JPH0428187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image reading and transfer system for a video signal obtained by optically scanning a document.

[Background technology of the invention] Image sensors such as CCD and photo data
A plurality of photoelectric elements corresponding to one line of a document and a shift register for addressing are formed on one substrate, and the output of each photoelectric element is sequentially sent out as a video signal.

A general image reading device using the above image sensor as shown in FIG.
Send the original 2 such as a photograph in the sub-scanning direction Y, and
LEDs and fluorescent lights arranged in the main scanning direction X on the top.
The original 2 is irradiated with a light beam 3 such as a halogen lamp. The light reflected from the original 2 by the light source 3 is reflected by the lens 4.
By focusing an optical image on an image sensor 5 such as a CCD or a photodiode arranged in the main scanning direction, the image information of the original 2 is separated into dots and read by a plurality of photoelectric elements of the image sensor. It's summery. By sequentially feeding the document in the sub-scanning direction, image information can be obtained as a video signal using a raster scan method.

For example, in an image sensor where one line consists of 5000 photoelectric elements, the scan timing of one element is
When driving at T ₀ =0.75 μs, scan data of maximum data amount D ₀ =5000 bits (625 Bytes) can be obtained every 1 line scan timing T ₁ =D ₀ ×T ₀ =3.75 (ms). Then, the total data amount D generated by processing trimming and magnification on this one scan data D ₀ becomes transfer data.

[Problems with Background Art] Generally, image information read by an image reading device is transferred to an external device such as a computer or a printer and subjected to various processing. However, since the reading speed of image information read by an image reading device and the receiving speed at which the image information can be received by an external device are different, a problem arises in that image information must be transferred efficiently. For example, as shown in FIG. 3, when scanning image information at scan timing T ₁ of one line of document 2 and document feed speed V,
Scan timing for one line as shown in Figure 4a
Trim the image data read with T ₁ ,
When transmitting data with a total data amount D that has been subjected to magnification conversion etc. to an external device with a receivable data amount H (H≧D) _per scan timing T, one line is shown in Figure 4b. Data can be transferred with a scan timing of _T1 .

However, when transferring data to an external device whose receivable data amount is H (H<D), it takes T ₂ to finish transferring the total data amount D as shown in Figure 4c.
This takes time by (T ₂ > T ₂ ), and data cannot be transferred at scan timing T ₁ . In such a case, it is sufficient to scan one line at the transfer timing _T2 , but there is a problem that the change in time causes a difference in the amount of light, resulting in a decrease in the output of the image sensor. Therefore, an interface and control tailored to the scan timing _T1 is required.
Problems have arisen in that devices have become complex, large, and expensive.

[Object of the Invention] An object of the present invention is to provide an image reading and transfer method that efficiently transfers data according to the amount of data that can be received by an external device.

[Summary of the Invention] To achieve the above object, the present invention provides an image sensor including a photoelectric element that scans image information on a document to obtain a video signal; and an image sensor that drives the image sensor at a constant scan timing T. A total data amount D for one scan data generated by driving the image sensor is calculated, and from the total data amount D and the receivable data amount H of the external device per one scan timing T, D≦H. xN (however, N=1, 2, 3...); a calculation unit that calculates the minimum transfer parameter N that satisfies the condition; based on the transfer parameter N, the relative relationship between the document and the image sensor to obtain one scan data; a feed control unit that controls the target feed speed V to a speed of V/N; a read timing control unit that commands a read timing for each T×N based on the transfer parameter N; and a read timing control unit that controls the transfer data according to the read timing. It is equipped with a data control unit that transfers data to an external device, and reads and transfers the transfer data at a reading timing determined from the receivable data amount H of the external device per one scan timing and the total data amount D of the transfer data, and The present invention provides an image reading and transferring method in which the relative feeding speed V between the document and the image sensor is based on the reading timing.

[Embodiment of the Invention] FIG. 1 is a block diagram showing an embodiment of an apparatus that can optimally carry out the present invention. In the figure, 1 is the document table on which the document 2 is placed, 3 is the LED, fluorescent light,
Light source such as halogen lamp, 4 is lens, 5 is
Image sensor such as CCD, 6 is data transfer,
A control unit that performs various controls; 7 a feed control unit that controls the feed of the document table 1; 8 a feed drive unit; 9 an image sensor drive unit that is driven at a constant scan timing from the control unit 6; 10 an image sensor 5; 11 is an analog-digital (AD) converter, 12 is an arithmetic unit, 13 is a read timing control unit that instructs the read timing of the transfer data, and 14 is a read timing control unit that reads the transfer data according to the transfer timing. A data control unit 15 for transferring data to an external device is an interface with an external device 16.

Next, the operation will be explained. First, in order to obtain the total data amount D based on one scan data generated in one scan, the control unit 6 uses the external device 16 via the interface 15 to calculate the magnification in the scan direction, the magnification in the feed direction, and the trimming in the scan direction. Enter parameters such as quantity. When the control section 6 inputs the parameters, it instructs the feed control section 7 to move the document table. The feed control section 7 drives the feed drive section 8 at a preset feed speed to move the document to a separately input document reading position. At this time, since the image sensor 5 is not driven, the document can be fed at high speed. While the document is moving, the control section 6 sends the parameters to the calculation section 12 to calculate the transfer parameter N. The calculation unit 12 calculates the total data amount D of the transfer data based on the parameters of trimming and magnification. For example, if the magnification in the scan direction is doubled for one scan data, the total data amount will be doubled. Similarly, if the magnification in the feed direction is doubled, the total amount of data will be doubled. From the total data amount D obtained in this way and the receivable data amount H per one scan timing of the external device 16, D≦H×
Find the minimum transfer parameter N (N=1, 2, 3...).

When the document comes to the document reading position, the control section 6 sends the transfer parameter N to the feed control section 7. Then, the feed control section 7 drives the feed drive section 8 to feed the document 2 at a feed speed V/N, which is the preset feed speed V during document scanning.

On the other hand, the control unit 6 sends the transfer parameter N to the read timing control unit 13. The read timing control unit 13 instructs the data control unit 14 to set a read timing every T _{1 ×N timing, which is N times the scan timing T 1 ,} according to the scan timing T 1 of one line from the image sensor drive unit 9 . The data control section 14 consists of a write control section 14a, a memory (A) 14b, a memory (B) 14c and a read control section 14d as shown in FIG. 5, and in FIG. 6, a and b are N=1 and N=2, respectively. Each timing chart of the data control unit 14 is shown when the following conditions are met. In FIG. 6a, read timing 61 coincides with T ₁ of scan timing 60 since N=1. The write control unit 14a selects the memory (A) 14b and writes the transfer data of the first line at the first read timing at one scan timing _T1 . When the writing is completed, the read control unit 14b that has selected the memory (A) 14b transfers the transfer data, and the transfer data ends at one scan timing _T1 . At the same time as reading the memory (A) 14b, the write control unit 14a selects the memory (B) 14c according to the next reading timing,
Write the second line transfer data. Memory (B) 14
When the writing to the memory (A) 14a is completed, the reading control unit 14d reads the memory (B) 1.
Select 4c to transfer the transfer data. At this time, the document is being fed at a speed of V.

In FIG. 6b, since N=2, the read timing 61 becomes the timing T ₁ ×2 of the scan timing 60. Transfer data written at a read timing of T ₁ ×2 is written in the same manner as in FIG. 6a, and data transfer requires a timing of T ₁ ×2. At this time, since the document is fed at a speed V/2 as shown in FIG. 7, the reading position when the reading timing is commanded coincides with the second line in FIG. 6a. During that time, the image sensor 5 scans the scan timing T ₁
When reading is performed, data on the 1'th line is read, but this data is skipped. Thereafter, read the data of lines 2, 3... in the same way, 2',
3',...I skip the line.

In the above description, the document table 1 is driven to feed the document, but the light source 3, lens 4, and image sensor 5 are moved relative to the optical system side, so that the document can be scanned. Of course, it is fine as long as it is.

[Effects of the Invention] As described above, the present invention makes it possible to efficiently transfer data by reading and transmitting the transfer data at a reading timing that corresponds to the amount of data to be transferred and the amount of data that can be received by an external device. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a device that can optimally implement the present invention, FIG. 2 is a diagram for explaining an image reading device, and FIGS. 3 and 4 show conventional reading and transfer timing and A diagram for explaining the feeding of the original, Figure 5 is a diagram for explaining Figure 1,
FIGS. 6 and 7 are diagrams for explaining the reading transfer timing and document feeding in the present invention. 5... Image sensor, 7... Feed control section, 1
2... Arithmetic unit, 13... Read timing control unit, 14... Data control unit, 15... Interface, 16... External device.

Claims (1)

[Claims] 1. An image sensor comprising a photoelectric element that scans image information on a document to obtain a video signal; an image sensor drive section that drives the image sensor at a constant scan timing T; and a drive for the image sensor. Calculate the total amount of data D for one scan data generated in 2, 3,...); and a calculation unit that calculates the minimum transfer parameter N that satisfies the conditions of (2, 3, ...); a read timing control unit that commands a read timing for each T×N based on the transfer parameter N; and a data control unit that reads transfer data according to the read timing and transfers it to an external device. It reads and transfers the transfer data at the reading timing determined from the receivable data amount H of the external device per one scan timing and the total data amount D of the transfer data, and also reads and transfers the transfer data with respect to the relative relationship between the original and the image sensor. An image reading transfer method in which the feed speed V is based on the reading timing.