JP3671716B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus that reads an image of an imaging target with a line sensor.
[0002]
[Prior art]
A line sensor is known as an imaging means for performing position recognition of an electronic component by image processing in an electronic component mounting apparatus or the like. In this line sensor, a light receiving element that accumulates electric charge according to the amount of received light and a transfer unit that receives electric charge from the light receiving element and outputs it as an electric signal are arranged in a line. When an image of the imaging target is formed on the line sensor by the optical system, electric charges corresponding to the image data of the target are stored in each light receiving element. By receiving the electric charges of the respective light receiving elements by the transfer unit and sequentially outputting them as electric signals, one-dimensional image data in the arrangement direction of the light receiving elements, that is, the main scanning direction can be obtained. Then, the desired two-dimensional image data is obtained by juxtaposing the one-dimensional image data obtained while moving the electronic component in the sub-scanning method orthogonal to the main scanning direction. In general, the size of a line sensor used for an imaging target is determined by the number of light receiving elements arranged.
[0003]
[Problems to be solved by the invention]
By the way, electronic component mounting apparatuses are classified into several types according to the types and sizes of electronic components to be handled. For example, there are a high-speed type that mounts only small-sized electronic components exclusively at high speed, and a multi-functional type that targets various types of electronic components from small to large sizes. For this reason, when the above-described line sensor is used in the electronic component mounting apparatus, it is necessary to use one that is suitable for the size of the mounting object. As a result, the versatility of the line sensor used in the image reading apparatus has been poor so far, and it is necessary to prepare various types of image reading apparatuses for each type of electronic component mounting apparatus, which hinders cost reduction of the image reading apparatus. It was.
[0004]
Therefore, an object of the present invention is to provide a low-cost image reading apparatus that can use the same line sensor for various types of electronic components.
[0005]
[Means for Solving the Problems]
The image reading apparatus according to claim 1, wherein a light receiving unit in which a plurality of light receiving elements are arranged in a line in the main scanning direction, and a transfer unit that receives electric charges accumulated in the light receiving unit and outputs them as an electrical signal to an output unit. A line sensor, an optical system for forming an image of the imaging object on the light receiving unit, a light shielding unit for partially shielding the light receiving unit during imaging, a control unit for controlling the line sensor, and a line A main scanning direction element number setting unit for setting the number of elements to be output when the sensor outputs the electrical signal, and the center position of the light receiving unit in the main scanning direction is offset with respect to the optical axis of the optical system An offset amount adjusting means for adjusting the amount of the offset is provided .
[0006]
According to a second aspect of the present invention, there is provided the image reading device according to the first aspect, further comprising a light shielding range adjusting unit that adjusts a light shielding range by the light shielding unit.
[0008]
According to the present invention, the line sensor is partially shielded according to the object at the time of imaging, and only the necessary range is received to read only one-dimensional image data in this range, and the center position of the line sensor is set to the optical system. By offsetting with respect to the optical axis so that the center position of the light receiving range is aligned with the optical axis, the same line sensor can be shared with many types of electronic components, reducing the cost of the image reading device. can do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 is a sectional view of an image reading apparatus according to an embodiment of the present invention, FIG. 2A is a partial plan view of the image reading apparatus, and FIG. 2B is a plan view of a mask plate of the image reading apparatus, 3A and 3B are partial plan views of the image reading apparatus, FIG. 4 is a block diagram showing the configuration of a control system of the image reading apparatus, and FIG. 5 is a cross-sectional view of an optical system of the image reading apparatus. FIGS. 6A, 6B, and 6C are partial enlarged views of the line sensor.
[0010]
First, the structure of the image reading apparatus will be described with reference to FIGS. In FIG. 1, an image reading apparatus 1 includes an optical system 2 having a lens 2 a and a one-dimensional CCD camera 3 housed in a case 4. A substrate holding plate 10 is mounted in the case 4, and the substrate 6 is held on the plate 10. A one-dimensional line sensor 5 is mounted on the substrate 6 by pins 5c. The line sensor 5 includes a light receiving unit 5a in which a plurality of light receiving elements are arranged in a line. The arrangement direction of the light receiving elements is the main scanning direction when the image reading object is imaged. On the line sensor 5, a mask plate 11 provided with an opening 11b is detachably disposed by a bolt 11a and is positioned in the main scanning direction by a positioning pin 11c.
[0011]
The optical system 2 includes a mounting flange 2a at the lower end, and is fixed to the upper surface of the case 4 by bolts 2c via the mounting flange 2a. Reference numeral 2d denotes a positioning pin that determines the position of the optical system 2 in the main scanning direction. By bringing the side end surface of the optical system 2 into contact with the positioning pin 2d, the optical system 2 is positioned in the main scanning direction. The optical system 2 forms an image of the reflected light from the electronic component 13 held by the nozzle 12 on the CCD camera 3 described below.
[0012]
Incident light incident from the optical system 2 is received by the light receiving unit 5a of the one-dimensional line sensor 5 through the opening 11b. The position and size of the opening 11b are such that the mask plate 11 serving as a light shielding means partially covers and shields the light receiving portion 5a, and only a predetermined range of the light receiving portion 5 receives light incident from the optical system 2. Is set. That is, the position of the opening portion 11b is set so that the right end portion substantially coincides with the right end portion of the light receiving portion 5a, and the size of the opening portion 11b is set according to the size of the electronic component 13 that is an image reading object. . FIG. 2A shows a state in which a mask plate 11 having a small opening 11b having an opening length L1 corresponding to a small size electronic component is mounted, whereas FIG. 2B shows a large size. A mask plate 11 ′ having an opening 11′b having an opening length L2 corresponding to the electronic component is shown.
[0013]
With the mask plate 11 mounted, the incident light incident through the optical system 2 substantially corresponds to the size of the opening 11b starting from the right end on the charge output side of the light receiving element of the light receiving unit 5a. Only the light receiving elements within the range to be read, that is, the range necessary for image reading of the electronic component 13 receive light. Therefore, the mask plate 11 is a light shielding means and a light shielding range adjusting means for adjusting the light shielding range by changing the size of the opening 11b. The position of the mask plate 11 in the attached state in the left-right direction, that is, the position in the main scanning direction is positioned by positioning pins 11c.
[0014]
Next, the positional relationship between the center position c passing through the optical axis a of the optical system 2 in the direction perpendicular to the main scanning direction and the light receiving unit 5 will be described with reference to FIG. As shown in FIG. 3, the elongated hole-shaped bolt hole 2 b provided in the mounting flange 2 a is not arranged symmetrically with respect to the position of the center position c of the optical system 2. Therefore, as shown in FIGS. 3 (a) and 3 (b), by changing the mounting direction of the mounting flange 2a in the left-right direction, even when the same optical system 2 is used, the light receiving unit at the center position c. 5, the offsets d1 and d2 of the center position c with respect to the sensor center position b can be changed. In FIG. 3A, the first side end face 2e of the mounting flange 2a is brought into contact with the positioning pin 2d. In FIG. 3B, the direction of the optical system 2 is rotated by 180 degrees, and the second side end face is obtained. 2f is brought into contact with the positioning pin 2d. Of course, the position of the center position c can also be changed by shifting the fixing position of the optical system 2 within the adjustment range of the bolt hole 2b without changing the mounting direction. That is, the optical system 2 serves as an offset amount adjusting means for adjusting the offset amount of the center position c with respect to the sensor center position b.
[0015]
In the case where the same optical system 2 is used, by changing the mounting direction in the left-right direction as described above (or by shifting the mounting position within the adjustment range of the bolt hole 2b), the position of the center position c is changed to the light receiving unit 5. The position of the bolt hole and the position of the pin 11c can be set so that the center position of the opening 11b coincides with the center position c. Thereby, the center position of the light receiving range of the light receiving unit 5 coincides with the center position c, and an image having excellent symmetry and no distortion due to aberration of the optical system can be obtained.
[0016]
In FIG. 1 again, the substrate 6 is connected to a control circuit substrate 7 disposed in the case 4. The circuit board 7 includes a control circuit that performs control for extracting an electrical signal from the line sensor 5 and a switch 8 that sets the number of elements in the main scanning direction, which will be described later. The image data acquired by the line sensor 5 is output to an external device through the connector 9.
[0017]
An electronic component 13 such as QFP held by the nozzle 12 is positioned on the optical system 2, and an image of the electronic component 13 is formed on the light receiving unit 5 a by the optical system 2 in a state where the electronic component 13 is illuminated by illumination means (not shown). By forming an image, one-dimensional image data of the electronic component 13 in the main scanning direction is obtained. Then, by sequentially performing the imaging while moving the electronic component 13 in the sub-scanning method (perpendicular to the paper surface in FIG. 1) orthogonal to the main scanning direction, a two-dimensional image obtained by arranging the one-dimensional images in parallel can be acquired. it can.
[0018]
Next, the configuration of the control system of the image reading apparatus will be described with reference to FIG. In FIG. 4, the line sensor 5 is provided with a transfer unit 5b made of a linear CCD (charge coupled device) arranged in parallel with the light receiving unit 5a. The charges accumulated by the light receiving elements of the light receiving unit 5a receiving light are transferred to the CCDs of the transfer unit 5b. The timing of this transfer is controlled by the main scanning control unit 22. The transferred charges are sequentially transferred from the CCD as an electrical signal based on the clock signal generated by the timing generator 21 and output to the output unit 20. The main scanning direction control unit 22 counts the signal output from the timing generation unit 21 and notifies the transfer timing when the count value matches the number of pixels set in the main scanning direction element setting unit 24 described later. A signal is output to the line sensor 5 and the count value is reset. That is, the timing generator 21 and the main scanning controller 22 are control means.
[0019]
The main scanning direction pixel number setting unit 24 sets the number of elements to be output when the transfer unit 5 b outputs an electrical signal based on the setting by the switch 8. That is, among all the elements of the transfer unit 5b, the number of elements to be output is set by one output signal from the main scanning control unit 22. In other words, according to the number of elements set in the main scanning direction pixel setting unit 24, the main scanning control unit 22 changes the output cycle of a signal that instructs the transfer timing from the light receiving unit 5a to the transfer unit 5b. The sub-scanning control unit 23 controls the timing of the imaging process in the direction orthogonal to the main scanning direction. The controller 25 is an overall control unit that controls the main scanning control unit 22 and the sub-scanning control unit 23 and controls the sub-scanning direction driving unit (not shown) to control the operation of the nozzle 12 in the sub-scanning direction. The controller 25 transmits a necessary signal to the image processing unit 26 of the image recognition apparatus provided separately from the image reading apparatus.
[0020]
This image reading apparatus is configured as described above, and the image reading method will be described below with reference to FIGS. First, the electronic component 13 held by the nozzle 12 is positioned on the optical system 2, and an image of the electronic component 13 is formed on the light receiving unit 5 a via the optical system 2. As a result, as shown in FIG. 5, only the range A1 positioned below the opening 11b of the light receiving portion 5a receives light, and charges corresponding to the image of the electronic component 13 are accumulated in each light receiving element in the range A1. Is done. On the other hand, since the light receiving elements in the range A2 are shielded from light by the mask plate 11, no charge is accumulated. Thus, by making the opening 11b of the mask plate 11 correspond to the size of the electronic component 13, charges can be accumulated only in the light receiving elements in the range necessary for imaging the electronic component 13.
[0021]
At this time, the center position b of the light receiving unit 5b in the main scanning direction is offset with respect to the center position c of the optical system 2, so that the center position of the light receiving element in the range A1 is changed to that of the optical system 2 as shown in FIG. The center position c can be matched. Therefore, the electronic component 13 can be placed at a position symmetrical to the center position c and imaged, and a highly accurate image with little influence of the aberration of the optical system 2 can be obtained.
[0022]
Next, as shown in FIG. 6A, the charge accumulated in the light receiving element (hatching is indicated by hatching indicating the accumulation of charges) in the range A1 of the light receiving portion 5a by imaging is designated from the main scanning control portion 22. The data is transferred to the transfer unit 5b at the transferred timing. As a result, the charge accumulated in each light receiving element of the light receiving portion 5a is transferred to each CCD of the transfer portion 5b. That is, the charge corresponding to the light receiving element in the range A1 of the light receiving unit 5a is transferred to the CCD in the range B1 of the transfer unit 5b, and the charge corresponding to the range A2 of the light receiving unit 5a is transferred to the range B2. Here, since there is no charge accumulation during imaging in the light receiving element in the range A2, there is no charge transfer due to imaging in the range B2.
[0023]
Next, as shown in FIG. 6B, the charge of the transfer unit 5 b is output to the output unit 20 at the timing of the signal output from the timing generation unit 21. At this time, the charge of each CCD is sequentially output from the transfer unit 5b. However, the number of elements to be output is set in advance by the main scanning direction element number setting unit 24, and only the elements in the range B1 are output. Therefore, only the charges transferred to the elements in the range B1 are output to the output unit 20.
[0024]
As a result, in the transfer unit 5b, the range B2 is positioned at the right end, and the count value of the main scanning control unit 22 matches the value of the main scanning direction element number setting unit 24. Thereafter, in accordance with the movement of the electronic component 13 in the sub-scanning direction and the transfer timing from the main scanning control unit 22, the charge transfer from the light receiving unit 5a is performed again. The charge of the light receiving element in the range A1 is transferred to the element in the corresponding range (the range C1 shown in FIG. 6C) of the transfer unit 5b. At this time, the element in the range B2 is actually transferred to the element in the previous transfer. Since no charge is transferred, there is no overlap of images due to mixing with the charge transferred from the light receiving element in the range A1 at the time of imaging.
[0025]
That is, this means that the transfer unit 5b can receive the transfer of the electric charge accumulated in the light receiving unit 5a by the next imaging immediately after outputting the electric signal obtained by the imaging. The line sensor can be used for various types of electronic components of different sizes, and unnecessary output time from elements without image information can be deleted to shorten image reading time and improve image reading efficiency. it can.
[0026]
As described above, the present invention enables the common use of the same line sensor for various types of electronic components of different sizes, thereby promoting the common parts of the components constituting the image reading apparatus, and The cost reduction of the reading device is realized.
[0027]
【The invention's effect】
According to the present invention, the line sensor is partially shielded according to the object at the time of imaging, received only in a necessary range and output only from the light receiving element in this range, and the center position of the line sensor is set to the light of the optical system. Since the center position of the light receiving range is offset with respect to the optical axis so as to be aligned with the optical axis, the same line sensor can be shared for many types of electronic components, and the cost of the electronic component reader is reduced. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an image reading apparatus according to an embodiment of the present invention. FIG. 2 (a) is a partial plan view of an image reading apparatus according to an embodiment of the present invention. FIG. 3A is a partial plan view of an image reading apparatus according to an embodiment of the present invention, and FIG. 3B is a partial plan view of an image reading apparatus according to an embodiment of the present invention. 4 is a block diagram showing a configuration of a control system of an image reading apparatus according to an embodiment of the present invention. FIG. 5 is a cross-sectional view of an optical system of the image reading apparatus according to the embodiment of the present invention. (a) Partial enlarged view of a line sensor according to an embodiment of the present invention (b) Partial enlarged view of a line sensor according to an embodiment of the present invention (c) Partial enlarged view of a line sensor according to an embodiment of the present invention [Explanation of symbols]
2 Optical system 2a Lens 3 One-dimensional CDD camera 5 Line sensor 5a Light receiving part 5b Transfer part 10 Plate 11 Mask plate 11b Opening part 13 Electronic component 20 Output part 21 Timing generation part 22 Main scanning control part 24 Main scanning direction element number setting part

Claims (2)

A line sensor having a light receiving unit in which a plurality of light receiving elements are arranged in a line in the main scanning direction and a transfer unit that receives charges accumulated in the light receiving unit and outputs them as an electrical signal to an output unit; and on the light receiving unit An optical system for forming an image of the imaging object, a light shielding means for partially shielding the light receiving unit during imaging, a control means for controlling the line sensor, and a line sensor for outputting the electrical signal. A main scanning direction element number setting unit for setting the number of elements to be output, and the center position of the light receiving unit in the main scanning direction is offset with respect to the optical axis of the optical system, and the amount of the offset is adjusted. An image reading apparatus comprising an offset amount adjusting means . The image reading apparatus according to claim 1, further comprising: a light shielding range adjusting unit configured to adjust a light shielding range by the light shielding unit.

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