JPS63287159A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent dispersion due to individual difference in focusing by reading a focusing, pattern on the same face as the original face and comparing it with a reference value. CONSTITUTION:A picture reader consists of an image sensor 1, a magnifying lens 2, a film 3, and a glass plate 4. In applying power, the film 3 is carried in the subscanning direction together with the film carriage. A black/white stripe pattern 5 is printed on the film carriage 4 and projected to a position at the outside of the original read area OR of the image sensor 1. The level difference and magnification of the white/black levels of the sampling and holding waveform of the image sensor output are sensed electrically and when they both satisfy the condition, the LED is lighted. The operator discriminates whether or not the focus of the lens 2 is matched by the lighting of the LED.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnification and focus adjustment of image input devices for facsimiles, personal computers, and the like.

[Conventional technology]

FIG. 8 shows an example of the configuration of a conventional film projector. In the figure, 31 is a line image sensor, 32 is a lens,
33 is a film, and 34 is a light source. When the light source 34 is turned on, an image on the film 33 is formed by a lens 32 onto a reading element of the line image sensor 31. The reading elements of the line image sensor 31 are arranged in the direction of the horizontal axis in the figure, which is the main scanning direction, and the film 33 is conveyed in a direction perpendicular to the plane of the paper, which is the sub-scanning direction.

In the film projector constructed as described above, since the state of image formation on the image sensor reading surface cannot be directly viewed when adjusting the focus, the following construction is adopted.

That is, a half mirror 35 is placed in the middle of the optical path from the lens 32 to the image sensor 31, and a screen 36 is placed so that the optical path length from this to the imaging plane of the image sensor 31 is equal. And focus adjustment is half mirror 3
This is done by moving the position of the lens 32 while looking at the image projected on the screen 36 in step 5.

[Problem that the invention is trying to solve] However,
In the above-mentioned conventional example, since focusing is performed visually, individual differences occur.

In addition, there are other problems in that in order to create the projection plane, the device becomes larger and the number of parts increases, and many of these parts require strict precision.

[Means for solving problems]

The present invention aims to eliminate variations in focus due to individual differences, reduce the number of expensive parts conventionally required for focus as much as possible, and achieve miniaturization of the device. It has a reading optical system configured to form a transmitted image on a line image sensor for reading the original, and compares the image sensor output obtained by reading a focus adjustment pattern on the same surface as the original with a predetermined reference value. Based on this comparison result, it is displayed whether the image formation state by the reading optical system is within a permissible range.

〔Example〕

1 to 6 show a first embodiment of the present invention, and FIG. 1 shows the configuration of a reading optical system. l in the figure is CCD
2 is a magnifying lens, 3 is a film that is an original to be read, and 4 is a glass plate that is a film carriage.

5 is a striped pattern printed at regular intervals in black and white perpendicular to the main scanning direction on the same plane as the film installation surface of the glass 4 and at a position away from the loading position.As shown in the figure, this striped pattern is The image is projected onto a focus reference region PR outside the document reading range OR of the image sensor 1.

When the power is turned on in the above configuration, the film 3 in the figure
A light source (not shown) above turns on. Next, when you press the reading start button on the operation panel, a drive source (not shown) moves the film 3 along with the film carriage in the direction of the arrow.
That is, it is transported in the sub-scanning direction. The film 3 is fed one line in the sub-scanning direction every time one line is read in the main-scanning direction. Note that the reading start position and end position are the upper end 3a and lower end 3b of the film 3, respectively.
It is.

Now, in order to use this device, it is first necessary to adjust the focus. As described above, the black and white striped pattern 5 is printed on the film carriage 4 and is projected at a position outside the original reading area OR of the image sensor 1. The sample-and-hold waveform of this portion read by the image sensor 1 has a shape as shown in FIG.

Here, there are two factors to judge whether the focus is on or not.
There is one. The first is the dynamic range, that is, the level difference between the white part and the black part, and the second is the magnification. If these two points are detected electrically and an LED or the like lights up when both conditions are met, the operator can judge whether the lens 2 is in focus based on the lighting of the LED. This eliminates variations in focus adjustment due to individual differences.

Next, a method for processing the above two points will be described using an example of the configuration of the focus detection circuit shown in FIG. During focusing, the output of the image sensor 1 via the sample and hold circuit 51 is input to the focus calculation circuit 61 by the switch 53.

First, regarding the level difference between black and white at the first point, it is desirable that the potential difference ΔV between the white part and the black part of the sample-and-hold waveform of the image sensor output shown in FIG. 2 be maximized. On the other hand, the level difference that can be considered to be in focus is ΔVa
ll, and the actual level difference obtained through the maximum and minimum peak detection circuit 52 for the read signal of the image sensor 1 is Δ.
When ν, it is sufficient if the condition Δν>ΔVall is satisfied. The level comparison is performed by the comparator 54, and if the condition is satisfied, the comparator 54 outputs a high level signal.

Next, confirmation of the magnification will be explained.

For simplicity, it is assumed that one stripe of the black-and-white stripe pattern 5 printed on the film carriage glass 4 described above corresponds to one pixel of the image sensor 1. In this case, the relationship between the output waveform of the image sensor 1 and the output when this is binarized by the binarization circuit 55 at a certain slice level VSL is as shown in FIG.

Even if we consider a case where the positional relationship between the striped pattern 5 and the image sensor 1 is slightly shifted in the direction of the arrow, whether it is white or black when binarized is determined by the area ratio of black and white occupied by each pixel, so the binarized output is is as shown in FIG.

- Now, let the number of pixels for focus reference of this image sensor 1 be n. At this time, assuming that the striped pattern on the film carriage 4 and the pixels of the image sensor 1 have a perfect l-to-l correspondence as described above, there will be a change point from white to black or from black to white in the binarized output waveform. The number of is n.

Next, it is assumed that the number of stripes of the stripe pattern 5 falling in the n-pixel focus reference region PR of the image sensor is (n+a). In this case, the correspondence between the striped pattern 5 and the image sensor pixels, the image sensor output waveform, and the binarized output waveform are as shown in FIG. At this time, the number of points of change from white to black or from black to white counted by the counter 56 is (n-Δn). Here, n: natural number, Δn=
[1α1] (the largest integer that does not exceed the absolute value of a) On the other hand, at this time, the magnification is n/(n+a) times.

When the allowable magnification is (l-α) times to (1+α) times (
0≦α<1) 1-α< n/ (n+a) < 1+α
Therefore, -nα/(1+α)<a<nα/(1-α)la
Since l<nα/(1+α) satisfies the above formula, Δn<n
If α/(1+α) is satisfied, it can be determined that the magnification is within the allowable range. That is, in the reference range of n pixels of the image sensor 1, the sum of the points of change from white to black or from black to white obtained by counting the binary output from the binary circuit 55 by the counter 56 is [n- nα
/(1+α)] or more, it can be determined that the magnification is within the allowable range. This judgment is made by a comparator 57,
If this condition is satisfied, comparator 57 outputs a high level signal.

Therefore, when the above-mentioned black-white level difference Δν>ValL and the number of black-white changing points n'>[n-nα/(1+α)] are satisfied, the high-level signal output from each comparator 54 and 57 is sent to the AND circuit 58. If the configuration is such that the output of the AND circuit 58 lights up the LED 60 via the display circuit 59, the LED 60 will indicate whether or not the focus has been adjusted.
This can be easily determined by the lighting of 60.

In addition, in the above-mentioned embodiment, the case where the number of striped patterns and the number of reference pixels of the image sensor have a one-to-one correspondence was described, but for example, if the magnification ratio is large and you try to make a one-to-l correspondence, the number of stripes in the striped pattern If the width is less than the printable limit, one stripe may correspond to m pixels of the image sensor. In this case, if the number of reference pixels is n, the number of black and white inversions when the magnification is matched is n/m.

In addition, in the above example, if the magnification is correct when the number of stripes that enter n pixels of the image sensor is (n + a), the number of black and white inversions is (n - Δn) as a standard, and the allowable magnification is If it is within the range that takes into consideration, it may be determined to be OK.

In other words, the correspondence between the number of striped patterns and the number of pixels of the image sensor does not necessarily have to be 1:1 or 1:m (m: an integer), and the standard number and allowable range for black and white inversion are calculated according to this ratio. can do.

In the embodiment described above, the focus reference area was provided outside the image reading range of the image sensor l, but as shown in FIG. Adjustments may be made using the entire area. In this case, a striped pattern 5' is printed at a position away from the reading start end 3a or end end 3b of the film set portion of the film carriage 4.

When adjusting the focus, the switch 62 is switched to the focus adjustment mode, the output of the image sensor 1' is inputted to the focus calculation circuit 61, and the film carriage 4 is adjusted to the focus adjustment position. In this state, the focus of the lens 2 is adjusted, and when the above-mentioned LED 60 lights up, the adjustment is completed and the switch is switched to the image reading mode to scan the film.

In this case, since the number of focus reference pixels can be increased, focusing accuracy is improved.

The above is an example of application to a film scanner, but the present invention can also be applied to reading devices using a reduction optical system (book document reading type, sheet document reading type), such as document reading devices for facsimiles and computer input. Can be done.

In this case, a mode changeover switch 62 is used as in the embodiment shown in FIG. When the mode changeover switch 62 is switched to the focus adjustment mode, the image signal is connected to the focus adjustment circuit 61, and the driving of the drive source is cut off. Then, a document with a black and white striped pattern is placed at the document reading position and the focus is adjusted.

In the above, only the in-focus state was displayed, but the LED
By arranging a plurality of LEDs, the state in which the focus approaches the allowable range, the state in which the focus falls within the allowable range, and the state in which the focus matches the allowable range may be indicated by increasing the number of LEDs lit.

FIG. 7 shows an example of the configuration of an image reading device which can be equipped with a film projector as an option in addition to reading images of books, documents, etc. This reading device is a contact type image sensor 1
1, a short focus lens array 12°, and a light source 13. During normal document reading, the image sensor unit moves to scan a document 19 placed on a document table glass 18.

When reading a film, the image sensor unit moves to a position outside the scanning range during normal reading and stops. At this time, the mirror 14 fixedly supported on the main body of the device 17
A and 14b form an optical path as shown in the figure in order to project the image on the film 15 onto the image sensor 11. The image on the film is magnified to a predetermined magnification by a magnifying lens 16 in the projector 20 and formed on the image sensor 11.

In this configuration, as described above, the film projector 2
0 is an option, so it needs to be able to be installed and removed at any time. Therefore, by incorporating the above-mentioned focus adjustment function, it is possible to check the focus adjustment condition without the need for special measuring instruments when setting up the projector.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to adjust the focus without variations due to individual differences, and it is also possible to eliminate expensive focus adjustment parts such as screens and mirrors, thereby achieving miniaturization. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a reading optical system embodying the present invention, FIG. 2 is a diagram showing an example of the sample and hold output of the image sensor when the focus adjustment stripe pattern and the magnification between the image sensors match, and FIG. The figure shows an example of the output when this is binarized, Figure 4 shows an example of the output when the magnification does not match, Figure 5 shows an example of the focus calculation circuit, Figure 6,
FIG. 7 is a diagram showing another embodiment of the present invention, and FIG. 8 is a diagram showing a conventional example, where l is a line image sensor, 2 is a magnifying lens, 3 is a film, 4 is a film carriage, and 5 is a stripe. It's a pattern.

Claims (4)

[Claims] (1) An image sensor that has a reading optical system configured to form a reflected or transmitted image of the original onto a line image sensor for reading the original, and is obtained by reading a focus adjustment pattern on the same surface as the original. An image reading device, characterized in that the output is compared with a predetermined reference value, and based on the comparison result, it is displayed whether the imaging state by the reading optical system is within an allowable range. (2) The image reading device according to claim (1), wherein the focus adjustment pattern is a black and white pattern with equal intervals. (3) The image sensor is divided into an image reading area and a focus adjustment reference area, and the focus adjustment pattern is provided at a position corresponding to the focus adjustment reference area of the image sensor on the document placement surface, and the image sensor The image reading device according to claim 1, wherein the output from the image reading area is connected to an image reading circuit, and the output from the focus adjustment reference area is connected to a focus calculation circuit. (4) The output of the image sensor is configured to be connected to either the image reading circuit or the focus calculation circuit by switching, and when adjusting the focus, the image sensor output is connected to the focus calculation circuit, and when reading the image, the image sensor output is connected to the image sensor output. An image reading device according to claim 1, wherein the image reading device is connected to a reading circuit.