Document scanners

A document scanner is described for scanning a page of a book comprising a movable housing having at least one flat face containing a window through which light from a document to be copied can pass. A scanner within the housing adapted to scan an image of the document to generate an electrical video signal corresponding to the information carried by the document, a device for supporting a book face upwards so that the book can be moved into contact with the window, and a pivoting joint between the housing and a support therefor to permit rotation of the housing into at least one other position in which the window is unobstructed and light from a remote document can be directed therethrough to form the image to be scanned.

DESCRIPTION 
1. Field of invention 
This invention concerns scanners for converting an image of a document into 
an electrical video signal which may be digitized for storage such as on a 
magnetic medium, and on replay can be made to assemble a display on a 
television screen or the like corresponding to the original document, or 
may be employed as an input signal to a printer/plotter. 
In this specification the term document is intended to mean any generally 
flat surface bearing information and includes a page of a book, a sheet of 
film or picture, map, drawing and the like. 
2. Background to the invention 
Conversion of information contained on a document into an electrical signal 
can be achieved in a number of ways. 
In one arrangement relative movement is effected between a spot of light 
and an information bearing surface and reflected light from the spot is 
focused onto a photocell. As the spot moves over the surface so the 
reflected light level varies in relation to the information content and a 
varying electrical signal derived from the photocell comprises the 
electrical video signal. 
In another arrangement an electron beam is scanned over a photoconductive 
surface onto which an image of the surface is focussed. The electron beam 
current varies with the light level at different points of the 
photoconductive surface and an electrical signal derived from these 
current variations comprises the said electrical video signal. 
In all cases however it is necessary to present the document to the 
scanning device and provide appropriate illumination for the document so 
as to image the latter correctly and it is an object of the present 
invention to provide a scanner which can be used with a variety of 
documents from large maps and the like to microfiche. 
SUMMARY OF THE INVENTION 
According to the present invention a document scanner for scanning a page 
of a book comprises: 
1. a movable housing having at least one flat face containing a window 
through which light from a document to be copied can pass. 
2. a scanner within the housing adapted to scan an image of the document to 
generate an electrical video signal corresponding to the information 
carried by the document, 
3. means for supporting a book face upwards so that the book can be moved 
into contact with the window, 
4. a pivoting joint between the housing and a support therefor to permit 
rotation of the housing into at least one other position in which the 
window is unobstructed and light from a remote document can be directed 
therethrough to form the image to be scanned. 
Lamp means may be located within the housing along with the scanner, so 
that a document can be both illuminated and scanned through the window. 
The book support is conveniently formed from two upwardly divergent plates, 
in the form of a trough, and the two plates may be relatively movable so 
as to alter either the included angle therebetween or the lateral spacing 
between the two lowermost edges of the two plates, or both, so as to 
accommodate different sizes of book. Conveniently means is included for 
changing the direction of sequential address of the elements in the said 
line of elements, to allow the scanning direction relative to a book to 
always be in the same sense even when the book has been turned through 
180.degree.. 
Typically scanning device is a camera which includes a line of the 
photoconductive elements are charge coupled devices having very small 
dimensions. 
In such an arrangement scanning is achieved by moving the detector within 
the housing so that effectively a slit like field of view is moved across 
the window, always parallel to the said one edge thereof whilst all the 
time a sequential sampling of the light is performed at points along the 
length of the detector so as to produce an electrical video signal. 
Preferably means is provided for altering the focus of and/or the depth of 
focus of the image. 
Where a light source is located within the second housing, and light 
therefrom is directed through the window to illuminate a document located 
on the other side thereof. 
An elongate lamp is preferably employed as the said light source and is 
positioned parallel to the slit like field of view of the scanning device 
but just off axis and moves with the scanning device so as to be just out 
of the field of view of the scanning device. 
Preferably means is provided for converting the video signal into a digital 
signal suitable for storage in a digital computer store. 
A film (microfiche or transparency) carrier with or without a source of 
illumination may be detachably mounted on the movable housing itself or 
mounted permanently or removably on a second support spaced from and fixed 
relative to the first mentioned support (i.e. the movable housing support) 
so that as the latter is moved so the window therein will align with the 
carrier to allow an image of the film to be found on the scanner. 
The carrier may be mounted laterally of the book position so that the 
housing has only to be rotated through 45 or so to align therewith. 
Alternatively the carrier may be mounted above the book position so that 
the housing must be rotated through in excess of 90.degree. to align 
therewith leaving the lateral position unobstructed. This is to advantage 
in that when the window faces side ways light from a large document such 
as a map or picture or large drawing hanging for example on a wall or a 
suitable support or screen, can be focussed therethrough to allow an image 
of the large document to be formed and scanned. 
The invention thus provides a very versatile and adaptable scanner-which 
can handle all document sizes from micro-to macro- which can in turn 
supply output signals to a printer/plotter (known per se) to allow copies 
to be produced while the document is scanned or immediately thereafter.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
FIG. 1 illustrates in side elevation a complete document scanner unit which 
includes a book support which is the subject of a copending application. 
The support comprises a pair of diverging plates generally designated 10 
and 12 each comprising a metal inner member 14 and 16 and an outer coating 
of plastics material 18 and 20 respectively. 
The two metal struts 14 and 16 are joined in a channel arrangement at 22 
which itself is attached to an upper ring 24 of a bearing assembly having 
a lower ring 26 which is secured to a lifting base 27 (to be described in 
more detail hereinafter) mounted on a lower final base 28. 
A ball-race 30 allows for rotation of the upper ring 24 relative to the 
lower ring 26 and a hand grip 32 extends around the upper ring to allow 
for manual rotation of the ring and support assembly. 
A springloaded ball 34 and depressions such as 36 in the underside of the 
upper ring 24 provide stops to define at least two preferred angular 
positions separated by 180.degree. of rotation of the ring 24. The base 28 
serves as a support for a column 37 and associated housing 38 which houses 
controls and drives as required. 
At the upper end the column provides a support for a housing 40 within 
which is located a detector 42 such as a Fairchild camera type CCD 1500. 
The latter is mounted rigidly on a platform 44 the underside of which 
slidably engages a guide rail 46 and includes a driving collar threadedly 
engaged on a screw threaded rod 48. Rotation of the collar produces 
lateral movement of the platform 44 parallel to the guide rail 46. 
A further guide rail at 50 prevents any torsional movement of the platform. 
A drive means (not shown) such as an electric motor is provided on the 
underside of the platform to drive the latter from one end of its traverse 
to the other. 
The position of the platform 44 at the opposite end of its traverse is 
shown in dotted outline at 52. 
Protruding from the platform is an arm 54 which is shown broken in order to 
reduce hidden detail to the minimum. The lower end of the arm 54 carries a 
strip light 56 and electrical connection to the strip light is achieved 
through a flexible cable (not shown). 
As the platform 44 moves along its rails, so the light 56 travels by the 
same lateral distance. 
The light 56 is positioned just behind a window 58 in the lower end of the 
housing 40 and the camera/detector 42 views a narrow strip which extends 
perpendicular to the direction of travel of the platform 44. With movement 
of the platform 44 from one end to the other of the rails 46 and 50, the 
viewing strip moves laterally from the end 60 to the end 62 of the window 
58 and in the reverse direction back again from 62 to 60. 
The camera/detector comprises a linear array of photoconductive junctions 
and an appropriate lens (all not shown) so that a document positioned just 
to the left-hand side of the window shown in FIG. 1 will be in focus in a 
plane containing the line of photoconductive junctions. A document surface 
bearing against the underside of the window 58 will thus be brought to 
focus on the linear array of photoconductive junctions. An electrical 
scanning circuit scans the junctions in succession so as to produce a 
series of electrical pulses corresponding to the illumination falling on 
the junctions along the linear array. By synchronising the movement of the 
detector 42 and the rate of movement along the rails 46 and 50, the output 
signal will approximate to a video signal similar to that obtained by 
rectilinear line scanning. 
A book is shown in dotted outline at 64, opened and resting on the two 
inclined diverging supports 10 and 12. The upwardly facing surface of the 
left hand open page 66 will be viewed by the scanner 42 through the window 
58 and a video signal of the page concerned can be otained by scanning in 
the manner previously described. 
By rotating the platform ring 24 through 180.degree., the opposite facing 
page 68 will be presented to the window 58 and can be scanned and 
converted into a video signal in a similar manner. 
In order to present the appropriate page of the book to the window 58, the 
support assembly carried by the lifting platform 27 can be elevated until 
the pages of the book are in contact with the window 58 and the underside 
of the housing 70. To this end an electric motor drive shown in dotted 
outline at 72 is provided in the housing 38 and the lifting platform 27 is 
attached to a sleeve 74 carried by the colum 37 which is driveable up and 
down the column by means of the electric motor 72 typically via the 
gearbox and clutch mechanism. 
Up and down controls at 76 and 78 respectively are provided for appropriate 
rotation of the electric motor 72. 
A stop mechanism is provided which detects when the book is just below the 
housing 40 with the book still out of contact with the window 58 and 
underside 70 of the housing 40. At this position the motor 72 is stopped 
automatically and a form of manual control is provided to allow the book 
to be offered up into contact with the housing 40 under hand control. 
Although not shown, some form of ratchet or clutch mechanism is provided 
which allows the assembly carried by the lifting platform 27 to be moved 
in an upward direction without fall-back occurring and a de-clutching 
device (again not shown) is provided to allow the platform to be moved in 
a downward direction after the page 64 has been scanned. Although not 
shown, stop means is provided at the bottom of the travel to arrest the 
movement of the motor and downward movement of the sleeve 74 before 
bottoming. 
In order to provide for a degree of shock absorbing, the ring 26 may be 
carried by rubber bushes at 77 and 79. 
FIG. 2 is a cross-section through the housing 40 viewed from above and 
shows the window 58 in relation to the elongate fluorescent tube 56 
previously shown in FIG. 1. In addition the field of view of the detector 
42 is demonstrated by the diverging lines 80 and 82. To this end the 
divergence is intended to accommodate the full height of the window 58 and 
the lateral movement of the scanner 42 is intended to cover the 
perpendicular dimension of the window 58. 
FIG. 3 which is an end elevation of the equipment shown in FIG. 1, 
illustrates the extent of the window 58 in the lower inclined face 84 of 
the housing 40. 
The left hand side of the book support 10 can clearly be seen in FIG. 3 as 
also can the handwheel section 32 attached to the upper ring. 
As is more clearly seen in FIG. 3, the column 37 is one of a pair the other 
being denoted by reference numeral 39 and drive to the lifting platform 27 
is achieved through rotating screw 86 located between and parallel to the 
two columns of 37 and 39. 
By using two columns any tendency of the book support assembly to twist 
about the axis of the screw threaded drive 86 will be prevented. 
FIG. 3 also shows the handle 88 (also shown in FIG. 1) which extends 
laterally from the sleeve 74 and can be used by the opertor to raise and 
lower the support manually during the last part of the travel. 
Although not shown a modified document scanner may be constructed from 
components such as are shown in FIGS. 1 to 3 but excluding the lamp 56. In 
such a modified scanner light from a document which may be a transparent 
film such as a microfiche, is directed through the window 58 and focussed 
using the aforementioned lens or additional lens means (not shown) onto 
the linear array of photoconductive junctions (not shown). Scanning and 
production of the video signal as then performed is beforementioned. 
The second housing containing the detector may itself be hinged so as to 
allow it to be pivoted into a range of positions to accommodate different 
documents and/or image forming optical systems. 
In FIG. 4 the same reference numerals as have been employed in FIGS. 1 to 3 
are used to denote similar items. 
In order to provide for a degree of self centering of a book about the 
lower edge 60, the support trough 10, 12 is movable freely in the 
direction of the arm 29 relative to the platform support 27. 
In FIG. 5 the housing 40 is shown tilted to a horizontal position and a 
projection device 116 is shown mounted adjacent to or on the housing 40 
comprising a lamp 118, a condensor 120 and film holder 122 for 
transparencies or microfiche or the like. 
A focussing lens 124 is adjustable to form an in focus image of the film or 
other device 126 on the line of photosensitive elements (not shown) in the 
camera tube or scanner 42. 
The projection device 116 may be removed to leave only the lense 124 and 
its relative supports 128 and 130 to enable, with an appropriate focal 
length lens, a large document such as a picture or map shown dotted at 132 
to be focussed onto the camera 42. 
A lamp 134 may be mounted on the support 130 to illuminate a document such 
as at 132. 
Although not shown the housing 40 may be rotated further in the direction 
of arrow 136 until the window 58 faces upwards and is substantially 
horizontal to allow for imaging from above.