JP4864746B2 - Document reader - Google Patents

Description

  The present invention relates to a document reading apparatus provided in a main body of an image forming apparatus such as a copying machine, and more particularly to a document reading apparatus provided with an openable / closable transport guide means for guiding a document fed.

  2. Description of the Related Art Generally, a document reading device provided in a main body of an image forming apparatus such as a copying machine has a document transport path for a document set on a paper feed tray to reach a paper discharge tray via an image reading unit provided in a transport unit. . This conveyance path is formed in a substantially U shape with a folding portion for folding back in order to discharge the document from the upper paper feed tray to the lower paper discharge tray via the image reading unit. There are many (Patent Documents 1 and 2).

  The document flowing on the conveyance path is read by an image reading unit having a flat platen glass provided on the upper surface of the image forming apparatus main body. In addition, the apparatus having a function for reading both sides of a document is provided with a switchback mechanism that reads the surface of the document with the image reading unit, then turns the document over, back to the image reading unit, and reads the back surface. There is also. Further, in order to increase the speed of double-sided reading, a second image reading unit is provided in the middle of the conveyance path of the document reading device separately from the image reading unit provided on the image forming apparatus main body side. There are cases (Patent Document 3).

In the document reading apparatus including the second image reading unit, the document set on the sheet feeding tray is first sent out to the upstream conveyance path by a plurality of rollers provided on the upper side of the conveyance path, and this upstream conveyance is performed. It is sent out toward the downstream conveyance path extending downward from the path. A contact glass for reading provided in the second image reading unit is disposed in the downstream side conveyance path. Then, after one side of the original is read by the second image reading unit, the other side of the original is read when passing through the first image reading unit provided above the image forming apparatus main body. . As described above, the document reading apparatus including the second image reading unit has a structure in which the cross section is bent in a substantially U shape from the upstream conveyance path to the downstream conveyance path. For this reason, the conveyance guide means provided with a guide cover for nipping the document from the upstream conveyance path to the downstream conveyance path is also bent. This conveyance guide means can be opened by rotating one end as a fulcrum so that it can be opened when removing documents that have jammed on the upstream conveyance path or downstream conveyance path, or during maintenance such as cleaning. The shaft is supported so that
JP 2002-182437 A JP 2005-231873 A JP-A-2005-47701

  However, in the document reading apparatus provided with the second image reading unit as described above, a part of the downstream conveyance path extends long in the height direction, so that the conveyance guide means including this downstream conveyance path The total length of the also becomes longer. Further, when the transport guide means is completely opened to the downstream transport path, it must be opened largely to a horizontal position of 180 degrees. For this reason, there is a problem that the main body of the image forming apparatus must be installed in consideration of the open space of the transport guide means having a long overall length. Further, the conveyance guide means must open the entire upstream conveyance path and the downstream conveyance path regardless of the position of the document in which a paper jam or the like has occurred or the maintenance position. Further, since the conveyance guide means is provided with conveyance rollers or the like for smoothly conveying the document along the upstream conveyance path or the downstream conveyance path, the overall weight increases, and the conveyance guide means There was also a problem that the burden of opening and closing increased.

  Accordingly, an object of the present invention is to divide the transport guide means that covers the transport path of the original and install them independently so that the open space of the transport guide means can be minimized and paper jams can be prevented. It is an object of the present invention to provide a document reading apparatus that can be performed for each part that requires maintenance such as removal or cleaning of a raised document.

In order to solve the above-described problem, a document reading apparatus according to the present invention includes a paper feed tray on which a document is placed, a paper discharge tray disposed below the paper feed tray, and a first surface that reads one surface of the document. An image reading unit, a conveyance path for guiding a document from the paper feed tray to the first image reading unit, a conveyance guide member for guiding the document conveyed along the conveyance path, and the first image And a second image reading unit that reads the other surface of the document on the upstream side of the reading unit, wherein the conveyance guide member moves the document on the paper feed tray to the downstream side of the conveyance path. An upstream guide member that guides toward the first image reading unit, and a downstream guide member that is disposed to face the reading surface of the second image reading unit and guides a document from the upstream guide member to the first image reading unit. dividedly formed by a, and the upstream guide member With serial and downstream guide member is configured to be freely opened and closed with respect to the conveying path, provided the interlocking means for opening operation of the downstream guide member in conjunction with the opening operation of the upstream guide member It is characterized by.

  According to the document reading apparatus of the present invention, the upstream side conveyance path and the downstream side conveyance path that form the conveyance path in the conveyance path of the document bent in a substantially U shape from the paper feed tray to the paper discharge tray. Are provided with an upstream guide member and a downstream guide member that can be divided and opened, respectively, so that a planar space when opening the upstream guide member and the downstream guide member can be minimized. it can.

  Further, since the upstream side transport path and the downstream side transport path can be opened and closed independently by the upstream side guide member and the downstream side guide member, a part where a paper jam has occurred or a transport path that requires maintenance is required. Can only be opened and closed. Moreover, the burden at the time of opening and closing each guide member in that case is also reduced.

  Furthermore, by providing the engaging means in each of the upstream guide member and the downstream guide member configured to be separable, the upstream transport path and the downstream transport path can be opened and closed in conjunction with each other.

  Embodiments of a document reading apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. As shown in FIGS. 1 to 3, the document reading apparatus A according to the present embodiment includes a transport unit F, a first image reading unit H <b> 1, and a second image reading unit H <b> 2. In this document reading device A, a document set on the paper feed tray of the transport unit F is transferred from the second reading platen (second contact glass) provided in the second image reading unit H2 to the first image reading unit H1. A document is read through a first reading platen (first contact glass) 1 provided on the upper surface.

  The first image reading unit H1 irradiates a document with light emitted from a light source such as a lamp via the first contact glass 1, reflects the reflected light with a plurality of mirrors, and passes the lens through a CCD. A first reading unit 3 that reads a document image by photoelectric conversion by photoelectric conversion means such as the above is provided, and a first image reading unit H1 is configured on the upper surface of the first contact glass 1. Further, the first image reading unit H1 includes a second reading platen (second contact glass) 2 behind the first contact glass 1. The second contact glass 2 has an area where a document can be placed. A thick document such as a book or a magazine is placed with the transport unit F opened upward, and the first reading unit 3 is placed. Can be read in the sub-scanning direction.

  The transport unit F is disposed on the lower side of the paper feed tray unit T, and includes a paper feed tray unit T having a paper feed tray 41 and a lift tray 42 on which a large amount of documents can be placed at one time. A paper discharge tray 11 for storing a document whose original image has been read by one image reading unit H1, a pressure cover 12 for pressing the second contact glass 2, and a paper discharge tray from the paper feed tray unit T. 11 includes a transport path 13 for transporting the document. The pressing cover 12 is composed of, for example, a porous member such as sponge and a film member such as white mylar.

  Further, in the document reading apparatus A in this embodiment, a second image reading unit H2 having a second reading unit 4 for reading the back side image of the document is provided on the curved portion of the transport path 13. Similar to the first reading unit 3, the second reading unit 4 is emitted from a light source such as a lamp via a third reading platen (third contact glass) 7 that forms a part of the transport path 13. The third contact glass 7 is configured to irradiate the original with light, reflect the reflected light with a plurality of mirrors, and photoelectrically convert the original through a lens by photoelectric conversion means such as a CCD. Is configured as a second image reading unit H2. As described above, in the document reading apparatus A, one-side document image of the document passing through the second image reading unit H2 provided in the middle of the conveyance path 13 is read by the second reading unit 4, and the first image is read. Since the first reading unit 3 reads the other one-sided document image of the document passing through the reading unit H1, the image reading time for the two-sided document can be greatly shortened.

  The transport path 13 includes an upstream transport path (upper transport path) 13a extending in the horizontal direction, a first downstream transport path (side transport path) 13b extending downward from the upper transport path 13a, and this side. A second downstream conveyance path (lower conveyance path) 13c that is folded back from the partial conveyance path 13b and extends in the opposite direction to the upper conveyance path 13a is formed in a substantially U shape. The upper transport path 13a is provided to feed out the document set on the paper feed tray 41 in the horizontal direction, and the side transport path 13b passes the third contact glass 7 provided in the second reading unit 4 to the side transport path 13b. Provided for passing through. The lower conveyance path 13c is for passing the first contact glass 1 or the second contact glass 2 provided in the first image reading unit H1 and storing the original in the paper discharge tray 11. Among these, an upstream guide member 19 and a downstream guide member 14 are attached to the upper transport path 13a and the side transport path 13b, respectively, so that they can be opened and closed.

  The upper transport path 13a is guided so that a document can be transported when the upstream guide member 19 is closed (FIG. 1), and the nip of the document is released when the upstream guide member 19 is opened (FIG. 3). A feeding roller 21 for feeding out the original from the paper feeding tray unit T; a separating unit comprising a paper feeding roller 22 and a separation pad 23 for separating and feeding the originals fed out from the feeding roller 21 one by one; A registration roller pair 24 is provided that aligns the leading edge of the document when the leading edge of the document fed from the sheet feeding roller 22 abuts on the nip point, removes skew, and then drives the document to the downstream side. . Further, a feed roller pair 25 is provided that feeds the original from the registration roller pair 24 toward the second image reading unit H2 and the first image reading unit H1.

  The side conveyance path 13b is guided so that a document can be conveyed when the downstream guide member 14 is closed (FIG. 1), and the nip of the document is released when the downstream guide member 14 is opened (FIGS. 2 and 3). A first reading roller pair 26 that supplies a document from the feed roller pair 25 to a second image reading unit H2, and a document that is read on one side by the second image reading unit H2 is a first image. A second reading roller pair 27 that supplies the reading unit H1.

  The lower conveyance path 13c includes a third reading roller pair 28 for carrying out a document that has passed through the second image reading unit H2 and the first image reading unit H1, and a first image reading unit H1. A first paper discharge roller 29 that receives the original after passing through the third reading roller pair 28 and conveys the original toward the paper discharge tray 11, and discharges the original to the paper discharge tray 11. A second paper discharge roller pair 30 is provided. In this embodiment, the transport path 13 is configured as a transport unit F incorporating a plurality of members.

  Next, a document conveying operation by the document reading apparatus A having the above configuration will be described. First, the empty sensor S1 detects that an original is placed on the paper feed tray unit T, and the feeding roller 21 and the paper feed roller 22 are driven by a paper feed command signal from the second image reading unit H2. To do. As a result, a plurality of documents placed on the sheet feed tray unit T are sequentially fed out, separated one by one by the separation pad 23, and then fed. When the registration sensor S2 detects the leading edge of the fed document, the document is transported by a predetermined amount from the point of detection, whereby the leading edge of the document abuts against the nip portion of the registration roller pair 24 to be aligned, and the skew is removed. . Thereafter, the registration roller pair 24, the feed roller pair 25, and the reading roller pairs 26, 27, and 28 are driven. As a result, the document is transported along the transport path 13 so that the front and back thereof are reversed, and passes through the second image reading unit H2 and the first image reading unit H1 in this order. One side of the document is read when passing through the second image reading unit H2, and the other side of the document is read when passing through the first image reading unit H1.

  Before the leading edge of the document reaches the first paper discharge roller pair 29, the first paper discharge roller pair 29 and the second paper discharge roller pair 30 are driven, and the second image reading unit H2 and the first image reading are performed. The document whose both sides are read by the portion H1 is discharged onto the discharge tray 11.

  In the document reading apparatus A described above, a double feed detection sensor GS is provided in a path between the registration roller pair 24 and the feed roller pair 25 in the transport path 13. This double feed detection sensor GS is arranged so that an oscillating unit that oscillates ultrasonic waves and a vibration receiving unit that receives ultrasonic waves are opposed to each other across a path, and performs double feeding of a document according to the vibration level of the received ultrasonic waves. To detect. Further, an imprinter 8 is provided in the paper discharge unit on the paper discharge tray 11 side of the transport path 13. The imprinter 8 can print about five characters on the document surface discharged by the first discharge roller 29 and the second discharge roller 30. Here, characters notifying that a transport error such as double feeding of documents and a reading error by the first and second reading units 3 and 4 have occurred are printed on the document in which the error has occurred.

  As shown in FIG. 4, the second image reading unit H <b> 2 includes a second reading unit 4 and a downstream guide member 14 disposed to face the reading unit 4. 1 and 4 are sectional views showing a normal use state in which the downstream guide member 14 is closed with respect to the document reading apparatus A side, and FIGS. 2 and 3 show the downstream guide member 14. 4 is a cross-sectional view showing a maintenance state separated from the document reading apparatus A. FIG. The second reading unit 4 includes a third contact glass 7, a light source 6 a such as a lamp for irradiating light on the original continuously conveyed on the third contact glass 7, and reflected light from the original. A plurality of mirrors 6b, 6c, 6d, and 6e that guide the light in a predetermined direction, a lens 6f that converges the reflected light guided by the plurality of mirrors 6b to 6e, and a photoelectric conversion that photoelectrically converts the light converged by the lens 6f And a photoelectric conversion unit 15 including an element 6g and the like.

  A characteristic feature of the present invention is that the upper conveyance path 13a and the side conveyance path 13b are divided so that maintenance work such as removal or cleaning of a document that has jammed during conveyance becomes easy. It is in the point which is configured to be openable. Further, the working space when opening the upper transport path 13a and the side transport path 13b is minimized, and the upper transport path 13a and the side transport path 13b are interlocked so that they can be opened and closed in conjunction with each other. The upstream guide member 19 and the downstream guide member 14 are configured to have means. Hereinafter, the configurations, opening / closing structures, and interlocking means of the upstream guide member 19 and the downstream guide member 14 will be described. In addition, (a) in a figure is a principal part enlarged view which shows the operation state from a front direction, (b) is a principal part enlarged view which shows the operation state from a side surface direction.

  As shown in FIG. 4, the downstream side guide member 14 includes a downstream side guide cover 14a that can be opened and closed between a position facing the third contact glass 7 and a position away from the third contact glass 7 with the mounting shaft 14b as a fulcrum. The backup unit 9 is provided in the guide cover 14a. The backup unit 9 has a box-shaped base member 9a whose inside is sealed, and a surface facing the third contact glass 7 is a guide surface 9g. A backup glass 9b is provided on the back side of the guide surface 9g. Further, a white plate 9d having a rotation fulcrum 9c is provided inside the backup unit 9, and the inner wall surface 9e of the base member 9a is black. The backup unit 9 having such a configuration reads the white plate 9d by the second image reading unit H2 at any timing such as when the power is turned on or immediately before reading the document, and acquires shading correction data. When reading a single-sided document with an image formed on one side, the white plate 9d is rotated by an actuator (not shown) to a position adjacent to the surface of the backup glass 9b. Further, when reading a double-sided document with images formed on both sides, the white plate 9d is rotated to a position retracted from a position adjacent to the backup glass 9b surface. As a result, when a single-sided original is read, the backup color of the original is the white surface of the white plate 9d, and when a double-sided original is read, the backup color of the original is black on the inner wall surface 9e of the base member 9a. Thus, it is possible to reliably prevent so-called document show-back, in which an image formed on a surface different from the reading surface is read.

  On the guide surface 9g of the backup unit 9, guide protrusions 9f are provided at positions along both ends in the document conveyance width direction. The guide protrusion 9f forms a gap with the minimum width for transporting the document between the downstream guide member 14 and the third contact glass 7 when the downstream guide member 14 is set to face the third contact glass 7. Is to do. The backup unit 9 is urged toward the second image reading unit H2 by the compression spring 10 so that the guide projection 9f comes into contact with or is close to the reading surface of the third contact glass 7. Is held so that it can pass smoothly.

  As shown in FIGS. 5 to 7, the downstream guide member 14 is provided with first engagement means 31 that restricts the opening / closing operation at a position facing the side conveyance path 13 b. The first engagement means 31 includes a rotation lever 32 that is rotatably attached to a side surface of the downstream guide member 14 via a rotation shaft 35, and a lock groove 33 and a slide groove 34 provided on the rotation lever 32. It consists of The rotary lever 32 is supported by a shaft so as to be rotatable by a second operating means 36 provided on the upstream guide member 19 or a manual operating portion 37 operable from the guide cover 14a side. When the downstream guide member 14 having such a configuration is closed at a position facing the side conveyance path 13b as shown in FIG. The lock pin 38 is engaged and locked. Further, the rotation lever 32 is rotated upward by the second engaging means 36 engaged with the slide groove 34 or the operation portion 37 by manual operation, so that the lock groove 33 is released from the lock pin 38 and locked. Is released. By releasing the lock, as shown in FIG. 6, the downstream guide member 14 can be freely opened in the range of about 90 degrees in the left direction in the drawing with the mounting shaft 14b as a fulcrum.

  As shown in FIG. 3, the upstream guide member 19 includes a guide cover 19a that covers the upper conveyance path 13a, and a plurality of rollers and sensors provided in the guide cover 19a. . The upstream guide member 19 is attached so as to close and open the upper conveyance path 13a with the attachment shaft 19b as a fulcrum. As shown in FIGS. 5 to 7, the upstream guide member 19 is engaged with the first engaging means 31 of the downstream guide member 14 and interlocked with the first engaging means 31 (second relation). Combination means) 36 is provided. The second engagement means 36 includes an engagement plate 39 that is slidably attached in a direction orthogonal to the rotation direction of the upstream guide member 19, and a protrusion 40 provided at the lower end of the engagement plate 39. It is configured.

  As shown in FIG. 8, when the upstream guide member 19 and the downstream guide member 14 are closed, the engaging plate 39 has a protrusion 40 in the vicinity of the rotary shaft 35 on which the rotary lever 32 is axially supported. Together they are in a stationary state. From this state, as shown in FIG. 9, when the upstream guide member 19 is lifted upward with the mounting shaft 19b as a fulcrum, the engagement plate 39 is also moved upward accordingly. With the movement of the engagement plate 39, the protrusion 40 provided at the lower end of the engagement plate 39 slides in the slide groove 34 of the first engagement means 31 toward the end while moving the rotary lever 32 to the upstream side. The guide member 19 is rotated in the opening direction. The lock groove 33 is disengaged from the lock pin 38 by the rotating operation of the rotary lever 32. When the upstream guide member 19 is further lifted from this state as shown in FIG. 10, the projection 40 is completely removed from the slide groove 34, and the downstream guide member 14 can be freely opened with the mounting shaft 14b as a fulcrum. Become. FIG. 11 shows a state in which the upstream guide member 19 and the downstream guide member 14 are completely opened. Thus, the upstream guide member 19 and the downstream guide member 14 can be freely opened within a range of about 90 degrees with respect to the upper transport path 13a and the side transport path 13b.

  Next, an operation of closing the upstream guide member 19 and the downstream guide member 14 will be described with reference to FIGS. The downstream guide member 14 can perform the closing operation regardless of the closing or opening of the upstream guide member 19 in the same manner as the opening operation. As shown in FIG. 12, when the upstream guide member 19 is closed, the downstream guide member 14 is raised and rotated as it is toward the closed position facing the side conveyance path 13b. In this way, when the downstream guide member 14 approaches the closed position, the lock pin 38 rides on the inclined guide surface 43 on the lower end side of the rotary lever 32. When the downstream guide member 14 reaches the closed position as it is, the lock pin 38 38 is engaged with the lock groove 33 of the rotary lever 32 to be locked.

  As shown in FIG. 13, when the upstream guide member 19 is open, the downstream guide member 14 is closed first, or when the upstream guide member 19 is already closed, as shown in FIG. The member 19 can be closed by pushing it down toward the upper conveyance path 13a as it is. In this configuration, the engagement plate 39 provided in the second engagement means 36 has a slide means that can be retracted in the vertical direction along the long hole 44 provided in the upstream guide member 19. Because. Therefore, when the upstream guide member 19 is to be closed, the protrusion 40 provided at the tip of the engagement plate 39 forms the inclined surface of the inclined slide portion 60 provided in the first engagement means 31. By descending while sliding, it is set at the lock position as shown in FIG.

  As described above, in the document reading apparatus of the present invention, the upstream transport path and the downstream transport path forming the document transport path are divided and opened and closed. The upstream guide member and the downstream guide member that respectively guide the side conveyance path and the downstream conveyance path can be opened in a compact manner, so that installation space can be reduced and maintenance work can be facilitated. Further, since the engaging means is provided in each of the downstream guide member and the upstream guide member, the downstream guide member can be opened and closed in conjunction with the upstream guide member, so that the operability is excellent. ing.

  When the upstream guide member is opened, the downstream guide member is opened in conjunction with this, so that a paper jam or the like has occurred on the transport path, but the document can be easily removed. This will not damage the contact glass or backup glass that reads the original. In addition, paper dust and roller ridges are not dropped into the transport path when the document is removed.

  In addition, since it is possible to open only the downstream guide member alone without opening the upstream guide member, it is possible to easily remove dirt and dust such as dust and dirt attached to the contact glass and backup glass, Since such a cleaning can be opened and closed only on a necessary conveyance path, it is possible to suppress dust and dust from entering other conveyance paths as much as possible.

1 is a cross-sectional view illustrating an overall configuration of a document reading apparatus according to the present invention. FIG. 6 is a cross-sectional view of the original reading apparatus when a downstream conveyance path is opened. FIG. 3 is a cross-sectional view of the document reading apparatus when an upstream conveyance path and a downstream conveyance path are opened. It is sectional drawing which shows the structure of a 2nd image reading part. It is an effect | action figure which shows the initial stage operation | movement of lock release of a downstream guide member. It is an effect | action figure which shows the state which the downstream guide member opened. It is a principal part perspective view which shows the connection structure of an upstream guide member and a downstream guide member. It is an effect | action figure when both an upstream guide member and a downstream guide member are in a closed state. It is an effect | action figure which shows the state which the upstream guide member and the downstream guide member connected. It is an effect | action figure which shows the operation | movement at the time of both an upstream guide member and a downstream guide member heading to an open state. It is an effect | action figure which shows the state in which both the upstream guide member and the downstream guide member were open | released. It is an effect | action figure which shows the state which transfers a downstream guide member to a closed state. It is an effect | action figure which shows the operation | movement at the time of both an upstream guide member and a downstream guide member heading to a closed state. It is an effect | action figure which shows the closing operation | movement of an upstream guide member.

Explanation of symbols

A Document reading device F Conveyance unit H1 First image reading unit H2 Second image reading unit T Paper feed tray unit 1 First contact glass 2 Second contact glass 3 First reading unit 4 Second reading unit 7 Third contact glass 9 Backup unit 9b Backup glass 11 Discharge tray 13 Transport path 13a Upper transport path 13b Side transport path 13c Lower transport path 14 Downstream guide member 14a Guide cover 14b Mounting shaft 19 Upstream guide member 19a Guide Cover 19b Attaching shaft 31 First engaging means 32 Rotating lever 33 Lock groove 34 Slide groove 35 Rotating shaft 36 Second engaging means 37 Operation part 38 Lock pin 39 Engaging plate 40 Projection part 41 Paper feed tray 43 Inclined guide surface 44 long hole 60 inclined slide part

Claims (5)

A paper feed tray for placing a document, a paper discharge tray disposed below the paper feed tray, a first image reading unit for reading one side of the document, and the first image from the paper feed tray A transport path for guiding the document to the reading unit; a transport guide member for guiding the document transported along the transport path; and a second for reading the other surface of the document on the upstream side of the first image reading unit. In an original reading apparatus provided with an image reading unit of
The transport guide member includes an upstream guide member that guides a document on the paper feed tray toward the downstream side of the transport path ;
The second image reading unit is arranged so as to face the reading surface, and is divided and formed by a downstream guide member that guides the document from the upstream guide member to the first image reading unit ,
The upstream guide member and the downstream guide member are configured to be openable and closable with respect to the conveyance path, respectively, and the downstream guide member is opened in conjunction with the opening operation of the upstream guide member. An original reading apparatus characterized by comprising interlocking means for operating . The transport path includes an upper transport path extending in a horizontal direction from the paper feed tray and a side transport path extending downward from the upper transport path, and the upper transport path is opened by opening the upstream guide member. The document reading device according to claim 1, wherein the side conveyance path is opened by opening the downstream guide member. The upstream guide member is provided with a guide cover that covers the upper conveyance path, and the downstream guide member is provided with a guide cover that covers the side conveyance path, and is integrated with each of these guide covers. The document reading apparatus according to claim 2, wherein a side guide member and a downstream guide member are attached to the upper conveyance path and the side conveyance path so as to be freely opened and closed. The downstream guide member is engaged with the second image reading unit when the downstream guide member is closed, and the first guide is opened by releasing the engagement. Means are provided,
The document reading apparatus according to claim 1, wherein the engagement by the first engagement means is released along with the opening operation of the upstream guide member . The interlocking means is provided in the upstream guide member, and when the upstream guide member is closed, the interlocking means is engaged with a first engagement means provided in the downstream guide member, and the upstream guide member is opened. 2. The document reading apparatus according to claim 1, wherein the engagement with the first engagement means is released .

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