3is stopped thereby ending the replenishment.

In STEP5, the end of the job is monitored, and the operation of replenishment is ended when the job is completed, and the operation is returned to STEP1if the job has not ended.

In the control, although one replenishment operation is from STEP1to STEP5, the prescribed value determining the quantity of replenishment in one replenishment operation is changed according to the thickness of the booklet, and the prescribed value is set to a large value when the thickness of the booklet is more.

The thickness of the booklet is obtained from the information of the number of sheets constituting the booklet as set in the operation section of the image forming apparatus A, or, after detecting the thickness of the booklet in the stacking section50ofFIG. 1, it is obtained from the detected information.

In this manner, by carrying out replenishment control based on the result of detection by the replenishment sensor, during the bookbinding of a thick booklet, when the amount of consumption of the adhesive is large, the pellets of adhesive are replenished accurately according to the amount of consumption.

In the present invention, since the quantity of replenishment of adhesive is detected and the replenishment control is carried out based on the result of detection, not only the quantity of adhesive in the adhesive reservoir is controlled accurately, but also, a control is carried out that corresponds speedily to the changes in the quantity of adhesive in the adhesive reservoir, and hence booklets are prepared with a stable quality.