JP3215064B2 - Control method of image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an image reading apparatus for reading a transparent original such as a photographic film, and more particularly to a control method for realizing high quality image reading.

[0002]

2. Description of the Related Art In an image reading apparatus having a function of reading a transparent original such as a transparent film, a light source for irradiating the original and a light receiving sensor for reading image light transmitted through the original are moved while facing each other. For reading the image information of the original. In order to read the image of the transparent original with high quality, it is necessary that the light source for irradiating the original and the light receiving unit for reading the image light transmitted through the original maintain the relative positional relationship at an appropriate value. is there.

An example of the configuration of an image reading apparatus according to the prior art will be described with reference to FIG. The light source unit 62 incorporated in the upper housing 65 has a light source 61,
The light irradiated by the light source 1 passes through the original 75 placed on the transmission glass 73 provided on the upper surface of the lower housing 74, and changes its traveling direction by a mirror 66 provided in an optical unit 69 built in the lower housing 74 to be collected. The light reaches the CCD 68 via the optical lens 67.

The light source unit 62 includes a driving pulley 71
a and the drive belt 7 driven by the driven pulley 72a
0a moves along the original 75. The optical unit 69 also moves along the original 75 in synchronization with the movement of the light source unit 62 by the driving belt 70 driven by the driving pulley 71 and the driven pulley 72.

The relationship between the optical axis of light emitted from the light source 61 and the amount of light received by the CCD 68 will be described with reference to FIG. The curve shown in FIG. 9 indicates that when the optical axis of the light emitted from the light source 61 coincides with the optical axis of the CCD 68, the position C0 is reached, and the amount of light detected is 100%. Indicates that the detected light amount changes to K1% when the position shifts to the position C1.

As shown by the curve in FIG. 9, for example, when the optical axis shifts to C1, the amount of light detected by the CCD changes to K1%. Although there is an area where the light amount changes little, when the shift becomes large and the optical axis shifts to C4, for example, the light amount detected by the CCD changes to K3% and departs from the area where the change rate is gentle. And the amount of light detected greatly decreases.

From the above, in order to maintain high image quality without lowering the amount of light detected by a CCD in an image reading apparatus for reading a transparent original, it is necessary to take the following measures.

The optical axis of the light emitted from the light source is C
Align to the center of the CD.

The above-mentioned optical axis does not shift during the process of reading and scanning along the original.

As described above, in order to align the optical axis of the light emitted from the light source with the center of the CCD of the light receiving unit, in the conventional technique, a sufficient optical axis adjustment is performed in the manufacturing process of the image reading apparatus. Ship.

As described above, in order to prevent the optical axis from being displaced in the process of reading and scanning along the original, a driving source necessary for scanning the optical unit 69 as shown in FIG. The position control accuracy during scanning is secured by using a pulse motor or the like, and the pulse motor or the like is similarly used for scanning of the light source unit 62 as well.
The accuracy of the light source unit 62 following the scanning of the optical unit 69 is ensured to be sufficient.

By adopting the above-mentioned method, an image reading apparatus in which the optical axes coincide with each other can be obtained practically, but the driving system including the driving pulley 71a, the driven pulley 72a, the driving belt 70a and the like is housed. Therefore, the size of the upper housing 65, which must be opened and closed at the time of operation, needs to be increased, which is a factor that hinders operability.

As shown in FIG. 8, by integrating the optical unit 69 and the light source unit 65, the positional relationship between the optical unit 69 and the light source unit 62 is fixed. However, in the above case, the upper housing 65
This makes it difficult to open and close the image reading device and makes it difficult to use a reading mechanism using reflected light, which greatly limits the applicable range of the image reading apparatus.

[0014]

In view of the above, in order to maintain high image quality without lowering the amount of light detected by the CCD during reading scanning in an image reading apparatus for reading a transparent original, the following is required. Action needs to be taken on the item.

The optical axis of the light emitted from the light source is C
Align to the center of the CD.

The above-mentioned optical axis does not cause a deviation in the process of performing scanning for reading along the original.

[0017]

In order to solve the above problems, the present invention employs the following means.

1) At the start of reading of a transparent original by the image reading apparatus, the position of the optical unit is controlled in accordance with the position of the light source unit, and the reading is started after preparing the optimal positional relationship at the start of reading. .

By this means, an operation of setting a reference for correcting the reading start position of the optical unit is obtained.

2) At the start of reading the transparent original, a qualitative displacement amount in the reading scan of the light source unit is detected in advance, and a correction value of the reading start position of the optical unit is calculated.

By this means, an operation of calculating a correction value for correcting the reading start position of the optical unit is obtained.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention takes the following forms.

1) A driving system for reading and scanning a light source unit used for reading a transparent original and a driving system for reading and scanning an optical unit for obtaining an image signal are separately provided.
When necessary, the drive system for reading and scanning the light source unit is operated.

2) When reading a transparent original, the position of the optical unit is adjusted and corrected with respect to the light source unit at the reading start point, and the optical axis is made coincident with the light source unit at the reading start point.

3) Next, pre-reading is performed. The position of the optical unit is adjusted again at the end of the pre-reading, a point where the optical axis coincides with the light source unit at the reading start point is obtained, and the accumulated deviation of the optical axis in the pre-reading is obtained. .

4) The position where the optical unit has been corrected at the start of reading with a half amount of the optical axis shift amount in the above-mentioned pre-reading is shifted to the opposite side to the direction of the above-mentioned pre-reading and corrected. , The correction value of the subsequent reading start position.

5) The correction value at the start of reading of the optical unit is determined by the EEPRO built in the image reading apparatus.
Stored in M section.

By taking this form, the image reading apparatus has an effect of correcting the scanning start position of the optical unit in accordance with the scanning start position of the light source unit and the accuracy of the scanning movement when reading a transparent original.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A representative embodiment according to the present invention will be described with reference to FIGS.

FIG. 1 shows the configuration of an embodiment of an image reading apparatus according to the present invention. The image reading apparatus includes an upper housing 5 and a lower housing 14, and includes a hinge 1
6 are openably and closably locked.

The light source unit 2 is built in the upper housing 5, and the driving unit 3 built in the light source unit 2 is fixed to the upper housing when an instruction to read a transparent original is received. The light source unit 2 is moved by the rack 4.

The original 15 placed on the transmission glass 13 fixed on the upper surface of the lower housing 14 is irradiated by the light source 1 built in the light source unit 2.

The optical unit 9 built in the lower housing 14 includes a mirror 6 for changing the direction of the optical axis transmitted through the original 15, a condenser lens 7, and a CCD 8 for receiving the light transmitted through the original 15. ing.

The drive pulley 11 provided on the lower housing 14
Has a pulse motor (not shown) as a driving source, and a driving belt 10 applied between the driving pulley 11 and the driven pulley 12 causes the optical unit 9 to move.

The front fixed point 21 and the rear fixed point 22 are places where the original 15 is not placed, and the light source 1 is positioned when necessary to provide light transmitted only through the transmission glass 13 to the optical unit.

FIG. 2 shows a block diagram of the control of a representative embodiment according to the present invention. Image reading device B0
1 has a control unit B02, a light source unit B03, an optical unit B04, and a driving unit B42 for driving the optical unit B04, and the control unit B02 is a computing unit B21.
And an EEPROM section B22. The light source unit B03 has a light source B31 and a driving unit B32.

Referring to FIG. 3, a control flow of the optical unit correction according to the present invention will be described.

In step S01, upon receiving the instruction to read the transmissive original, the operation unit B21 proceeds to step S02 to execute E.
The EPROM section B22 is examined, and if it is confirmed that the correction value has already been stored, the process proceeds to step S11, the reading process is started using the correction value, and if the reading process is completed in step S12, the reading operation is performed. finish.

If no correction value is stored in the EEPROM B22 in step S02, the flow advances to step S03 to start a correction process, and in step S04, the preceding correction is performed.

The details of the preceding correction in step S04 will be described with reference to FIG. The light source unit B03 is moved to the front fixed point 21 (see FIG. 1) in step S04a, and the light source B31 is turned on in step S04b.

In step S04c, the optical unit B04 is moved to the front fixed point 21a (see FIG. 1). Here, the previous fixed point 21 and the previous fixed point 21a are set so as to deviate from each other.

In step S04d, the optical unit B04 is minutely moved, and the number of pulses of the pulse motor required for the movement of the optical unit and the change in the amount of light detected by the CCD unit B41 are retracted and measured. In step S04e. A median value at which the optical axis of the optical unit B04 matches the optical axis of the light source unit B03 is determined.

Here, as shown in FIG.
The process of changing the amount of light detected by is described.

As described in the above description, the optical unit B
If the front fixed point 21a (see FIG. 1) in which the light source unit B04 is located coincides with the front fixed point 21 (see FIG. 1) in which the light source unit B03 is located, the optical unit B04 is positioned at A3 in FIG. Although the light amount detected by B41 is 100%, the light amount detected by the CCD unit B41 is A% since the optical unit B04 is actually located at A1.

The optical unit B04 is slightly moved to move A1.
As the position approaches A3, the amount of light detected by the CCD unit B41 increases, reaches a peak at the point A3, starts decreasing, reaches the initial A% at the point A3, and further decreases.

Since the curve shown in FIG. 6A is bilaterally symmetric, the distance from the point A1 to the point A3 is determined by knowing the number of pulses of the pulse motor.
The distance L0 from 1a (see FIG. 1) to the previous fixed point 21 (see FIG. 1) can be determined.

In step S04f, the distance L0 is used as a correction value for setting the front fixed point of the optical unit, and the front fixed point of the optical unit is set to coincide with the optical axis of the light source unit.

In step S04g, the optical unit B04 is moved to the pre-fixed point after the correction, and the pre-correction operation ends.

Proceeding to step S05 (FIG. 3), the light source unit B03 and the optical unit B04 move synchronously, and reach the rear fixed point 22 (see FIG. 1).

In step S06, the light amount detected by the CCD unit B41 is detected. In step S07, the detected light amount at the previous fixed point is compared with the detected light amount. It is determined that the deviation is so small that no correction is necessary, and the process proceeds to step S09.
The correction processing ends.

If the difference value exceeds the predetermined range in step S07, the flow advances to step S08 to perform the subsequent correction.

Referring to FIG. 5, the details of the subsequent correction in step S08 will be described. In step S08a, the optical unit B04 is minutely moved while the light source unit B03 is fixed, and the number of pulses of the pulse motor required for the movement of the optical unit B04 and the change in the amount of light detected by the CCD unit B41 are retracted and measured. If it can be confirmed in step S08b that the detected amount of light amount tends to increase, the process proceeds to step S08c to continue the minute movement as it is, and if it can be confirmed that the detected amount of light amount tends to decrease, the process proceeds to S08d. To reverse the direction of the minute movement.

In step S08e, a median value at which the optical axis of the optical unit B04 matches the optical axis of the light source unit B03 is determined.

Here, as shown in FIG.
The process of changing the amount of light detected by is described.

FIG. 6B shows that when the optical unit B04 and the light source unit B03 reach the rear fixed point, for example, the stop position of the light source unit at the rear fixed point due to the accumulation of the deviation in the scanning movement of the light source unit B03. This shows a case where the optical unit B04 is shifted by a distance L from a stop position of the optical unit B04.

Assuming that the light quantity detected by the CCD unit B41 when the optical axis of the optical unit B04 coincides with the optical axis position B3 of the light source unit B03 is 100%, the detected light quantity of B% at the position B1. Is shown.

Here, the light source unit B03 is fixed, and the optical unit B04 is slightly moved to move the CCD unit B4.
The amount of light detected by No. 1 is observed, and the light amount is slightly moved in a direction in which the change in the amount of light shows an increasing tendency. The optical unit B described above
The movement distance of 04 can be observed by knowing the rotation direction and pulse number of the pulse motor required for the movement.

When the optical axis of the optical unit B04 reaches the point B3 from the point B1, the amount of light detected by the CCD section shows the maximum value, and further moves to return to the original detection amount when the light reaches the point B2. .

Accordingly, the distance from the point B1 to the point B2 is 2L, and the half distance L is the distance between the point B1 and the point B3.
The distance L is a cumulative shift amount that occurs when the optical unit B04 and the light source unit B03 scan and move in synchronization from the previous fixed point to the rear fixed point, and this is the distance L. The above CCD in the process
This shows that the detected light amount of the portion B41 decreases along the curve from P0 to P1.

Next, in step S08f, a distance L / 2, which is half of the distance L, is calculated, and the scanning movement start position of the optical unit B04 set in the correction in the preceding stage of step S04 is corrected.

Here, the correction of the scanning movement start position of the optical unit B04 set in the previous correction will be described with reference to FIG. 6B.

It has been found that the cumulative displacement distance between the light source unit B03 and the optical unit B04 is L in the scanning scan of the transparent original by the image reading apparatus. That is, if the optical axes of the light source unit B03 and the optical unit B04 are aligned at the start of the reading, they are shifted by the distance L at the end of the reading.

At the start of reading, the setting of the optical unit B04 is previously set to a distance L / half of the distance L.
It is shifted in the direction opposite to the direction in which the shift occurs by two.

That is, as shown in FIG. 6B, at the start of the reading of the transparent original by the image reading apparatus, the position is set at the position B4 with respect to the optical axis position B3 of the light source unit B03 by the correction before the step S04. A value shifted from the set position by L / 2 is set as a correction value.

By taking the above measures, the amount of light detected by the CCD unit B41 is emitted from P4, passes through P0,
Move on the curve leading to P5. Therefore, the above C
The light amount detection amount obtained by the CD portion B41 reaches 100% from C%, and thereafter decreases to the initial C%.

Next, in step S08g, the correction value of the set value in the preceding stage is determined, and the correction in the subsequent stage is terminated.

The flow advances to step S09 (FIG. 3) to store the correction value in the EEPROM B22. The above EEPROM
The correction value stored in the unit B22 is stored until the time when the light source B31 is replaced.

In step S10, the correction process is completed, and the flow advances to step S11 to start scanning for reading a transparent original.

In step S12, the reading operation ends.

[0070]

According to the present invention, the following effects can be expected.

1) A driving system for reading and scanning a light source unit used for reading a transparent original and a driving system for reading and scanning an optical unit for obtaining an image signal are separately provided.
When necessary, the drive system for reading and scanning the light source unit is operated.

2) At the start of reading a transparent original, the position of the optical unit is adjusted and corrected with respect to the light source unit at the reading start point, and the optical axis is aligned with the light source unit at the reading start point.

3) Next, pre-reading is performed. The position of the optical unit is adjusted again at the end of the pre-reading, a point where the optical axis coincides with the light source unit at the reading start point is obtained, and the cumulative shift amount of the optical axis in the pre-reading is obtained. .

4) The position where the optical unit was corrected at the start of reading with half the amount of deviation of the optical axis in the above-mentioned pre-reading was corrected by being shifted to the opposite side to the direction of the above-mentioned pre-reading deviation. , The correction value of the subsequent reading start position.

5) The correction value at the start of reading of the optical unit is determined by the EEPRO built in the image reading apparatus.
Stored in M section.

By this means, when the transmission original reading mode is designated, the reading start position of the optical unit is corrected to keep the deviation of the optical axis to a minimum, and the decrease in the light amount due to the deviation of the optical axis does not hinder reading in practice. There is an effect of being placed in a range where there is no.

Further, the above-mentioned correction value is stored inside the apparatus, and is reproduced even in a repeated operation. Further, when re-correction is required, an effect is obtained that the re-correction is automatically performed to maintain a posture for performing an optimal reading scan.

[Brief description of the drawings]

FIG. 1 is a mechanism diagram according to the present invention.

FIG. 2 is a block diagram according to the present invention;

FIG. 3 is a flowchart (1) according to the present invention.

FIG. 4 is a flowchart (2) according to the present invention.

FIG. 5 is a flowchart (3) according to the present invention.

FIG. 6 is an explanatory diagram of a deviation amount of an optical axis and a sensor detection value.

FIG. 7 is a mechanism diagram (1) according to a conventional technique.

FIG. 8 is a mechanism diagram (2) according to a conventional technique.

FIG. 9 is an explanatory diagram of a deviation amount of an optical axis and a sensor detection value.

[Explanation of symbols]

 1: Light source 2: Light source unit 9: Optical unit 15: Original

Claims (2)

(57) [Claims] An original (1) placed on a transmission glass (13).
5) In a method for controlling an image reading apparatus having a light source unit (2) for holding a light source (1) for irradiating light and an optical unit (9) for reading light transmitted through the original, the optical unit (9) ) And the movement of the light source unit (2) are read, and at the start of the reading scan, the relative position between the optical unit (9) and the light source unit (2) is read. A method for controlling an image reading apparatus, characterized in that the position is shifted in advance in the opposite direction where the above-mentioned cumulative difference occurs, thereby reducing the shift of the optical axis caused during scanning. 2. The method of controlling an image reading apparatus according to claim 1, further comprising the step of changing a point at which the optical unit (9) starts reading and scanning at the time of starting scanning and determining a position where the optical axis shift amount is the minimum from the output value. Further, at the end of the reading scan, the point of the end of the reading scan of the optical unit (9) is changed to obtain the position of the minimum amount of deviation of the optical axis from the output value, thereby obtaining the cumulative displacement caused by the reading scan. And setting the starting point of the reading scan of the optical unit (9) in a direction opposite to the cumulative shift generated by the reading scan by using a value of half of the cumulative shift amount. The method for controlling an image reading device according to claim 1, wherein: