JPH05268424A - Original reader - Google Patents

Abstract

PURPOSE:To reduce mutual interference between signals by applying time division to plural output signals and transferring the divided signals serially when output signals of plural A/D converters are transferred between signal processing units so as to decrease the number of cores of a cable. CONSTITUTION:Outputs from a CCD 4 are fed to A/D converters 6a-6e via five amplifiers respectively. A control signal is fed to converters 6a-6e from a digital signal processing unit 9 and outputs of the converters 6a-6e are fed to 5 gates 29a-29e. Then other control signal 28 is fed to the gates 29a-29e from the unit 9 and its output is transferred serially in time division. Thus, each output of the gates 29a-29e has 8-bits in total 40 lines and since the data are subjected to time division, the data line number of the cable 22 is 8 lines. A rearrangement circuit 25 transfers the data transferred serially to the signal processing circuit in the order corresponding to the arrangement of the CCD. Thus, the number of cable cores is reduced and mutual interference between signals is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transfer technique,
In particular, it relates to a signal transfer technique in a document reading device.

[0002]

2. Description of the Related Art In a document reading device such as a copying machine, a fax machine, or an OCR, when a document is optically scanned to process a document image, an image line sensor, that is, a CCD (charge coupled device) is generally used for this scanning. used. Multiple CCD chips (eg 5
Often used. This is to enable parallel processing of read image data and downsizing of elements. The CCD converts the optical data on the document surface into electric signals. The output of each CCD is amplified and digitized by the A / D converter (for example, 8-bit data). All of these processes are performed in the reading unit. This reading unit is generally provided under the document table and moves in a direction perpendicular to the line formed by the light receiving elements of the CCD to scan the document. The digital signal is amplified for transmission and then transferred in parallel to the digital signal processing unit using a long cable. Here, a ground line is provided between each output line of each A / D converter 6 in order to avoid interference between the lines. Therefore A
Only the output line of the / D converter requires a total of 60 cable cores. Further, recently, the reading unit tends to be an LSI, and in that case, the LSI requires a data line for transferring a command and a control line for transferring a control signal. Therefore, when 5 CCDs are used and each A / D converter is 8 bits, the total number of cable cores used for this parallel transfer is 114.

The digital signal processing unit divides the parallel digital signals received from the reading unit into CCDs, rearranges them in order, and then transfers the data to the host device via a line filter or a host interface.

[0004]

As mentioned above, a large number of digital signal lines from the A / D converter output in a movable reading unit are digitally transmitted using a cable having a large number of cores corresponding to that number. It is transferred in parallel to the signal processing unit. Therefore, it is difficult to handle and route the cables that connect the units, and the cost of the cables is high. Also, since signals are sent in parallel and close to each other, mutual interference between signals may occur.

Therefore, an object of the present invention is to serially convert a plurality of digital signals after A / D conversion from a unit equipped with an A / D converter to another unit. This minimizes the number of cores of the cable connecting the units, facilitates the routing of the cable, and reduces the cable cost. Another object of the present invention is to reduce the mutual interference of signals by serializing the signals from each CCD chip.

[0006]

In a scanner device for inputting image data of an original using a plurality of image sensors, a plurality of A / D conversions for converting outputs of the plurality of image sensors into parallel digital signals. And a plurality of A /
Select one of the parallel outputs in the D converter and have a single parallel output for supplying the parallel output, and sequentially output a plurality of the parallel digital signals in units of the D / A conversion means. A device having a gate circuit. One A / D converter parallel output is selected by the gate circuit, and a plurality of A / D converter outputs are time-divisionally transmitted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 schematically shows a document reading device, that is, a scanner device according to the present invention. A document 1 placed on a document table (generally transparent glass) 26 is irradiated with light from two document illumination light sources 2. The light reflected from the document is guided to the CCD 4 via the rod lens array 3, so that the image on the document is formed on the CCD 4. C
The CD is an image sensor that outputs a voltage corresponding to the amount of incident light. After the CCD output voltage is amplified by the amplifier 5, A /
The D converter 6 converts the signal into an 8-bit parallel digital signal, for example. Light source 2, rod lens array 3, CCD
4, amplifier 5, A / D converter 6 is a reading unit 7
Built into. The image signal digitized by the A / D converter 6 is transferred from the reading unit 7 to the digital signal processing unit 9 via the flexible cable 8. The signal transferred to the digital signal unit is
First, the rearrangement circuit 10 rearranges the images according to the arrangement of the corresponding CCDs, and then the digital image processing circuit 11
Thereby removing noise and improving signal quality. The signal of improved quality is sent from the document reading apparatus to an external host apparatus via the host interface 12. The control circuit 13 performs overall control of the present device, such as setting parameters for the digital signal processing circuit 9. The control circuit 13 sends a command signal to the motor driver 14, and the motor 15 is driven to move the reading unit in the direction of the arrow or vice versa. By thus performing the reading while moving the reading unit 7, two-dimensional document reading is realized. The timing generation circuit 16 generates a signal that controls the operation timing of the reading unit 7, the rearrangement circuit 10, and the digital signal processing circuit 11.

As in the conventional example shown in detail in FIG. 4, C
The light receiving portion of the CD is divided into five. The divided chips of the respective light receiving parts are CH1, CH2, CH3, CH4,
Defined as CH5. Each chip has amplifiers 5a-5
e and A / D converters 6a to 6e are connected to each other.
As shown in the figure, conventionally, each A / D converter 6a ...
A current driver 17 is connected to 6e. If the resolution of the A / D converter is 8 bits, eight current drivers 17 are provided for each A / D converter.

Each current driver output is read by the reading unit 7.
Connector 19 for connecting the cable 20 and the cable 20, and the cable 2
0 and a connector 18 connecting the cable 20 and the digital signal processing unit 9 to the signal receiver 24 in the digital signal processing unit 9 in parallel.

FIG. 1 shows the detailed construction of the reading apparatus according to the present invention. In this figure, the same components as those in FIGS. 2 and 4 are designated by the same reference numerals. The CCD is divided into five parts as described above, and each CCD chip has an amplifier 5
a-5e are connected, and the outputs of these amplifiers are supplied to A / D converters 6a-6e. A / D converter 6a
Control signals are supplied from the digital signal processing unit 9 to 6e, and outputs of the A / D converters 6a to 6e are supplied to five gates 29a to 29e, respectively. Each gate 29
Separate control signals 28 are supplied from the unit 9 to a to 29e. The output of each of the gates 29a to 29e is 8 bits and has a total of 40 lines. However, since it is time-divided, the number of data lines in the cable 22 is 8. The time-divided A / D converter output is sent through the cable 22 to the rearrangement circuit 25 in the digital signal processing unit 9.
Is supplied to. The rearrangement circuit 25 transfers the serially transferred data to the digital signal processing circuit or the like in the order corresponding to the arrangement of the CCDs.

Next, the operation of the present invention will be described in detail. Figure 3
Is a timing chart of signals related to the gates 29a to 29e. (A) is the output of the A / D converters 6a to 6e, each having 8 bits. Also, (A) is 5 CCDs
Only the signal for the period corresponding to one pixel of is shown by the solid line. The signal of each A / D converter chip is thus transferred in parallel. A gate open signal obtained by dividing one pixel processing time into five is individually transferred from the timing generating circuit 16 to each of the gates 29a to 29e as shown in (B). Therefore, the signal shown in (C) is generated on the cable 22. Each numbered data is 8 bits, and this number corresponds to each CCD channel. In this way, the output signal of the D / A converter is serially transferred on the cable 22 in 8-bit units. Therefore, in this example, including the ground line between the signal lines, a total of 64
The core wire of the book is reduced.

[0013]

The output signals of a plurality of A / D converters are
When transferring between the signal processing units, the plurality of output signals are next divided and transferred in series, whereby the number of core wires of the cables connecting the units can be reduced to a minimum. As a result, the cable can be easily routed and the cable cost can be reduced. Further, since signals are transferred in series, interference between signals is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a detailed configuration of a reading device according to the present invention.

FIG. 2 is a schematic diagram of a document reading apparatus according to the present invention.

FIG. 3 is a timing chart of signals related to gates.

FIG. 4 is a schematic diagram of a conventional document reading device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original document, 2 ... Original illumination light source, 3 ... Rod lens array, 4 ... CCD, 5a-5e ... Amplifier, 6a-6e ... A
/ D converter, 7 ... reading unit, 8 ... multi-core cable, 9 ... digital signal processing unit, 10 ... rearrangement circuit, 11 ... digital image processing circuit, 12 ... host interface, 13 ... control circuit, 14 ... motor driver,
15 ... Motor, 16 ... Timing generation circuit, 17a-1
7e ... current driver, 18/19 ... connector, 20 ... multi-core cable, 21/23 ... connector, 22 ... multi-core cable, 24/25 ... signal receiver, 26 ... manuscript table, 27
28 ... control line, 29a-29e ... gate.

Claims (2)

[Claims] 1. A scanner device for inputting image data of an original using a plurality of image sensors, comprising a plurality of A / D conversion means for converting each serial analog signal of the plurality of image sensors into a parallel digital signal. A single parallel output for selecting one of the parallel outputs of the plurality of A / D converting means and supplying the parallel output, and converting the plurality of parallel digital signals to the D / A converting means. Means for sequentially outputting in units, cable means for transferring the digital signal, and inputting the digital signal through the cable means,
A document reading apparatus comprising: a digital signal processing unit that processes the digital signal. 2. The apparatus further comprises a single unit on which the sensor, an A / D conversion unit, and a unit for sequentially outputting are mounted, and the single unit is mounted on the document for scanning the document. 2. The document reading apparatus according to claim 1, wherein the cable means is a flexible cable.