JPS5824066B2 - Chart reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical chart reading, and more particularly to a chart reading device configured to correct errors related to lens aberrations by electronic means.

The recent development of facsimile has been remarkable, and the importance of facsimile in the field of telecommunications is increasing year by year.

With the progress of facsimile technology, a system has been developed in which the optical reading means used in facsimile IJ is applied to a chart reading device as a measuring instrument, and a system is developed in which complex charts are read by the chart reading device and processed by a computer.

An example in which reading means conventionally used in facsimiles is applied to a chart reading device will be described below.

FIG. 1 shows the optical arrangement of a chart 2 and an image sensor 3 centered on a lens 1.

For example, a BBD or CCD is used as the image sensor.

In Fig. 1, if the ratio of the distance between the lens and the chart and the lens and the image sensor is 5:1, and if the image sensor is, for example, 0PA1024 (Oki Electric Manufacturing Co., Ltd.), the image sensor will be Since only 1024 bits of photoelectric conversion elements are arranged, the range on the chart is 0.125mm (-〇, 025X5
), a range of 0.125 mm x 1024 = 128 mm can be read.

This reading means will be explained with reference to the time chart shown in FIG.

First, a reference counter is provided that scans a chart on a sheet of paper.

At the same time as starting this counter, a start pulse S shown in FIG. 2C is applied to the image sensor.

The image sensor is given the same clock pulse as the clock pulse for counting the reference counter, and starts reading at the same time as the start pulse is applied.

Next, if there is data on the paper as shown in Figure 2 A, and this data is detected as an image sensor output when the reference counter counts up to address 800, then the value of address 800 on the reference counter at this time is the data. It's about location.

In such a case, problems arise due to errors in the optical arrangement of the paper, lens, and image sensor, and errors in the aberrations of the lenses at both ends of the image sensor.

Errors due to optical arrangement can be reduced to some extent by mechanically adjusting the image sensor, but errors due to lens aberrations cannot be alleviated by the conventional methods described above.

If the same thing as a chart is to be reproduced graphically like in a facsimile, there is no practical problem even if some errors are allowed. However, when using a chart reading device as a measurement method, very strict High precision is required.

SUMMARY OF THE INVENTION Accordingly, the present invention aims to improve the above-mentioned drawbacks of the prior art, and its object is to provide a chart reading device in which reading errors due to lens aberrations are easily corrected by electronic means.

The chart reading device according to the present invention is characterized by projecting a chart figure on a sheet of paper onto a single image sensor through an optical lens, and extracting an electrical signal corresponding to the chart through optical-electrical conversion. In the reading device,
A reference counter that scans the position on the paper, a data counter that is driven by the same pulse source as the reference counter and indicates the currently scanned point on the paper, and divides the entire area of the paper into multiple areas, and means for correcting the counted value of the data counter so that the contents match by comparing the contents of the reference counter and the data counter; The present invention is provided in a chart reading device that indicates the position on the paper of the output of the image sensor whose distortion has been corrected.

The embodiments will be described above with reference to the drawings.

FIG. 3 shows a block diagram of the electrical circuit of a chart reading device according to the invention.

In FIG. 3, 1 is a reference counter that scans the chart on the paper.

2 is a gate circuit, 3 is an image sensor, and 4 is a data counter.

A start pulse is given to the image sensor 3 through the gate circuit 2, and at the same time the reference counter 1 and the image sensor 4
The data counter starts counting.

Reference numeral 5 denotes a data selector, and since it is selected by the reference counter output of 1, it is possible to subdivide the range of the chart on the paper.

Reference numeral 6 indicates a switch corresponding to each subdivided range of the chart on the paper, and by turning on this switch, correction of the day and evening of that range can be performed.

Correction circuit No. 7) This circuit is used to decide in advance whether to increment the contents of the data counter No. 4 by +1 or -1.

The data counter 4 counts in the same way as the reference counter, but in addition, the correction circuit 7 counts +1 or -1.
It is configured so that it can be done.

Next, the present invention will be explained in detail.

In Figure 4, A is a subdivision of the paper, and if we follow the example in Figure 1, 1 clock of the counter in A is 0 on the paper.
．． Compatible with 125mm.

If 0.125 mm on the paper is correctly projected for each element on the image sensor, no error will occur.

If the image is projected as shown in FIG. 4, the nth position on the paper is projected onto the (n-1)th element of the image sensor.

Therefore, as can be seen from the explanation of the time chart in Figure 2,
Since the data on the paper is detected when the image sensor counts up to n-1, the address of this data is n-1, which is a value that is one pulse less than the actual value at address n. It ends up being measured with a value that is 0.125mm smaller.

Since errors occur in this way, a reference counter 1 and a data counter 4 are provided separately as shown in FIG. 3, so that the contents of the data counters can be corrected.

The operation shown in FIG. 3 will be explained with reference to the time chart shown in FIG.

In the example in Figure 5, the size on the paper is 0.125mm x 1024-1
28 words = 64 clocks or 0.125yut x 64
It is subdivided into a range of =8 myn.

That is, it is divided into 16 ranges.

Switch groups 1 to 16 for determining whether or not to correct data correspond to each range.

Select this switch group sequentially using the data selector,
For example, if switch 2, switch 4, and switch 16 are turned on as shown in FIG. 5, an output signal as shown in FIG. 5C is output as the data selector output.

At this time, the contents of the data counter 4 are corrected using a correction pulse as shown in FIG.

In other words, due to the correction pulse, the content of the redata counter 4 becomes +
1 or -1.

In this way, the position of the image signal output from the image sensor on the paper is correctly displayed by the output of the data counter 4.

The range for this correction can be determined using the following formula.

If the projection on the paper has a uniform deviation of 0.5% on the image sensor, this is 1 bit or 100
%, it is sufficient to make a 1-bit correction.

That is, the correction may be made every 100% 10.5% - 200 bits.

Further, if there is a deviation of 2% at both ends of the image sensor, the correction may be performed every 100%/2%-50, that is, every 50 bits.

It is clear that if you set the range for correcting the expected deviation in advance in this way, you can read with an accuracy of ±1 clock, or ±0.125 mm, no matter what range you measure on the paper. .

In addition, in Fig. 5, the case where the deviation is only in one direction, either positive or negative, was explained, but as shown in Fig. 6, one more set of data selectors (5') is added, and data selectors are set separately for the + side and the - side. By providing , it is possible to correct deviations in both directions.

If the reading range is further subdivided and a reversible counter is used in the correction circuit 7 in Fig. 3, and the data counter is corrected when the reversible counter reaches a certain value, it corresponds to 6 in Fig. 3. The correction switch instructs correction that further divides one clock pulse, allowing fine-grained correction.

As explained in detail in the embodiments above, according to the chart reading device of the present invention, the electronic correction means can read the chart within an error of one element, and it is possible to perform very highly accurate reading. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between an image sensor and a lens, FIG. 2 is a diagram explaining the principle of chart reading, FIG. 3 is a block diagram of a chart reading device according to the present invention, and FIG. 4 is a diagram explaining reading errors. FIG. 5 is an operation time chart of the device shown in FIG. 3, and FIG. 6 is a block diagram of another embodiment of the chart reading device according to the present invention. 1; Reference counter, 2: Gate, 3; Image sensor,
4: data counter, 5: data selector, 6: switch, 7: correction circuit.

Claims (1)

[Claims] 1. In a chart reading device that projects a chart figure on a sheet of paper onto a single image sensor through an optical lens and extracts an electrical signal corresponding to the chart through optical-electrical conversion, the position on the sheet is determined. a reference counter for scanning, a data counter driven by the same pulse source as the reference counter and indicating the point currently being scanned on the paper, and dividing the entire area of the paper into a plurality of areas, and for each area, the reference counter and It has means for correcting the count value of the data counter so that the contents match by comparing the contents of the data counter, and the distortion of the image due to the aberration of the optical lens is corrected by the output of the data counter. A chart reading device characterized in that the position of the output of the image sensor on the paper is indicated.