Portable image scanner having manual or automatic feed

A portable image scanner capable of selecting a manual document loading mode in which a cover member is united to a scanner body to feed a cut-sheet document through a document passage defined between the united scanner body and cover member for scanning the document, or a self-propelling mode in which the cover member is separated from the scanner body to move the independent scanner body on a thick document such as a book. The scanner body has a document sensor for detecting the cut-sheet document placed in the document passage in the manual document loading mode, and the thick document in the self-propelling mode to prevent the scanner body moving on the document from falling out of the edge of the thick document.

BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention relates to an image scanner for automatically scanning a 
document to optically read out and output image date that is on the 
document to an image processing device such as a computer, and more 
particularly to a portable image scanner capable of selectively uniting a 
cover member to a scanner body to feed a cut-sheet document to be scanned, 
or detaching the cover member from the scanner body to move the 
independent scanner body on a thick document such as a book. 
Description of the Prior Art 
Portable image scanners can be generally classified into a manually 
scanning type for manually moving the scanner along an image face of a 
document to be scanned, and an automatic scanning type for automatically 
moving a given document moved relative to the scanner to read out the 
image on the document. The portable automatic image scanner capable of 
scanning the whole image face of a given document is in widespread use for 
various image processing or optical character recognition (OCR), replacing 
hand scanners which are manually handled for scanning only a part of the 
image on the document. 
The portable image scanners capable of automatically moving on the image 
face of the given document are further subdivided into 1 a 
document-feeding type portable scanner, generally called a "mannually 
document loading type scanner", capable of automatically feeding a 
cut-sheet document through a stationary scanner body to scan an image on 
the document, as proposed in U.S. Pat. No. 4,667,253, and U.S. Pat. No. 
4,677,495; 2 a scanner-moving type portable scanner, generally called a 
"self-propelling type scanner", capable of moving along an image face on a 
fixed document so as to obtain image data directly even from a thick book, 
as described in U.S. Patent No. 5,182,450, Japanese Patent Application 
Public Disclosures Nos. SHO 61-251356(A) and SHO 63-42275(A) and Japanese 
Utility Model Appln. Public Disclosure No. SHO 58-127753(A); and 3 a 
combined type portable scanner having both functions of the aforesaid 
document-feeding type scanner and the self-propelling type scanner, as 
proposed in Japanese Patent Appln. Public Disclosures Nos. HEI 
2-226958(A), HEI 2-22958(A), and HEI 4-117764(A). 
The prior art combined type portable scanner capable of selectively feeding 
the cut-sheet document and moving on the fixed document has excellent 
applicability to various purposes, but tends to be complicated in 
structure and therefore is susceptible to mechanical trouble and awkward 
to handle. 
For instance, the combined type portable scanner of Japanese Pat. Appln. 
Pub. Discl. No. HEI 2-22958(A) is composed of a combination of a 
detachable image reading unit and a document feeding unit. The image 
reading unit of this conventional scanner has a driving motor and a train 
of gears including a coupling gear, and the document feeding unit has a 
driving roller and a train of gears including a counterpart coupling gear 
to be engaged with the coupling gear of the image reading unit, so that 
which rotational motion produced by the motor in the image reading unit is 
transmitted to the driving roller through the gears including the coupling 
gears, so as to forward a cut-sheet document. However, the document 
feeding unit of this conventional scanner incorporating the driving gears 
becomes complicated in structure, and therefore, the scanner is unduly 
large and difficult to carry. 
There has not been proposed so far a portable scanner with an automatic 
document feeder capable of automatically feeding a plurality of cut-sheet 
documents one by one in succession, even if it can automatically feed a 
single cut-sheet document. Thus, conventional portable scanners are 
inconvenient in handling a number of cut-sheet documents. Furthermore, 
since the conventional portable scanner uses an external power source in 
spite of its normal user with a handheld computer or the like, it is 
restricted in its use. 
The conventional "self-propelling" type portable scanner capable of moving 
by itself on a fixed document such as a thick book to scan an image on the 
document must be manually stopped by giving a stop instruction from an 
external image processing device to the scanner or lifting up the scanner 
by hand when the scanner moving on the document arrives at the edge of the 
document. If an operator fails to stop the scanner, the scanner will fall 
from the edge of the thick document. 
OBJECT OF THE INVENTION 
This invention is made to eliminate the drawbacks suffered by the 
conventional portable image scanner as described above and has an object 
to provide a simple and convenient portable image scanner capable of 
readily selecting a "manual document loading mode" in which a cut-sheet 
document is introduced by hand into a document entrance and then 
automatically fed to a document exit through an image reading portion, or 
a "self-propelling mode" in which a scanner body moves by itself on a 
fixed document to automatically read out the image data on the document. 
Another object of this invention is to provide a portable image scanner 
capable of stably scanning the image on various kinds of documents with 
high resolution, and is well balanced to be easily handled. 
Still another object of this invention is to provide a portable image 
scanner having a detachable document feeder capable of automatically 
feeding a plurality of documents one by one. 
Yet another object of this invention is to provide a portable image scanner 
having a safety mechanism for automatically stopping a scanner body moving 
on a document for scanning when the scanner body arrives at the edge 
portion of the document. 
SUMMARY OF THE INVENTION 
To attain the object described above according to this invention, there is 
provided a portable image scanner comprising a scanner body including 
driving rollers for imparting a relative motion to a document to be 
scanned, and image reading means for scanning the document while 
relatively moving the document, and a cover member detachably attached to 
the scanner body so as to cover the bottom of the scanner body, wherein 
the cover member is attached to the scanner body to feed a cut-sheet 
document, and removed from the scanner body to allow the scanner body to 
move on a thick document such as a book. 
The cover member is provided with press rollers which come into contact 
with the driving rollers of the scanner body to define a document passage 
including an image reading portion between the united scanner body and 
cover member, so as to stably feed the cut-sheet document through the 
document passage. 
A document feeder having a document tray and document separation means can 
be attached to at least one of the scanner body and the cover member, so 
that a plurality of cut-sheet documents stacked on the document tray can 
be automatically sent out one by one into the document passage. 
The scanner body is provided with a document sensor with the sensor lever 
dangling, and switching means which is actuated by the sensor lever. The 
sensor lever assumes its upright posture in the free state, meaning that 
no document is placed in the document passage. When the document to be 
scanned is in the document passage, the sensor lever is pushed up by the 
document to switch on the switching means, thus recognizing the document 
being ready for scanning. 
By putting the scanner body separated from the cover member on a thick 
document such as a book, the sensor lever comes in touch with the document 
to detect the document, thereby allowing the scanner body to move on the 
document to scan the image on the document. When the moving scanner body 
arrives at the edge portion of the document, the sensor lever comes off 
from the edge of the document to halt the operation of the scanner body, 
thus preventing the scanner body from falling out of the thick document. 
In the manual document loading mode in which the cover member is attached 
to the scanner body to define the document passage through which the 
cut-sheet document passes for scanning, the document sensor operated by 
the sensor lever serves to detect the leading edge of the cut-sheet 
document so as to provide timing information as to the scanning of the 
document under the control of a control system in the scanner body. The 
detection of the leading edge or end of the document is particularly 
useful for automatically feeding the cut-sheet documents one by one into 
the document passage defined between the united scanner body and cover 
member by use of the document feeder. 
Other and further objects of this invention will become obvious upon an 
understanding of the illustrative embodiments about to be described or 
will be indicated in the appended claims, and various advantages not 
referred to herein will occur to one skilled in the art upon employment of 
the invention in practice.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will become more fully understood from the detailed 
description given hereinbelow and the accompanying drawings which are 
given by way of illustration only, and thus are not limitative of the 
present invention. 
In the exemplary embodiment of the invention as described in the drawings, 
a portable image scanner of this invention generally comprises a scanner 
body 1, a cover member 20 which is detachably attached to the scanner body 
1, and a document feeder 30. By uniting the cover member 20 to the scanner 
body 1, a cut-sheet document of a standard size can be automatically fed 
through a document passage P defined between the united scanner body 1 and 
cover member 20 for scanning an image printed on the document (manual 
document loading mode). By detaching the cover member 20 from the scanner 
body 1, the scanner body 1 can itself move on a thick document such as a 
book while reading out image data from the document (self-propelling 
mode). When the document feeder 30 is attached to the united scanner body 
1 and cover member 20, a plurality of cut-sheet documents can be 
automatically fed one by one into the document passage P formed between 
the united scanner body 1 and cover member 20 (automatic document loading 
mode). 
The scanner body 1 comprises a housing 2 with a bottom 2a in which a 
scanning slit 2b having a length nearly equal to the effective image 
scanning width of the scanner is formed, image reading means 4 for 
optically reading out image data from the document, a circuit board 6, a 
motor 8, and driving rollers 10. The image reading means 4 and the motor 8 
are fixed on the bottom 2a. The circuit board 6 is supported on a mounting 
frame 11 within the housing 2. The driving rollers 10 are formed of two 
rows of rollers 10a and 10b respectively held by driving shafts 12a and 
12b rotatably supported by the mounting frame 11. 
The mounting frame 11 for supporting the circuit board 6 and driving 
rollers 10 is resiliently mounted on the housing 2 through spring means 
11a so as to protect the circuit board 6 from shock and vibration and give 
proper resiliency to the driving rollers 10. 
The given document D to be scanned moves relative to the scanner body 1, 
though the scanner body 1 moves on the document in the self-propelling 
mode. Accordingly, the relative moving direction in which the document D 
moves relative to the scanner body 1 in the manual document loading mode 
and the scanner body 1 moves relative to the document in the 
self-propelling mode is herein defined as the "document feeding direction" 
for convenience. The document D to be scanned for optically reading out 
image data is placed opposite to the bottom 2a of the scanner body 1. The 
document passage P defined between the scanner body 1 and cover member 20 
united in the manual document loading mode has a document entrance M1 on 
the back side relative to the document feeding direction, and a document 
exit M2 on the front side relative to the same direction. 
The image reading means 4 includes a linear image sensor formed of CCD or 
the like and lighting means for illuminating the document placed opposite 
to the bottom 2a of the scanner body 1, and has a function of optically 
reading out the image on the given document and converting image data thus 
obtained to electric data signals. The structure and elements constituting 
the image reading means 4 are by no means limitative and may be composed 
of any other conventional elements. 
The circuit board 6 includes an image processing circuit for processing the 
image data read out by the image reading means 4, a control circuit for 
not only the image processing circuit but also the motor 8, and an 
interface circuit for sending out the image data processed in the image 
processing circuit to an external image processing device (not shown) such 
as a computer and word processor through a cable 6a and a connector 6b. 
The motor 8 may preferably be a rotation-controllable electric motor such 
as a pulse motor, and is secured at one side portion on the bottom 2a 
other than the scanning slit 2b. 
Through a power switch 9, an electric current is selectively supplied to an 
electric system including the image processing circuit and other circuits 
on the circuit board 6 and the motor 8. However, in place of the power 
switch 9, the supply of the electric current to the electric system in the 
scanner body 1 may be controlled from the external image processing 
device. 
The driving rollers 10 consisting of the entrance side rollers 10a 
supported by the driving shaft 12a and the exit side rollers 10b supported 
by the driving shaft 12b are arranged on both sides of the scanning slit 
2b, and partially protrude downward from the bottom 2a so as to come into 
touch with the image face on the document D to be scanned. 
In this embodiment, the driving shaft 12a on the side of the document 
entrance M1 extends substantially over the whole width of the scanner body 
1 and supports the four driving rollers 10a, and the driving shaft 12b on 
the side of the document exit M2 is shorter than the scanning slit 2b and 
supports the three driving rollers 10b. However, the length each of the 
driving shafts 12a and 12b and the number of the driving rollers 10 
supported by the respective driving shafts 12a and 12b are not limitative. 
The driving shafts 12a and 12b have gears 14a and 14b engaged with a 
toothed endless belt 8a through which the rotational motion produced by 
the motor 8 is transmitted to the driving shafts 12a and 12b. 
The driving shaft 12a is provided on its one end with a gear 14c which is 
engaged with a driving gear 31 incorporated in the document feeder 30 
through a gear hole 2d bored in the housing 2 of the scanner body 1 for 
driving the document feeder 30. 
On the edge portion of the bottom 2a on the side of the document entrance 
M1, there is disposed a document sensor 16 consisting of a rotational 
sensor lever 16a rotatably supported by the mounting frame 11 and 
switching means 16b actuated by the sensor lever 16a. 
The sensor lever 16a assumes its upright posture in the free state, with 
its lower end dangling below the lower parts of the driving rollers 10, so 
that it comes into contact with the document D placed opposite to the 
bottom 2a of the scanner body 1, and consequently, it is pushed up by the 
document to actuate the switching means 16b, thus detecting the document 
D. 
Though the document sensor 16 in this embodiment is composed of such 
mechanical elements including the rotational sensor lever 16a, it may be 
formed of a non-contact photoelectric detector consisting of, for example, 
a light emitting element and a photodetector. 
Within the scanner body 1, an electric power source 18 such as a battery is 
disposed above the image reading means 4. Though it is preferable to use a 
charging battery as the power source 18, a battery holder or an AC adapter 
may be mounted instead of the battery as occasion demands. In case of 
need, the power source 18 may of course be left out to make the scanner 
more small and light, and instead, an external power source may be 
utilized. However, it is desirable to use the power source 18 such as the 
charging battery to balance the scanner body 1, and particularly, permit 
the scanner body 1 to move stably along the image face of the document in 
the self-propelling mode. For this purpose, the charging battery may be 
preferably located aside a little to the side opposite to the motor 8, 
preserving the entire balance of the scanner body 1. Thus, by positioning 
the center of gravity of the scanner body 1 at the middle of the scanner 
body 1, the stability of the scanner body 1 can be improved. 
The cover member 20 is formed in a flat plate having a plane shape 
coincident with the bottom 2a of the scanner body 1. 
The cover member 20 is provided on its upper side 20a facing the bottom 2a 
of the scanner body i with engaging means 22 by which the cover member 20 
is securely united to the scanner body 1. Each engaging means 22 in this 
embodiment is formed of a substantially L-shaped hook which is inserted 
into an engaging hole 2c formed in the bottom 2a of the scanner body 1 and 
cooperatively engaged with the edge of the engaging hole 2c in a hooked 
manner. 
Though the substantially L-shaped engaging means 22 is used in this 
embodiment, this should not be understood as limitative, and may of course 
be of any type of engaging structure and is essential to enable the 
scanner body 1 and the cover member 20 to be detachably united with each 
other. Though it is desirable to position the engaging means 22 at the 
corner portions of the cover member 20 and correspondingly the engaging 
holes 2c at the corner portions of the bottom 2a of the scanner body, 
these engaging elements 22 and 2a may not necessarily be positioned at the 
corners in the light of the other components as shown in the illustrated 
embodiment. 
In the side wall of the cover member 20 on the entrance M1 side, there are 
formed engaging holes 20a for receiving engaging means 34 of the document 
feeder 30, which will be described later in detail. 
The cover member 20 is provided on its upper side with two rows of press 
rollers 24 corresponding to the driving rollers 10 on the bottom 2a of the 
scanner body 1. When uniting the cover member 20 to the scanner body 1, 
the press rollers 24 come into contact with the driving rollers 10 to form 
the document passage P therebetween in the manual document loading mode. 
In order to bring the press rollers 24 in resilient contact with the 
driving rollers 10 with a moderate pressure force, the press rollers 24 
may be held by resilient shafts. It is desirable that the pressure force 
of the press rollers 24 on the entrance M1 side should be somewhat 
stronger than that of the press rollers 24 on the exit M2 side, thus 
imparting an adequate tension to the document to be fed through the 
document passage P. 
The cover member 20 further has a pressure member 26 between the two rows 
of the press rollers 24. The pressure member 26 comes in press contact 
with the image reading means 4 of the scanner body 1 when uniting the 
cover member 20 with the scanner body 1, so as to bring the document being 
fed through the document passage P in close contact with the image reading 
means 4 in scanning the image on the document as shown in FIG. 5. The 
pressure member 26 may be desirably formed of a flexible and resilient 
sheet or plate material such as of plastic resin. To permit the document 
to pass through the document passage P without hindrance, the sheet-like 
pressure member 26 should be inclined upward in the backward direction. 
Though the pressure member 26 used in this embodiment is shaped in a sheet, 
it may be of course formed of a roller or other material, or omitted if 
the document being fed through the document passage P can be brought in 
close and stable contact with the image reading means 4 of the scanner 
body 1 by, for example, narrowing the distance between the rows of the 
driving rollers 10 or other possible measures. 
In the drawings, reference numeral 28 denotes document guide pieces formed 
on the upper surface of the cover member 20 for restricting the width of 
the document to be scanned, and 29 denotes a hinged lid for opening and 
shutting the document entrance M1. 
The document feeder 30 is detachably attached to the united scanner body 1 
and cover member 20 on the entrance M1 side, so that a plurality of 
cut-sheet documents are automatically sent one by one into the document 
passage P between the scanner body 1 and the cover member 20. The document 
feeder 30 has engaging means 34 which come in engagement with engaging 
holes 20a formed in the cover member 20 on the entrance M1 side. The 
engaging means 34 in this embodiment is formed in a substantially L-shape 
so as to be hooked on the edge of the corresponding engaging hole 20a 
formed in the cover member 20. 
Though the document feeder 30 in this embodiment comes into direct 
engagement with the cover member 20, it may be directly engaged with the 
scanner body 1. It is desirable to form the document feeder 30 with its 
lower surface leveling with the lower surface of the cover member 20 
united with the scanner body 1 so as to secure the stability of the 
scanner. 
The document feeder 30 has a document inlet opening M3 and a document guide 
member 35 extending from the document inlet opening M3 to the document 
entrance M1 of the united scanner body 1 and cover member 20. The document 
feeder 30 has a document tray 36 for stacking the cut-sheet documents 
thereon. The document feeder 30 further includes document separating means 
37 consisting of at least one set of separation roller 37a and separation 
pad 37b which are in frictional contact with each other. The separation 
roller 37a is driven by acquiring rotational motion produced by the motor 
8 in the scanner body 1 through the driving gear 31 which is engaged with 
the gear 14d held on the driving shaft 12a in the scanner body 1 as 
touched upon above. That is, when the scanner body 1 united with the cover 
member 20 and document feeder 30 is operated for scanning the document, 
the driving gear 31 is driven in conjunction with the driving rollers 10 
to rotate the separation roller 37a. Therefore, even if two cut-sheet 
documents to be fed intend to come into between the separation roller 37a 
and the separation pad 37b, only the document being in direct contact with 
the separation roller 37a is allowed to advance to the document passage P 
defined between the scanner body 1 and the cover member 20 through the 
document entrance M1 by the rotating separation roller 37a. However, the 
other document being in frictional contact with the separation pad 37b is 
prevented from being forwarded toward the document passage P by the 
frictional resistance brought about by the separation pad 37b. Thus, the 
documents stacked on the document tray 36 can be fed infallibly one by one 
into the document passage P. 
The manner of operation of the portable image scanner described in this 
connection with the illustrated embodiment will be explained hereinafter. 
Manual Document Loading Mode 
In the case of manually loading a single cut-sheet document to be scanned, 
the cover member 20 is attached to the scanner body 1. The connection of 
the cover member 20 to the scanner body 1 is accomplished by hooking the 
engaging means 22 in the engaging holes 2c formed in the bottom 2a of the 
scanner body 1. When the scanner body 1 is united with the cover member 
20, the driving rollers of the scanner body 1 are in frictional contact 
with the press rollers 24 on the cover member 20 as illustrated in FIG. 4. 
Even in the ready state in which the scanner body 1 is switched on, if the 
cut-sheet document is not introduced into the document entrance M1, the 
sensor lever 16a of the document sensor 16 assumes its non-operated state 
as indicated by the imaginary line in FIG. 5, as a result of which the 
motor 8 is not yet activated. 
By inserting the cut-sheet document D into the document entrance M1 by 
hand, the sensor lever 16a is pushed up to switch on the switching means 
16b of the document sensor 16, thereby activating the motor 8 to rotate 
the driving rollers 10 through the toothed endless belt 8a. With the 
rotation of the driving rollers 10, the document D advances toward the 
document exit M2 through the document passage P while being scanned to 
read out the image data on the document. 
To be more specific, in the manual document loading mode, the image 
scanning operation is started after a prescribed time of detecting the 
leading end of the document D introduced through the document entrance M1 
with the document sensor 16. In other words, the image scanning operation 
is controlled so as to scan the document D at the time that the document D 
reaches the image reading means 4. 
When the document D completely passes through the sensor lever 16a, the 
tail end of the document D is detected to turn off the switching means 
16b. However, the motor 8 is controlled to continue rotating until a 
prescribed time elapses, so that the document D is completely sent out 
through the document exit M2. 
As described above, the cut-sheet document manually inserted into the 
document entrance M1 between the united scanner body 1 and cover member 20 
is subjected to image scanning while being automatically forwarded along 
the document passage P, and at the time, the image data read out from the 
document by the image reading means 4 are delivered in succession to the 
external image processing device such as a computer electrically connected 
to the scanner body 1. The image scanning area (image width and length) on 
the document D can be determined with complete control by the external 
image processing device. 
Self-propelling Mode 
In the case of moving the scanner body 1 on a thick document such as a book 
for scanning and reading out the image data on the document, the scanner 
body 1 is separated from the cover member 20. At the time that the 
independent scanner body 1 is put on the document, the sensor lever 16a is 
in touch with the image face of the document and pushed up to turn the 
document sensor 16 into its ON state, so that the scanner body 1 assumes 
its ready state for scanning. Then, by switching on the power switch 9 or 
operating the external image processing device to give a start instruction 
to the scanner body 1, the motor 8 starts rotating to drive the driving 
rollers 10, consequently to move the scanner body 1 on the document D 
while reading out the image date from the document with the image reading 
means 4. 
While the scanner body 1 moves along the image face of the document, the 
sensor lever 16a is pushed up by the document, maintaining the document 
sensor 16 in the 0N state, and slides following the moving scanner body 1 
To halt the scanning operation, the operator may give a stop instruction to 
the external image processing device connected to the scanner body 1 or 
merely lift up the scanner body i to turn off the document sensor 16. 
Also, the scanner body 1 moving along the image face of the document stops 
automatically when arriving at the edge portion or level difference of the 
thick document, since the sensor lever 16a comes off from the edge of the 
thick document to turn off the document sensor 16 as shown in FIGS. 6 and 
7, thus preventing the scanner body 1 from falling out of the thick 
document due to carelessness. In this case, it is desirable to issue a 
warning sound and/or signal light at the time of stopping the movement of 
the scanner body 1 when the edge or level difference of the document is 
detected by the sensor lever 16a. 
Though the scanner body 1 is basically deactivated to stop moving and image 
reading at the moment that the edge or level difference of the document is 
detected, it is rather desirable to move a little the scanner body 
backward at that time, thereby securing its stability on the document. 
Automatic Document Loading Mode 
In the case of automatically introducing the documents one by one into the 
document passage P formed between the scanner body 1 and the cover member 
20 which are united with each other for attaining the manual document 
loading mode as noted above, the document feeder 30 is attached to the 
united scanner body 1 and cover member 20 as shown by the imaginary line 
in FIG. 5. 
On the document tray 36 of the document feeder 30 attached to the united 
scanner body 1 and cover member 20, one or more cut-sheet documents are 
stacked with their leading ends touching the separation means 37 within 
the document inlet opening M3 of the document feeder 30. By giving a 
scanning instruction to the scanner body 1 in that state, the motor 8 
starts rotating to simultaneously drive the driving rollers 10 and the 
separation roller 37a. Even if two or more cut-sheet documents come into 
between the separation roller 37a and the separation pad 37b, only the 
document being in direct contact with the separation roller 37a is 
permitted to pass therethrough toward the document passage P defined 
between the united scanner body 1 and cover member 20. Thus, the cut-sheet 
documents can be surely sent one by one into the document passage P. 
Until the document sent into the document passage P through the document 
entrance M1 is completely discharged from the document exit M2, the same 
operation as in the manual document loading mode is executed. 
EFFECT OF THE INVENTION 
As is clear from the description given above, the portable image scanner of 
the present invention can reliably scan the whole image area on a 
cut-sheet document or thick document such as a book, and readily select 
the "manual document loading mode" for scanning the cut-sheet document and 
the "self-propelling mode" for scanning the thick document by a simple 
operation of attaching or detaching the cover member. The cover member 
which is attached to the scanner body when selecting the manual document 
loading mode is notably simple in structure and can easily be attached to 
or detached from the scanner body. Thus, according to the image scanner of 
this invention, various kinds of documents can be easily dealt with and 
subjected to high resolution scanning 
The image scanner of this invention incorporates the components including 
the charging battery which are arranged so as to acquire well balance and 
secure the stability thereof can be vary easily handled and made compact 
and therefore, it is suitable particularly to a handheld computer. 
Furthermore, since the image scanner of this invention has the document 
feeder, one or more cut-sheet documents can be automatically fed and 
scanned one by one in succession. 
The portable image scanner of this invention has a safety mechanism 
including the sensor lever and switching means, so that the scanner body 
can automatically stop when arriving at the edge portion of the document. 
Besides, the portable automatic image scanner of this invention can be 
properly applied for various uses such as image scanning, optical 
character recognition (OCR), optical pattern recognition and other image 
processing. By not only electronically processing the image data outputted 
from the image scanner, but also varying the rotation of the driving 
rollers for feeding the document at the reading rate maintained constant 
for reading out the image data from the document, an image resultantly 
reproduced can be freely reduced or magnified with ease congruously to the 
original image on the given document. 
Utilizing the document sensor having the sensor lever which is generally 
operated by the document placed opposite to the bottom of the scanner 
body, an full automatic scanning system capable of automatically 
recognizing the manual document loading mode or the self-propelling mode 
can readily be accomplished by providing the sensor lever with a function 
of behaving when the cover member is united to the scanner body. 
It is to be understood that the invention is not limited in its application 
to the details of construction and arrangement of parts illustrated in the 
accompanying drawings, since the invention is capable of other embodiments 
and of being practiced or carried out in various ways. Also it is to be 
understood that the phraselogy or terminology employed herein is for the 
purpose of description and not of limitation.