JPH0126587B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention provides a solid-state scanning element that is optimal for adjusting the position and orientation of a solid-state scanning element with respect to the optical axis of a lens used in a solid-state electronic scanning document reading unit. The present invention relates to a method for adjusting the position of a scanning element.

[Prior art]

FIG. 1 is a perspective view of the basic configuration of a document reading section using a solid-state electronic scanning method using a solid-state scanning element.

In FIG. 1, a readout line 2 is provided that scans the document width l ₁ in line, and a lamp 3 disposed on the readout line 2 illuminates the document 1 including the readout line 2. Further, on the readout line 2, four solid-state scanning elements 5 are arranged which divide the effective readout width _l2 into four and condense the reflected light from each width through the reduction lens 4. There is.
These four combinations consisting of the reduction lens 4 and the solid-state scanning element 5 each take a share in reading out the necessary effective width. In such a document reading section, the solid-state scanning element 5 needs to be electrically positioned at the highest sensitivity position with respect to the optical axis 6' of the lens.

FIG. 2 shows the direction of adjustment of the solid-state scanning element. In FIG. 2, the solid-state scanning element 5 is shown horizontally to make the drawing easier to read, but the position and orientation of the solid-state scanning element 5 directly affect the reading sensitivity. The photodiode array 6 of the solid-state scanning element 5 has an accuracy of several tens of micrometers for the five axes: the Z-axis and rotation axis in the focal direction, and the X-axis, Y-axis, and θ-axis in the document plane, which directly affect the positional accuracy of the readout line. It is necessary to position.

By the way, in order to correctly determine the position of the solid-state scanning element 5, it is relatively easier to use an appropriate adjustment pattern than to adjust the position by receiving reflected light from the original. The position adjustment pattern of a conventional solid-state scanning element is a pattern 7 that is continuous in the order of black and white, as shown in FIG. When this conventional black-and-white pattern 7 is correctly imaged onto the photodiode array 6 through the reduction lens 4, each image of the black-and-white pattern 7 becomes equal to the unit light-receiving area of the photodiode array 6, that is, one bit. It's getting bigger. When the photodiode array 6 and the black and white pattern 7 match perfectly as shown in FIG. 4a, the output waveform becomes as shown in FIG. 4b. Here, the horizontal axis corresponds to the bits of the photodiode array 6, and "0" on the vertical axis represents the dark signal level, and "100" represents the bright signal level.

To adjust using the conventional position adjustment pattern 7,
The solid-state scanning element 5 may be moved so as to obtain an output waveform as shown in FIG. 4b. However, in the case where the solid-state scanning element 5 shifts in the focal direction and the magnification changes as shown in FIG. 5a, and in the case where the photodiode array 6 is tilted with respect to the black and white pattern 7 as shown in FIG. The output waveforms are almost the same as shown in Fig. 5c and d, and it is not clear in which direction the adjustment should be made.Furthermore, there is always variation in the bit size of the solid-state scanning element 5, as shown in Fig. 4b. It is not possible to obtain perfectly matched waveforms as shown in the figure, and the positioning accuracy decreases. In the end, you have to make adjustments through trial and error. Therefore, with such a conventional adjustment pattern, positioning of a solid-state scanning element with a small number of bits is relatively easy, but with a large number of bits, e.g.
In the case of 128 bits and 1024 bits, the number of positioning steps is large, and it is difficult to automate the position adjustment, so it has been impossible to obtain an inexpensive and highly accurate document reading section.

[Purpose of the invention]

SUMMARY OF THE INVENTION In order to improve the above-mentioned conventional drawbacks, it is an object of the present invention to provide a solid-state scanning element having the highest electrical sensitivity with respect to the optical axis of a lens used in a document reading section. It is an object of the present invention to provide a method for adjusting the position of a solid-state scanning element, which allows adjustment of five axes for setting the position and orientation at the same time using one position adjustment pattern.

[Summary of the invention]

In order to achieve the above object, a method for adjusting the position of a solid-state scanning element according to the present invention is provided in a document reading device that optically scans a document through a lens with a solid-state scanning device and reads the document, with respect to the optical axis of the lens. The diode array of the solid-state scanning element is arranged in the following directions: X, which is the scanning direction of the solid-state scanning element; A method for adjusting the position of a solid-state scanning element, which adjusts the position of the solid-state scanning element by moving in the three-dimensional direction of Z, which is the optical axis direction, the method comprising a plurality of striped patterns of a predetermined pitch provided on both sides and the center. 10', at least one strip pattern 8 provided between the plurality of striped patterns, and at least two line patterns 9 provided in a direction perpendicular to the striped direction of the striped pattern 10'. a step of adjusting the Z direction by setting a strip pattern 10' in front of the lens and adjusting the strip pattern 10' to a position where the entire surface of the diode array has substantially uniform sensitivity; The step of scanning the line pattern 9 to calculate the center based on the change in black and white at the edge, and detecting the difference from the center of the diode array to adjust the X direction; and the step of scanning the line pattern 9 to calculate the center of the diode array. In the step of adjusting the Y direction by calculating the amount and adjusting the amount of inclination to zero,
A feature of the present invention is that the position of the solid-state scanning element is adjusted.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 6 to 18.

First, adjustment in the X-axis direction is performed by adjusting the center bit of the black band pattern 8, which is symmetrical with respect to the Y-axis, as shown in Figure 6.
This is done by reading n ₁ +n ₂ /2 with the photodiode array 6. That is, the virtual center bit n 1 +n 2 /2 at the initial position of the solid-state scanning element 5 is calculated from n ₁ bits changing from white level to black level and n ₂ bits changing from black level to white level, and the virtual center bit n ₁ +n ₂ /2 at the initial position of solid-state scanning element 5 is calculated. For example, in the case of a 1024-bit solid-state scanning element, the difference between the true center bit of 512 bits and n ₁ +n ₂ /2 bits is calculated, and positioning in the X-axis direction is performed.

Adjustment in the Y-axis direction and θ rotation are performed using two black line patterns 9 arranged symmetrically on the X-axis and the Y-axis, as shown in FIG. That is, the Y-axis adjustment is performed by moving the solid-state scanning element 5 equipped with the photodiode array 6 in the direction of arrow a along the Y-axis and positioning the photodiode array 6 of the solid-state scanning element 5 on the black line pattern 9. conduct. At the same time as this Y-axis adjustment, the tilt amount of the photodiode array 6 is calculated based on the amount of positional shift in the Y-axis direction of the photodiode array 6 obtained by reading the left and right black line patterns 9, and the θ rotation is adjusted.

Next, adjustment of the focus direction, that is, the Z axis and rotation will be explained.

As shown in Fig. 9a, the output voltage difference between the white background and the black background when reading the black strip pattern 8 increases as it approaches the just focus, and decreases as it moves away from the just focus, as shown in Fig. 9b. . However, the position where the output voltage difference between the white background and the black background peaks is about 100 μm, and the black band pattern 8
is not suitable for highly accurate focal positioning.

Furthermore, the output voltage difference between adjacent bits when reading the black and white striped pattern 10 as shown in FIG. It responds sensitively and enables highly accurate focus positioning. However, during the positioning process, due to variations in the bit size of the solid-state scanning element 5, etc., the black and white striped pattern 10 and the photodiode array 6 do not necessarily match as shown in the eleventh example. Even if the solid-state scanning element is moved in the Z-axis direction in this state, it is difficult to detect just focus.

Therefore, the black and white striped pattern was improved as shown in FIG. P ₁ is the pitch width of the black stripes, and P ₂ is the pitch width of the white stripes, which correspond as much as possible to the bits of the solid-state scanning element. Then, at predetermined intervals, the pitch width of the white stripes was changed to 7/8P ₂ . If 8 groups of black and white striped patterns having white stripes with a pitch width of 7/8P ₂ are arranged in 8 groups, either group 10' or 8 will completely correspond to the photodiode array 6 as shown in FIG. .

In this embodiment, the pitch width of the white stripes is changed, but the pitch width of the black stripes may be changed. Further, the pitch width may be changed by either enlargement or reduction. Furthermore, although the degree of change is set to 7/8, it can also be changed to, for example, 6/7 or 8/9, and in these cases, 7 groups and 9 groups of black and white striped patterns are required, respectively. In general,
Assuming that the degree of change is n/m, the number of groups X of necessary black and white striped patterns can be found from the following equation.

X=m/｜m−n｜ (1) However, X, m, and n are each positive integers.

Just like the above black and white striped pattern 10'
Focus can be detected, but a further problem with focus positioning is that it takes lens aberrations into consideration.
This is the arrangement position of the black and white striped pattern 10'.

For example, if the black and white striped pattern 10' is provided only at the center of the reduction lens 4 as shown in FIG. Since it is curved, both ends are shifted from the just focus by the aberration of the reduction lens 4. Further, even if the photodiode array 6 is tilted as shown in a and b, it cannot be determined. on the other hand,
When a black and white striped pattern 10' is provided at both ends as shown in FIG.
It is possible to position the lens in focus, but the sensitivity will be poor in the center.

Therefore, as shown in FIG. 16, a black and white striped pattern 10' is provided at the center and both ends so that the entire surface of the photodiode array 6 can be adjusted to a position where the sensitivity is almost uniform. Therefore, since the sensitivity can be made almost uniform over the entire surface, the effective reading width can be determined by using the approximately 10-bit black band pattern 12 provided at the end of the effective reading width area. For example, in the case of a 1024-bit photodiode array, 1 bit of photodiode array 6 and 1024-bit
If the bit is within the black band pattern 12, the effective reading width specification is met. Further, if 1 bit and 1024 bit are outside the black band pattern 12, it can be easily determined that the effective reading width is defective due to the magnification of the lens.

If the respective adjustment patterns described above are integrated as shown in FIG. 18 or 19, five axes can be adjusted simultaneously with one pattern. In addition, the adjustment pattern 13 shown in FIG.
Although the black belt pattern 8 for X-axis adjustment is arranged at two places in the above, adjustment can be made even at one place. Further, the black belt pattern 8 is not arranged in the center, unlike the above explanation, but is arranged in a position shifted from the center. Therefore, the positioning in the X-axis direction is done using the black belt pattern 8 on the left.
The virtual center bit is calculated from the bit that changes from white to black and the bit that changes from black to white of the black strip pattern 8 on the right side, and is calculated based on the difference from the center bit of the photodiode array 6. The X-axis adjustment in the embodiment of FIG. 19 is performed by the difference between the virtual center bit and the true center bit, as described above. Furthermore, the relationship between each pattern and the pattern material on which the pattern is arranged as described above corresponds to the relationship between a negative and a positive in photographic film, and in addition, in this embodiment, the difference in brightness between the pattern and the pattern material is The position is adjusted by determining the resulting output voltage difference of the solid-state scanning element 5. Therefore, even if the relationship in brightness difference between the pattern and the pattern material is reversed, the same output voltage difference will occur, so pattern 1 in FIG.
Patterns in which the black and white of patterns 3 and 14 in FIG. 19 are reversed can also be implemented.

Next, the operation of adjusting the position and orientation of the solid-state scanning element 5 using the position adjustment pattern 13 of this embodiment will be described.

FIG. 20 shows the output voltage waveform when the position and orientation are completely adjusted using pattern 13. 512 bit is the center bit of pattern 13,
The S bit and the E bit are bits for checking the effective reading width, and these 20th bits
The bits and five-axis positioning algorithm shown in the figure are stored in memory 101 shown in FIG.

FIG. 21 shows an outline of a system for adjusting the position of the solid-state scanning element 5. A position adjustment pattern 13 for adjusting the position of the solid-state scanning element 5 is set on a position adjustment jig (not shown). This pattern 13 is irradiated by a lamp 3, and the reflected light is guided to a solid-state scanning element 5 via a reduction lens 4 to form an image. The imaged reflected light is photoelectrically converted by the photodiode array 6 and sent to the detection circuit 100. The detection circuit 100 detects the output voltage for each bit. On the other hand, a 5-axis positioning algorithm is stored in the memory 101, and the output voltage of each bit when the solid-state scanning element 5 is moved in 5 axes is calculated by the calculation circuit 102 to recognize the amount of position/orientation deviation. , based on that recognition, the control circuit 1
03 adjusts the position and orientation of the solid-state scanning element 5.

In this way, automation of position adjustment, which was impossible with conventional methods, can be achieved.

〔Effect of the invention〕

As explained above, according to the present invention, a solid-state scanning element having a multi-bit photoelectric conversion section is set at a position and orientation that provides the highest electrical sensitivity with respect to the optical axis of a lens used in a document reading section. Since five-axis adjustments can be made simultaneously in one pattern, adjustments can be made easily and with high precision.

[Brief explanation of drawings]

Figure 1 is a perspective view of the basic configuration of the solid-state electronic scanning document reading section, Figure 2 is the adjustment direction of the solid-state scanning element,
FIG. 3 is a conventional adjustment pattern, FIG. Output waveforms. Figure 6 shows the X-axis adjustment pattern, Figure 7 shows the Y-axis adjustment pattern, and Figure 8 shows the output waveform when the solid-state scanning element is moved in the Y-axis direction on the adjustment pattern in Figure 7. Figure 9a shows the black belt pattern for focus adjustment, and Figure 9b shows the white-black output voltage difference and Z when the solid-state scanning element is moved in the Z-axis direction on the black belt pattern of Figure 9a. The relationship between the axis movement amount, Figure 10a shows the black and white striped pattern for focus adjustment, and Figure 10b shows the output voltage between adjacent bits when the solid state scanning element is moved in the Z-axis direction on the black and white striped pattern. The relationship between the difference and the Z-axis movement amount, Figure 11, is as follows:
FIG. 12 shows the state of bits of the solid-state scanning element for a black-and-white striped pattern, and FIG. 13 shows an image of the solid-state scanning element for a black-and-white striped pattern with a shifted pitch. Figures 14 to 16 show the state of the focal position when a black and white striped pattern is provided at each position, and Figure 17.
The figure shows the 18th black belt pattern for checking the effective reading width.
The figure shows the position adjustment pattern of the first embodiment of the present invention, FIG. 19 shows the output voltage when the position adjustment is completed using the pattern of FIG.
0 is a diagram showing a position adjustment pattern according to a second embodiment of the present invention, and FIG. 21 is a diagram showing an outline of a system when performing position adjustment using the position adjustment pattern of the present invention. 1: original, 2: reading line, 3: lamp,
4: Lens, 5: Solid-state scanning element, 6: Photodiode array, 7: Conventional adjustment pattern, 8: X
Black band pattern for axis adjustment, 9: Y axis, black line pattern for θ rotation adjustment, 10': Z axis, black and white striped pattern for rotation adjustment, 11: Focus position, 12: Black band pattern for confirming effective reading width, 13 , 14: Position adjustment patterns in different embodiments of the present invention.

Claims (1)

[Scope of Claims] 1. In a document reading device that optically scans a document through a lens with a solid-state scanning element and reads the document, a diode array of the solid-state scanning device is fixedly scanned with respect to the optical axis of the lens. Move in the three-dimensional directions of X, which is the scanning direction of the element, Y, which is perpendicular to the scanning direction of the solid-state scanning element and perpendicular to the optical axis direction of the lens, and Z, which is the optical axis direction of the lens. A method for adjusting the position of a solid-state scanning element by adjusting the position of the solid-state scanning element, the method comprising: a plurality of striped patterns of a predetermined pitch provided on both sides and the center; and a plurality of striped patterns provided between the plurality of striped patterns. A position adjustment pattern comprising at least one strip pattern and at least two line patterns provided in a direction perpendicular to the stripe direction of the stripe pattern is set in front of the lens, and the stripe pattern is scanned. By adjusting the entire surface of the diode array to a position where the sensitivity is almost uniform, there is a step of adjusting the Z direction, and a step of scanning the band pattern and calculating the center based on the change in black and white at the edge. The step of adjusting the above-mentioned X direction by detecting the difference between A method for adjusting the position of a solid-state scanning element, characterized in that the position of the solid-state scanning element is adjusted by the step of adjusting the position of the solid-state scanning element. 2. The solid according to claim 1, wherein the Y direction includes a Y-axis direction and a rotation direction around the Y-axis, and the Z direction includes a Z-axis direction and a rotation direction around the Z-axis. How to adjust the position of the scanning element.