JP2007276388A - Focal position detector and detection method of line head, and focal position adjuster and adjusting method of line head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for detecting the focal position of a line head easily and appropriately and adjusting the focal position based on the detection. <P>SOLUTION: In an adjuster 1 for adjusting the focal position of a line head 2, imaging height position of a line sensor camera 3 can be varied by a stage 12, light emission state of the line head 2 is imaged, respectively, from a plurality of positions where the distance B between a reference position A for arranging a photosensitive drum and the line sensor camera 3 is different, and each focal position with reference to the reference position A can be detected based on the relation of the distance B and the pixel area of a predetermined light intensity or above in each image formed through each lens 22 of the line sensor camera 3. Since distribution of focal position of each lens 22 in the line head 2 can be obtained, focal position of the entire line head 2 can be detected easily and appropriately. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to detection and adjustment of a focal position of a line head.

2. Description of the Related Art Conventionally, a line head is known in which a large number of light emitting elements and a large number of imaging elements (lenses) are arranged in a row and are configured to be long. This line head is used, for example, in an electrophotographic printer to expose a photoconductor at a time along a line perpendicular to the paper feed direction. In this case, the light flux emitted from each light emitting element is used for each lens. Are converged and imaged on the surface of the photoconductor, and the toner bonded to the exposed portion of the photoconductor is transferred onto the paper.
Due to such a configuration of the line head, when assembling the line head, it is necessary to accurately set the distance between the light emitting element and the lens to a predetermined dimension. Further, after assembling the line head, it is necessary to adjust so that the focal point of each lens is positioned on the surface of the photosensitive member, and the accuracy of this adjustment affects the print quality.

  Here, several methods for adjusting the focal position of the line head are known (Patent Document 1 and Patent Document 2). In Patent Document 1, the light emission state of the LED head is imaged by three CCD cameras arranged on the side where the photoconductor is arranged while changing the height of the LED head by a mechanism for moving the LED head up and down. Then, the focal position of the LED head is adjusted while visually checking the captured image on the monitor. The LED head height adjusting mechanism includes a guide roller that separates the line head from the photosensitive member by a predetermined dimension, an adjustment screw that is provided at both ends of the line head and adjusts the distance between the line head and the photosensitive member, A link block that holds both ends of the guide roller and elastically deforms by tightening an adjustment screw is provided, and positioning pins for guiding the raising and lowering of the LED head are provided at both ends of the guide roller.

  On the other hand, in Patent Document 2, a positioning pin is provided so as to have an accurate protruding height on a heat sink to which an LED element is mounted, and a lens is adsorbed and held at a constant height by a linear motor or the like. Press the distal end of the positioning pin toward the proximal end. As a result, the relative distance between the LED element and the lens is adjusted based on the height of the positioning pin. After this adjustment, the lens and the LED element are assembled using an adhesive, thereby assembling accuracy of the LED head. Has improved.

Japanese Patent Laid-Open No. 2-52762 JP-A-8-20133

  However, the adjustment method in Patent Document 1 is merely to search for a position where the light emission state is good by appropriately moving the height of the LED head in either the vertical direction while viewing the monitor screen. That is, since an appropriate focal position cannot be grasped, it is unclear whether the LED head should be moved in the vertical direction, and adjustment work is time-consuming because it requires trial and error. Further, even after adjustment, it has been difficult to accurately determine whether or not the adjustment has been properly made.

  On the other hand, in the adjustment method in Patent Document 2, although the assembly accuracy of the LED head is improved, the influence of the curing of the adhesive is also considered, and adjustment after the assembly of the LED head is necessary for improving the print quality. I wo n’t. In other words, in order to achieve high-quality printing performance, it is necessary to adjust the focal position of the LED head on the surface of the photoreceptor, and for that purpose, it is necessary to appropriately detect the focal position of the LED head. there were.

  In view of the problems as described above, an object of the present invention is to easily and appropriately detect the focal position of a line head and to realize adjustment of the focal position based on the detection of the focal position.

The focal position detection device for a line head according to the present invention includes a plurality of light emitting elements arranged on a straight line, and a plurality of imaging elements arranged on the line so as to face the light emitting elements. A detection device for detecting a focal position by the imaging element of a light beam emitted from the light emitting element in a long line head,
It is arranged so as to be orthogonal to the optical axis of each imaging element and is exposed to the image by the imaging element, and is opposed to the line head, and at least the plurality of imaging elements Imaging means for imaging the images formed by the imaging elements disposed in the vicinity of both ends in the longitudinal direction of the line head;
A distance variable means for changing a distance between the linear reference position along the surface of the exposure body on the line head side and the imaging means along the optical axis of the imaging element;
In each captured image captured by the imaging unit from a plurality of positions having different distances, for each image formed by the same imaging element among the plurality of imaging elements, the pixel information of the imaging and the distance And a focus position detecting means for detecting the focus position with respect to the reference position based on the relationship.

  The line head focal position adjusting apparatus according to the present invention includes the above-described detection apparatus, the focal position with respect to the reference position for each imaging element detected by the focal position detection means, and the imaging elements. And a focal position adjusting means for enabling movement of both ends in the longitudinal direction of the line head along the optical axis of the imaging element based on the respective positions of the line head. The adjusting means includes first moving means provided at one end of the line head and second moving means provided at the other end of the line head.

  Furthermore, the focus position detection method of the line head according to the present invention includes a plurality of light emitting elements arranged on a straight line and a plurality of image forming elements arranged on the line so as to face each of these light emitting elements. A detection method for detecting a focal position of the light beam emitted from the light emitting element by the imaging element in a long line head, which is arranged so as to be orthogonal to the optical axis of each imaging element. And an imaging means arranged to face the line head on the exposure body side exposed by imaging by the imaging element, a linear reference position along the surface of the exposure body on the line head side, and the Using at least a front of the plurality of imaging elements by the imaging unit from a plurality of positions where the distances are different from each other using a distance variable unit that changes the distance to the imaging unit along the optical axis of the imaging element. In the imaging step of imaging each of the images formed by the imaging elements arranged in the vicinity of both ends in the longitudinal direction of the line head, and in each captured image captured by the imaging means, the same connection among the plurality of imaging elements. A focus position detecting step of detecting the focus position with respect to the reference position based on the relationship between the pixel information of the image formation and the distance for each image formation by the image element.

  The method for adjusting the focal position of the line head according to the present invention includes the above-described detection method, the focal position with respect to the reference position for each imaging element detected by the focal position detection step, and the imaging elements. And a focus position adjusting step capable of changing the posture of the line head based on the respective positions in the line head.

  Here, the detection and adjustment of the focal position of the line head as described above is performed by forming an image of a light beam emitted from each light emitting element of the line head and passing through each imaging element on the surface of an exposure body such as a photosensitive drum of a printer. Done to make.

  According to these inventions, the distance between the reference position where the exposure object is disposed and the imaging means is variable by the distance variable means, and the imaging means respectively changes the distance from the reference position to a plurality of different positions. Of the plurality of imaging elements included in the line head, imaging by a light beam converged by at least the imaging elements arranged in the vicinity of both ends of the line head is imaged by the imaging means. In a plurality of captured images obtained at this time, pixel information in the image formation relating to the same element image formation determined to be due to the same image formation element in each image formation element of the line head by the focal position detection means and process And the focal position relative to the reference position can be detected based on the relationship between the imaging means and the distance between the reference position. Thereby, since the distribution of the focal position of each imaging element in the line head is obtained, the focal position in the entire line head can be detected easily and appropriately.

Further, the posture of the line head is corrected based on the distribution of the focal position thus detected, that is, the focal position with respect to the reference position for each imaging element and the respective positions in the line head of each imaging. Since the direction to be performed is easily grasped, the focal position of the entire line head can be easily and appropriately adjusted by the focal position adjusting means and the process using the first moving means and the second moving means.
By adjusting the focal position of the line head as described above, it is possible to contribute to uniform light intensity in the entire line head, and thus it is possible to contribute to improvement in printing performance in a printer product or the like in which the line head is incorporated.
In addition, the distance variable means can change the distance between the image pickup means and the reference position stepwise with a smaller width, and increase the number of times of image pickup, thereby increasing the resolution related to the detection of the focal position.

  Here, the image picked up by the image pickup means only needs to include an image formed by image forming elements arranged at least near both ends among the image forming elements of the line head. It is preferable that each image formed by is imaged. In this case, since the shift of the focal position of each imaging element with respect to the reference position can be grasped over the entire line head, the direction in which the line head is moved by the first moving means and the second moving means can be determined more appropriately. Is possible.

  Further, in addition to the first moving means and the second moving means respectively disposed at both ends of the line head, third and fourth moving means that can move the line head along the optical axis of the imaging element are also provided. It can also be considered to appropriately provide a section between both ends of the line head. As a result, in each imaging element aligned in the longitudinal direction of the line head, the relative distance between the focal position of each imaging element and the reference position is not monotonously increasing or decreasing monotonously, but is good even when it is increasing or decreasing. It can correspond to. In other words, the focus position can be adjusted with higher accuracy by changing the posture of the line head in an appropriate direction by the first to fourth moving means.

In the detection device for the focal position of the line head according to the present invention, the imaging means is a line sensor camera having a plurality of photosensor elements arranged on a straight line, and the line sensor camera includes the photosensor element as the photosensor element. It is preferable that they are arranged along the longitudinal direction of the line head.
According to the present invention, by using the line sensor camera, it is possible to easily and rapidly image an image by a large number of imaging elements of the line head. Therefore, based on the distribution of focal positions of many imaging elements, The focus position of the entire line head can be adjusted more appropriately.

In the focal position detection device for a line head according to the present invention, it is preferable that the focal position detection means detects the focal position based on an area of a pixel having a light intensity equal to or higher than a predetermined threshold included in the imaging.
According to the present invention, in a plurality of captured images, in the comparison between the same element images formed by the same image forming element of the line head, the area of the pixel that is equal to or higher than the predetermined light intensity included in the image formation The focal position can be detected more appropriately quantitatively based on the relationship between the reference position and the distance between the imaging means. In addition, it can be estimated that the smaller the area of the pixels having a predetermined light intensity or more included in the image formation, the more the light beam is converged by the image formation element, which is closer to the focused state.
The “light intensity” is represented by the illuminance of light incident on the photosensitive surface, that is, the incident light flux per unit area.

In the line head focal position adjusting apparatus of the present invention, it is preferable that the first moving means and the second moving means are each provided with a moving amount measuring means for measuring the moving amount of the line head.
Here, the first moving means and the second moving means are configured as pins that can be screwed into screw holes of a member to which the line head is assembled, for example. Further, as the movement amount measuring means, for example, a micrometer can be used.
According to the present invention, since the movement amount measuring unit is provided, the relationship between the movement amount of the line head by the first movement unit and the second movement unit and the focal position of the line head can be obtained quantitatively. When the adjustment is performed, the amount of movement of the line head by the first and second moving means can be accurately controlled. That is, since the movement direction and the movement amount of the line head are grasped, the focal position of the line head can be adjusted more appropriately based on this, and the work efficiency of the focus adjustment can be improved.

Note that the above-described focus position detection means can be realized by hardware, but can also be realized by using a software program.
In the program, a computer incorporated in the detection device or the adjustment device may function as the focus position detection means.
If comprised in this way, the effect similar to the above-mentioned detection apparatus or adjustment apparatus can be enjoyed.
Here, the program may be incorporated in a computer, or may be incorporated via a computer-readable storage medium storing the program.
By incorporating such a program into an existing image display device or the like, the function of detecting the focal position of the line head can be easily realized at low cost.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1. Configuration of focus adjustment device for line head]
FIG. 1 is a schematic external view of a configuration of an adjusting device 1 that adjusts the focal position of a line head in the present embodiment. The adjustment device 1 includes a stage 11 on which the line head 2 in a state assembled to the frame 100 of the printer is mounted, a stage 12 provided above the stage 11, and a light emission state of the line head 2 provided on the stage 12. A line sensor camera 3 as an image pickup means for picking up an image, and an image processing device 4 for processing a picked-up image picked up by the line sensor camera 3, and has a function of detecting the focal position of the line head 2. Based on the detection, the focal position of the line head 2 is adjusted.

The stage 11 is configured to be movable left and right along the X direction in FIG.
Further, the stage 12 is configured to be movable up and down along the Z direction, and is a distance variable means for changing the height of the line sensor camera 3.

  Although not shown in detail, the line sensor camera 3 includes a CCD sensor element 31 as an optical sensor element, a lens 32 directed to the stage 11, and a circuit board (not shown) such as a driver. The light emission state of the line head 2 is imaged from different heights by driving the stage 12. The CCD sensor element 31 includes a large number of photodiodes arranged in a row and a CCD (charge-coupled device) shift register that outputs charges transferred from the photodiodes as image pulse signals to the image processing device 4. Each photodiode transfers charges to the CCD shift register at a time by inputting a parallel transfer pulse (scan signal).

The line head 2 has a configuration in which a large number of light emitting elements 21 and a large number of lenses 22 as imaging elements are arranged in a line. In the present embodiment, the number of light emitting elements 21 and lenses 22 is 5000, that is, the number of pixels is 5000.
In the present embodiment, the liquid crystal shutters as the light emitting elements 21 are one-dimensionally arranged, and a fluorescent lamp is provided as a light source and a converging fiber lens array is provided as an imaging element. As the element 21, an arbitrary configuration including an LED (Light Emitting Diode), an organic EL (electro-luminescence), a phosphor, a plasma, and the like can be used.

  Each light emitting element 21 and each lens 22 are arranged opposite to each other to form parallel lines, and the light beams emitted from each light emitting element 21 are converged by each lens 22 to form an image. In this embodiment, since the light emitting area 20 of the line head 2 provided with the light emitting element 21 and the lens 22 is larger than the field of view of the line sensor camera 3, when the line sensor camera 3 captures the light emission state of the line head 2. The stage 11 is driven, and the entire light emitting region 20 by the line head 2 is imaged a plurality of times.

The frame 100 of the printer is placed on the stage 11 so that the lens 22 of the line head 2 faces upward and the longitudinal direction of the line head 2 is oriented along the X direction. Thereby, the optical axis of the lens 22 of the line head 2 is along the Z direction.
Here, after the adjustment by the adjustment device 1, a photosensitive drum (not shown) as an exposure body is incorporated in the frame 100 in accordance with a reference position A that is a line along the X direction. That is, the side surface on the line head 2 side along the axial direction of the photosensitive drum is along the reference position A.

The frame 100 is provided with pins 101 and 102 as first moving means and second moving means for moving up and down both ends in the longitudinal direction of the line head 2 along the Z direction. A male screw portion (not shown) is formed on the outer periphery of the pins 101 and 102, and the male screw portion is screwed into female screw portions 103 and 104 formed on the frame 100.
The pins 101 and 102 are provided with micrometers 101A and 102A for measuring the amount of movement with respect to the reference position A, and these micrometers 101A and 102A are connected to the image processing apparatus 4, respectively. .

  FIG. 2 is a block diagram showing an internal configuration of the image processing apparatus 4. The image processing device 4 uses the line sensor camera 3 (FIG. 1) for each element image formation that is evaluated to be image formation by the same lens 22 in a plurality of captured images captured from positions with different heights. The same element imaging analysis means 41 for obtaining the relationship between the height and the light intensity with respect to the position A, and the same position for detecting the focal position for each of the same element imaging based on the information obtained by the same element imaging analysis means 41. Based on the results of the focus position distribution acquisition means 43, the focus position distribution acquisition means 43 that obtains the distribution of the focus positions of all the same element image formation with respect to the reference position A, and the pin 101 , 102 and a focal position adjusting means 44 for controlling the moving amount and moving direction. These means 41 to 44 are respectively read and executed by a control means 40 such as a CPU mounted on the image processing apparatus 4.

[2. Procedure for adjusting the focus position of the line head]
A procedure for adjusting the focal position of the line head 2 by the adjusting device 1 described above will be described with reference to the flow of FIG. In the adjusting device 1, the line head 2 as a workpiece has already been assembled to the printer frame 100. In the following procedure, the shift amount of the focal position related to the image formation of each lens 22 of the line head 2 with respect to the reference position A is determined. Thus, the focus position of the line head 2 is adjusted.

[2-1. Imaging process]
First, in the imaging process P <b> 1, the stage 11 is driven several times, the entire light emitting area 20 of the line head 2 is imaged by the line sensor camera 3, and the captured image is taken into the image processing device 4. By imaging the entire light emitting region 20 of the line head 2 and driving the stage 12 to change the height of the line sensor camera 3, a distance B (FIG. 1) between the line sensor camera 3 and the reference position A is obtained. Repeat in different states. Here, a state where the predetermined distance between the line sensor camera 3 and the reference position A is “0”, and from this “0” state, upward (height +) and downward (height −), respectively. The line sensor camera 3 is moved to take an image.

  FIG. 4 shows an example of a captured image taken into the image processing device 4 by the imaging process P1. The captured image M1 includes 5000 images (dots) formed by the lenses 22 of the line head 2. IDs of images formed by the same lens 22 are indicated by d1 to d5000. In this embodiment, an image such as the picked-up image M1 has a height of −100 μm, −50 μm, 0 μm, 50 μm, and 100 μm with the above-mentioned “0” position as the center value for each height of the line sensor camera 3. Although acquired, specific illustrations of the captured images M2 to M5 other than the captured image M1 are omitted.

[2-2. Same element imaging focus position detection process]
Next, in the focal position detection process P2, the same element image forming means 41 of the image processing apparatus 4 is used to form the same ID, which is an image formed by the same lens 22, using each captured image obtained in the imaging process P1. The relationship between the distance B and the light intensity is obtained for each image (same element imaging).
In FIG. 5, in the captured images M <b> 1 to M <b> 5, only the same element imaging with the same ID of d5000 (FIG. 4) is extracted and schematically illustrated. For each of the images m1 to m5 including the image with the ID of d5000, the element image analysis unit 41 integrates (counts) the areas of the pixels having the light intensity equal to or greater than a predetermined threshold. FIG. 6 shows the relationship between the obtained area and the distance B as an approximate curve.

  Subsequently, the focus position related to the imaging of d5000 is detected by the element imaging focus position detecting means 42 based on the relationship between the area and the distance B as shown in FIG. In FIG. 6, the pixel area having a predetermined light intensity is substantially minimum at a height of +10 μm, and is assumed to be in focus at this time. Is detected as the focal position for the imaging of d5000.

The procedure by the same element imaging analysis means 41 and the same element imaging focus position detection means 42 is performed for all the imaging of d1 to d5000 shown in FIG. 4, and the focus position in each imaging is detected. . Based on this, the focal position distribution acquisition means 43 acquires the distribution of the focal positions regarding the imaging of d1 to d5000, and the data is shown in FIG. 7 that the focal position is lower than the reference position A on the imaging d1 side, and conversely, the focal position is higher than the reference position A on the imaging d5000 side.
Since the focal positions related to the imaging of d1 to d5000 are estimated based on the light intensity in the captured image, the distribution in FIG. 7 shows the light emission intensity of each light emitting element 21 of the line head 2. It can also be used to evaluate variations in

[2-3. Focus position adjustment process]
Based on the result of the focus position detection process P2, the focus position adjustment process P3 adjusts the focus position of the entire line head 2.
In the focal position adjustment step P3, the amount of movement of the pins 101 and 102 provided on the frame 100 by the focal position adjustment means 44 based on the focal positions of the respective imagings d1 to d5000 detected in the focal position detection step P2. Determine the direction of movement. In other words, the height of the focal position on the imaging d1 side is adjusted by the vertical movement of the pin 101, and the height of the focal position on the imaging d5000 side is adjusted by the vertical movement of the pin 102. In the example of FIG. 7, the height of the pin 101 is raised and the height of the pin 102 is lowered to change the posture of the line head 2. If the focal position of the imaged d1 is higher than the reference position A and the focal position of the imaged d5000 is lower than the reference position A, unlike the case of FIG. Increase the height. The amount of movement of the pins 101 and 102 at this time is determined by the amount of deviation from the reference position A of the focal position of each image formation on both ends of the line head 2. The amount of movement of these pins 101 and 102 is the micrometer 101A, It is controlled by the focal position adjusting means 44 through the measurement by 102A.

[2-4. Adjustment confirmation process]
Finally, in the adjustment confirmation process P4, the same processing as in the imaging process P1 and the focus position detection process P2 is performed again, so that the entire light emitting region 20 of the line head 2 is imaged again, and the predetermined allowable ranges R1 to R2 It is confirmed whether or not the focal positions of the respective imagings d1 to d5000 are in (FIG. 7). At this time, the light intensity of the imaging d1 to d5000, the shape of the imaging, and the like are detected, and the driver of the line head 2 is informed of each light emitting element 21 so as to eliminate the variation in the light emission intensity of each light emitting element 21 of the line head 2. The correction value may be written.

According to this embodiment described above, the following effects can be obtained.
(1) In the adjusting device 1 that adjusts the focal position of the line head 2, the height position at which the line sensor camera 3 is imaged is variably configured by the stage 12, and the reference position A where the photosensitive drum is arranged and the line sensor camera 3 A pixel area that is equal to or greater than a predetermined light intensity in each of the imaging d1 to d5000 through the lenses 22 of the line sensor camera 3, respectively, from a plurality of positions at different distances B from Based on the relationship with the distance B, each focal position based on the reference position A can be detected. Thereby, since the distribution of the focal position of each lens 22 in the line head 2 is obtained, the focal position in the entire line head 2 can be detected easily and appropriately.

(2) Further, the distribution of the focal positions related to the image formations d1 to d5000 detected in this way, that is, the focal position with respect to the reference position A for each lens 22, and the line head 2 of each image formation d1 to d5000. Since the direction in which the posture of the line head 2 is to be corrected is easily grasped based on each position, the focal position of the entire line head 2 can be easily and appropriately adjusted. By adjusting the focal position of the line head 2 in this way, it is possible to contribute to uniform light intensity in the entire line head 2, so that the printing performance of a printer in which the line head 2 is incorporated can be improved.

(3) The entire light emitting region 20 of the line head 2 is imaged in the imaging step P1, and the focal position is detected for all the images d1 to d5000 of the lens 22 in the focal position detecting step P2, and the focal position of the lens 22 is detected. Since the deviation with respect to the reference position A can be grasped over the entire line head 2, the direction in which the line head 2 is moved can be determined more appropriately in the focal position adjustment step P3.
Thus, by detecting all the focal positions regarding the imaging images d1 to d5000, the line head 2 can be installed with high accuracy inside the printer.

(4) In the focal position detection step P2, the focal position related to the imaging d1 to d5000 is quantitatively and appropriately detected based on the relationship between the distance B and the area of the pixel that is equal to or higher than the predetermined light intensity included in the imaging. can do.

(5) Since the pins 101 and 102 are provided with the micrometers 101A and 102A, respectively, the relationship between the amount of movement of the line head 2 by the pins 101 and 102 and the focal position of the line head 2 can be obtained quantitatively. When the focal position is adjusted, the amount of movement of the line head 2 by the pins 101 and 102 can be accurately controlled. That is, since the moving direction and the moving amount of the line head 2 are grasped, the focal position of the line head 2 can be adjusted more appropriately based on this, and the work efficiency of the adjustment can be improved. Automation of the driving of the pins 101 and 102 can also be considered.

(6) Further, in the production of the line head 2, it is important to make the light intensity uniform in the entire light emitting region 20, but the light emission intensity of the light emitting element 21 is detected through the detection of each focal position by the preparation method of the present embodiment. And the focal length of the lens 22 can be known, and also the light intensity at the focal position (light emission variation of the light emitting element 21 alone) and the light intensity when the focal distance is changed can be detected. it can. That is, when the light emission intensity of the light emitting element 21 is directly measured, the light intensity value may vary depending on the light emission variation of the light emitting element 21 alone and the distance between the sensor and the light emitter at the time of measurement. There is no inconvenience. That is, with the preparation method of the present embodiment, it is possible to further improve the print quality by calculating a correction coefficient according to characteristics such as the light intensity at the focal position and the light intensity when the focal length is changed. .

[Modification of the present invention]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  In each of the above embodiments, the entire light emitting region 20 of the line head 2 is imaged, and the focal positions are obtained for all the imaged d1 to d5000 via each lens of the line head 2, but the present invention is not limited to this. It is sufficient that the image picked up by the above includes at least the image formations d1 and d5000 arranged at both ends of the line head 2. Even in this case, the pins 101 and 102 are adjusted in either the upper or lower direction based on the deviation amount of the focal positions from the reference position A in the imaged d1 and d5000, and the focal position of the entire line head 2 is adjusted. Is possible. This method is suitable for mass production.

  In the above-described embodiment, the line sensor camera 3 is used. However, as described above, it is only necessary to detect the focal position for at least the image formation at both ends of the line head 2. Such imaging means can also be used. In this case, for example, two area sensor cameras may be arranged toward both ends of the line head 2. Note that one area sensor camera can also be used, for example, when the area sensor camera has a large number of pixels or is synchronized with the movement of the stage 11. Regardless of the type of imaging means, the number of units is not limited.

In the embodiment, the pins 101 and 102 are arranged at both ends of the line head 2 as moving means for adjusting the focal position. However, the configuration of the focal position adjusting means is not limited to this. For example, it can be considered that a pin or the like that supports the approximate center in the longitudinal direction of the line head 2 and that can be adjusted in height is provided on a frame or a housing to which the line head 2 is assembled. Accordingly, unlike FIG. 7, when the focal position distribution of each of the imaged d <b> 1 to d5000 is not monotonously increasing or decreasing monotonically, that is, the gradient of the focal position of the imaged d <b> 1 to d5000 increases. Even if it is lowered, the focal position of the entire line head 2 can be adjusted by adjusting the pins 101 and 102 that support the line head 2 and the pin at the center of the line head 2. It becomes. The number of pins to be added is not limited, and for example, several pins may be provided at equal intervals in the longitudinal direction of the line head 2.
Further, since the focus position distribution of each imaging element can be obtained by the detection method and the detection apparatus of the present invention, in addition to adjusting the focus position by a pin or the like, a correction value is written in the driver, and the light intensity of the light emitting element. It is also possible to adjust this.

  Furthermore, in the above-described embodiment, the adjustment amounts of the pins 101 and 102 are accurately controlled using the micrometers 101A and 102A. However, even if such micrometers 101A and 102A are not used, the focal position of FIG. Since the direction in which the pins 101 and 102 are moved up and down is grasped, the focal position can be adjusted by moving the pins 101 and 102 in either direction.

  In the above embodiment, the area value is calculated by counting the number of pixels having a light intensity equal to or greater than a predetermined threshold in order to estimate the focal position of the element imaging. However, the focal position may be estimated using a standard deviation or the like.

  In the above-described embodiment, the printer is exemplified as the device in which the line head is incorporated. However, the present invention is not limited to this, and can be widely used for various information devices that write information on a recording medium by image formation of light.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

BRIEF DESCRIPTION OF THE DRAWINGS The structure schematic of the focus position adjustment apparatus of the line head in embodiment of this invention. The block diagram which shows the internal structure of the image processing apparatus in the said embodiment. The flowchart which shows the focus position adjustment procedure of the line head in the said embodiment. The figure which shows the captured image by the imaging process in the said embodiment. The figure which shows the same element image formation in the said embodiment for every distance from the reference position at the time of imaging. In the said embodiment, the graph which shows the relationship between the distance from the reference position at the time of imaging, and the area of the pixel which has the light intensity more than the predetermined threshold value in the same element image formation. The figure which shows distribution of the focus position of each lens of the line head in the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Adjustment apparatus, 2 ... Line head, 3 ... Line sensor camera (imaging means), 12 ... Stage (distance variable means), 21 ... Light emitting element, 22 ... Lens ( Imaging element), 42... Element imaging focal position detecting means (focus position detecting means), 44... Focus position adjusting means, 101... Pin (first moving means), 102. (Second moving means), 101A, 102A ... micrometer (moving amount measuring means), A ... reference position, B ... distance (distance between reference position and imaging means), d1 to d5000,. Image formation, M1 to M5 ... captured image, P1 ... imaging step, P2 ... focus position detection step, P3 ... focus position adjustment step, P4 ... adjustment confirmation step.

Claims (7)

In a line head formed in a long shape having a plurality of light emitting elements arranged on a straight line and a plurality of imaging elements arranged on the line so as to oppose these light emitting elements, A detection device for detecting a focal position of the emitted light beam by the imaging element,
It is arranged so as to be orthogonal to the optical axis of each imaging element and is exposed to the image by the imaging element, and is opposed to the line head, and at least the plurality of imaging elements Imaging means for imaging the images formed by the imaging elements disposed in the vicinity of both ends in the longitudinal direction of the line head;
A distance variable means for changing a distance between the linear reference position along the surface of the exposure body on the line head side and the imaging means along the optical axis of the imaging element;
In each captured image captured by the imaging unit from a plurality of positions having different distances, for each image formed by the same imaging element among the plurality of imaging elements, the pixel information of the imaging and the distance And a focal position detection means for detecting the focal position with respect to the reference position based on the relationship between the focal position and the reference position. The apparatus for detecting a focal position of a line head according to claim 1,
The imaging means is a line sensor camera having a plurality of photosensor elements arranged on a straight line,
The line sensor camera is arranged such that the optical sensor elements are arranged along the longitudinal direction of the line head. The apparatus for detecting a focal position of a line head according to claim 1 or 2,
The focus position detection unit detects the focus position based on an area of a pixel having a light intensity equal to or higher than a predetermined threshold included in the image formation. The detection device according to any one of claims 1 to 3,
Both ends in the longitudinal direction of the line head based on the focal position with respect to the reference position for each imaging element detected by the focal position detection means and the respective positions of the imaging elements in the line head. Each of which includes a focal position adjusting means that enables movement along the optical axis of the imaging element,
The focus position adjusting means includes a first moving means provided at one end of the line head and a second moving means provided at the other end of the line head. Focus position adjustment device. The apparatus for adjusting the focal position of the line head according to claim 4,
The apparatus for adjusting the focal position of the line head, wherein the first moving means and the second moving means are each provided with a moving amount measuring means for measuring the moving amount of the line head. In a line head formed in a long shape having a plurality of light emitting elements arranged on a straight line and a plurality of imaging elements arranged on the line so as to oppose these light emitting elements, A detection method for detecting a focal position of an emitted light beam by the imaging element,
An imaging unit disposed so as to be orthogonal to the optical axis of each imaging element and exposed by imaging by the imaging element, and opposed to the line head; and the line of the exposure body Using a linear reference position along the head-side surface and a distance variable means for changing the distance between the imaging means along the optical axis of the imaging element, the distance from the plurality of positions different from each other. An imaging step of imaging each of the images formed by the imaging elements disposed in the vicinity of both ends in the longitudinal direction of the line head among the plurality of imaging elements by an imaging unit;
In each captured image captured by the imaging unit, for each image formed by the same image forming element among the plurality of image forming elements, the reference position based on the relationship between the pixel information of the image forming and the distance And a focus position detecting step of detecting the focus position of the line head. A method for detecting the focus position of a line head. The detection method according to claim 6;
The posture of the line head can be changed based on the focal position with respect to the reference position for each imaging element detected by the focal position detection step and the respective positions of the imaging elements in the line head. And a focal position adjustment step. A method for adjusting the focal position of the line head.

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