JPH04183163A - Image reader - Google Patents

Abstract

PURPOSE:To correct a mutual physical deviation of sensors by installing delay circuits for synchronous signal between non-standard sensors of a plurality of an array of line sensors arranged in the subscanning direction and a timing generator. CONSTITUTION:Outputs from n line sensors 101-10n are taken out, and converted into digital outputs by A/D converters 111-11p. In order to obtain one line of data by using a multiplexor 12 to composed, between line sensors 102-10n except the first one and a timing generator 13, delay circuits 142-14n are installed. Although a synchronous signal from a timing generator 14 is input in the first line sensor 101 as it is, to other line sensors 102-10n, synchronous signals are input delaying them by DELTAt. Since the deviation of scanning lines occurring after a plurality of line sensors are mechanically adjusted in the subscanning direction can be corrected simply, the scanning accuracy can be drastically improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device such as a wide-width copying machine, a wide-width facsimile machine, or an electronic blackboard, in which a plurality of line sensors are arranged in the scanning direction so as to be able to read wide-width originals.

Figures 4 and 5 show conventional image reading devices of this type, respectively, with Figure 4 showing the case of a reduction optical system and Figure 5 showing the case of a same-magnification optical system. In the case of Fig. 4, the document surface is placed with lens L,
,L, Reduced by ,L, COD line sensor RS,
, R32, R3,. In the case of FIG. 5, the document surface is read by CCD line sensors R3, R3, R3, through rod lens arrays RL, RL, RL, RL, . In any of these cases, the CCD line sensor R
3, , R82, RS, is a pair of lenses L, , L,
,L.

Or rod lens array RL, , RL, , RL.

The angle can also be adjusted. Also, electrically, as shown in Fig. 6, the timing generator TG
The synchronization signal from CCD line sensor R8,, R3,...
Simultaneously input to R3, and take output from these at the same time, and convert them to A/D converters AD, , AD, , respectively.
It was converted into digital data using an AD, and synthesized using a multiplexer circuit MP to obtain data for one line.

However, in the past, CCD line sensors RS, ,
To align the scanning lines of R3,, R3, with the fourth
In both cases of Fig. 5 and Fig. 5, the CCD line sensor R
3. Adjust the angle of each CCD line sensor R3, R5, R3, so that when R32, R3, reads one white thin line WL, each output becomes maximum as shown in Figure 7. Was.

However, with only such adjustment, for example 400dpi
In a reading system with a sub-scanning resolution of (0.06351ulTl per line), the CCD line sensor R
Even if the scanning lines 3, , R3, , R3, are aligned within the white thin line of 00llTIII width, a deviation of about 2 lines at most will occur. Even if it were possible to adjust the deviation to less than 1 line using a white thin line with a width of 0.0635 mm, it would be difficult to adjust to a higher accuracy, and
Preparing a white thin line with a width of 0635 mm is itself technically difficult. In other words, the higher the resolution, the
Accuracy adjustment becomes difficult.

The second object of the present invention is to make it possible to easily correct the above-described deviation by electrical processing even if the above-mentioned deviation occurs physically.

Means for Solving the Problems The present invention provides an image reading device in which a plurality of line sensors each consisting of a large number of light receiving elements are arranged in the scanning direction, and an output is taken out from each line sensor according to a synchronization signal from a timing generator. A delay circuit for delaying a synchronization signal from the timing generator is provided between the line sensors other than the reference line sensor among the line sensors and the timing generator.

Now, after mechanically adjusting the scanning line of the first line sensor and the scanning line of the second line sensor by the above-mentioned conventional technology, it is still physically possible to adjust Δd as shown in FIG. Suppose there is a discrepancy. In this case, when a straight line is scanned by this reading system at a scanning speed of V, the straight line reaches the scanning position of the second line sensor after Δ=Δd/v time after being scanned by the first line sensor. Therefore, if the synchronization signal to the second line sensor is delayed by Δ[ with respect to the synchronization signal to the first line sensor, the above straight line will be scanned on the same line as the scanning line of the first line sensor, and there will be a deviation of Δd. The first line sensor and the second line sensor scan substantially on the same straight line.

1-l-■ Next, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, there are n line sensors l○1 to Ion numbered 1 to 3, and their outputs are taken out separately.
Each is converted into digital data by an A/D converter 11° to lln. When the multiplexer circuit 12 synthesizes the data to obtain one line of data, there is a delay between each of the second and third line sensors 10□ to Ion excluding the first line sensor and the timing generator 13. Circuits 14, to 14n are provided.

The timing generator 14 outputs a synchronization signal with a period T. This synchronization signal is transmitted to the first line sensor 10. is input as is.

However, the other 2nd to 3rd line sensors 1
0. ~IOn includes respective delay circuits 14, ~14n.
It is input after being delayed by the time Δ determined by . FIG. 3 shows the relationship. The delay time Δ[ is the first line sensor 10. is determined according to the deviation Δd between the scanning line and the scanning line of the line sensor 10° to Ion. For example, when scanning at a scanning density of 400 dpi and a scanning speed of 6 μ/S6 (2), the scanning line of the second line sensor 10 is 1/1 o that of the first line sensor.
When the line shift L/ (Δd=0.0635./10) is reset, the second delay circuit 14. The delay time Δt is approximately 105 μsec.

Note that if there is a deviation of one line or more, the A/D converter 11. It is sufficient to prepare a line buffer after the .

The present invention can also be applied to a same-size type sensor in which a plurality of line sensors are arranged in a staggered manner.

According to the present invention, even after a plurality of line sensors are mechanically adjusted in the sub-scanning direction, even if there are still deviations in the scanning lines, the deviations can be easily corrected by electrical processing. Therefore, scanning accuracy can be dramatically improved.

Further, since a plurality of line sensors can achieve the same level of accuracy as a single long line sensor, a highly accurate image reading device can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining that even if there is a mechanical deviation between line sensors, this can be corrected by the present invention, and 3rd rg
J is a timing chart for explaining the delay effect of the synchronization signal by the delay circuit in the present invention. 4 and 5 show conventional examples, respectively. FIG. 4 is a conceptual diagram in the case of a reduction optical system, and FIG. 5 is a perspective view in the case of a same-magnification optical system. FIG. 6 is a block diagram of a conventional example, and FIG. 7 is an output waveform diagram of a line sensor therein. 10, ~Ion... Line sensor, 13
......timing generator, 14. ~
14n...Delay circuit. Patent applicant Shunsuke Nakao Patent attorney Ricoh Elemets Co., Ltd. Figure 1 Location I Figure 3 Δ Meeting Figure 4 R9I R52R53

Claims (1)

[Claims] In an image reading device that arranges a plurality of line sensors each consisting of a large number of light-receiving elements in the scanning direction and extracts an output from each line sensor according to a synchronization signal from a timing generator, a plurality of line sensors other than a reference line sensor among the plurality of line sensors An image reading device comprising a delay circuit between a line sensor and the timing generator to delay a synchronization signal from the timing generator.