preferred embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings . note that the scope of the invention is not limited to the dimensions , materials , shapes , relative positions , and the like of the building components described in this embodiment , unless otherwise specified . the first embodiment will be described below with reference to fig1 a to 5 . at first , an overall arrangement of an image reading apparatus will be described with reference to fig1 a to 3 . [ 0023 ] fig1 a to 1 c show the arrangement of an image reading apparatus according to this embodiment . fig1 a is a partially cutaway plan view , fig . lb is a partially cutaway front view , and fig1 c is a side explanatory view . fig2 is a schematic sectional view showing the arrangement of a contact image sensor . as shown in fig1 a to 1 c , a document image is read by setting a document on a document table glass 2 attached to the upper surface of an apparatus main body 1 , and scanning a contact image sensor 3 as an image reading device in the apparatus main body 1 parallel to the document table glass 2 . as shown in fig2 the contact image sensor 3 incorporates three - color leds 3 r , 3 g , and 3 b as light sources for document illumination , a rod lens array 3 l for forming an optical image of light reflected by a document on a light - receiving element of an image sensor 3 s , and the image sensor 3 s . the contact image sensor 3 turns on the three - color leds 3 r , 3 g , and 3 b while switching them in turn , and the image sensor reads light reflected by a document for each color , thus reading color - separated images . as shown in fig1 a and 1b , the contact image sensor 3 is fixed on and supported by a slider 5 , which slides along a guide shaft 4 fixed to the apparatus main body 1 . also , a motor serving as a scan drive source is fixed to the slider 5 . by rotating the motor in the forward and reverse directions , the contact image sensor 3 can reciprocally scan the range of the document table glass 2 . the building components of the image reading apparatus include electrical components such as a control board and power supply , in addition to the above components . these building components are arranged in the apparatus main body 1 that fixes and supports the document table glass 2 . a document cover 6 serving as a document pressing member that presses a document against the surface of the document table glass 2 is attached to the apparatus main body 1 to be free to open / close the document table glass 2 . a document contact pressing sheet 8 formed of a sheet member and sponge is adhered to the inner surface that faces the document table glass 2 of the document cover 6 . a read image data process in the image reading apparatus will be described below . fig3 is a block diagram of a read image data process in the image reading apparatus . image output signals , which are read by the image sensor 3 s in synchronism with the leds 3 r , 3 g , and 3 b that are turned on / off in turn , are sent to and amplified by an amplifier 9 , and the amplified signals are converted into digital image signals by an a / d converter 10 . the a / d converter 10 divides the dynamic range ( the read output difference between true white and black portions on a document ) of the image sensor 3 s in correspondence with its number of bits , and assigns gray levels in accordance with the luminance levels of an image on the document . for example , when the a / d converter 10 with an 8 - bit resolution is used , the range between white and black can be identified by 256 gray levels . on the other hand , in case of a 10 - bit a / d converter , that range can be identified by 1024 gray levels . therefore , an image reading apparatus using an 8 - bit a / d converter can identify 24 bits = around 16 . 7 million colors , and an image reading apparatus using a 10 - bit a / d converter can identify 30 bits = around 1 . 074 billion colors , in case of color reading using three , i . e ., r , g , and b light sources . the image reading apparatus has several output formats of an image signal , and can select an output format suitable for the purpose of a read image . when text is read and its contents are input to an ocr , or when a monochrome line image is read , a monochrome binary image is suitable , and image data obtained by binarizing an image signal , which is obtained by turning on only the g light source of the r , g , and b light sources , using a given threshold value by an image processing circuit built in a gate array 11 is used . when an image is read for the purpose of outputting an image such as a photo or the like to a monochrome printer , image data binarized by a halftone process such as dithering , error diffusion , or the like also using an image signal by turning on only the g light source is used . when a color image is processed , multi - valued ( 24 bits , etc .) image data is suitable . the image signal output from the image processing circuit is output to an apparatus such as a personal computer 13 or the like via an interface circuit 12 . the arrangement of an ffc as a connection device according to the first embodiment of the present invention will be described below . as shown in fig4 an ffc 23 is arranged in the apparatus to send a signal from a control board 21 placed in the apparatus main body 1 to the contact image sensor 3 and a motor 33 arranged in the slider 5 . one end of the ffc 23 is connected to the control board 21 as a signal processing device , and its other end is connected to the contact image sensor 3 and motor 22 to wrap around the contact image sensor 3 from its longitudinal direction . the ffc 23 consists of 12 signal lines 23 a for the contact sensor , 4 signal lines 23 b for the motor , i . e ., a total of 16 signal lines . since this embodiment uses the ffc with a line spacing = 1 mm , the ffc has a band shape having a width of 17 mm . in the aforementioned prior art , the ffc is used nearly parallel to the document table glass . however , in such arrangement , since the ffc contacts glass to stain glass or to cause a jam and operation errors , this embodiment uses an ffc standing upright in a direction perpendicular to the document table glass , i . e ., in nearly the vertical direction in association with a movable portion . with this arrangement , since the ffc 23 can be prevented from contacting the glass 2 , the aforementioned problem can be solved greatly . however , it is impossible to simply set a 17 - mm wide ffc upright in the image reading apparatus which is compact and has a limited space in its thickness direction . for this reason , several dummy lines 23 c serving as a folding margin are arranged between the aforementioned 12 signal lines and 4 signal lines , and a movable portion upon scanning is vertically folded into two at the dummy lines 23 c , thus reducing the total width ( the height ). the dummy lines include no lead wires or are not used as signal lines . at this time , when the ffc is simply folded into two , the folded portion cannot smoothly move upon scanning the contact image sensor 3 . to avoid this , in this embodiment , a slit is formed in some of the dummy lines 23 c of the ffc , as shown in fig5 and the ffc is divided into an ffc including 12 lines , and that including 4 lines , thus removing the resistance of the folded portion , and realizing smooth movement upon scanning . in the above embodiment , the ffc is partially bifurcated into two ffc parts , i . e ., an ffc including 12 lines , and that including 4 lines . in place of completely bifurcating the ffc into two parts , relatively long slits which do not suffer any resistance of the folded portion upon scanning may be formed via several - mm wide portions , as shown in fig6 so as to obtain the same effect . with this arrangement , when one of the divided ffcs has a smaller number of pins and is narrower than those of the other like in this embodiment , it is effective to maintain the rigidity of the narrower ffc . also , occurrence of any jam , operation errors , and the like due to interference of the divided ffcs can be avoided , thus realizing more stable image reading . in the second embodiment , some portions of the ffc are joined using the ffc itself . alternatively , as shown in fig7 movable portions of the divided ffcs may be partially fixed using a tape 24 such as a double - stick tape or the like , thus obtaining the same effect . in the above embodiments , the 17 - mm wide ( 12 + 4 lines ) ffc is folded into two . however , the present invention is not limited to this , and the same effect can be obtained for a width other than 17 mm and an ffc which is folded in three or more . as described above , according to the above embodiments , an ffc can operate stably with a simple , low - cost arrangement . for this reason , any image errors due to stain on glass can be avoided , and any image errors and operation errors can be avoided since a jam can be prevented , thus realizing stable , clear image reading . to restate , according to the above embodiments , a flexible flat cable which connects a control board and an image reading unit can be prevented from contacting a document table glass . the present invention is not limited to the above embodiments and various changes and modifications can be made within the spirit and scope of the present invention . therefore , to apprise the public of the scope of the present invention the following claims are made .