JPH0481068A - Picture reader - Google Patents

Abstract

PURPOSE:To shorten time for reading by automatically adjusting the rotating speed of a drum and the moving speed of a reading original corresponding to the opening width or opening position of a color filter. CONSTITUTION:Before reading a picture, an adjusting means 33 detects the minimum opening width and respective opening start positions of color filters 22a-22c and automatically adjusts the rotating speed of a drum 3 when reading a reading original 8 while controlling a driving means 4 based on the minimum opening width. Further, the moving speed when reading the reading original 8 is automatically adjusted while controlling a scanning means 13 based on the exposure time of a linear image sensor 6 synchronized to the opening start position. Thus, time for reading is shortened at an irreducibly minimum corresponding to the actual opening width or opening positions of the color filters 22a-22c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device that reads color images.

[Prior Art] As an image reading device for reading color images, the present applicant has developed a device in which a light source is disposed in a hollow portion and color filters for color separation of 83 colors of red, R, green, G, and blue are attached at predetermined intervals in the circumferential direction. An image reading device having a cylindrical drum has been proposed (Japanese Patent Application No. 1-98181).
.

According to this device, when reading an image, the drum is rotated to sequentially transmit the transmitted light of each color filter from the light source to the read document, and this transmitted light is imaged on the linear image sensor via the imaging optical system. One line of color image data of the read original is read, then the read original is moved one line and one line of color image data of the read original is read in the same way, and this operation is repeated to read the read original.

By the way, in such an image reading device, in order to increase the reading speed, the exposure (
The rotation speed of the drum is set based on the aperture width of the color filter (width of the area through which light from the light source passes through) so that the storage time is minimized, and the linear image is synchronized with the aperture start position of the color filter. The moving speed of the document to be read is set based on the exposure time of the sensor.

[Problems to be Solved by the Invention] However, there are variations in the aperture width and opening position of each color filter, and it is necessary to set the rotational speed of the drum and the moving speed of the document in consideration of this variation. In other words, the rotational speed of the tram is set based on an aperture width that is much smaller than the actual aperture width of the color filter, and the exposure of the linear image sensor is started from a position that is much closer to the aperture start position of the actual color filter. The moving speed of the scanned document was set based on time. As a result, the exposure time of the linear image sensor during reading becomes longer than necessary, resulting in a problem that the reading time becomes longer.

An object of the present invention is to provide an image reading device that can reduce the reading time to the necessary minimum by automatically adjusting the rotational speed of the drum and the moving speed of the document to be read in accordance with the actual opening width and opening position of the color filter. It is about providing.

[Means for Solving the Problems] In order to achieve the above object, the image reading device according to the present invention includes a cylindrical drum disposed on one side of a document to be read, and a cylindrical drum disposed in a hollow portion of the drum. a plurality of color separation color filters attached at predetermined intervals in the circumferential direction of the drum; a driving means for rotating the tram; A linear image sensor that reads the original, a scanning means that moves the original and the linear image sensor relatively, and a color filter that detects the minimum color filter by changing the output of the linear image sensor when the original is not installed before reading the original. Detecting the aperture width and each aperture start position and controlling the driving means based on the minimum aperture width to adjust the rotational speed of the drum when reading the original, and the exposure time of the linear image sensor synchronized with the aperture start position. and adjusting means for controlling the scanning means and adjusting the moving speed at the time of reading the original to be read.

[Operation] When reading an image, the drum is rotated by the driving means to sequentially transmit the transmitted light of each color filter from the light source to the read document, and this transmitted light is imaged on the linear image sensor via the imaging optical system. One line of color image data of the read original is read by the scanning means, and then the read original is moved one line by the scanning means and one line of color image data of the read original is read in the same way, and this operation is repeated to read the read original.

Before reading this image, the minimum aperture width of the color filter and each aperture start position are detected by the adjusting means, and the driving means is controlled based on the minimum aperture width to automatically adjust the rotational speed of the drum when reading the original. The scanning means is controlled based on the exposure time of the linear image sensor synchronized with the aperture start position, and the moving speed when reading the original is automatically adjusted. Incidentally, the term "before image reading" includes, of course, immediately before the image reading operation, or at the time of initialization (initial setting) after device assembly.

Therefore, when reading an image, the rotational speed of the tram is automatically adjusted based on the actual aperture width of each color filter, and the moving speed of the document to be read is adjusted based on the exposure time of the linear image sensor, which is synchronized with the actual aperture position of the color filter. Even if there are variations in the color filter aperture width or aperture position, the rotational speed of the drum and the moving speed of the document to be read are automatically adjusted to reduce the time required to read the document to the necessary minimum. can.

[Embodiment] FIG. 1 shows a schematic configuration of an image reading device according to the present invention.

In this image reading device, as shown in FIG. 1, a mounting base 2 is installed above a document table 1, and on this mounting base 2 is mounted a drum 3 and a stepping motor 4 as a driving means for rotationally driving the drum 3. is located. In addition, the manuscript table 1
A linear image sensor 6 is disposed below the tram 3, facing the tram 3 via an imaging optical system 5.

The document table 1 is provided with two flat glasses 7.7, and an original document 8 to be read is set between these flat glasses 7.7. The document table 1 is mounted on a carrier 9 supported by a base (not shown) so as to be slidable in a direction perpendicular to the axial direction of the drum 3 (in the direction indicated by the arrow), so that it can move together with the carrier 9. The carrier 9 has a driving wire lobe 10. Pulley 11 and reduction mechanism 1
2, it is driven by the driving force of a stepping motor 13 serving as a scanning means. Therefore, the document table 1 can be moved together with the document 8 to be read in a direction perpendicular to the axial direction of the tram 3 (in the direction of arrow A) by the driving force of the stepping motor 13.

The imaging optical system 5 is used to form an image on the linear image sensor 6, and for example, a reduction lens, SELFOC lens array (trade name), etc. are applied thereto.

In this embodiment, the number of pixels of the linear image sensor 6 is 5000 in the axial direction of the drum 3, and image data can be determined within this range.

A bearing block 1 is mounted on the mounting base 2 as shown in FIG.
4 is erected, and a bearing plate 15 is erected parallel to and facing the bearing block 14, and both ends of the drum 3 are supported by the bearing block 14 and the bearing plate 15. Furthermore, a narrow opening 2a is formed in the mounting base 2 at a portion between the bearing block 14 and the bearing plate 15 and facing the drum 3, and this opening 2a is for light transmission. .

Sleeves 17.18 are fixed coaxially to both ends of the tram 3, and the tram 3 is rotatably supported by the bearing block 14 and the bearing plate 15 of the mounting base 2 via the sleeves 17.18. The sleeve 17 is rotatably fitted into a bearing hole of the bearing block 14 via a sliding bearing 19. The sleeve 18 is rotatably fitted onto the support shaft 16 fixed to the bearing plate 15 via a rolling bearing 20.

In the middle part of the tram 3, as shown in FIG. 2, a large number of slits 21 are bored at predetermined intervals in the circumferential direction, and within each of these slits 21, a red R color filter 22a for color separation is installed. The rotation direction of the drum 3 (
They are held sequentially lined up in the direction of arrow B). slit 2
1 has a step formed on its inner wall, and this step holds each color filter 22a, 22b, 22c so that it will not fall off due to wind pressure or centrifugal force caused by the rotation of the drum 3. The slit 21 is formed to be elongated in the axial direction of the drum 3, as shown in FIGS. 3 and 5, and each color filter 22a is formed in a corresponding manner.

22b and 22c are also elongated in the axial direction of the drum 3, and their lengths are determined in accordance with the width of the original document 8 to be read in relation to the imaging optical system 5 (shown in FIG. 1).

Fluorescent tubes 23 are coaxially arranged in the hollow part of the tram 3, and the light from the fluorescent tubes 23 passes through each color filter 22a.
. Holders 24.25 are fitted to both ends of the fluorescent tube 23, and the holders 24.2
It is supported by the mounting base 2 via 5. The holder 24 is supported by the bearing block 14 of the mounting base 2 via a mounting plate 26. The holder 25 is attached to the support shaft 16 and is supported by the bearing plate 15 via the support shaft 16. This holder 24.25 has grooves 24a, 25a formed therein,
These grooves 24a and 25a elastically hold the fluorescent tube 23 and are used to take out one lead wire 23b. That is, one Riet wire 2.3b is connected to the holder 25.
It is pulled out from inside through the split groove 252, and its tip enters into the holder 24 through the split groove 24a, joins the other lead wire 23a in the holder 24 in an insulated state, passes through the holder 24, and is brought out to the outside. (See Figure 4).

As shown in FIGS. 3 and 5, this drum 3 has a disc 27 for detecting rotational position attached to one end, and a timing gear 28 attached to the other end. The disc 27 is clamped and fixed between the inner circumferential surface of the drum 3 and the outer circumferential surface of the sleeve 17 so as to rotate together with the drum 3. As shown in FIG. 2, a narrow notch 29 is formed in this disc 27, and a sensor 30 is disposed corresponding to this notch 29. The sensor 30 is attached to the mounting base 2, facing the notch 29, and detects the home position (reference position If) of the drum 3. The timing gear 28 is coaxially fixed to the outer periphery of the sleeve 18 and is used for transmitting the driving force of the stepping motor 4.

The stepping motor 4 is fixed to the mounting base 2, and a timing gear 31 is coaxially fixed to the drive shaft of the stepping motor 4, as shown in FIG. A timing belt 32 is wound around the timing gear 31, and this timing belt 32 is also wound around the timing gear 28 of the tram 3, and the timing belt 32 is wound around the timing gear 31, and the timing belt 32 is also wound around the timing gear 28 of the tram 3.
It has the role of transmitting driving force to.

Therefore, the stepping motor 4 is connected to the timing gear 3.
1. The drum 3 can be rotated via the timing belt 32 and timing gear 28.

This stepping motor 4 is connected to a control device 33 together with a stepping motor 13, as shown in FIG. The control device 33 is also connected to the sensor 30 and the linear image sensor 6 , and controls the stepping motors 4 .
13, the rotational speed of the drum 3 and the feeding speed of the document 8 to be read can be adjusted. The control device 33 is provided with an A-D conversion circuit 34, a storage circuit 35, and a control circuit 36, and the A-D conversion circuit 34 converts the output signal from the linear image sensor 6 from an analog signal to a digital signal. The data is stored in a memory circuit 35, and the stepping motors 4 and 13 are controlled based on the output data of the linear image sensor 6.

Next, the operation of the image reading device according to the present invention will be explained.

When reading an image, the drum 3 is rotated by the driving force of the stepping motor 4, and the transmitted light from the fluorescent tube 23 through the R2G, B color filters 22a, 22b, 22C is sequentially transmitted to the read document 8, and this transmitted light is The image is formed on the linear image sensor 6 via the imaging optical system 6, and one line of color image data of the read original 8 is read.Then, the driving force of the stepping motor 13 moves the original platen 1 by one line of the read original 8. Similarly, one line of color image data of the read original 8 is read, and this operation is repeated until the read original 8 is read.
Read.

Before this image reading, each color filter 22a, 2 is
The minimum aperture width of 2b and 22c and each aperture start position are detected, and the rotational speed of the drum 3 during image reading is adjusted based on the aperture width, and the exposure time of the linear image sensor 6 is synchronized with the aperture start position. Based on this, the moving speed of document table 1 during image reading is adjusted. Here, the opening width of the color filters 22a, 22b, 22c is the width of the fluorescent tube 23.
The width of the portion through which light passes through, and the width S of the slit 21
(as shown in FIG. 2). Moreover, each color filter 22a, 22b.

The opening start position of the slit 22c is the end position of the portion of the fluorescent tube 23 through which the light passes in the drum rotation direction, and the slit 21
This is the position corresponding to the end on the drum rotation direction side. Further, the exposure time of the linear image sensor 6 is an exposure time that is roughly set based on the image quality of the original 8 and the like.

To explain in detail, before reading the image, as shown in the operation flowchart of FIG. Calculate the average value of output data. Here, the purpose of setting the tram 3 to the home position is to set the tram 3 to a reference position, and the sensor 30 detects the position. Furthermore, the output data around the three locations of the linear image sensor 6 is stored in the storage circuit 35 via the A-D conversion circuit 34, and the average value thereof is calculated. Also,
The purpose of collecting output data around three locations of the linear image sensor 6 is to absorb variations in each location in the axial direction of the drum 3. In this embodiment, one of the linear image sensors 6
Output data was obtained at plus and minus seven pixels of 00.2500.4900 pixels (see Figure 7). In addition, the color filter 22a at each part in the axial direction of the drum 3
, 22b, 22c, it is sufficient to collect output data at a plurality of locations of the linear image sensor 6, and the sampling position of the output data can be selected as appropriate.

After calculating the average value of the output data around the three locations of the linear image sensor 6, in step 39, the tram 3
It is determined whether output data for one rotation (average value of output data around three locations of the linear image sensor 6) has been stored. If the output data has not been stored, the process returns to step 38, and if the output data has been stored, the color filters 22a, 22b are processed in step 40 based on this data.

22c is determined, and each color filter 22a is selected in step 41 based on this closing period.

The reference outputs of 22b and 22c are determined. Here, the closing period of each color filter 22a, 22b, 22c is the period T of the portion of the fluorescent tube 23 through which light does not pass, and the difference in transmittance of the color filters 22a, 22b, 22c and the difference between the fluorescent tubes It can be easily obtained regardless of the stability of the light quantity of 23 (see Fig. 8). Note that each color filter 22
The reference outputs of a, 22b, and 22c are for each color filter 2.
It is determined as the output at the midpoint in the width direction of the aperture of each color filter 22a, 22b, 22c, which is determined based on the closing period of color filters 2a, 22b, and 22C, or as the maximum output at the aperture (see FIG. 8).

Each color filter 22 a, 22 b, 22
After determining the reference output of c, in step 42, for each aperture of each color filter 22a, 22b, 22c, the portion where the output level of the linear image sensor 6 is 90% or more of the reference output is regarded as an aperture, and the 8th (see symbol C in the figure), and based on this, in step 43, each color filter 22a, 22b.

Verify the opening width of 22c (see Figure 9).

Then, in step 44, it is determined whether or not the aperture widths of the color filters 22a, 22b, 22c for one rotation of the drum 3 have been verified. If the verification has not been performed, the process returns to step 43, and the verification has been completed. If so, in step 45 each color filter 22a, 22
The number of driving steps of the stepping motor 4 corresponding to the minimum opening width of the openings b and 22c is determined.

After determining the number of driving steps of the stepping motor 4 corresponding to the minimum opening width of each color filter 22g, 22b, 22c, in step 46, the stepping motor 4 is moved from the home position to the opening start position of each color filter 22a, 22b, 22c. Find the number of drive steps for 4. As a result, the color filters 22a, 22b, 22
The actual aperture width of c and each aperture start position are detected. Note that the color filters 22a, 22b, 22 are
Since the minimum aperture width of c and each aperture start position are detected, the color filter 22 is detected as shown in FIG.
Even when the linear image sensor 6 is assembled obliquely to the openings of the color filters 22a, 22b, and 22c.

Color filter 2 for opening width S1 of 22b and 22C
2a, 22b, and 22c can be reliably detected. In FIG. 10, the two-dot chain line indicates a state in which the linear image sensor 6 is displaced relative to the openings of the color filters 22a, 22b, and 22c due to the rotation of the drum 3.

When reading an image, as shown in the operational flowchart of FIG. 7, the document table 1 is first set at the reading start position of the document 8 in step 47, and then the drum 3 is set at the home position in step 48.

After the drum 3 is set at the home position, in step 49 the drum 3 is rotated to the opening start position of the R color filter 22a. When the tram 3 is rotated to this position, the exposure time of the linear image sensor 6 is started in step 50. Then, the drum 3 is rotated by the opening width of the color filter 22a, and the exposure time of the linear image sensor 6 ends. Here, the aperture width of the color filter 22a is the aperture width detected before image reading, and is the actual aperture width of the color filter 22a. Further, the aperture start position of the color filter 22g is the aperture start position detected before image reading, and is the actual aperture start position of the color filter 22a.

Next, in step 51, the tram 3 is rotated to the opening start position of the next G color filter 22b, and in step 52, the operation of step 50 is repeated. and,
In step 53, the tram 3 is rotated to the opening start position of the next B color filter 22c, and in step 54, the operation of step 50 is repeated, and after this operation is completed, the document table 1 is moved by one line in step 55.

Then, in step 56, it is determined whether or not the document table 1 has been moved to the end position for reading the document 8. If this movement has not been made, the process returns to step 49. This completes the reading operation of the original 8. Here, document table 1
The moving speed of the color filters 22a and 22b is detected before image reading.

This is done based on the exposure time of the linear image sensor 6 which is synchronized with the actual aperture start position of 22C.

Therefore, when reading an image, each color filter 22
The rotational speed of the drum 3 is adjusted based on the minimum aperture width of the color filters 22a, 22b, and 22c, and the original is adjusted based on the exposure time of the linear image sensor 6, which is synchronized with the aperture start position of each color filter 22a, 22b, and 22c. The moving speed of platform 1 is adjusted. For this reason, the color filter 22
Even if there are variations in the opening width and opening position of the openings a, 22b, and 22c, the rotational speed of the drum 3 during image reading and the feeding speed of the original to be read 8 are automatically adjusted accordingly, thereby reducing the reading time for the original to be read 8. It can be shortened to the minimum necessary.

In particular, since the minimum aperture width and each aperture start position of the color filters 22a, 22b, and 22c are detected while the drum 3 is rotating, the rotational speed of the drum 3 and the read original 8 are determined in consideration of the inertia of the stepping motor 4. The moving speed can be adjusted and actual movement can be reliably corrected.

Further, since the rotational speed of the drum 3 and the moving speed of the read document 8 can be automatically adjusted in accordance with the actual opening width and opening position of the color filters 22a, 22b, 22c, the color filters 22a, 22b.

The manufacturing accuracy of the opening width and opening position of the color filters 22c and the assembly of the color filters 22a, 22b, 22c and the linear image sensor 6 has a wide tolerance range, and manufacturing costs can be reduced.

In addition, before reading the document 8, the linear image sensor 6
color filter 22 based on output data at multiple locations.
Since the minimum aperture width and each aperture start position of color filters 22a, 22c are detected, color filters 22a, 22
b Even if the linear image sensor 6 is assembled obliquely to the opening of the color filter 22a.

By detecting the effective minimum aperture width of 22b and 22c and the respective aperture start positions, the reading time can be reliably shortened to the necessary minimum.

Note that the opening widths of the color filters 22a, 22b, and 22c are unique to the device, and once the rotational speed of the drum 3 and the feeding speed of the document 8 to be read are adjusted, there is no need to adjust them thereafter. It may be done only once.

Also, in the above embodiment, one line is read by the R, G, and B color filters 22a, 22b, and 22c while the document table 1 is advanced line by line. It is also applicable to a method in which one side is read, then the first side is read with a G color filter, and then the first side is read with a B color filter, and the document table 1 is moved three times.

Further, the drum 3 is not limited to a cylindrical shape, but can be modified as appropriate, such as being formed into a hexagonal column shape in which two sets of RG and B color filters 22a, 22b, and 22c are arranged.

In addition, the tram 3 may be made into a transparent cylindrical shape, and a color filter may be attached to the outer periphery, or a gelatin film may be formed to provide R, G, and G.
It is also possible to form a color filter by dyeing with , B dye.

Further, a lamp may be used instead of the fluorescent tube 23, and an optical fiber may be used to guide light from a light source such as a lamp to the hollow portion of the tram 3.

Further, the linear image sensor 6 is not limited to one having 5000 pixels, but it is of course applicable even if it has less than 5000 pixels or more.

[Effects of the Invention] As explained above, in the image reading device according to the present invention,
Before reading the original, the minimum aperture width of the color filter and each aperture start position are detected based on changes in the output of the linear image sensor when no original is installed, and the driving means is controlled based on the minimum aperture width to read the original. Adjustment means is provided for adjusting the rotational speed of the drum when reading the document and controlling the scanning means based on the exposure time of the linear image sensor synchronized with the aperture start position to adjust the moving speed when reading the original. Therefore, the rotational speed of the drum and the moving speed of the document to be read can be automatically adjusted in accordance with the actual opening width and opening position of the color filter, thereby reducing the reading time to the necessary minimum. In particular, since the aperture start position and minimum aperture width of the color filter are detected while the drum is rotating, the inertia of the drive means such as the motor that rotates the drum is taken into account to determine the drum rotational speed and the movement of the document to be read. The speed can be adjusted automatically, making it possible to reliably correct the actual operation. In addition, since the rotational speed of the drum and the moving speed of the document to be read can be automatically adjusted in accordance with the actual aperture width and aperture position of the color filter, it is possible to adjust the manufacturing accuracy of the aperture width and aperture position of the color filter or the linearity of the color filter. When assembled with an image sensor, the tolerance range for accuracy is widened and manufacturing costs can be reduced. Furthermore, if the aperture start position and minimum aperture width of the color filter are detected based on output data from multiple locations of the linear image sensor before reading the original, the linear image sensor can detect the aperture of the color filter. It has various excellent effects such as being able to cope with cases where it is assembled at an angle or at an angle.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image reading device according to the present invention, FIG. 2 is a sectional view of the main part along the drum radial direction, FIG. 3 is a sectional view of the main part along the drum axial direction, and FIG. The figure is a partially cutaway perspective view of the fluorescent tube, Figure 5 is a partially cutaway view, Figure 6 is a flowchart before image reading, Figure 7 is a flowchart during image reading, and Figure 8 is a drum. FIG. 9 is a graph showing output changes of the linear image sensor at three locations as the drum rotates; FIG. 1st
FIG. 0 is a plan view of the aperture of the color filter showing a state in which the linear image sensor is disposed obliquely with respect to the aperture of the color filter. 3. Drum, 4. Stepping motor (driving means), 5. Imaging optical system, 6. Linear image sensor, 8. Original to be read, 13. Stepping motor (scanning means), 22a
22b, 22cm - Color filter, 23...
Fluorescent tube (light source), 33. Control device (adjustment means). that's all

Claims (1)

[Scope of Claims] A cylindrical drum disposed on one side of a document to be read; a light source disposed in a hollow portion of the drum; and a plurality of color separation units attached at predetermined intervals in the circumferential direction of the drum. a color filter for rotationally driving the drum; a linear image sensor disposed on the other side of the original to read the original through an imaging optical system; a scanning means for moving the image sensor relative to the image sensor; and detecting the minimum aperture width and each aperture start position of the color filter based on output changes of the linear image sensor in a state where the read document is not installed before reading the read document. The driving means is controlled based on the minimum aperture width to adjust the rotational speed of the drum when reading the original, and the driving means is controlled based on the exposure time of the linear image sensor synchronized with the aperture start position. An image reading apparatus comprising: an adjusting means for controlling a scanning means to adjust a moving speed during reading of the original to be read.