JP2000241116A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device at a low cost which can use a common line sensor to many kinds of electronic components. SOLUTION: This image reading device reads one-dimensional image in the main scanning direction of an electronic component 13 with a line sensor 5, and reads a two-dimensional pictorial image by moving the electronic component 13 in the subscanning direction. This reading device is equipped with a mask plate which optically shields a light receiving part 5a partially when an image is picked up, a main scanning control part controlling the line sensor 5, and a setting part of the number of elements in the main scanning direction which sets the number of elements of an object to be outputted when the line sensor 5 outputs an electric signal. The center position (b) of the main scanning direction of the light receiving part 5a is offset against an optical axis (a), and the center position of the light receiving part 5a is always made to coincide with the optical axis (a). As a result, the same line sensor can be commonly applied to many kinds of electronic components, so that the cost of the image reading device can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus for reading an image of an object to be imaged by a line sensor.

[0002]

2. Description of the Related 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. This line sensor includes a light-receiving element that stores electric charge according to the amount of received light, and a transfer unit that receives electric charge from the light-receiving element and outputs the electric signal as an electric signal. When an image of an object to be imaged is formed on the line sensor by an optical system, electric charges corresponding to image data of the object are stored in each light receiving element. The charge of each light receiving element is received by the transfer unit and sequentially output as an electric signal, whereby one-dimensional image data in the arrangement direction of the light receiving elements, that is, the main scanning direction can be obtained. Then, desired two-dimensional image data is obtained by moving the one-dimensional image data obtained while moving the electronic component in a sub-scanning method orthogonal to the main scanning direction. In general, the size of a line sensor used for an imaging object is determined by the number of light receiving elements arranged.

[0003]

Electronic component mounting apparatuses are classified into several types according to the type and size of electronic components to be handled. For example, there are a high-speed type in which only small-sized electronic components are exclusively mounted at a high speed, and a multi-function type in which various types of electronic components from a small size to a large size are targeted. For this reason, when the above-mentioned line sensor is used for the electronic component mounting apparatus, it is necessary to use an apparatus suitable for the size of the mounting target. As a result, the versatility of the line sensor conventionally used in the image reading device is poor, and it is necessary to prepare various types of image reading devices for each type of electronic component mounting device, which is a factor that hinders the cost reduction of the image reading device. I was

Accordingly, an object of the present invention is to provide a low-cost image reading apparatus in which the same line sensor can be used for various types of electronic components.

[0005]

According to a first aspect of the present invention, there is provided an image reading apparatus, comprising: a light receiving section in which a plurality of light receiving elements are arranged in a line in a main scanning direction; A line sensor having a transfer unit for outputting to an output unit, an optical system for forming an image of an imaging target on the light receiving unit, a light shielding unit for partially shielding the light receiving unit during imaging, and the line Control means for controlling the sensor, comprising a main scanning direction element number setting unit that sets the number of elements to be output when the line sensor outputs the electric signal, the center position of the light receiving unit in the main scanning direction is the It is offset with respect to the optical axis of the optical system.

According to a second aspect of the present invention, there is provided the image reading apparatus according to the first aspect, further comprising a light shielding range adjusting means for adjusting a light shielding range by the light shielding means.

According to a third aspect of the present invention, there is provided the image reading apparatus according to the first aspect, further comprising an offset amount adjusting means for adjusting the offset amount.

According to the present invention, at the time of imaging, the line sensor is partially shielded in accordance with the target object, light is received only in a required range, only one-dimensional image data in this range is read, and the center position of the line sensor is determined. By offsetting with respect to the optical axis of the optical system so that the center position of the light receiving range is aligned with the optical axis, the same line sensor can be shared for various types of electronic components, and the image reading device Cost can be reduced.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 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, 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 device, FIG. 4 is a block diagram illustrating a configuration of a control system of the image reading device, FIG. 5 is a cross-sectional view of an optical system of the image reading device, 6A, 6B, and 6C are partially enlarged views of the line sensor.

First, the structure of the image reading apparatus will be described with reference to FIGS. In FIG. 1, an image reading device 1
Comprises an optical system 2 having a lens 2a and a one-dimensional CCD camera 3 housed in a case 4. A plate 10 for holding a substrate 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 board 6 by pins 5c.
The line sensor 5 includes a light receiving section 5a in which a plurality of light receiving elements are arranged in a line. The arrangement direction of the light receiving elements is a main scanning direction when capturing an image reading target. On the line sensor 5, a mask plate 11 provided with an opening 11b is detachably provided by bolts 11a, and is positioned in the main scanning direction by positioning pins 11c.

The optical system 2 has a mounting flange 2a at the lower end.
And is fixed to the upper surface of the case 4 via the mounting flange 2a by bolts 2c. 2d is a positioning pin for determining 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. Optical system 2
Causes the reflected light from the electronic component 13 held by the nozzle 12 to form an image on the CCD camera 3 described below.

The incident light from the optical system 2 is incident on the aperture 1.
The light is received by the light receiving unit 5a of the one-dimensional line sensor 5 via the line 1b. The position and the size of the opening 11b are set so that the mask plate 11, which is a light shielding unit, partially covers the light receiving unit 5a to shield the light, and only a predetermined range of the light receiving unit 5 receives light incident from the optical system 2. Is set. That is,
The position of the opening 11b is set so that the right end thereof substantially coincides with the right end of the light receiving unit 5a, and the size of the opening 11b is set according to the size of the electronic component 13 which is the object to be read. 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-sized electronic component is mounted, whereas FIG. Mask plate 1 having an opening 11'b having an opening length L2 corresponding to an electronic component
1 'is shown.

With the mask plate 11 mounted,
The incident light that enters through the optical system 2 is, in the light receiving element of the light receiving unit 5a, a range starting from the right end on the charge output side and substantially corresponding to the size of the opening 11b, that is, the image of the electronic component 13. Only the light receiving elements in the range necessary for reading receive light. Therefore, the mask plate 11 is a light shielding means, and also 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 left-right direction in the mounted state, that is, the position in the main scanning direction is determined by the positioning pins 11c.

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 section 5 will be described with reference to FIG. As shown in FIG. 3, the elongated bolt holes 2 b provided on the mounting flange 2 a are not symmetrically arranged with respect to the position of the center position c of the optical system 2. Therefore, FIG.
As shown in (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 section 5 at the center position c is used.
Can be changed relative to the sensor center position b in the main scanning direction, and the offset amounts 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 surface 2e of the mounting flange 2a is brought into contact with the positioning pin 2d.
In (b), the direction of the optical system 2 is rotated by 180 degrees, and the second side end surface 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 fixed 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.

When the same optical system 2 is used, the position of the center position c is changed 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). Offset from the sensor center position b of the light receiving unit 5 and the opening 1
The position of the bolt hole and the position of the pin 11c can be set so that the center position of 1b coincides with the center position c. As a result, the center position of the light receiving range of the light receiving unit 5 becomes the center position c.
And an image with excellent symmetry and without distortion due to aberration of the optical system can be obtained.

Referring again to FIG. 1, the board 6 is connected to a control circuit board 7 provided in the case 4. The circuit board 7 includes a control circuit for controlling the extraction of an electric signal from the line sensor 5 and a switch 8 for setting the number of elements in the main scanning direction, which will be described later. Image data acquired by the line sensor 5 is output to an external device by the connector 9.

An electronic component 13 such as a QFP held by the nozzle 12 is positioned on the optical system 2, and the electronic component 13 is illuminated on the light receiving unit 5a by the optical system 2 while the electronic component 13 is illuminated by illumination means (not shown). Is formed to obtain one-dimensional image data of the electronic component 13 in the main scanning direction. Then, by sequentially performing the imaging while moving the electronic component 13 in a sub-scanning method (perpendicular to the paper surface in FIG. 1) orthogonal to the main scanning direction, a two-dimensional image in which one-dimensional images are arranged in parallel can be obtained. it can.

Next, the configuration of a control system of the image reading apparatus will be described with reference to FIG. In FIG. 4, the line sensor 5
Is a linear CCD arranged in parallel with the light receiving section 5a
(Charge-coupled device). The charges accumulated by receiving light by the respective light receiving elements of the light receiving unit 5a are transferred to each CCD 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 as electric signals from the CCD based on the clock signal generated by the timing generation unit 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.

The number-of-pixels setting section 24 in the main scanning direction sets the number of elements to be output when the transfer section 5b outputs an electric signal based on the setting by the switch 8. That is, of 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, the main scanning control unit 22 changes the output cycle of the signal indicating the transfer timing from the light receiving unit 5a to the transfer unit 5b according to the number of elements set in the main scanning direction pixel setting unit 24. The sub-scanning control unit 23 controls the timing of the imaging process in a 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 an unillustrated sub-scanning direction driving unit to control the operation of the nozzle 12 in the sub-scanning direction. Further, the controller 25 transmits a necessary signal to an image processing unit 26 of an image recognition device provided separately from the image reading device.

This image reading apparatus is configured as described above, and an 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 area A1 located below the opening 11b of the light receiving section 5a receives light, and electric charges corresponding to the image of the electronic component 13 are accumulated in each light receiving element in this area 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, the opening 11b of the mask plate 11
Is made to correspond to the size of the electronic component 13, the electric charge can be stored only in the light receiving elements in a range necessary for imaging the electronic component 13.

At this time, the center position b of the sensor in the main scanning direction of the light receiving section 5b is offset from the center position c of the optical system 2 so that the center position of the light receiving element in the range A1 can be optically adjusted as shown in FIG. The center position c of the system 2 can be matched. Therefore, the electronic component 13 is arranged at a position symmetrical with respect to the center position c and an image is taken, and a high-precision image with little influence of the aberration of the optical system 2 can be obtained.

Next, as shown in FIG. 6A, the charge accumulated in the light receiving element (hatched to indicate the accumulation of charge) in the range A1 of the light receiving section 5a by imaging is the main scanning control section. The data is transferred to the transfer unit 5b at the transfer timing specified by the transfer unit 22. Thereby, each CCD of the transfer unit 5b is
The electric charge accumulated in each light receiving element of the light receiving section 5a is transferred to the light receiving section 5a. 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 no charge is accumulated in the light receiving element in the range A2 at the time of imaging, no charge is transferred in the range B2 by imaging.

Next, as shown in FIG.
The charge 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 transfer unit 5
b, the charge of each CCD is sequentially output. 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 to be output. Only the charges transferred to the elements in the range B1 are output to the output unit 20.

As a result, in the transfer unit 5b, the range B2 is located at the right end, and the count value of the main scanning control unit 22 and the value of the main scanning direction element number setting unit 24 match.
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 transfer of the electric charge from the light receiving unit 5a is performed again. Then, the charge of the light receiving element in the range A1 corresponds to the corresponding range of the transfer
The charge is transferred to the elements in the range C1) shown in (c). At this time, since the charges have not actually been transferred to the elements in the range B2 at the previous transfer, the charges are transferred from the light receiving elements in the range A1 at the time of the current imaging. No overlapping of images occurs due to mixing with the charged electric charge.

That is, this means that the transfer section 5b can immediately receive the transfer of the electric charge accumulated in the light receiving section 5a by the next imaging after outputting the electric signal obtained by the imaging. As a result, the same line sensor can be used for various types of electronic components of different sizes, and unnecessary image output time from devices without image information is eliminated to reduce image reading time and improve image reading efficiency. Can be done.

As described above, according to the present invention, the same line sensor can be used for various types of electronic components having different sizes, thereby promoting the common use of each component constituting the image reading apparatus. Thus, the cost of the image reading apparatus can be reduced.

[0027]

According to the present invention, at the time of imaging, the line sensor is partially shielded in accordance with the target object, light is received only in a necessary range and output from only the light receiving elements in this range, and the center position of the line sensor Is offset from the optical axis of the optical system so that the center position of the light receiving range is aligned with the optical axis, so that the same line sensor can be shared for various types of electronic components, and the electronic component reading device Cost can be reduced.

[Brief description of the drawings]

FIG. 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 an image reading apparatus according to one embodiment of the present invention; FIG. 2B is a plan view of a mask plate of the image reading apparatus according to one embodiment of the present invention;

3A is a partial plan view of an image reading device according to an embodiment of the present invention; FIG. 3B is a partial plan view of an image reading device according to an embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a control system of the image reading apparatus according to the embodiment of the present invention;

FIG. 5 is a sectional view of an optical system of the image reading apparatus according to the embodiment of the present invention;

6A is a partially enlarged view of a line sensor according to an embodiment of the present invention. FIG. 6B is a partially enlarged view of a line sensor according to an embodiment of the present invention. Partial enlarged view of sensor

[Explanation of symbols]

 Reference Signs List 2 optical system 2a lens 3 one-dimensional CDD camera 5 line sensor 5a light receiving unit 5b transfer unit 10 plate 11 mask plate 11b opening 13 electronic component 20 output unit 21 timing generation unit 22 main scanning control unit 24 main scanning direction element number setting unit

Claims (3)

[Claims] 1. A line sensor comprising: a light receiving section in which a plurality of light receiving elements are arranged in a line in a main scanning direction; and a transfer section for receiving electric charges accumulated in the light receiving section and outputting it as an electric signal to an output section. An optical system that forms an image of an object to be imaged on the light receiving unit, a light shielding unit that partially shields the light receiving unit during imaging, a control unit that controls the line sensor, and a line sensor that outputs the electric signal. A main scanning direction element number setting unit that sets the number of elements to be output when outputting the light, wherein 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. Characteristic image reading device. 2. The image reading apparatus according to claim 1, further comprising a light shielding range adjusting means for adjusting a light shielding range of said light shielding means. 3. An image reading apparatus according to claim 1, further comprising an offset amount adjusting means for adjusting the offset amount.