JP2005070067A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speed up an optical scanner and to increase the resolution of the optical scanner, in which a plurality of photoreceptors are scanned with a plurality of laser beams emitted from a single light source. <P>SOLUTION: In a light source 14, a group of light emitting points PK, PC, PM, and PY are arranged in the subscanning direction, in which light emitting points P are arranged in a line being inclined, with respect to the main scanning direction and the subscanning direction. Thus, the respective photoreceptors are simultaneously scanned with a plurality of scanning lines and the speeding-up is accomplished. Further, the pitch of the light emitting points in the subscanning direction in respective light-emitting point groups is made short, and high resolution is attained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical scanning apparatus that separates a plurality of light flux groups emitted from a single light source and scans a plurality of scanned objects.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a tandem color laser printer, a method of scanning a plurality of photoconductors by separating a plurality of laser beams emitted from a single light source and deflected by a single deflector has been devised (for example, , See Patent Document 1).
[0003]
In Patent Document 1, for the purpose of increasing the printing speed and increasing the resolution of a color image, 8 is emitted from a multi-laser beam array having four groups of light emitting points each composed of two light emitting points. A system is disclosed in which two laser beams are separated into four groups of laser beams, and four photoconductors are scanned.
[0004]
However, in this method, since the eight light emitting points are arranged in a line in the direction corresponding to the sub-scanning direction of the photosensitive member, three or more light emitting points in each group are provided in order to realize higher speed and higher resolution. In this case, the entire length of the multi-laser beam array becomes very long, making it difficult to manufacture.
[0005]
Further, the interval between the light emitting points is 14 μm, and in order to realize a high resolution of 1200 dpi or 2400 dpi, the optical magnification in the sub-scanning corresponding direction needs to be 1.5 times or 0.75 times. .
[0006]
In this case, considering the laser efficiency and truncating at about half the laser divergence angle, the beam diameter becomes small and the depth of focus becomes very narrow. Further, as the optical magnification in the sub-scanning corresponding direction is small, the focal length of the optical element in the sub-scanning direction must be shortened, and the F number of the optical element in the sub-scanning direction becomes small. For this reason, since the effective width of the optical element has to be increased, the manufacturing cost of the optical element increases. Further, as the effective width of the optical element is increased, the exit pupil on the scanning optical system is increased, so that the light flux width at the separation position is increased. Accordingly, the interval between adjacent pairs is narrowed, and it is difficult to separate the laser beams in each pair.
[0007]
In addition, when an aperture that narrows the beam diameter of the laser beam to 50 μm is used in order to ensure a sufficient depth of focus, the amount of truncation increases and the amount of light loss increases. For this reason, in order to secure the necessary light quantity of the laser, the laser output must be increased, and the reliability is lowered. In addition, there is a problem that the cost increases due to the use of a high-power laser array.
[0008]
[Patent Document 1]
JP-A-6-286226
[0009]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above-mentioned facts, and it is possible to increase the speed and resolution of an optical scanning device that scans a plurality of photosensitive members by separating a plurality of laser beams emitted from a single light source unit. With the goal.
[0010]
[Means for Solving the Problems]
The optical scanning device according to claim 1 includes a plurality of light emitting points arranged two-dimensionally in a main scanning corresponding direction corresponding to a deflection scanning direction and a sub scanning corresponding direction corresponding to a direction orthogonal to the deflection scanning direction. A light source that emits a group of light beams arranged in a plurality of rows in the sub-scanning corresponding direction, a pre-deflection optical system through which a plurality of light beam groups emitted from the light source pass, and a plurality of columns that have passed through the pre-deflection optical system And a deflecting unit that deflects the light beam group in the main scanning direction and a scanning optical system that separates a plurality of light beam groups in different directions and focuses the light beam groups on a plurality of scanned objects.
[0011]
In the optical scanning device according to the first aspect, light beam groups arranged in a plurality of rows in the sub-scanning corresponding direction are emitted from a plurality of light emitting points provided in the light source. A plurality of rows of light beams emitted from the light source pass through the pre-deflection optical system and are deflected in the main scanning corresponding direction by the deflecting unit. The plurality of light beam groups are separated in different directions by the scanning optical system and are individually focused on the plurality of scanned objects. Thereby, a plurality of scanned objects are scanned with a plurality of light beams at a time.
[0012]
Here, the plurality of light emitting points are two-dimensionally arranged in the main scanning corresponding direction which is the deflection scanning direction and the sub scanning corresponding direction orthogonal to the deflection scanning direction. For this reason, even if the number of light emitting points is increased in the main scanning correspondence direction, the light source can be prevented from spreading in one direction in the sub scanning correspondence direction, and the light source can be easily manufactured. Therefore, scanning can be performed at higher speed and higher resolution.
[0013]
Further, since it is possible to suppress the spread in the sub-scanning corresponding direction, a margin for widening the interval between the light emitting points in the sub-scanning corresponding direction is generated, so that it becomes easy to separate the light beam groups.
[0014]
In addition, by scanning with a plurality of light emitting points, the amount of light output from one light emitting point can be reduced.
[0015]
An optical scanning device according to a second aspect is the optical scanning device according to the first aspect, wherein the light source is formed of a plurality of light emitting points that are linearly arranged with an inclination with respect to the main scanning corresponding direction. A plurality of light emitting point groups are arranged in the sub-scanning corresponding direction.
[0016]
In the optical scanning device according to the second aspect, the light emitting point group in which a plurality of light emitting points are arranged in a straight line is inclined with respect to the main scanning corresponding direction. In addition, since a plurality of rows of light beams can be simultaneously scanned in the sub-scanning direction orthogonal to the deflection scanning direction of the scanning object, the scanning speed can be increased. Furthermore, even if the number of light emitting points in the light emitting point group is increased, it is possible to suppress the spread of the light source in the main scanning corresponding direction and the sub scanning corresponding direction, and there is a margin for widening the interval between the light emitting point groups accordingly. The intervals between the light beam groups can be widened, and the light beam groups can be easily separated.
[0017]
Further, even when the interval between the light emitting points in each light emitting point group is the same as the interval between the light emitting points in each light emitting point group of the conventional light source in which the light emitting points are arranged one-dimensionally in the sub-scanning corresponding direction, The spot interval in the sub-scanning corresponding direction of the body is narrower than the conventional one. For this reason, the imaging magnification can be increased, and accordingly, the laser utilization efficiency can be improved, and the F number of the scanning optical system can be increased, so that the depth of focus is widened.
[0018]
Further, since the effective width of the optical element can be reduced by increasing the F number of the scanning optical system, the manufacturing cost of the optical element can be reduced.
[0019]
Further, since the effective width of the optical element can be reduced, the width of the light beam on the exit pupil of the scanning optical system is narrowed, so that the width of the light beam at the separation position of the scanning optical system is reduced, and separation of adjacent light beam groups is easy. become.
[0020]
The optical scanning device according to claim 3 is the optical scanning device according to claim 2, wherein the light source has adjacent intervals A in the direction corresponding to the sub-scanning of light emitting points at both ends of each light emitting point group. The light emitting point group is narrower than the interval B in the sub-scanning corresponding direction between the light emitting points closest to each other in the sub-scanning corresponding direction.
[0021]
In the optical scanning device according to claim 3, the interval A in the sub-scanning correspondence direction of the light emission points at both ends of the light emission point group corresponds to the sub-scan correspondence of the light emission points closest to each other in the sub-scan correspondence direction in the adjacent light emission point group. It is narrower than the interval B in the direction. That is, since the adjacent light emitting point groups are divided in the sub-scanning corresponding direction, each light beam group can be separated in the sub-scanning corresponding direction.
[0022]
The optical scanning device according to a fourth aspect is the optical scanning device according to the third aspect, wherein the distance between the light source A and the distance B is B / A> 4. And
[0023]
In the optical scanning device according to claim 4, since the interval B is four times or more than the interval A, each light beam group can be easily separated, and a high-density scanning line can be formed in the sub-scanning direction. It is advantageous for high speed and high resolution exceeding 2400 dpi.
[0024]
The optical scanning device according to claim 5 is the optical scanning device according to claim 3 or 4, wherein the light source includes the interval A, the interval B, and the light emitting points at both ends of each light emitting point group. The interval C in the main scanning correspondence direction is characterized by B <C <(A + B) × 3.
[0025]
In the optical scanning device according to claim 5, the relationship between the distance C, the distance A, and the distance B in the main scanning correspondence direction of the light emitting points at both ends of each light emitting point group is B <C <(A + B) × 3. It has become. As a result, the size of the light source composed of the four light emitting point groups can be minimized, and the manufacturing cost can be reduced.
[0026]
An optical scanning device according to a sixth aspect is the optical scanning device according to any one of the second to fifth aspects, wherein the light sources are arranged such that the light emitting points of the respective light emitting point groups are arranged on the same straight line at a predetermined pitch. It is characterized by being.
[0027]
In the optical scanning device according to the sixth aspect, the light emitting points of each light emitting point group are arranged on the same straight line at a predetermined pitch. For this reason, scanning lines can be formed at predetermined intervals in the main scanning direction and the sub-scanning direction of the scanning target.
[0028]
An optical scanning device according to a seventh aspect is the optical scanning device according to any one of the second to sixth aspects, wherein the light source has a light emitting point group having a larger number of light emitting points than other light emitting point groups. It is provided.
[0029]
In the optical scanning device according to the seventh aspect, for example, the number of light emitting points in the light emitting point group for forming an image of a specific color that is frequently used, such as black, is larger than other light emitting points. For this reason, it is possible to increase the printing speed of specific colors that are frequently used.
[0030]
The optical scanning device according to claim 8 is the optical scanning device according to claim 7, wherein the light source has a light emitting point group in which the number of light emitting points is larger than other light emitting point groups, corresponding to the sub-scanning. It is provided in the center of the direction.
[0031]
The light scanning device according to claim 8, wherein the light emitting point group having a larger number of light emitting points than the other light emitting point groups is provided at a central portion in the sub-scanning direction, and aberrations in the pre-deflection optical system and the scanning optical system Has been reduced. For this reason, a small-diameter optical element can be used for the pre-deflection optical system and the scanning optical system, and the cost can be reduced.
[0032]
An optical scanning device according to a ninth aspect is the optical scanning device according to any one of the first to eighth aspects, wherein the pre-deflection optical system includes a plurality of light beam groups and an interval between the light beam groups as the sub-scanning. It is enlarged in the corresponding direction and is incident on the deflecting means.
[0033]
In the optical scanning device according to the ninth aspect, the pre-deflection optical system causes the plurality of light beam groups to enter the deflecting means with the interval between the light beam groups being enlarged. This facilitates separation of the light beam groups.
[0034]
An optical scanning device according to a tenth aspect is the optical scanning device according to any one of the first to ninth aspects, wherein the scanning optical system includes a first scanning optical system provided on the deflection unit side; And a second scanning optical system provided on the scanned body side, and a plurality of light beam groups pass through at least the first scanning optical system.
[0035]
In the optical scanning device according to claim 10, a plurality of light beam groups are allowed to pass through at least one of the first scanning optical system and the second scanning optical system constituting the scanning optical system, so that most of the optical system is divided into a plurality of optical systems. Since the light beam group can be shared, the cost of the optical system can be reduced.
[0036]
An optical scanning device according to an eleventh aspect is the optical scanning device according to the tenth aspect, wherein both the first scanning optical system and the second scanning optical system have a positive power in the deflection scanning direction. It is characterized by that.
[0037]
In the optical scanning device according to claim 11, since both the first scanning optical system and the second scanning optical system have positive power in the sub-scanning corresponding direction, the magnification of the scanning optical system in the sub-scanning corresponding direction is increased, Laser utilization efficiency can be improved and a plurality of light beam groups can be focused on a plurality of scanned objects.
[0038]
An optical scanning device according to a twelfth aspect is the optical scanning device according to the tenth or eleventh aspect, wherein the pre-deflection optical system divides a plurality of light beams into a principal ray of each light beam in the sub-scanning corresponding direction. The first scanning optical system corrects the aberration of each light beam group in the sub-scanning corresponding direction with the cross-sectional shape in the sub-scanning corresponding direction being a non-arc shape in parallel or converging and entering the deflecting unit. Features.
[0039]
In the optical scanning device according to the twelfth aspect, the plurality of light beam groups are incident on the deflecting unit after the principal rays of the respective light beams are converged in parallel or in the sub-scanning corresponding direction by the pre-deflection optical system. For this reason, when a plurality of light beam groups are crossed by the first scanning optical system, a short distance is sufficient, so that the optical path of each light beam group can be shortened and the optical scanning device can be downsized.
[0040]
The first scanning optical system has a non-arc cross-sectional shape in the sub-scanning corresponding direction, and corrects aberrations of light beams having different passing positions. This makes it possible to obtain a uniform spot when scanning the scanning line with scanning lines at a predetermined interval.
[0041]
An optical scanning device according to a thirteenth aspect is the optical scanning device according to any one of the tenth to twelfth aspects, wherein the scanning optical system includes a first scanning optical system and a second scanning optical system. And a separation unit that is provided between the first scanning optical system and the second scanning optical system. And the second scanning optical system is provided for each light beam group and focuses each light beam group separated by the separation device on each scanned object. To do.
[0042]
In the optical scanning device according to the thirteenth aspect, the plurality of light beam groups are crossed between the first scanning optical system and the second scanning optical system by the first scanning optical system and are incident on the separating unit. For this reason, in the separation means, since the light beam centers of the respective light beam groups are diffused, it is possible to easily separate the light beam groups.
[0043]
In addition, each light beam group separated by the separating unit is focused on each scanning object by a second scanning optical system provided for each light beam group. Here, since the second scanning optical system is provided for each light beam group, the tilt of each light beam group can be corrected for each light beam group by changing the characteristics of each second scanning optical system. is there. Further, the imaging magnification for each light beam group from the light source to each scanned object can be made the same.
[0044]
An optical scanning device according to a fourteenth aspect is the optical scanning device according to the tenth aspect, provided between the first scanning optical system and the second scanning optical system, and different in a plurality of light beam groups. And a pre-deflection optical system that causes a plurality of light beam groups to be incident on the deflecting unit in parallel or in a direction corresponding to the sub-scanning direction and diffusing the principal ray of each light beam. The scanning optical system has no power in the sub-scanning corresponding direction, and the second scanning optical system is provided for each light beam group, and focuses each light beam group separated by the separating unit on each scanned object. It is characterized by that.
[0045]
In the optical scanning device according to the fourteenth aspect, a plurality of light beam groups are incident on the deflecting means after the principal ray of each light beam is parallel or diffused in the sub-scanning corresponding direction by the pre-deflection optical system. Then, the plurality of light beam groups deflected by the deflecting unit pass through the first scanning optical system having no power in the sub-scanning corresponding direction and enter the separating unit. In other words, the plurality of light flux groups enter the separating means after the principal rays of each light flux are parallel or diffused. Therefore, each light beam group can be easily separated.
[0046]
Further, since there is no power in the sub-scanning corresponding direction of the first scanning optical system, the scanning line curve generated by the deflection is very small, and the color registration deviation in the plurality of scanned objects is also reduced. In particular, when the light is incident on the deflecting means in parallel in the sub-scanning corresponding direction, the scanning line is not curved, which is more advantageous in terms of color registration performance.
[0047]
An optical scanning device according to a fifteenth aspect is the optical scanning device according to the thirteenth or fourteenth aspect, wherein the optical scanning device has at least one reflecting means for reflecting the light beam groups, and the number of reflections between the light beam groups. The difference is 0 or an even number.
[0048]
In the optical scanning device according to claim 15, since the difference in the number of reflections between the light beam groups by the reflecting means is 0 or an even number, the order of the scanning lines and the arrangement of the spots formed on each scanned body are reversed. There is nothing.
[0049]
An optical scanning device according to a sixteenth aspect is the optical scanning device according to the fifteenth aspect, wherein the separating unit directly causes each light beam group to be incident on each scanning object.
[0050]
In the optical scanning device according to the sixteenth aspect, since each light beam group is directly incident on each scanning object by the separating unit, the scanning line on each scanning object is not reversed.
[0051]
The optical scanning device according to claim 17 is the optical scanning device according to any one of claims 13 to 16, wherein the separating means includes the reflecting means, and the reflecting means is a reflecting mirror. It is characterized by.
[0052]
In the optical scanning device according to the seventeenth aspect, the respective light beam groups are separated by the reflecting mirror, and an expensive reflecting optical element such as a prism is not required, so that the cost can be reduced.
[0053]
The optical scanning device according to claim 18 is the optical scanning device according to any one of claims 13 to 17, wherein the second scanning optical system is capable of adjusting a posture and a distance from the object to be scanned. It is provided in.
[0054]
In the optical scanning device according to claim 18, the second scanning optical system provided for each light beam group is capable of adjusting the posture and the distance to the scanned body. For this reason, since the posture, magnification, beam waist position, and the like of the scanning lines can be adjusted for each light beam group, scanning lines with a predetermined interval can be formed on each scanning target.
[0055]
The optical scanning device according to claim 19 is the optical scanning device according to any one of claims 1 to 18, wherein the pre-deflection optical system has a plurality of light beam groups that emit principal rays of the respective light beams. It is characterized in that it is incident on the deflecting means in parallel or in a convergent direction.
[0056]
In the optical scanning device according to the nineteenth aspect, a plurality of light beam groups are incident on the deflecting unit after the principal rays of the respective light beams are converged in parallel or in the main scanning corresponding direction by the pre-deflection optical system. For this reason, the spread of each light beam group on the deflection surface can be suppressed, and an increase in the size of the deflection means can be prevented.
[0057]
The optical scanning device according to claim 20 is the optical scanning device according to any one of claims 1 to 19, wherein the pre-deflection optical system condenses a plurality of light flux groups emitted by the light source. A coupling lens and a plurality of light bundles collected by the coupling lens are aligned in the main scanning correspondence direction in which the principal ray of each light flux is parallel to or converged in the main scanning correspondence direction and is incident on the deflecting unit. And an optical system having power.
[0058]
In the optical scanning device according to claim 20, a plurality of light flux groups emitted from the light source are condensed by coupling, and the principal ray of each light flux is made parallel to the main scanning corresponding direction by an optical system having positive power or It is focused and incident on the deflecting means. For this reason, the optical path length of the pre-deflection optical system is set to a predetermined length and the desired sub-scanning magnification is set, and the spread of each light beam group in the main scanning-corresponding direction can be suppressed, preventing an increase in the size of the deflecting means. it can.
[0059]
An optical apparatus according to a twenty-first aspect is the optical scanning apparatus according to any one of the first to twentieth aspects, wherein an effective imaging magnification from the light source to the plurality of scanned objects is approximately in each light beam group. It is characterized by being identical.
[0060]
In the optical scanning device of the twenty-first aspect, the effective imaging magnification from the light source to the plurality of scanned objects is substantially the same in each light beam group. For this reason, the interval between the scanning lines scanned by each scanning object is substantially the same in the scanning region, and a color image without color misregistration can be formed.
[0061]
An optical scanning device according to a twenty-second aspect is the optical scanning device according to any one of the second to twenty-first aspects, wherein the light amount detecting means detects a light amount of a plurality of light beams emitted from the light source, and the light amount. A first control unit that controls the light amount for each light emission point based on the light amount of the light beam detected by the detection unit, and a light amount control for each light emission point group based on the light amount of the light beam detected by the light amount detection unit. And a second control means.
[0062]
In the optical scanning device according to the twenty-second aspect, the light amount of the plurality of light beams emitted from the light source is detected by the light amount detecting means. Then, the first control means controls the light quantity for each light emission point based on the detected light quantity, and the second control means controls the light quantity for each light emission point group.
[0063]
When the amount of light is controlled for each light emitting point, it takes time to control, but can be controlled with high accuracy. Also, when controlling the amount of light for each light emitting point group, it can be controlled in a short time, and thus is suitable for control during image formation.
[0064]
An optical scanning device according to a twenty-third aspect is the optical scanning device according to the twenty-second aspect, wherein the first control unit corrects the amount of light before each job and at least one of the light emitting points between pages. The second control means corrects the amount of light for each light beam group when scanning outside the scanning region of the scanning object during image formation.
[0065]
In the optical scanning device according to the twenty-third aspect, the light amount is corrected for each light emitting point by the first control unit before the job starts and when there is a time margin between pages. Further, when the outside of the scanning area of the scanning object is scanned during image formation, the amount of light is corrected for each light emitting point group by the second control means.
[0066]
Here, normally, only one light emission point can be corrected during a single scan outside the scanning area of the scanned object. Therefore, when light amount correction is performed for each light emission point, each light emission point is The amount of light can be corrected only for each number of scans corresponding to the number of light emission points. For this reason, density fluctuations occur for each number of scans according to the number of light emission points.
[0067]
On the other hand, since the second control unit corrects the light amount of each light emitting point group for each number of scans corresponding to the number of light emitting point groups, it is possible to suppress density fluctuations for each number of scans corresponding to the number of light emitting point groups. It becomes difficult to feel uneven density.
[0068]
In addition, since the light amount is corrected for each light emitting point group instead of correcting the light amounts of all the light emitting points at the same time, it is possible to reduce the thermal effect that occurs between the light emitting points.
[0069]
An optical scanning device according to a twenty-fourth aspect is the optical scanning device according to any one of the second to twenty-third aspects, wherein the deflecting means emits light from a light emitting point in a reference light emitting point group serving as a reference of a writing position. And a delay from when a detection signal is transmitted from the light beam detecting unit to when a light emitting point in the reference light emitting point group is turned on. First storage means for storing time T1, and second storage means for storing delay time T2 from when the light emitting point of one adjacent light emitting point group is turned on until the light emitting point of the other light emitting point group is turned on. A third storage means for storing a delay time T3 from when one adjacent light emitting point in each light emitting point group is turned on until the other light emitting point is turned on; and a light emitting point in the reference light emitting point group Is turned on, and the detection signal is received from the light beam detecting means. Then, the delay time T1, the delay time T2, and the delay time T3 are read out from the first storage means, the second storage means, and the third storage means and added to light up each light emitting point. And a control means.
[0070]
In the optical scanning device of the twenty-fourth aspect, the writing control means turns on the light emitting point in the reference light beam group which becomes the reference of the writing position and emits the light beam. This light beam is deflected out of the scanning area of the scanning object by the deflecting means and detected by the light beam detecting means.
[0071]
When the write control means receives the detection signal transmitted from the light flux detection means, it reads the delay time T1 stored in the first storage means, and after the delay time T1 has elapsed, first the light emission points in the reference light emission point group are read out. Lights up. Then, the writing control means reads the delay time T2 stored in the second storage means, and the light emission of the other light emitting point group after the delay time T2 has elapsed since the light emitting point of one adjacent light emitting point group is turned on. Light the point.
[0072]
That is, the writing control means turns on the light emitting points of the light emitting point group adjacent to the reference light emitting point group after the delay time (T1 + T2) has elapsed after receiving the detection signal from the light flux detecting means, and further delay time Each time T2 elapses, the light emitting points of the adjacent light emitting point groups are turned on. When the light emitting points of adjacent light emitting point groups are arranged on the same straight line in the sub-scanning corresponding direction, the delay time T2 is 0, and all the light emitting point groups may be written simultaneously. This makes it easy to control the writing position.
[0073]
Further, the writing control means reads the delay time T3 stored in the third storage means, and after the delay time T3 has elapsed after the one adjacent light emitting point in each light emitting point group is turned on, the other light emitting point is determined. Light up. That is, each light emitting point in each light emitting point group is turned on one after another as the delay time T3 elapses.
[0074]
In this way, the writing control means adds the delay time T1, the delay time T2, and the delay time T3 to light up each light emitting point, thereby aligning the writing position of each light beam group to each scanned object. And a color image without color misregistration can be formed.
[0075]
In addition, since the write position is controlled by determining the delay time T1, the delay time T2, and the delay time T3, it is sufficient to provide only one light beam detecting means for detecting one light beam. There is no need to set a delay time for the light emitting point. Therefore, writing of each light emitting point can be controlled with a simple control circuit.
[0076]
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment will be described below with reference to the drawings.
[0077]
As shown in FIG. 1, an optical scanning device 10 provided in a color laser printer includes four photosensitive members 12Y, 12M, 12C, and 12K as scanned bodies, and laser beam groups LY, LM, A latent image is formed by irradiating LC and LK. The latent images formed on the photoconductors 12Y, 12M, 12C, and 12K are developed with yellow (Y), magenta (M), cyan (C), and black (K) toners, respectively. Then, the toner on each photoconductor is transferred to a transfer belt (not shown). At this time, the toners of the respective colors are superimposed to form a full-color image and transferred to a recording medium such as plain paper.
[0078]
The optical scanning device 10 includes a light source 14, a pre-deflection optical system 16, a polygon mirror 18 as a deflection unit, and a scanning optical system 20, and includes four laser beam groups LY, LM, LC, LK is emitted, and each laser beam group is separated in the scanning optical system and image-scanned on the four photoconductors 12Y, 12M, 12C, and 12K. The deflection scanning direction by the rotation of the polygon mirror of the optical scanning device is referred to as a main scanning corresponding direction, and the direction orthogonal to the deflection scanning direction is referred to as a sub scanning corresponding direction. That is, in the photoconductors 12Y, 12M, 12C, and 12K, a direction corresponding to the axial direction is referred to as a main scanning corresponding direction, and a direction corresponding to the rotation direction is referred to as a sub scanning corresponding direction.
[0079]
The light source 14 is a surface emitting laser beam array in which a total of 32 light emitting points P of 8 columns × 4 rows are arranged two-dimensionally in the main scanning corresponding direction and the sub-scanning corresponding direction. The beam groups 12K, 12C, 12M, and 12Y are emitted, and the photosensitive members 12K, 12C, 12M, and 12Y are scanned with eight laser beams, respectively.
[0080]
As shown in FIG. 2A, in the sub-scanning corresponding direction of the light source 14, four light emitting point groups PK, PC, PM, and PY each composed of eight light-emitting points P are sub-scanning corresponding directions. Is arranged. Each light-emitting point group is composed of eight light-emitting points P that are linearly arranged with an inclination with respect to the main scanning corresponding direction and the sub-scanning corresponding direction. That is, all the light emitting points constituting each light emitting point group are not arranged on the same straight line in the main scanning corresponding direction or the sub scanning corresponding direction. For this reason, the spread of the light emission point P in the main scanning corresponding direction and the sub scanning corresponding direction can be suppressed, and a light source capable of emitting 32 laser beams can be configured compactly.
[0081]
The light emitting points P of each light emitting point group are arranged on the same straight line at a predetermined pitch (the main scanning corresponding direction is 25 μm and the sub scanning corresponding direction is 5 μm), and the light emitting points P of the other light emitting point groups They are arranged on the same straight line in the sub-scanning corresponding direction. For this reason, if each light emitting point is turned on with a predetermined delay time, which will be described later, the writing position in the main scanning direction is aligned, and a color image without color misregistration can be formed.
[0082]
The distance A between the light emitting points P1 and P2 at both ends of each light emitting point group in the sub-scanning corresponding direction is set to 35 μm, and the distance B between the light emitting points P1 and P2 closest to each other in the adjacent light emitting point group is set to 165 μm. Yes. Here, the interval A is narrower than the interval B, and the light emission point P1 of the lower light emission point group is located below the light emission point P2 of the upper light emission point group in the sub-scanning corresponding direction. ing. For this reason, each light beam group emitted from each light emitting point group can be easily separated in the sub-scanning corresponding direction.
[0083]
Further, the interval B is four times or more (4.7 times) the interval A, and the interval A and the interval B satisfy the relationship of B / A> 4. Can be separated and each photoconductor can be scanned at a resolution of 2400 dpi.
[0084]
Further, the interval C in the main scanning correspondence direction between the light emitting points P1 and P2 at both ends of each light emitting point group is 175 mm, and satisfies the relationship of B (= 165 μm) <C <(A + B) × 3 (= 570 μm). The light source 14 has a minimum size capable of separating the light beam groups. Thereby, the manufacturing cost of the light source 14 can be reduced.
[0085]
As shown in FIGS. 1 and 3, the pre-deflection optical system 16 includes a coupling lens 22, an aperture 24, and a cylinder lens 26 that are common to the four laser beam groups. The coupling lens 22 is provided facing the light source 14 and has a focal length of 23.3 mm. The aperture 24 is provided at the rear focal position of the coupling lens 22. The cylinder lens 26 is provided with the front focal position aligned with the opening 24A of the aperture 24, and the focal length is 97.86 mm. The cylinder lens 26 has no power in the main scanning direction and has positive power in the sub-scanning direction.
[0086]
The laser beam groups LK, LC, LM, and LY emitted from the light source 14 are condensed by the coupling lens 22, pass through the opening 24 </ b> A of the aperture 24 while being truncated, and the principal ray is made to correspond to the sub-scanning direction by the cylinder lens 26. In parallel with or focused on, the light enters the deflecting surface 18A of the polygon mirror 18. Here, the aperture 24 was set to have an opening width that narrows the beam diameter to 50 μm in order to ensure a sufficient depth of focus.
[0087]
As a result, the imaging magnification of the pre-deflection optical system in the sub-scanning corresponding direction is 4.2 times, and the deflection surface 18A of the polygon mirror 18 has a pitch in the sub-scanning corresponding direction of the laser beams in each laser beam group. Is enlarged by 21 μm, and the pitch of each laser beam group in the sub-scanning corresponding direction is enlarged to 0.693 mm. For this reason, it is easy to separate the laser beam groups later in the scanning optical system 20.
[0088]
Further, each laser beam group is incident on the deflecting surface 18A with the principal ray parallel or focused. For this reason, since the distance to the crossing position of each laser beam group in the scanning optical system 20 to be described later can be shortened and the distance to the separating means can be shortened, the optical scanning device 10 can be miniaturized.
[0089]
The polygon mirror 18 has six deflection surfaces 18A, rotates at a speed of 30,000 revolutions per minute, and moves the scanning line to each photoconductor at a speed of 254 mm per second.
[0090]
The scanning optical system 20 includes an aspheric lens 28 as a first scanning optical system through which the laser beam groups LK, LC, LM, and LY pass, a plane mirror group 30 as a separating unit, and each laser beam group. It comprises toroidal lenses 32Y, 32M, 32C and 32K as the provided second scanning optical system. Both the aspheric lens 28 and the aspheric lens 32 have positive power.
[0091]
The aspherical lens 28 is provided in the optical path of the laser beam groups LY, LM, LC, and LK deflected by the polygon mirror 18, and has a focal length of 60 mm in the sub-scanning corresponding direction. Further, the distance from the deflection surface 18A is also about 60 mm.
As a result, the laser beam groups intersect with each other at the rear focal position of the aspheric lens 28 and enter the plane mirror group 30. Each laser beam becomes substantially parallel light.
[0092]
Here, the aspherical lens 28 is formed by plastic shaping so that the cross-sectional shape in the sub-scanning corresponding direction becomes an aspherical shape, and the laser beam group LY that passes through a position away from the optical axis of the aspherical lens 28. , LK aberration is corrected, and the imaging magnifications in the sub-scanning corresponding directions of the laser beam groups are made substantially the same. Further, the aspheric lens 28 is configured to have an fθ characteristic in cooperation with the toroidal lenses 32Y, 32M, 32C, 32K in the main scanning corresponding direction.
[0093]
Since the aspherical lens 28 is a plastic lens, the change in refractive index due to environmental fluctuations is larger than that of a glass lens, but all laser beams pass through the same lens, and the behavior of all the beams changing is the same. Therefore, there is little influence on the change of the color register.
[0094]
Further, although the cross-sectional shape of the aspherical lens 28 in the sub-scanning corresponding direction is an aspherical shape, the shape is not limited to this and may be a wave shape optimized for the position through which each laser beam group passes. Any non-arc shape that can correct the aberration of the group may be used.
[0095]
The plane mirror group 30 includes first plane mirrors 34Y, 34M, 34C, 34K and second plane mirrors 36Y, 36M, 36C, 36K provided for each laser beam group.
[0096]
The first plane mirrors 34Y, 34M, 34C, and 34K reflect each laser beam group incident on the plane mirror group 30 by diffusing the optical axis of each laser beam group by the aspheric lens 28 in the negative direction. The second plane mirrors 36Y, 36M, 36C, and 36K reflect the laser beam groups reflected by the first plane mirrors 34Y, 34M, 34C, and 34K toward the photoconductors.
[0097]
The first plane mirrors 34Y, 34M, 34C, and 34K are disposed at a position 300 mm away from the aspheric lens 28, and the interval in the sub-scanning corresponding direction of each laser beam group at this position is 2.8 mm. Therefore, a sufficient space for arranging the first plane mirrors 34Y, 34M, 34C, 34K can be secured.
[0098]
Thus, since the mechanism for separating the laser beam groups is configured by combining a plurality of inexpensive plane mirrors, the manufacturing cost can be reduced. The plane mirror group 30 is provided with two plane mirrors for each laser beam group, and each laser beam group is folded twice. Therefore, each laser beam group is incident on each photoconductor without reversing the order in the sub-scanning corresponding direction and the following order.
[0099]
The toroidal lenses 32Y, 32M, 32C, and 32K focus the laser beam groups reflected by the second plane mirrors 36Y, 36M, 36C, and 36K on the respective photosensitive members at intervals of 10.58 μm in the sub-scanning direction. As a result, a latent image is formed on each photoconductor by 2400 scanning lines per inch. At this time, the toroidal lenses 32Y, 32M, 32C, and 32K correct the beam position variation due to the tilt of the deflecting surface 18A, and prevent image quality deterioration due to pitch unevenness. The toroidal lenses 32Y, 32M, 32C, and 32K are adjusted in position so that the imaging magnification from the light source 14 to each photoconductor is substantially the same, and the focal length is set.
[0100]
In addition, the toroidal lenses 32Y, 32M, 32C, and 32K can be adjusted with respect to the distance and inclination with respect to each scanning object by known adjusting means. For this reason, the attitude of the scanning line on each scanning object, the imaging magnification, and the beam waist position can be adjusted for each laser beam group.
[0101]
Here, since the spot interval in the sub-scanning direction of each photoconductor is 10.58 μm and the interval between the light emitting points in each light emitting point group of the light source 14 is 5 μm, the imaging magnification from the light source to each photoconductor is about 2. .1 times. That is, the light emitting points are arranged in a one-dimensional array in one direction corresponding to the sub-scanning direction, and the image is formed as compared with the conventional optical scanning device in which the imaging magnification in the sub-scanning direction is 0.75 times when the resolution is 2400 dpi. A large magnification can be set. For this reason, if the spot diameter is the same, the amount of truncation by the aperture 24 can be reduced, so that the laser utilization efficiency can be improved.
[0102]
When the same truncation amount is used, the F-numbers of the pre-deflection optical system 16 and the scanning optical system 20 increase as the imaging magnification in the sub-scanning direction increases. Therefore, the effective width of each optical element can be reduced, and the manufacturing cost of each optical element can be reduced.
[0103]
Further, since the exit pupil on the scanning optical system becomes small, the light flux width at the separation position becomes small. Accordingly, the interval between the laser beam groups is widened, so that the laser beams can be easily separated.
[0104]
In addition, while maintaining the minimum interval of 25 μm between the light emitting points in each light emitting point group, it is possible to give more flexibility to the magnification setting in the sub scanning correspondence direction by narrowing the sub scanning correspondence direction interval. It is possible to optimize the separation distance, spot diameter, and laser utilization efficiency of each light beam group.
[0105]
Next, the light quantity control mechanism of the optical scanning device 10 will be described.
[0106]
As shown in FIG. 4, a half mirror 38 as an amplitude dividing unit is provided between the coupling lens 22 and the aperture 24. One laser beam divided by the half mirror 38 is incident on the light quantity detection means 40. The light amount detection means 40 detects the light amount of the laser beam and transmits a light amount detection signal to the laser beam drive control circuit 42. The laser beam drive control circuit 42 corrects the light amount for each light emitting point P or for each light emitting point group based on the light amount detection signal.
[0107]
Next, a light amount control method of the optical scanning device 10 will be described with reference to the flowchart of FIG.
[0108]
First, when the power of the color laser printer including the optical scanning device 10 is turned on, this flow is started and the process proceeds to Step 100. In step 100, the control board (not shown) of the color laser printer receives the job signal and proceeds to step 101. In step 101, a predetermined light amount is set for each light emitting point P before starting the job.
[0109]
In step 102, all the light emitting points in each light emitting point group are turned on simultaneously for each light emitting point group, and the light quantity of each laser beam group at this time is stored. In step 103, the job is started and image formation for the first page is performed.
[0110]
In step 104, while each laser beam group is scanning outside the scanning area of each photoconductor, all the light emitting points in each light emitting point group are turned on simultaneously for each light emitting point group, and each laser beam group is turned on. The amount of light is corrected so as to be the same as the amount of light initially stored.
[0111]
Here, normally, during a single scan outside the scanning area of the photoconductor, the amount of light can be corrected only by about one light emitting point, and each light emitting point can only emit light for each number of scans corresponding to the number of light emitting points. It cannot be corrected. That is, when there are 32 light emitting points as in the present embodiment, the light amount can be corrected only every 32 scans. For this reason, when eight scanning lines are formed in one scan as in the present embodiment, density fluctuation occurs every 32 scans, that is, every 256 lines.
[0112]
The width of the 256 scanning lines corresponds to 2.7 mm when the resolution is 2400 dpi. When the thickness is 2.7 mm, the human sensitivity to the density fluctuation is high, so that the allowable density fluctuation is small, and more accurate light amount control is required.
[0113]
However, in the present embodiment, since the control is performed for each light emitting point group, the light amount can be corrected for each number of scans corresponding to the number of light emitting point groups. That is, the amount of light is corrected every four scans. The density fluctuation every four scans is density control for every 32 lines, and when the resolution is 2400 dpi, the density fluctuation is 0.34 mm pitch. For this reason, the allowable density fluctuation increases, and the required accuracy of the light amount control also decreases.
[0114]
In addition, since all the light emitting points are not lighted at the same time but are lighted simultaneously for each light emitting point group, there is little thermal influence between the light emitting point groups.
[0115]
Then, the process proceeds to Step 105. In step 105, it is determined whether or not there is a job command for the second page. If the determination is affirmative, the process proceeds to step 106, and if the determination is negative, the flow ends.
[0116]
In step 106, the light amount control for each light emitting point is performed between pages. Then, the process returns to step 104, and light amount correction during image formation is performed again.
[0117]
Next, a control mechanism for the writing position of the optical scanning device 10 will be described. Here, the description will be made assuming that the number of light emitting points of the light source 14 is 16 in total in 4 rows × 4 columns.
[0118]
As shown in FIG. 4, a BD sensor 44 as a light beam detecting means is provided between the second flat mirror 36K and the aspheric lens 32K. The position of the BD sensor 44 is a position at which the laser beam group LK emitted from the light emitting point group PK and deflected by the polygon mirror 18 toward the outside of the scanning area of the photoconductor 12K is incident. When the BD sensor 44 receives the laser beam LK ′ of the laser beam group LK emitted from the first light emission point P (1, 1) (see FIG. 6) of the light emission point group PK, it sends a detection signal to the writing position control circuit 46. Send.
[0119]
The write position control circuit 46 includes a first storage unit 48 that stores the delay time T1, a second storage unit 50 that stores the delay time T2, and a third storage unit 52 that stores the delay time T3. It is included.
[0120]
As shown in the timing chart of FIG. 6, after the detection signal is transmitted from the BD sensor 44, the delay time T1 is the first light emission point P ( This is the time until 1, 1) is turned on.
[0121]
The delay time T2 is a delay time between adjacent light emission point groups. For example, the light emission point adjacent to the light emission point group PK after the first light emission point group P (1, 1) of the light emission point group PK is turned on. This is the delay time until the light emitting point P (2, 1) of the group PC is turned on.
[0122]
Further, the delay time T3 is a delay time between adjacent light emitting points of each light emitting point group, for example, from when the light emitting point P (1,1) is turned on until the light emitting point P (1,2) is turned on. The delay time from when the light emitting point P (4, 3) is turned on to when the light emitting point P (4, 4) is turned on.
[0123]
By sequentially adding such delay times T1, T2, and T3 by a simple AND circuit as shown in FIG. 7, the writing position of all the laser beams is controlled. That is, a plurality of BD sensors for each laser beam group are not required and there is no need to store a delay time corresponding to the number of light emission points. Therefore, the write control circuit 44 can be easily configured, and the cost is reduced.
[0124]
Next, a method for controlling the writing position will be described with reference to the timing chart shown in FIG.
[0125]
When the job is started, automatic light quantity control (APC) is performed as described above. Next, the light emission point P (1, 1) is turned on, and a laser beam LK ′ (shown by a dotted line in FIG. 4) is emitted.
[0126]
When the laser beam LK ′ is detected by the BD sensor 44, the light emitting point P (1, 1) is turned on according to the image signal after the delay time T1 has elapsed. The light emitting points P (1,2), P (1,3), P (1,4) in the light emitting point group PK are after the time when the delay time T3 is successively added to the delay time T1. Lit one after another.
[0127]
The light emission point P (2, 1) of the light emission point group PC adjacent to the light emission point group PK is turned on after the time obtained by adding the delay time T2 to the delay time T1, and the light emission in the light emission point group PC. The points P (2, 2), P (2, 3), and P (2, 4) are lit one after another after a time obtained by sequentially adding the delay time T3 to the delay time (T1 + T2).
[0128]
Similarly, the light emission point P (3, 1) of the light emission point group PM and the light emission point P (4, 1) of the light emission point group PY are turned on after the delay time (T1 + T2 + T2) and the delay time (T1 + T2 + T2 + T2) have elapsed, respectively. Is done.
[0129]
The light emission point P (3, 2) of the light emission point group PM and the light emission point (4, 2) of the light emission point group PY are turned on after the delay time (T1 + T2 + T2 + T3) and the delay time (T1 + T2 + T2 + T2 + T3) have elapsed. .
[0130]
As a result, the writing position of each laser beam group to each photoconductor is aligned, so that each latent image is visualized with toners of yellow, magenta, cyan, and black, and the toner on each photoconductor is superimposed on the transfer belt. Sometimes a color image without color shift is obtained.
[0131]
In the present embodiment, the light source 14 has a light emitting point P (1, 1), a light emitting point P (2, 1), a light emitting point P (3, 1), and a light emitting point P (4, 1) corresponding to sub-scanning. Since they are arranged on the same straight line in the direction, the delay time T2 becomes 0, and the control of the writing position becomes easier.
[0132]
Next, a second embodiment will be described. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and description is abbreviate | omitted.
[0133]
As shown in FIGS. 8 and 9, the optical scanning device 60 differs from the first embodiment in the arrangement of the light emitting points P of the light source 62. In the direction corresponding to the sub-scanning of the light source 62, a light emitting point group PC, a light emitting point group PK, a light emitting point group PM, and a light emitting point group PY are arranged in order from the top. The light emission point groups PC, PM, and PY are each composed of four light emission points P, and the light emission point group PK is composed of eight light emission points P.
[0134]
Here, in color laser printers, color copiers, and the like, monochrome black monochrome printing is more frequently used than color printing. For this reason, it is required to make the monochrome printing speed faster than the color printing, and this is usually dealt with by increasing the process speed. However, when the optical scanning device that simultaneously scans a plurality of scanning lines does not have a beam interval adjusting device as in the present invention, the scanning line interval is equal in the group scanned at the same time. Unlikely, pitch unevenness occurs.
[0135]
Therefore, in the present embodiment, the number of light emitting points of the light emitting point group PK corresponding to black is set to eight, and the process speed is increased up to twice as much as that of the other light emitting point groups having four light emitting points. The rotational speed of the polygon mirror 18 is not changed. For this reason, even if the beam interval adjusting device is not provided, the pitch unevenness does not occur. In this embodiment, when the process speed is increased by 25%, the number of light emission points is five, and when the process speed is increased by 50%, the number of light emission points is six. It is possible to cope with the speed increase.
[0136]
The light emission point group PK is arranged at the second stage from the top, that is, near the center of the light source 62. For this reason, the laser beam emitted from the outermost light emitting point P of the light emitting point group PK passes through the coupling lens 22 as close as possible to the optical axis of the coupling lens 22. Therefore, the influence of off-axis aberration of the coupling lens 22 can be reduced.
[0137]
Next, a third embodiment will be described. In addition, the same code | symbol is attached | subjected to the structure same as 1st, 2 embodiment, and description is abbreviate | omitted.
[0138]
As shown in FIGS. 10 and 11, in the optical scanning device 70, the pre-deflection optical system 72 is composed of a coupling lens 22 and a cylinder lens 74. The cylinder lens 74 has positive power in the sub-scanning corresponding direction.
[0139]
Unlike the first and second embodiments, the laser beam groups LK, LC, LM, and LY emitted from the light source 14 are coupled to the respective laser beams in the sub-scanning corresponding direction by the coupling lens 22 and the cylinder lens 74. The distance between the optical axes of the groups is diffused and incident on the deflecting surface 18A.
[0140]
The cylinder lens 76 as the first scanning optical system does not have power in the sub-scanning corresponding direction. For this reason, each laser beam group diffused at the optical axis interval of each laser beam group and incident on the deflecting surface 18A passes through the cylinder lens 76 while being diffused, reaches the plane mirror group 30, and passes through the optical path. Divided.
[0141]
Further, since the scanning line curve generated by the rotational deflection of the deflecting surface 18A can be very small, the influence of color registration shift due to the scanning line curve on each photoconductor can be suppressed. In particular, as in the second embodiment, when the principal ray of each laser beam group by the pre-deflection optical system is incident on the deflection surface 18A in parallel with the sub-scanning corresponding direction, the first scanning optical system supplies power in the sub-scanning corresponding direction. Since it does not have this, scanning line bending does not occur, and color registration misalignment due to the mutual difference in scanning line bending of each photoconductor can be avoided.
[0142]
Next, a fourth embodiment will be described. In addition, the same code | symbol is attached | subjected to the structure same as 1st thru | or 3rd embodiment, and description is abbreviate | omitted.
[0143]
In the first to third embodiments, the second group of the pre-deflection optical system is configured with a cylinder lens that does not have power in the main scanning-corresponding direction. However, as shown in FIG. The second group of the system is a positive power optical system 82 having a positive power in the main scanning corresponding direction. By this positive power optical system 82, the principal ray of each laser beam group is made parallel to or focused on the main scanning corresponding direction, and each laser beam is incident on the deflecting surface 18A. Expansion can be suppressed. As a result, it is possible to suppress the deflection surface 18A from spreading in the direction corresponding to the main scanning, and to reduce the size of the polygon mirror.
[0144]
【The invention's effect】
Since the present invention has the above-described configuration, it is possible to increase the speed and resolution of an optical scanning apparatus that separates a plurality of laser beams emitted from a single light source unit and scans a plurality of photosensitive members.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical scanning device according to a first embodiment.
FIG. 2A is a plan view showing a light source of the optical scanning device according to the first embodiment.
(B) It is a top view which shows the photoconductor of 1st Embodiment.
FIG. 3 is a schematic view showing the optical scanning device of the first embodiment.
FIG. 4 is a schematic diagram illustrating an optical scanning device according to the first embodiment.
FIG. 5 is a flowchart illustrating a light amount control method of the optical scanning device according to the first embodiment.
FIG. 6 is a timing chart illustrating a method for controlling the writing position of the optical scanning device according to the first embodiment.
FIG. 7 is a circuit diagram illustrating a writing position control circuit of the optical scanning device according to the first embodiment.
FIG. 8 is a perspective view showing an optical scanning device according to a second embodiment.
FIG. 9 is a schematic diagram illustrating an optical scanning device according to a second embodiment.
FIG. 10 is a perspective view showing an optical scanning device according to a third embodiment.
FIG. 11 is a schematic diagram illustrating an optical scanning device according to a third embodiment.
FIG. 12 is a schematic diagram illustrating a modification of the optical scanning device according to the fourth embodiment.
[Explanation of symbols]
10 Optical scanning device
12 Photoconductor (scanned body)
14 Light source
16 Pre-deflection optical system
18 Polygon mirror (deflection means)
20 Scanning optical system
22 Coupling lens
28 Aspherical lens (first scanning optical system)
30 plane mirror group (separation means)
32 Toroidal lens (second scanning optical system)
34Y first plane mirror (reflecting means)
34M first plane mirror (reflecting means)
34C First plane mirror (reflecting means)
34K first plane mirror (reflecting means)
36Y second plane mirror (reflection means)
36M Second plane mirror (reflection means)
36C Second plane mirror (reflection means)
36K second plane mirror (reflection means)
40 Light quantity detection means
42 Laser beam drive control circuit (first control means, second control means)
44 BD sensor (light flux detection means)
46 Write position control circuit (write control means)
48 1st memory | storage part (1st memory | storage means)
50 Second storage section (second storage means)
52 3rd memory | storage part (3rd memory | storage means)
60 Optical scanning device
62 Light source
70 Optical scanning device
72 Pre-deflection optical system
76 Cylinder lens (first scanning optical system)
80 Optical scanning device
82 Positive power optical system (optical system with positive power)

Claims (24)

A plurality of light emitting points arranged in a two-dimensional manner in a sub scanning corresponding direction corresponding to a main scanning corresponding direction corresponding to the deflection scanning direction and a sub scanning corresponding direction corresponding to a direction orthogonal to the deflection scanning direction are arranged in a plurality of rows in the sub scanning corresponding direction. A light source that emits a luminous flux group;
A pre-deflection optical system through which a plurality of light beam groups emitted from the light source pass;
Deflecting means for deflecting a plurality of rows of light beam groups that have passed through the pre-deflection optical system in the main scanning corresponding direction;
An optical scanning device comprising: a scanning optical system that separates a plurality of rows of light flux groups in different directions and focuses the light beams on a plurality of scanned objects separately. 2. The light source according to claim 1, wherein a plurality of light emitting point groups including a plurality of light emitting points arranged linearly and inclined with respect to the main scanning corresponding direction are arranged in a plurality of rows in the sub scanning corresponding direction. 2. An optical scanning device according to 1. In the light source, the distance A in the sub-scanning corresponding direction between the light-emitting points at both ends of each light-emitting point group is the distance in the sub-scanning corresponding direction between the light-emitting points closest to each other in the sub-scanning corresponding direction in the adjacent light-emitting point groups. The optical scanning device according to claim 2, wherein the optical scanning device is narrower than B. 4. The optical scanning device according to claim 3, wherein the distance A and the distance B of the light source satisfy a relationship of B / A> 4. 5. In the light source, the interval A, the interval B, and the interval C in the main scanning correspondence direction between the light emitting points at both ends of each light emitting point group have a relationship of B <C <(A + B) × 3. The optical scanning device according to claim 3 or 4. 6. The optical scanning device according to claim 2, wherein the light source has light emitting points of each light emitting point group arranged on the same straight line at a predetermined pitch. The optical scanning device according to claim 2, wherein the light source is provided with a light emitting point group having a larger number of light emitting points than other light emitting point groups. The optical scanning device according to claim 7, wherein the light source has a light emitting point group having a larger number of light emitting points than other light emitting point groups in a central portion in the sub-scanning corresponding direction. 9. The light according to claim 1, wherein the pre-deflection optical system causes a plurality of light beam groups to be incident on the deflecting unit with an interval between the light beam groups being expanded in the sub-scanning corresponding direction. Scanning device. The scanning optical system has a first scanning optical system provided on the deflection means side, and a second scanning optical system provided on the scanned object side,
The optical scanning device according to claim 1, wherein a plurality of light beam groups pass through at least the first scanning optical system. The optical scanning apparatus according to claim 10, wherein both the first scanning optical system and the second scanning optical system have positive power in the sub-scanning corresponding direction. The pre-deflection optical system causes a plurality of light beam groups to be incident on the deflecting means with the optical axis of each light beam group being parallel or focused in the sub-scanning corresponding direction,
12. The optical scanning according to claim 10, wherein the first scanning optical system corrects the aberration in the sub-scanning corresponding direction of each light beam group in which the cross-sectional shape in the sub-scanning corresponding direction is a non-arc shape. apparatus. The scanning optical system includes a separating unit that is provided between the first scanning optical system and the second scanning optical system and separates a plurality of light beam groups in different directions. The first scanning optical system includes: A plurality of light beam groups intersecting between the first scanning optical system and the second scanning optical system to be incident on the separating unit;
13. The second scanning optical system is provided for each light beam group, and focuses each light beam group separated by the separating unit on each scanned object. Optical scanning device. The scanning optical system includes a separating unit that is provided between the first scanning optical system and the second scanning optical system and separates a plurality of light beam groups in different directions.
The pre-deflection optical system causes a plurality of light beam groups to be incident on the deflecting means by diffusing the principal ray of each light beam in parallel or in the sub-scanning corresponding direction,
The first scanning optical system has no power in the sub-scanning corresponding direction,
The optical scanning device according to claim 10, wherein the second scanning optical system is provided for each light beam group, and focuses each light beam group separated by the separating unit on each scanned body. 15. The optical scanning device according to claim 13, further comprising at least one reflecting means for reflecting each light beam group, wherein the difference in the number of reflections between the nuclear light beam groups is 0 or the number of corners. The optical scanning device according to claim 15, wherein the separating unit causes each light beam group to directly enter each scanned body. The optical scanning device according to claim 13, wherein the separating unit includes the reflecting unit, and the reflecting unit is a reflecting mirror. 18. The optical scanning device according to claim 10, wherein the second scanning optical system is capable of adjusting a posture and a distance from the object to be scanned. 19. The pre-deflection optical system causes a plurality of light beam groups to be incident on the deflecting unit in such a manner that the principal rays of the respective light beams are parallel or converged in the main scanning corresponding direction. The optical scanning device described. The pre-deflection optical system includes a coupling lens that collects a plurality of light beams emitted by the light source,
An optical system having a positive power in the direction corresponding to the main scanning that causes the plurality of light fluxes collected by the coupling lens to be incident on the deflecting unit in such a manner that the principal ray of each light flux is parallel or converged in the direction corresponding to the main scanning. The optical scanning device according to claim 1, further comprising: 21. The optical scanning device according to claim 1, wherein an effective imaging magnification from the light source to the plurality of scanned objects is substantially the same in each light beam group. A light amount detection means for detecting the light amounts of a plurality of light beams emitted from the light source;
First control means for controlling the light quantity for each light emitting point based on the light quantity of the light beam detected by the light quantity detection means;
The optical scanning according to any one of claims 2 to 21, further comprising: a second control unit that controls a light amount for each light emitting point group based on a light amount of a light beam detected by the light amount detecting unit. apparatus. The first control unit corrects the light amount for each light emitting point before starting the job and at least one of the pages.
23. The optical scanning device according to claim 22, wherein the second control unit corrects the amount of light for each light beam group when scanning outside the scanning region of the scanning target during image formation. A light beam detecting means for detecting a light beam emitted from a light emitting point in a reference light emitting point group serving as a reference for a writing position and deflected outside the scanning region of the scanned object by the deflecting means;
First storage means for storing a delay time T1 from when a detection signal is transmitted from the luminous flux detection means to when a light emitting point in the reference light emitting point group is turned on;
Second storage means for storing a delay time T2 from when a light emitting point of one adjacent light emitting point group is turned on to when a light emitting point of the other light emitting point group is turned on;
Third storage means for storing a delay time T3 from when one adjacent light emitting point in each light emitting point group is turned on until the other light emitting point is turned on;
When a light emitting point in the reference light emitting point group is turned on and a detection signal is received from the light flux detecting means, the delay time T1, the delay from the first storage means, the second storage means, and the third storage means 24. The optical scanning device according to claim 2, further comprising writing control means for reading out and adding the time T2 and the delay time T3 to light each light emitting point.

Images