JP4378890B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus that reads an image to be imaged by a line sensor.
[0002]
[Prior art]
A CCD 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 CCD line sensor, pixels each having a light receiving cell for storing a charge corresponding to the amount of received light are arranged in a line, and a CCD (charge coupled device) transfer path is arranged on the side. When an optical image of the imaging target is formed on the CCD line sensor by the optical system, a charge corresponding to the optical image of the target is stored in each pixel. Then, one-dimensional image data in the pixel arrangement direction, that is, the main scanning direction can be obtained by sequentially transferring the charges of each pixel using the CCD transfer path, converting them into electric signals and sequentially outputting them. Then, desired two-dimensional image data is obtained by paralleling a plurality of one-dimensional image data obtained by relatively moving the electronic component in the sub-scanning direction orthogonal to the main scanning direction.
[0003]
By the way, when an image is read using such a CCD line sensor, there are some which are devised so that the resolution of an acquired image can be set according to the purpose of imaging. That is, an image with a desired resolution can be obtained by thinning out image data to be read out of image data output from each pixel arranged in the main scanning direction with a preset pattern.
[0004]
[Problems to be solved by the invention]
However, when setting the above resolution with a conventional CCD line sensor, it is necessary to sequentially output the image data of all the pixels including the pixels that are not the target of image data capture, and then the image data is thinned out. Is done. For this reason, even if the amount of data read by thinning is reduced, all image data must be output, so the time required for image data output is not shortened, and the image reading time is not shortened. It was.
[0005]
SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus capable of improving image reading efficiency.
[0010]
[Means for Solving the Problems]
An image reading apparatus according to claim 1, wherein a line sensor in which a plurality of pixels each including a light receiving cell and a data holding unit for holding image data output from the light receiving cell are arranged in series, and the line sensor A relative movement mechanism that moves relative to the imaging object; a pixel selection unit that can read image data from a data holding unit of an arbitrary pixel of the line sensor; and at least two adjacent pixels among the pixels An image data combining unit that generates combined image data obtained by combining the image data output from each light receiving cell of the pixel, and holds the combined image data in one of the data holding units connected to these light receiving cells; A control unit that reads the composite image data from a data holding unit that holds the composite image data by controlling the pixel selection unit.
[0011]
An image reading apparatus according to a second aspect is the image reading apparatus according to the first aspect , wherein the number of pixels to be combined is determined by a resolution of the image.
[0012]
The image reading apparatus according to claim 3, an image reading apparatus according to claim 1, wherein, the image data from the data holding unit of the pixel corresponding to the specified image capture regions of the pixel The pixel selector is controlled to read.
[0013]
The image reading device according to claim 4 is the image reading device according to claim 1 , wherein the relative movement mechanism is a relative movement speed between the line sensor and the imaging object when the image data is synthesized and output. Is made faster than when image data is synthesized and not output.
[0014]
According to the present invention, the pixel selection unit capable of reading the image data from the data holding unit of any pixel among the pixels constituting the line sensor is provided, and the pixel selection unit is controlled to change the pixels at predetermined intervals. By reading the image data from the data holding unit and by creating and reading composite image data obtained by combining the image data output from the light receiving cells of each of the adjacent pixels, image data with a desired resolution can be obtained. In addition, since only the image data of necessary pixels is output, the image reading time can be shortened.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of an electronic component mounting apparatus in which an image reading apparatus according to an embodiment of the present invention is incorporated. FIG. 2 is a block diagram illustrating a configuration of the image reading apparatus according to an embodiment of the present invention. 4 and 5 are diagrams showing the configuration of the line sensor of the image reading apparatus according to the embodiment of the present invention, and FIG. 6 is an explanatory diagram of the image capturing area of the image reading apparatus according to the embodiment of the present invention. .
[0016]
First, an electronic component mounting apparatus will be described with reference to FIG. In FIG. 1, a transport path 2 is arranged in the X direction at the center of a base 1. The transport path 2 transports and positions the substrate 3. Component supply units 4 that supply electronic components are disposed on both sides of the conveyance path 2, and a large number of tape feeders 5 are arranged in parallel in each component supply unit 4. The tape feeder 5 stores electronic components held on the tape, and feeds the electronic components to the pickup position by pitch-feeding the tape.
[0017]
Two Y-axis tables 6A and 6B are arranged in parallel at both end portions of the upper surface of the base 1, and an X-axis table 7 on which a transfer head 8 is mounted is installed on the Y-axis tables 6A and 6B. Has been. The transfer head 8 includes a plurality of suction nozzles 8a (FIG. 2) for sucking electronic components at the lower end. By driving the Y-axis tables 6A and 6B and the X-axis table 7, the transfer head 8 moves horizontally, picks up an electronic component from the pickup position of the tape feeder 5, and transfers and mounts it on the substrate 3.
[0018]
On the movement path of the transfer head 8 between the conveyance path 2 and the component supply unit 4, a camera 9 that reads an image of the electronic component is disposed. As will be described later, the camera 9 includes a line sensor 12 in which a plurality of pixels including photoelectric cells are arranged in series in the Y direction. With each electronic component held by the suction nozzle 8a of the transfer head 8 being individually positioned on the camera 9, a lighting device (not shown) is turned on to illuminate each electronic component from below, thereby An optical image is formed on the pixel. Then, image data obtained by converting the optical image into an electrical signal is always output.
[0019]
In FIG. 2, a motor 7a is a drive motor for the X-axis table 7, and the motor 7a includes an encoder 7b. When the camera control unit 10 (to be described later) receives a pulse signal output from the encoder 7b, the relative position of the electronic component that is the imaging target held by the suction nozzle 8a of the transfer head 8 with respect to the line sensor 12 is accordingly changed. It is detected as position information. The encoder 7b is a relative position detection unit that detects a relative position of the imaging target with respect to the line sensor 12.
[0020]
The camera 9 acquires a scanning image of the electronic component by imaging the electronic component P with the camera 9 while moving the transfer head 8. The X-axis table 7 is a relative movement mechanism that relatively moves in one direction (X direction) perpendicular to the pixel arrangement direction (Y direction) with respect to the line sensor 12 of the camera 9 of the electronic component that is the imaging target. It has become. The obtained scanned image is recognized as an image to identify and detect the position of the electronic component. When the electronic component is mounted on the board 3, the position deviation is corrected based on the result of component position detection.
[0021]
In FIG. 2, the camera 9 includes a line sensor 12, a pixel selection unit 11, and a camera control unit 10. The line sensor 12 includes a plurality of pixels 12a arranged in series in the Y direction. By forming an optical image on the line sensor 12, a light receiving cell provided in each pixel is exposed to accumulate electric charges. Then, the image data is read by outputting this electric charge as an electric signal.
[0022]
Here, the configuration of the line sensor 12 will be described with reference to FIG. As shown in FIG. 3, the line sensor 12 is connected to the pixel selection unit 11 and includes a light receiving cell 20, a shift gate 21, an output mode switching unit 22, a mixing unit 23, and a sample hold unit 24. Among these components, one light receiving cell 20, shift gate 21, and sample hold unit 24 constitute one pixel 12a shown in FIG.
[0023]
Each component will be described. The light receiving cell 20 accumulates electric charges by exposure. The shift gate 21 connects and disconnects the circuit when outputting the electric charge accumulated in the light receiving cell 20 as an electric signal. The output mode switching unit 22 performs switching for connecting the shift gate 21 to either the mixing unit 23 or the sample hold unit 24. This switching is performed by a control signal from the camera control unit 10 as will be described later, whereby the image data output mode is switched.
[0024]
The mixing unit 23 mixes the charges accumulated in the two adjacent light receiving cells 20 to combine them into one image signal, and performs a combining process for creating combined image data. The sample hold unit 24 holds the charge transferred from the light receiving cell 20 via the shift gate 21 and the output mode switching unit 22 or the charge synthesized by the mixing unit 23 as a voltage value. That is, the sample hold unit 24 is a data holding unit that holds charges output as image data from the light receiving cell 20, and the pixel 12a includes the light receiving cell 20 and the sample hold unit 24 as a data holding unit as a set. It is the composition to do.
[0025]
Each sample hold unit 24 is connected to the pixel selection circuit 25 of the pixel selection unit 11, and the pixel connected to the sample hold unit 24 of an arbitrary pixel by controlling the pixel selection unit 11 by the camera control unit 10. The selection circuit 25 can be controlled to open and close. That is, the pixel selection unit 11 can read image data randomly from the data holding unit of an arbitrary pixel 12a.
[0026]
In this open / close control, only the pixel selection circuit 25 at a predetermined interval is closed by a command from the camera control unit 10 so that image data is output only from the sample hold unit 24 connected to the pixel selection circuit 25. it can. That is, the camera control unit 10 is a control unit that controls the pixel selection unit 11 and reads image data from the data holding unit of the pixels 12a at predetermined intervals. The predetermined interval for specifying the pixel 12a from which the image data is read is determined by the required image resolution, as will be described later.
[0027]
The image data output mode will be described here. As shown in FIG. 3, in the state where the output mode switching unit 22 is switched to the “a” side, the charge output from each light receiving cell 20 via the shift gate 21 is held in the sample hold unit 24 as it is. Then, by controlling the pixel selection unit 11 and closing all the pixel selection circuits 25 as described above, a normal mode in which image signals are output from all the pixels 12a is realized.
[0028]
Further, by controlling the pixel selection unit 11 to control the opening and closing of the pixel selection circuit 25 so that the image data is output only from the sample hold unit 24 at a predetermined interval, the image data is output only from the pixel 12a at the predetermined interval. The thinning mode is realized. When this thinning mode is selected, image data is output only from the image reading target pixel 12a, so that the amount of image data to be output can be reduced and the image reading time can be greatly shortened.
[0029]
On the other hand, by switching the output mode switching unit 22 to the b side, the charges of the two adjacent light receiving cells 20 are mixed into one image data by the mixing unit 23 and held in the one sample hold unit 24. The Then, by controlling the pixel selection unit 11 by the camera control unit 10 so that only the pixel selection circuit 25 corresponding to the sample hold unit 24 is closed, the image data of the two pixels are mixed and output as composite image data. The synthesis mode is realized. That is, the camera control unit 10 is a control unit that reads the composite image data from the data holding unit that holds the composite image data by controlling the pixel selection unit 11. When this combination mode is selected, image data output from a plurality of pixels to be combined is performed simultaneously, and only the combined image data is finally output. The amount of data is reduced, and the entire image reading time can be greatly shortened.
[0030]
4 and 5 show the second and third embodiments of the line sensor according to the present embodiment, respectively. The line sensor 12 ′ shown in FIG. 4 has a three-pixel synthesis process for mixing and synthesizing image data of three adjacent pixels 12a in addition to the normal mode, the thinning mode, and the synthesis mode for two pixels. It can be done. That is, as shown in FIG. 4, in the line sensor 12 ′, the output mode switching unit 22 is connected to the left and right two pixels at both ends of three adjacent pixels.
[0031]
By switching the left output mode switching unit 22 to the a side and the right output mode switching unit 22 to the b side, the charges of the three adjacent light receiving cells 20 are mixed by the mixing unit 23. The synthesized image data is held in the central sample hold unit 24 and output via the pixel selection circuit 25. Then, the switching of the output mode switching unit 22 at both ends is reversed to the above, and the left output mode switching unit 22 is switched to the b side and the right output mode switching unit 22 is switched to the a side. The normal mode for outputting image data is set.
[0032]
Further, the line sensor 12 '' shown in FIG. 5 includes an output mode switching unit 22 and a mixing unit 23 in two stages, and after the charges output from the light receiving cells 20 for two adjacent pixels are synthesized by the mixing unit 23, Furthermore, it is possible to perform another stage of synthesis processing. As a result, in addition to the normal mode and the thinning mode, four-pixel synthesis processing is possible in which the charges of the light-receiving cells 20 for four pixels are mixed into one image data.
[0033]
That is, in each of the above-described embodiments, the mixing unit 23 creates composite image data by combining the image data output from the light receiving cells 20 of at least two adjacent pixels 12a among the pixels 12a. This is an image data synthesizing unit that holds the synthesized image data in one of the sample hold units 24 connected to these light receiving cells 20. The camera control unit 10 controls the pixel selection unit 11 to read the composite image data from the sample hold unit 24 that stores the composite image data.
[0034]
Next, image reading for the electronic component shown in FIG. 2 will be described with reference to FIG. When reading an image, first, an image capturing area corresponding to an image reading window (see FIG. 6) for each electronic component is set in the line sensor 12.
[0035]
Here, the image reading window is set to a size that is necessary and sufficient to include the electronic component to be read, and the Y direction depends on the range of pixels that should output an image signal among the pixels of the line sensor 12. The X direction is determined by a numerical value indicating the relative position between the line sensor 12 and the electronic component. In other words, the capture area setting data for setting the image capture area includes the image capture area indicating the range of pixels to which an image signal should be output among the pixels of the line sensor 12, and the relative relationship between the line sensor 12 and the electronic component. It consists of a numerical value indicating the position.
[0036]
Then, the camera control unit 10 controls the pixel selection unit 11 based on these capture area setting data, thereby causing the line sensor 12 to output an image signal necessary for obtaining an image of the image reading window. That is, the camera control unit 10 controls the pixel selection unit 11 so as to read the image data from the sample hold unit 24 of the pixel 12a corresponding to the designated image capturing area among the pixels 12a of the line sensor 12.
[0037]
The camera control unit 10 receives position information indicating the relative position between the line sensor 12 and the electronic component by receiving a pulse signal from the encoder 7b, and a plurality of capture area setting data are obtained based on the position information. Switch. In other words, if it is detected that the timing for switching the image reading window is reached by monitoring the position information, the image corresponding to the image reading window specified by the position information is selected from the prestored capture area setting data. The capture area is read, and the pixel selector 11 is controlled according to the image capture area data.
[0038]
The camera control unit 10 outputs output mode information to the pixel selection unit 11 as described later. That is, the pixel selection unit 11 is controlled to read the image data from the pixel data holding unit at predetermined intervals. Furthermore, the camera control unit 10 outputs a capture completion signal indicating that the capture of the image is completed to the image recognition unit 13. The image signal output from the line sensor 12 is captured by the image recognition unit 13. When receiving the capture completion signal transmitted from the camera control unit 10, the image recognition unit 13 recognizes the captured image data in accordance with a recognition algorithm specified by an algorithm number included in the component data.
[0039]
The input / output control unit 14 controls input / output of signals between the camera control unit 10, the image recognition unit 13, and the processing / calculation unit 15. Thereby, the camera control unit 10 receives and stores the capture area setting data from the input / output control unit 14. The processing / arithmetic unit 15 executes various processes / calculations by executing a processing program stored in the program storage unit 17 based on data stored in the data storage unit 16 described below.
[0040]
The data storage unit 16 stores mounting data 16a, component data 16b, and mounting schedule data 16c. The mounting data 16a is data relating to the mounting position of the component to be mounted, and the component data 16b is data unique to the component such as the shape and size of the component to be mounted, and is used for recognition processing performed by the image recognition unit 13. Contains the algorithm number attached to the algorithm. The mounting schedule data 16c is information related to the mounting work procedure, and the mounting order of each electronic component is indicated by the mounting schedule data 16c.
[0041]
The program storage unit 17 stores a capture area setting program 17a and a mounting operation program 17b. The capture area setting program 17a sets the size and scan interval of the image capture area according to the size and shape of the part in the part data as will be described later, and captures this information as well as the capture area setting data (pixel selection information, X This is a program that outputs as a numerical value indicating the position in the direction. The mounting operation program 17b is a sequence program for mounting operation for mounting electronic components on a board.
[0042]
Here, by executing the capture area setting program 17a in the processing / arithmetic unit 15, the electronic parts Pa, Pb, Pc, and Pd held by the transfer head 8 as shown in FIG. Image reading windows A, B, C, and D are set.
[0043]
Numerical values X1 to X8 in the X direction set corresponding to the respective image reading windows A, B, C, and D are numerical values on the machine coordinate system of the X axis table 7 that moves the transfer head 8 in the X direction (for example, (The number of pulses output from the encoder 7b of the motor 7a). Here, (X1, X2), (X3, X6), (X4, X5), and (X7, X8) indicate the start and end timing of image reading for the image reading windows A, C, B, and D, respectively. It is shown.
[0044]
In other words, each numerical value in the X direction shown in FIG. 6 corresponds to a specific relative positional relationship between the line sensor 12 and the transfer head 8 in the X direction, and the line sensor 12 is moving horizontally by these numerical values. The positional relationship with the transfer head 8 can be determined. For example, if the position information (pulse signal) from the encoder 7b of the motor 7a coincides with the numerical value X1, it means that the position where the image reading from the image reading window A for the electronic component Pa is to be started has been reached. Show.
[0045]
That is, when the position information sent from the encoder 7b of the motor 7a is monitored by the camera control unit 10 and this position information matches each of the above numerical values, a specific relative positional relationship corresponding to each numerical value is realized. Is detected. In accordance with the detection result, various types of operation control, for example, operation control of the transfer head 8, and setting update of the image capturing area in the line sensor 12 described below are performed.
[0046]
Then, in the image reading in which the transfer head 8 is moved in the X direction and imaging is performed, a range of pixels selected as an image signal output target, that is, an image capturing area of the line sensor 12 is set. For example, in the section in which the numerical value in the X direction is in the range of X1 to X2 and an image is read for the image reading window A, among the pixels 12a (Y0 to Ye) of the line sensor 12 as shown in FIG. An image signal is output only from the pixel 12a in the image capture area (range Y1 to Y2) set corresponding to the position in the Y direction of the image reading window A. Further, when the transfer head 8 is moved and image reading is performed for each of the image reading windows B, C, and D, the image capturing set similarly for each of the image reading windows B, C, and D is performed. An image signal is output only from the pixels in the region.
[0047]
In the above image reading, different necessary resolutions are set for each of the image reading windows A, B, C, and D depending on the shape and type of electronic components to be recognized, and image data output from the line sensor 12 is output. At this time, the normal mode, the thinning mode, and the synthesis mode are appropriately selected. That is, for the image reading windows A, B, C, and D targeted for electronic components that require high-accuracy recognition, the normal mode is selected in order to achieve high resolution.
[0048]
On the other hand, the thinning mode is selected for the purpose of realizing high-speed image reading for the image reading windows A, B, C, and D targeted for electronic components that do not require much resolution. In this case, the predetermined interval indicating the degree of thinning is determined by the required resolution. That is, as the required resolution decreases, the image data can be thinned out greatly. Therefore, the interval between the pixels for outputting the image data is set large.
[0049]
Then, the moving speed of the X-axis table 7 for moving the transfer head 8 holding the electronic component is set according to the predetermined interval. Here, the moving speed of the transfer head 8 for image reading is set to be higher as the degree of thinning is larger and the interval between pixels from which image data is to be output is larger. That is, the X-axis table 7 adjusts the relative movement speed between the line sensor 12 and the transfer head 8 holding the electronic components according to the predetermined interval.
[0050]
Instead of selecting the thinning mode, the synthesis mode may be selected. As a result, the number of data can be reduced to improve the image reading efficiency, and the degree of data discreteness between adjacent image data that occurs in the thinning mode can be reduced to obtain a smoother image. it can.
[0051]
Also in this synthesis mode, the number of adjacent pixels to be synthesized is determined by the required resolution. That is, as the required resolution decreases, the number of pixels to be combined is set larger. As the number of pixels to be combined increases, the moving speed of the transfer head 8 for image reading is set to be higher. That is, the X-axis table 7 sets the relative movement speed between the line sensor 12 and the imaging object when the image data is synthesized and output as compared with the case where the image data is not synthesized and output.
[0052]
As described above, according to the present invention, when a scanned image is acquired by a line sensor in which a plurality of pixels are arranged in series, a pixel to be read is selected according to a resolution required for an acquisition target image. A thinning-out mode or a combining mode in which image data of a plurality of adjacent pixels are combined and output in an output time for one pixel can be selected. As a result, when the resolution is set low, the time required to output the image data is shortened, and efficient image reading can be performed.
[0053]
【The invention's effect】
According to the present invention, the pixel selection unit capable of reading image data at random from the data holding unit of an arbitrary pixel among the pixels constituting the line sensor is provided, and the pixel selection unit is controlled to be arranged at predetermined intervals. Since the image data is read from the pixel data holding unit, and the composite image data obtained by synthesizing the image data output from the respective light receiving cells of the adjacent pixels is created and read, an image with a desired resolution is obtained. Data can be obtained and the image reading time can be shortened.
[Brief description of the drawings]
FIG. 1 is a perspective view of an electronic component mounting apparatus in which an image reading device according to an embodiment of the present invention is incorporated. FIG. 2 is a block diagram illustrating a configuration of the image reading device according to an embodiment of the invention. FIG. 4 is a diagram showing a configuration of a line sensor of an image reading apparatus according to an embodiment of the present invention. FIG. 4 is a diagram showing a configuration of a line sensor of an image reading apparatus according to an embodiment of the present invention. The figure which shows the structure of the line sensor of the image reading apparatus of one Embodiment. FIG. 6 is explanatory drawing of the image taking-in area | region of the image reading apparatus of one embodiment of this invention.
7 X-axis table 8 Transfer head 9 Camera 10 Camera control unit 11 Pixel selection unit 12 Line sensor 12a Pixel 20 Light receiving cell 21 Shift gate 22 Output mode switching unit 23 Mixing unit 24 Sample hold unit 25 Pixel selection circuit

Claims (4)

A line sensor in which a plurality of pixels each having a light receiving cell and a data holding unit for holding image data output from the light receiving cell are arranged in series, and the line sensor is moved relative to the object to be imaged. Output from each of the light receiving cells of at least two adjacent pixels among the pixels, and a relative selection mechanism that allows image data to be read from a data holding unit of an arbitrary pixel of the line sensor. The composite image data is generated by combining the image data, and the composite image data is held in one of the data holding units connected to the light receiving cells, and the pixel selection unit is controlled to control the pixel selection unit. An image reading apparatus comprising: a control unit that reads the composite image data from a data holding unit that holds the composite image data. The number of that the pixel of the synthesis image reading apparatus according to claim 1, characterized in that it is determined by the resolution of the image. Wherein the control unit, the image reading according to claim 1, wherein the controller controls the pixel selection unit to read the image data from the data holding unit of the pixel corresponding to the specified image capture regions of the pixel apparatus. The relative movement mechanism is characterized in that a relative movement speed between the line sensor and the imaging target when the image data is synthesized and output is higher than that when the image data is not synthesized and output. Item 2. The image reading apparatus according to Item 1 .

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