IMPROVEMENT IN ELECTROSTATIC COPYING APPARATUS

Abstract: The document holding device comprises a document holding member and a mounting mechanism therefor. The mounting mechanism includes a support member mounted for free oscillation and upward and downward movement, and the document holding member is pivotally mounted on the support member.

Description: This invention relates to an electrostatic copying apparatus. More specifically, it pertains to a device for holding a document of the kind referred to in the preamble of patent claim. Such a holding device is known from JP-A-50717/1977. The known document holding device itself to be provided in an electrostatic copying apparatus presents the following problem to be solved. Generally, the document holding device is comprised of a document holding member for covering a transparent plate disposed on the top of the housing of the copying apparatus and a document placed thereon and pressing the document against the transparent plate and a mounting mechanism for mounting the document holding member on a supporting base portion located adjacent to one side edge of the transparent plate in such a manner that the document holding member is free to pivot about a pivot axis extending along the aforesaid one side edge of the transparent plate. In the known document holding device, the movement of the document holding member mounted on the supporting base portion by the mounting mechanism is limited to a pivotal movement about the aforesaid pivot axis or to both this pivotal movement and an up-and-down movement as disclosed in US-A-4,124,296 or US-A-4,110,041. Accordingly, when the document is a relatively thick one such as a book, particularly with considerable variations in thickness in the direction of the pivot axis, the document holding member cannot well cover the transparent plate and the document placed thereon and cannot well press the document against the transparent plate. This problem still requires a solution. JP-A-50717/1977 discloses a document holding device for an electrostatic copying apparatus, said holding device comprising a holding member for holding a document placed on a transparent plate and a mounting mechanism for mounting the document holding member on a supporting base portion, located adjacent to a side edge of the transparent plate, so that the holding member is able to pivot about a pivot axis extending along one side of the transparent plate, to tilt relative to the pivot axis and to move up and down. It is an object of this invention to provide a stable document holding device for an electrostatic copying apparatus, in which a document holding member mounted on a supporting base portion by a mounting mechanism not only can turn about the pivot axis and move upwardly and downwardly, but also can make a tilting movement as viewed in a direction at right angles to the pivot axis, and therefore, even when the document is relatively thick with considerable variations in thickness in the direction of the pivot axis, can well cover the transparent plate and the document placed thereon. According to this invention, this object is achieved with a document holding device for an electrostatic copying apparatus as claimed in claim 1. Dependent claims are directed on features of preferred embodiments of the invention. Brief description of the figures: Figure 1 is an exploded perspective view showing a mounting mechanism for the document holding device and its related parts; Fig. 2-A and 2-B are a partial perspective view and a sectional view showing the mounting mechanism of the document holding device, and its related parts, in the state in which the document holding member is at its completely opened position; Figures 3-A and 3-B are a partial perspective view and a sectional view showing the mounting mechanism of the document holding device, and its related parts, in the state in which the document holding member is at its half-opened position; Figure 4 is a sectional view showing the mounting mechanism of the document holding device, and its related parts, in the state in which the document holding member is at its closed position ; and Figure 5 is a sectional view for illustrating the operation of the document holding device. The construction of the illustrated document holding device 4 in accordance with this invention is described below in detail. Again, the document holding device 4 includes the document holding member 5 and a mounting mechanism 316 for mounting the document holding member 5 in position. Two mounting mechanisms 316 spaced from each other in the direction of the pivot axis of the document holding member 5 are disposed in the illustrated embodiment. The document holding member 5 may be of any desired form which can cover the transparent plate 8 and an original document placed thereon at the aforesaid closed position. In the illustrated embodiment, it has a relatively rigid box-like frame member 318 formed of a suitable material such as a synthetic resin with its under side facing the transparent plate 8 being opened at the aforesaid closed position. An elastic member 320 formed of a suitable elastic material such as a sponge material is bonded to the inside surface of the frame member 318. Conveniently, a thin white sheet 322 made of a suitable plastic material such as a vinyl cloride resin or an urethan resin is attached to the exposed surface of the elastic member 320, namely that surface of the elastic member 320 which faces the transparent plate 8 at the aforesaid closed position. A gripping position 324 which can be handled in opening or closing the document holding member 5 is formed at the free end of the frame member 318. The mounting mechanisms 316 are described in detail with reference to Figures 1, 2-A, 2-B, 3-A, 3-B and 4. As Figure 1 clearly shows, each of the illustrated mounting mechanisms 316 has a support member 326, a linking member 328 and an intermediate member 330. The support member 326 has a pair of spaced side walls 332a and 332b, and three pins 334, 336 and 338 are mounted between the pair of side walls 332a and 332b. As will be appreciated from the following description, the axis of the pin 334 defines the pivot axis of the document holding member 5. A pair of leg portions 340a and 340b spaced from each other and extending downwardly in substantially parallel relationship to each other are formed in one side wall 332a as a one-piece unit. It is critical that the support member 326 should be mounted on a supporting base portion 342 located adjacent to one side edge of the transparent plate 8 in such a way that it is free to move upwardly and downwardly and oscillate in the direction of the pivot axis of the document holding member 5 (therefore, in the direction of the axis of the pin 334). Since in the illustrated embodiment, the transparent plate 8 is directly disposed on the top side of the housing 2 of the copying apparatus, the supporting base portion 342 on which to mount the support member 326 is defined by the top side itself of the housing 2. The document holding device 4 improved in accordance with this invention, however, is also applicable to a so-called document moving and scanning exposure type electrostatic copying apparatus in which a movable frame structure is provided slidably on the top surface of the housing 2 and a transparent plate is disposed on the movable frame structure. In this case, the support member 326 of the mounting mechanism 316 is mounted on the movable frame structure (and therefore, the movable frame structure defines the aforesaid supporting base portion). The manner of mounting the support member 326 on the support base portion 342 is described below. An opening 346 of a desired shape is formed at a subtantially horizontal top side 344 of an upper wall defining the top side of the housing 2. Correspondingly to the position of the opening 346, a mounting unit 350 utilized to mount the support member 326 as required is fixed to an upstanding plate 348 provided within the housing 2. The mounting unit 350 has a main portion 352 disposed substantially perpendicularly, and a pair of support shafts 354a and 354b spaced from each other a predetermined distance are fixed in the main portion 352. Guide rollers 358a and 358b having flanges 356 at both sides are rotatably mounted respectively on the free ends of the support shafts 354a and 354b. The mounting unit 350 further has a projecting portion 360 projecting horizontally from the upper edge of the main portion 352 and located below the opening 346 and a hanging portion 362 suspended from the projecting end of the projecting portion 360. As clearly shown in Figures 2-B, 3-B and 4, a circular opening 364 is formed in the projecting portion 360, and a linking piece 366 having a conically shaped part is inserted in the opening 364. A downwardly biasing spring member 370 for elastically biasing the linking piece 366 downwardly is interposed between the linking piece 366 and a projecting portion 368 projecting from the lower edge of the main portion 352. As shown in Figure 1, the opposite side portions of the projecting end of the projecting portion 360 are cut away to form shoulders 372a and 372b respectively, and guide grooves 374a and 374b are defined between these shoulders 372a and 372b and the hanging portion 362. As illustrated in Figure 2-A, the pair of leg portions 340a and 340b of the support member 326 are inserted into the mounting unit 350 through the guide grooves 374a and 374b respectively and through the space between the flanges 356 of the guide rollers 358a and 358b. In addition, as illustrated in Figures 2-B, 3-B and 4, the support member 326 is fixed to the linking piece 366 by screwing a setscrew 378 extending through a bottom wall 376 of the support member 326 into a threaded hole 380 (Figure 1) formed in the linking piece 366. Since the linking piece 366 of the support member 326 so mounted is free to move upwardly and downwardly with respect to the projecting portion 360 of the mounting unit 350, the support member 326 is movable upwardly and downwardly with respect to the mounting unit 350 and, therefore, with respect to the supporting base portion 342. Furthermore, since the linking piece 366 is elastically biased downwardly by the downwardly biasing spring member 370, the support member 326 is elastically biased downwardly by the spring member 370 with respect to the mounting unit 350, and, therefore, with respect to the supporting base portion 342. When the support member 326 is lifted from its lowermost position illustrated in Figures 2-A, 2-B, 3-A, 3B and 4 as stated hereinbelow, the guide grooves 374a and 374b and the flanges 356 of the guide rollers 358a and 358b guide the rising movement of the leg portions 340a and 340b of the support member 326. In addition, since the linking piece 366 is free to tilt with respect to the projecting portion 360 of the mounting unit 350 in any desired direction and the width of each of the guide grooves 374a and 374b (i.e., the size of each of these guide grooves in the direction of the axis of the pin 334) and the distance between the flanges 356 in each of the guide rollers 358a and 358b is set larger than the thickness of each of the leg portions 340a and 340b of the support member 326, the support member 326 is free to oscillate over a predetermined range with respect to the mounting unit 350 and, therefore, with respect to the supporting base portion 342 in the direction of the axis of the pin 334, i.e. in the direction of the pivot axis of the document holding member 5, as will be described below with reference to Figure 5. The range of the oscillation of the support member 326 is defined by the width of each of the guide grooves 374a and 374b and the spacing between the flanges 356 of each of the guide rollers 358a and 358b. It will be appreciated therefore that the support member 326 of the mounting mechanism 316 is mounted on the supporting base portion 342 in such 2 manner that it is free to move upwardly and downwardly and to oscillate in the direction of the pivot axis of the document holding member 5. As is seen from Figure 1, the linking member 328 of the mounting mechanism 316 has a bottom wall 382 and a pair of side walls 384a and 384b upstanding from the bottom wall 382. The linking member 328 is fixed to a predetermined position of the document holding member 5 by a setscrew 386 threadably received in the frame member 318 of the document holding member 5 through a bottom wall 382 of the linking member 328. Projecting portions 388a and 388b are formed respectively at one end portions of the side walls 384a and 384b of the linking member 328, and are rotatably mounted on the pin 334 mounted on the support member 326. Thus, the linking member 328 is pivotally mounted on the support member 326 and, therefore, the document holding member 5 is pivotally mounted on the support member 326 through the linking member 328. Elongated slots 390a and 390b having one open end (these slots will be described further hereinbelow) are formed at the other end portions of the side walls 384a and 384b of the linking member 328 respectively. If desired, the aforesaid linking member 328 may be formed with the frame member 318 of the document holding member 5 as a one-piece structure. Alternatively, the frame member 318 of the document holding member 5 may be directly mounted pivotally on the support member 326 while omitting the linking member 328. The intermediate member 330 of the mounting mechanism 316 has a bottom wall 392 and a pair of side walls 394a and 394b upstanding from the bottom wall 392. Slots 396 having one open end are formed respectively in one end portions of the side walls 394a and 394b as illustrated in Figures 2-B, 2-B and 4 (the drawings show only a slot 396 formed in the side wall 394b). By inserting the pin 336 mounted on the support member 326 in the slots 396, the intermediate member 330 is mounted on the support member 326 in such a manner that it is free to turn between a first angular position shown in Figure 4 and a second angular position shown in Figures 1, 2-A, 2-B, 3A and 3-B. At the first angular position shown in Figure 4, the outside surface of the bottom wall 392 of the intermediate member 330 abuts against the pin 338 mounted on the support member 326, whereby the turning of the intermediate member 330 in the clockwise direction in Figure 4 is restricted. At the second angular position shown in Figures 1, 2-A, 2-B, 3-A and 3-B, projecting portions 398 formed at one end portions of the side walls 394a and 394b of the intermediate member 330 (only a projecting portion 398 formed in the side wall 394b is shown in Figure 3B) abut against the pin 338 mounted on the support member 326 as clearly shown in Figure 2-B and 3-B, whereby the turning of the intermediate member 330 in the counterclockwise direction in Figures 2-B and 3-B is restricted. Slots 400a and 400b being open at the other end are formed at the other end portions of the side walls 394a and 394b of the intermediate member 330 respectively. Between these slots 400a and 400b is mounted a rod 404 having fixed in the opposite end portions thereof pins 402a and 402b projecting through the slots 400a and 400b (as will be described below these pins 402a and 402b cooperate with the slots 390a and 390b formed in the linking member 328). A pivoting-biasing spring member 406 is stretched between the rod 404 mounted on the intermediate member 330 and the pin 334 mounted on the support member 326. The rod 404 is connected to one end of the pivoting-biasing spring member 406 by screwing a screw member 408 into a threaded hole formed in the rod 404 and linking the aforesaid one end of the spring member 406 to one end portion of the screw member 408. The other end portion of the screw member 408 has an adjusting piece 410 threadably received thereabout, and by operating the adjusting piece 410, the degree of screwing of the screw member 408 with respect to the rod 404, and therefore, the tension of the pivoting-biasing spring member 406, can be adjusted. It will be easily appreciated by comparing Figures 2-B, 3-B and 4 that the pivoting-biasing spring member 406 is disposed such that when the intermediate member 330 is moved to a predetermined angular position which is between the first angular position shown in Figure 4 and the second angular position shown in Figures 2-B and 3-B, the opposite ends of the spring member 406 are located in alignment with the pivot axis of the intermediate member 330, and therefore with the axis of pin 336, and thus, the spring 406 is in the most stretched state. Accordingly, when the intermediate member 330 moves toward the first angular position from the aforesaid predetermined angular position, the pivoting-biasing spring member 406 elastically biases the intermediate member 330 to the first angular position clockwise in Figure 4. Conversely, when the intermediate member 330 moves toward the second angular position from the aforesaid predetermined angular position, the pivoting-biasing spring member 406 elastically biases the intermediate member 330 to the second angular position counterclockwise in Figures 2-B and 3-B. The operation of the document holding device 4 described hereinabove is now described. When the document holding member 5 is held at a totally opened position (i.e., the position shown in Figures 2-A and 2-B) which is displaced about 90 degrees in the opening direction from a closed position (i.e., the position shown in Figure 4), a part of the frame member 318 of the document holding member 5 (more specifically the outside surface of the rear side edge of the frame member 318) is in abutment against the substantially horizontal top side 344 formed in the supporting base portion 342. Thus, the document holding device 5 is prevented from further turning counterclockwise in Figure 2-B and is held at the totally opened position. Of course, it is possible to prevent the further counterclockwise turning of the document holding device 5 and hold it at the totally opened position by causing a suitable side of the document holding member 5 to abut against a suitable site of the supporting member 326 of the mounting mechanism 316, or causing a suitable site of the linking member 328 of the mounting mechanism 316 to abut against a suitable site of the supporting base portion 342 or a suitable site of the supporting member 326 of the mounting mechanism 316, instead of bringing a part of the document holding member 5 into abutment with the top side 344 of the supporting base portion 342. When the document holding member 5 is at the wholly opened position, the intermediate member 330 of the mounting mechanism 316 is held at the second angular position by the elastic biasing action of the pivoting-biasing spring member 406, as shown in Figures 2-A and 2-B. When the document holding member 5 is turned in the closing direction (i.e., clockwise in Figures 2-B and 3-B) from the aforesaid totally opened position to a half-opened position shown in Figures 3-A and 3-B, the free ends of the side walls 384a and 384b of the linking member 328 fixed to the document holding member 5 abut against the pins 402a and 402b provided in the intermediate member 330 and the pins 402a and 402b are positioned at the open ends of the slots 390a and 390b formed in the side walls 384a and 384b, as shown in Figures 3-A and 3-B. In the above state illustrated in Figures 3-A and 3-B, the linking member 328 fixed to the document holding member 5 abuts against the intermediate member 330 held in the second angular position by the elastic biasing action of the pivoting-biasing spring member 406; thus, the document holding member 5 is held at the position shown in Figures 3-A and 3-B, i.e. the half-opened position. Conveniently, this half-opened position of the document holding member 5 is displaced from the closed position by an angle of, for example, about 60 degrees. When the document holding member 5 is further turned in the closing direction (i.e., clockwise in Figure 3-B) from the half-opened position shown in Figures 3-A and 3-B, the linking member 328 fixed to it abuts against the intermediate member 330 and exerts a force on it. Thus, incident to the turning of the document holding member 5 in the closing direction, the intermediate member 330 is also turned clockwise in Figure 3-B against the elastic biasing action of the pivoting-biasing spring member 406. In response to this turning movement, the pins 402a and 402b disposed in the intermediate member 330 respectively advance into, and slide through, the slots 390a and 390b formed in the side walls 384a and 384b of the linking member 328. Thus, by the advancing of the pins 402a and 402b into the slots 390a and 390b, the linking member 328 and the intermediate member 330 are brought into engagement with each other. When the document holding member 5 is held at the closed position shown in Figure 4 and by two-dotted chain lines in Figure 3-A, the intermediate member 330 is brought to the first angular position shown in Figure 4 and by two-dotted chain lines in Figure 3-A, and therefore, is held at the aforesaid first angular position by the elastic biasing action of the pivoting-biasing spring member 406. The document holding member 5 is also surely held at the aforesaid closed position by the elastic biasing action of the spring 406 through the intermediate member 330 because the linking member 328 is in engagement with the intermediate member 330 by the slits 390a and 390b and the pins 402a and 402b. Now, let us assume that the document holding member 5 is turned in the opening direction (i.e., counterclockwise in Figure 4) from the closed position shown in Figure 4 and by two-dotted chain lines in Figure 3-A. Until the document holding member 5 is turned to the half-opened position shown in Figures 3-A and 3-B, the linking member 328 and the intermediate member 330 are held in engagement with each other through the slots 390a and 390b and the pins 402a and 402b. Thus, incident to the turning of the document holding member 5 in the opening direction, the intermediate member 330 is turned counterclockwise in Figure 4. Accordingly, the pins 402a and 402b slide through the slots 390a and 390b toward the open ends of these slots. When the document holding member 5 has been brought to the half-opened position, the intermediate member 330 reaches the second angular position and is held there by the elastic biasing action of the pivoting-biasing spring member 406, and the pins 402a and 402b are located at the open ends of the slots 390a and 390b. When the document holding member 5 is further turned in the opening direction (i.e., counterclockwise in Figure 3-B) from the half-opened position shown in Figures 3-A and 3-B to the totally opened position shown in Figures 2-A and 2-B, the pins 402a and 402b come out of engagement with the slots 390a and 390b and the linking member 328 comes out of engagement with the intermediate member 330. Hence, only the document holding member 5 and the linking member 328 fixed thereto are turned in the opening direction, and the intermediate member 330 is held at the second angular position shown in Figures 2-A and 2-B. When the document is a relatively thick one such as a book, the document holding device 4 is utilized. In this case, the document holding member 5 of the document holding device 4 is opened and closed according to the positioning of the document on the transparent plate 8 and the removal of the document from the transparent plate 8. In this mode, the document holding member 5 may be closed and opened between the closed position and the half-opened position shown in Figures 3-A and 3-B. Since in the improved document holding device 4 in accordance with this invention, the support member 326 of the mounting mechanism 316 described above is mounted on the supporting base portion 342 such that it is free to move upwardly and downwardly and to oscillate in the direction of the pivot axis (i.e., the axis of the pin 334) of the document holding member 5, it achieves the following excellent result especially when a document to be copied is a relatively thick one such as a book. When a relatively thick document as shown in Figure 5 is placed on the transparent plate 8 and the document holding member 5 is brought to the closed position, the support member 326 of the mounting mechanism 316 is lifted according to the thickness of the document by the elastic biasing action of the downwardly biasing spring member 370, as shown on the right side of Figure 5, and therefore, the rear end of the document holding member 5 is lifted. Accordingly, even when the document is relatively thick, the document holding member 5 can maintain a substantially parallel state or, as required, a forwardly tilted state with respect to the transparent plate 8 instead of a forwardly and upwardly inclined state, and thus can fully uniformly cover the document according to its thickness or changes in its thickness in the direction perpendicular to the sheet surface in Figure 5. In addition, when the thickness of the document on the transparent plate 8 varies considerably in the direction of the pivot axis of the document holding member 5, namely in the left-and-right direction in Figure 5, the document holding member 5 can properly tilt in the direction of its pivot axis according to changes in the thickness of the document. Accordingly, the document holding member 5 can fully uniformly cover the document according to its thickness and changes in its thickness even in the aforesaid direction of the pivot axis. Accordingly, the document holding device 4 improved in accordance with this invention can fully uniformly cover the document to conceal it completely and press it against the transparent plate 8 even when the document is relatively thick with considerable variations in thickness. Whilst the present invention has been described hereinabove with reference to the preferred embodiments taken in conjunction with the accompanying drawings, it should be understood that the invention is not limited to these specific embodiments alone, and various changes and modifications are possible without departing from the scope of the invention as claimed.

Claims: 1. A document holding device for an electrostatic copying apparatus, said holding device (4) comprising a holding member (5) for holding a document placed on a transparent plate (8) and a mounting mechanism (316) for mounting the document holding member (5) on a supporting base portion (342), located adjacent to a side edge of the transparent plate (8), so that the holding member (5) is able to pivot about a pivot axis (334) extending along one side of the transparent plate, to tilt relative to the pivot axis and to move up and down, characterised in that the holding member (5) is pivotally fixed to a pair of spaced support members (326) which form part of the mounting mechanism, each support member comprising a pair of leg portions which are so guided in corresponding grooves (374a, 374b) in said supporting base portion (342) and corresponding grooves in a pair of corresponding flanged roller members, positioned beneath said supporting base portion, as to allow said tilting and said up and down movement. 2. A document holding device of claim 1, characterized in that said two support members are disposed in spaced-apart relationship with each other in the direction of said pivot axis (334). 3. A document holding device of claim 1 or 2, characterised in that said each support member (326) has an associated linking member (328) interposed between the document holding member (5) and the support member (326), fixed to the document holding member (5) and mounted oscillably about said pivot axis (334) as a center, an intermediate member (330) mounted on the support member (326) for free pivoting between a first angular position and a second angular position, and a pivoting-biasing spring member (406) interposed between the support member (326) and the intermediate member (330) and biasing the intermediate member (330) elastically to said first angular position when the intermediate member (330) moves toward the first angular position from a predetermined angular position between the first and second angular positions and to said second angular position when the intermediate member (330) moves toward the second angular position from said predetermined angular position; when the document holding member (5) is at a position away toward the closing direction from a half-opened position which is displaced by a predetermined angle in the opening direction from a closed position at which it covers the transparent plate (8), the linking member (328) is in engagement with the intermediate member (330); when the document holding member (5) is turned between the closed position and the half-opened position, the intermediate member (330) is concomitantly turned between the first and second angular positions; and when the document holding member (5) is at a position away from said half-opened position in the opening direction, the linking member (328) and the intermediate member (330) come out of engagement with each other. 4. A document holding device of claim 3, characterized in that one of the linking member (328) and the intermediate member (330) has formed therein an elongated slot (390a, 390b) having one open end and the other has provided therein a pin (402a, 402b); when the document holding member (5) is held at the half-opened position and the intermediate member (330) is held at the second angular position, the pin (402a, 402b) is located at the open end of the slot (390a, 390b); when the document holding member (5) is turned in the closing direction from the half-opened position, the pin (402a, 402b) advances into the slot (390a, 390b) and slides therethrough; and when the document holding member (5) is turned in the opening direction from the half-opened position, the pin (402a, 402b) comes out of engagement with the slot (390a, 390b). 5. A document holding device of claim 3 or 4, characterized in that the half-opened position of the document holding member (5) is a position which is displaced from the closed position by an angle smaller than 90 degrees in the opening direction; and when the document holding member (5) is turned in the opening direction beyond the half-opened position to an angular position about 90 degrees displaced from the closed position and thus held at a totally opened position, the document holding member (5) itself and/or the linking member (328) abuts against the supporting base portion (342) and/or the support member (326), whereby the turning of the document holding member (5) beyond the totally opened position is hampered and the document holding member (5) is self-held at the totally opened position. 6. A document holding device according to one of claims 1 to 5, characterized in that a downwardly biasing spring member (370) is interconnected between each said support member (326) and the supporting base portion (342).

Inventors: ISEKI, MASAHIDE, KAJITA, HIROSHI, KAWAMORI, YOSHIZO, NAKAJIMA, TADANOBU
Applicants: MITA INDUSTRIAL CO. LTD.
Application year: 1982
Main classification: G03B27
IPC codes: G03B27, G03G15