JP2006301447A - Scanning line bending measurement apparatus and optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning line bending measurement apparatus at a low cost and with accuracy with which the bending of a scanning line is measured at many points on a scanning line and to provide an optical scanner in which the scanning line bending measurement apparatus is built. <P>SOLUTION: The scanning line bending measurement apparatus with which the bending of the scanning line at respective heights of an image is measured on the basis of the output of a light receiving means is provided with: a first light guide means 2 having an incident face which is long in a main scanning direction; a second light guide means 3 arranged in the vicinity of the first light guide means 2 dislocated in a subscanning direction; a first and a second light receiving means 4 and 5 which receive light beams emitted from the end part of the first and the second light guide means 2 and 3, respectively, and transform the received light quantity into electric signals; and a calculation means 21 which calculates the amount of bending of the scanning line at respective heights of image from the output of the first and the second light receiving means 4 and 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a laser printer, a digital copying machine, and a facsimile, in particular, a scanning line bending measuring apparatus for measuring a scanning line bending of an optical scanning apparatus in a digital color image forming apparatus, and a function of measuring the scanning line bending. The present invention relates to an integrated optical scanning device.

In recent years, there is an increasing demand for higher accuracy with respect to magnification error and scanning line bending. In particular, an electrophotographic apparatus having an image forming apparatus including a plurality of optical scanning devices and performing full-color printing at a printing speed equivalent to that of a single-color electrophotographic apparatus by sequentially transferring a plurality of color toners onto a recording sheet. Hereinafter, in the tandem system), it is known that the relative shift of the print position of each color greatly affects the quality of the output image (see, for example, Patent Documents 1 and 3).
The optical scanning device deflects a light beam emitted from a light source by a deflecting unit such as a rotating polyhedral mirror to form a scanning light beam, and collects the light beam by an optical system such as an fθ lens to form a light spot on the image plane. A trajectory scanned by a light spot in the vicinity of the image plane is called a scanning line.
The scanning line is a straight line, and the light spot preferably moves on the scanning line at a constant speed. However, errors occur due to the influence of the shape accuracy of the optical system, the mounting error of each optical element, the thermal expansion of each member, and the like. Here, fluctuation in the moving speed of the light spot at each position on the scanning line is referred to as a magnification error, and deviation from the straight line of the scanning line is referred to as scanning line bending.
Japanese Patent Application Laid-Open No. 2004-228561 describes an inclination measuring unit that measures the bending and inclination of a scanning line, and an image forming apparatus that interpolates and corrects image data according to the measurement result. However, the measuring means for measuring the bending and inclination of the scanning line described in Patent Document 1 is a plurality of misregistration detection units arranged with high accuracy in the main scanning direction.
Conventionally, the measuring means for measuring the scanning line bending is provided with detecting means for measuring the positional deviation of the spot light at a predetermined point at a plurality of points on the scanning line, and the scanning line bending which is the distribution of the positional deviation is obtained. I was measuring.
Patent Document 2 discloses an optical scanning device that detects a light beam reflected by the first surface of the dust-proof glass of the optical scanning device with a plurality of detection means, and performs dot position correction over time based on this by low cost. ing. Patent Document 3 discloses an image forming apparatus that measures the bend and inclination of a scanning line of an optical scanning device and corrects image data accordingly.
JP-A-9-90695 JP 2003-315708 A Japanese Patent No. 3556349

However, in Patent Document 1 described above, in order to correct a component having a higher spatial frequency, it is necessary to provide a large number of detection units, which is disadvantageous in terms of both accuracy and cost. Also, in Patent Document 2 and Patent Document 3, since a plurality of detection means are arranged side by side, in order to measure magnification error and scanning line bending up to a component with high spatial resolution, it is necessary to arrange a large number of detection means with high accuracy. Yes, both accuracy and cost are disadvantageous.
Accordingly, an object of the present invention is to incorporate a scanning line bending measuring apparatus that measures scanning line bending at a large number of points on a scanning line and a function for measuring scanning line bending with low cost and high accuracy in consideration of the above-described circumstances. It is to provide an optical scanning device.

In order to achieve the above object, the invention according to claim 1 is a scanning line bending measuring apparatus for measuring a scanning line bending at each image height, and a first light guide means having a long incident surface in the main scanning direction; The second light guide means disposed in the vicinity of the first light guide means and shifted in the sub-scanning direction, and the light emitted from the respective end portions of the first and second light guide means , And the first and second light receiving means for converting the received light amount into an electrical signal, and the scanning line bending amount at each image height based on the outputs from the first and second light receiving means. And an arithmetic means for calculating.
The invention according to claim 2 is characterized in that the first and second light guide means have at least an exit surface which is a surface with a large number of minute irregularities on a mirror surface. And
According to a third aspect of the present invention, in the first and second light guiding means, the reflectance of an end portion other than the end portion where the first and second light receiving means are installed is high. Alternatively, the scanning line bending measuring device described in 2 is characterized.
According to a fourth aspect of the present invention, in the scanning line bending measuring apparatus for measuring the scanning line bending at each image height, a rod-shaped first light guiding unit that is long in the main scanning direction, and the first light guiding unit. The second light guide means arranged in the vicinity of the center and shifted in the sub-scanning direction, and light emitted from both ends of the first light guide means are received, and the amount of received light is converted into an electrical signal First and third light receiving means, second and fourth light receiving means for receiving light emitted from both ends of the second light guiding means and converting the amount of received light into an electrical signal, and the first Calculating means for calculating the scanning line bending amount at each image height based on the output from each of the fourth light receiving means.
According to a fifth aspect of the present invention, there is provided spatial light modulation means having a plurality of openings provided at equal pitches in the main scanning direction in the vicinity of the incident surfaces of the first and second light guide means, 5. The scanning line bending measuring apparatus according to claim 1, wherein the calculating means obtains scanning line bending and magnification error.

According to a sixth aspect of the invention, there is provided a low-pass filter that performs low-pass filter processing on the output from each light receiving means, and the arithmetic means performs low-pass filtering on the output from each light receiving means by the low-pass filter. The scanning line bending measuring apparatus according to any one of claims 1 to 4, wherein the scanning line bending is obtained after performing the filtering process.
The invention according to claim 7 is an optical scanning device including the scanning line bending measuring device according to any one of claims 1 to 6, wherein the light source and a light beam emitted from the light source are deflected. Deflection means, an imaging optical system for condensing the light beam deflected by the deflection means on the image plane, and a transparent member, and a part of the light beam that has passed through the imaging optical system passes through the transparent member. The irradiated surface is irradiated, the other part is reflected by the transparent member, and the reflected light beam is incident on the scanning line bending measuring device.
According to an eighth aspect of the invention, the transparent member is a parallel plate, and the surface treatment conditions are set so that the reflectance of the incident surface is larger than the reflectance of the outgoing surface. Features a scanning device.
According to the ninth aspect of the present invention, the scanning line bending is made substantially linear by mechanically adjusting the optical components of the scanning optical system based on the measurement result of the scanning line bending output from the arithmetic means. 9. An optical scanning device according to claim 7 or 8, further comprising a scanning line bending adjusting means.
According to a tenth aspect of the present invention, the spot position is determined by performing resampling for correcting the image data to be output so as to cancel the scanning line curve, based on the measurement result of the scanning line curve output from the arithmetic means. The optical scanning device according to claim 7 or 8 is corrected.

  According to the present invention, since the scanning line bending measuring apparatus has few components and is easy to calculate, it is possible to measure the distribution of sub-scanning positional deviation amounts at a large number of points on the scanning line, that is, the scanning line bending, at low cost. Therefore, it becomes possible to evaluate an optical scanning device that requires the linearity of the scanning line with higher accuracy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view showing a first embodiment of a scanning line bending measuring device applied to the optical scanning device of the present invention.
In FIG. 1, the support member 1 of the scanning line bending measuring device 10 has a linear convex portion 1 a, and a first light guide member 2 and a second light guide member 3 are attached along this.
A first light receiving means 4 is attached to one end portion of the first light guide member 2, and a second light receiving means 5 is attached to one end portion of the second light guide member 3. A computing means 21 is connected to the first and second light receiving means 4 and 5.
2 is a cross-sectional view in the main scanning direction of the optical scanning device according to the present embodiment, and FIG. 3 is a cross-sectional view in the sub-scanning direction. The scanning line bending measurement operation will be described with reference to FIGS. .
2 and 3, the light beam emitted from the light source 11 passes through the collimator lens 12, the aperture stop 13, and the cylindrical lens 14 to form a line image on the reflection surface of the polygon motor 15. The reflected light beam from the polygon motor 15 passes through the imaging optical system 16 and forms a point image on the image plane 17.
The scanning line bending measuring device 10 is installed at a position where the focus is shifted (defocused) from the image plane 17 by a predetermined amount. In this way, when the image plane 17 is defocused and installed by a predetermined amount, the light flux width increases from several hundred μm to several mm and enters the light guide members 2 and 3. This is good because it is less susceptible to the effects of the optical characteristics.
When the light beam reaches the light guide members 2 and 3 of the scanning line bending measuring device 10, the light beam is transmitted through the front surface and irregularly reflected at a part of the back surface. A part of the irregularly reflected light beam propagates through the light guide members 2 and 3 and reaches the light receiving means 4 and 5.
The 1st and 2nd light-receiving means 4 and 5 output the 1st and 2nd electrical signal U1 and U2 according to the light quantity. The first and second electric signals U1 and U2 are sent to the calculating means 21 shown in FIG.
Specifically, the arithmetic means 21 may be realized by an analog circuit using a general operational amplifier or the like, or converted into a digital quantity via an A / D converter and realized by computer software. Also good.
FIG. 4 is a functional block diagram corresponding to the description of the calculation means.
In FIG. 4, the calculating means 21 calculates | requires ratio U of two electric signals U1 and U2. For example, an operation as shown in the following equation may be performed.
U = (U2-U1) / (U2 + U1)

FIG. 5 is a schematic diagram for explaining the output of the first and second electric signals U1 and U2.
Here, the output signal will be described with reference to FIG.
The light beam propagates from the irradiated position in the scanning direction through the first and second light guide members 2 and 3 and reaches the light receiving means 4 and 5 (see FIG. 1). In this case, although the amount of light is attenuated, the degree of attenuation hardly changes between the first and second light guide members 2 and 3.
Therefore, when there is no bend in the scanning line, the electric signal (output signal) U1 and the output signal U2 output substantially the same value over the entire scanning line, so the output U of the computing means is always zero. This state is the state (c) shown in FIG. When the light beam is shifted to the first light guide member 2 side, the state shown in FIG. 5B is obtained, and the output signal U1 becomes larger than the output signal U2 in accordance with the shift amount of the light beam.
Since the ratio between the output signals U1 and U2 is constant at any position on the scanning line, the spot position deviation amount in the sub-scanning direction can be obtained by the above-described calculation regardless of the position of the scanning line. The relationship between the positional deviation of the light beam, the output signals U1 and U2 of the first and second light receiving means 4 and 5, and the output signal U of the calculating means 21 is as shown in FIG. Can do.
That is, the output signal U of the computing means 21 is an output corresponding to the spot position error in the sub-scanning direction. The sensitivity of a sensor (not shown) indicating the inclination of the substantially linear range can be adjusted by defocusing the scanning line bending measuring device 10 from the image plane 17.
The actual scanning line bending measurement operation will be described with reference to FIGS.
The light source 11 is fully turned on and the output signal U of the computing means 21 is sequentially stored within one scan while the polygon mirror 15 is rotated.
Since the scanning line moves at a substantially constant scanning speed, if the time on the horizontal axis is converted into the corresponding position in the main scanning direction, the distribution of the spot position deviation amount in the sub-scanning direction at each position of the scanning line, that is, the image plane 17. Can be obtained.
Further, the optical scanning device is driven so that the light source 11 is turned on only at a predetermined position on the scanning line, and the output signal U of the computing means 21 at that time is stored. The curvature of the image plane 17 can also be obtained by performing this at a plurality of positions.

The first and second light guide members 2 and 3 diffusely reflect a part of the light beam on the back surface and propagate it to the first and second light receiving elements 4 and 5. For this reason, the 1st and 2nd light guide members 2 and 3 shall add many micro unevenness | corrugations to the mirror surface of the back surface at least.
In this way, the uneven portion (not shown) diffuses the incident light beam, and the mirror surface portion (not shown) totally reflects the light beam and propagates toward the first and second light receiving elements 4 and 5. This is advantageous because the amount of light that reaches it increases.
Since the surfaces of the first and second light guide members 2 and 3 are mirror surfaces, a sufficient amount of light reaches the back surface, and since the back surface has minute unevenness on the mirror surface, part of the light beam is irregularly reflected by the uneven portions. The light flux is totally reflected because the incident angle when it reaches the side surfaces of the first and second light guide members 2 and 3 and the mirror surface portions of the front and back surfaces is sufficiently large.
Therefore, the light beam efficiently propagates to the end portions of the first and second light guide members 2 and 3 and the amount of light received by the first and second light receiving elements 4 and 5 increases, so that the scanning line can be more stably performed. The bend can be measured.
Here, the first and second light guide members 2 and 3 are required to have a function of propagating a light beam in a portion closer to the first and second light receiving elements 4 and 5 than in a portion far away. For this reason, when the configuration is such that the uneven area occupies a smaller area than the first and second light receiving elements 4 and 5 and the mirror surface area occupies a larger area, the first and second light receiving elements 4 and 5 This is advantageous because the attenuation of the amount of light received by the first and second light receiving elements 4 and 5 when the light beam enters a distant portion is small.
When the end portions of the first and second light guide members 2 and 3 other than the end portions where the first and second light receiving elements 4 and 5 are installed have a high reflectance by attaching a metal film or the like. Since the amount of light received by the first and second light receiving elements 4 and 5 increases, it is more convenient.
In this manner, the reflectance of the end portions of the first and second light guide members 2 and 3 other than the first and second light receiving elements 4 and 5 is increased, and a larger amount of light is guided to the light receiving elements 4 and 5. As a result, more light flux propagates toward the light receiving elements 4 and 5, and the amount of light received by the light receiving elements 4 and 5 increases. Therefore, the output signal is stabilized, the signal-to-noise ratio of the signal is improved, and the scan line bending can be measured more stably.
In the present invention, the two light guide members 2 and 3 are characterized in that they are placed close to a straight line with high accuracy, and as a means for this, here the configuration is such that the projections 1a of the support member 1 are aligned. Other methods may be used as long as these conditions are met. For example, the structure which embeds and installs each light guide member in two grooves may be sufficient.

FIG. 6 is a schematic perspective view showing a second embodiment of the scanning line bending measuring apparatus.
In FIG. 6, a first light receiving means 4 and a third light receiving means 6 are attached to both ends of the first light guide member 2, respectively. Similarly, the second light receiving means 5 and the fourth light receiving means 7 are attached to both ends of the second light guide member 3, respectively.
Output signals U1, U2, U3, U4 from the respective light receiving means 4, 5, 6, 7 are sent to a calculating means (not shown). The calculation means performs the following calculation.
U = (U2 + U4- (U1 + U3)) / (U1 + U2 + U3 + U4)
Thereby, the deviation of the amount of received light due to the position of the scanning line is alleviated, and the SN of the signal is increased. This scanning line bending measuring device 10 is characterized in that the sum of the light emitted from both ends of the light guide members 2 and 3 is changed into an electric signal.
Therefore, for example, a configuration in which optical fibers are connected to both ends of the light guide members 2 and 3 and light emitted from both ends of each optical fiber is received by one light receiving element may be used.
In this way, the scanning line bending measuring device 10 is arranged in a bar-shaped first light guide member 2 that is long in the main scanning direction and a position that is shifted in the sub-scanning direction in the vicinity of the first light guide member 2. 2 light guide members 3 and first and second light receiving elements 4 and 5 that receive light emitted from both ends of the first light guide member 2 and convert the amount of received light into an electrical signal.
Further, the light output from both ends of the second light guide member 3 is received, and the third and fourth light receiving elements 6 and 7 for converting the amount of received light into electric signals, and the output from each light receiving means, each image height. The calculation means (refer FIG. 1) which calculates | requires the amount of scanning line bends in FIG.
By guiding the emitted light from both ends of the light guide members 2 and 3 to the light receiving elements 4, 5, 6 and 7, the light emitted from both ends of the light guide members 2 and 3 can be received and converted into electrical signals. Therefore, the scanning line bending can be measured more stably.

FIG. 7 is a schematic perspective view showing a third embodiment of the scanning line bending measuring apparatus.
A third embodiment will be described with reference to FIG. On the first and second light guide members 2 and 3, a mask 8 having openings opened at an equal pitch is installed. Further, the calculation means (see FIG. 1) outputs the sum signal U1 + U2 of the output signals U1 and U2 of the first and second light receiving means 4 and 5 together with the calculation result U described above.
Since the openings of the mask 8 are formed at an equal pitch, the sum signal U1 + U2 becomes a pulse having a constant time interval when there is no magnification error. However, if there is a magnification error, an error occurs in the pulse time interval. Therefore, the velocity distribution at each main scanning position is obtained by measuring the time interval at each main scanning position.
Specifically, the sum signal U1 + U2 is pulsed by a comparator or the like (not shown), the time between each pulse is counted with a reference clock, and the pitch of the mask 8 is divided by the time interval, or the pulse counted within a specified time This can be realized by dividing the distance corresponding to the number by the specified time.
The specified time can be realized by interrupt processing of the CPU or DSP. By subtracting an ideal speed from this speed distribution, a speed error distribution, that is, a magnification error can be obtained. Therefore, in this embodiment, both the scanning line bending and the magnification error can be measured. Here, the output from each of the light receiving means 4, 5, 6, and 7 is not shown in the figure, but if the calculation process is performed after the low band (low pass) filter process, the influence of electrical noise can be reduced. Convenient. In addition, since the speed error distribution is also differential data, the low-pass filter processing is still advantageous because the influence of noise can be reduced.
As described above, the scanning line bending measuring apparatus according to the present embodiment is a spatial light modulator having a plurality of openings provided at equal pitches in the main scanning direction in the vicinity of the incident surfaces of the first and second light guide members 2 and 3. (Mask) 8 is provided, and the calculation means obtains the scanning line bending and magnification error.
By adding the mask 8 which is a spatial modulation means, the output signal becomes a pulse shape, and the magnification error can be measured by measuring the distribution of the pulse interval, so the magnification error and the scanning line curve can be measured with one apparatus. Both of them can be measured.
As described above, the calculation means obtains the scanning line curve after performing low-pass filter processing on the output from each light receiving means. Therefore, after the light quantity signal is converted into an electrical signal by the light receiving element, low-pass filter processing is performed to reduce the influence of high-frequency electrical noise, obtain an output signal that is more resistant to noise, and more stably scan lines. It is possible to measure bending and the like.

FIG. 8 is a schematic diagram for explaining an embodiment of an optical scanning device to which a scanning line bending measurement function is added. An embodiment of an optical scanning device to which a scanning line bending measurement function is added will be described with reference to FIG.
The light beam reflected by the polygon motor 15 passes through the imaging optical system 16, and most of the light passes through the optical window 18 provided with an inclination with respect to the optical axis and forms an image on the image plane 17. Further, a part of the light beam reflected by the incident surface of the optical window 18 enters the scanning line bending measuring apparatus 10. Portions other than the optical window 18 are installed in an optical box 19 and are protected from foreign matters such as toner and dust.
Here, the incident surface of the optical window 18 has a reflectance of only a few percent if it is not coated, but this may not provide the amount of light necessary for the scanning line bending measuring device 10. In that case, it is more preferable to apply an appropriate coating to increase the reflectance. Further, it is advantageous that the exit surface is provided with a anti-reflection coating so that all light is transmitted as much as possible.
The light beam reflected from the optical window 18 enters the scanning line bending measuring apparatus 10, and output signals U 1 and U 2 from the first and second light receiving means are sent to the scanning line bending calculating means 21. Here, the scanning line curve is obtained, and the obtained scanning line curve is sent to the scanning line curve control means 22. The scanning line bending control means 22 controls the scanning line bending adjusting means 23 to reduce the scanning line bending.

FIG. 9 is a schematic view showing a state in which the lens and the scanning line bending adjusting means are viewed from the optical axis direction. In FIG. 9, the center of the lens 16 is abutted against the protrusion 24 a of the base 24, and is supported by being sandwiched between the leaf springs 25.
The first and second actuators 26 and 27 are provided with expandable and contractible probe portions 26a and 27a, respectively, which are in contact with the lens 16 via the probe portions 26a and 27a, and the first and second plates. The lens 16 is supported by being sandwiched between the springs 28 and 29.
The scanning line bending control means 22 (see FIG. 8) controls the first and second actuators 26 and 27 based on the output of the scanning line bending calculation means 21 (see FIG. 8), and the probe portions 26a and 27a are controlled. By changing the length, the lens 16 is tilted or bent to reduce the scanning line bending. This is repeated until the scanning line curve reaches a predetermined width.
FIG. 10 is a flowchart showing the scanning line curve adjustment operation. In FIG. 10, it outputs from the scanning line curve calculating means 21 (refer FIG. 8) (S1). Based on this output, it is determined whether or not the scanning line bending is within a predetermined width (S2). If it is within the predetermined width, the operation is terminated. If it is not within the predetermined width, the control is further repeated by the scanning line bending control means 22 (see FIG. 8) (S3).
An existing method can be applied to the method of correcting the scan line curve obtained from the scan line curve measuring device 10 using the magnification error. For example, as described in Patent Document 2, scanning line bending is corrected by tilting or deflecting some optical elements of the imaging optical system.
Further, as described in Patent Document 1, the measured scanning line curve is modeled by a function or the like, and the image data is shifted in the sub-scanning direction and output so as to cancel the correction. Also good.
In particular, in the present invention, since scanning line bending can be measured at multiple points, it is possible to model scanning line bending at a high spatial frequency. Since the combination of the present invention and this correction method can correct scanning line bending at a high spatial frequency, the correction effect is higher than that of the conventional example.

As shown in FIG. 8, the optical scanning device according to the present invention deflects light source (not shown), deflecting means (polygon motor) 15 for deflecting the light beam emitted from the light source, and deflecting means 15. The imaging optical system 16 which condenses a light beam by the image surface 17, the transparent member (optical window) 18, and the scanning line bending measuring apparatus 10 mentioned above are included.
Part of the light beam that has passed through the imaging optical system 16 passes through the transparent member (optical window) 18 and irradiates the irradiated surface, and the other part is reflected by the transparent member (optical window) 18 so that the reflected light beam is reflected. The scanning line bending measurement apparatus 10 is configured to be incident.
As described above, the scanning line bending measuring device 10 can be obtained at low cost by measuring the scanning line bending using the reflected light beam from the optical window 18 attached to the conventional optical scanning device for the purpose of dust prevention. It can be incorporated into an optical scanning device. Therefore, it is possible to provide an optical scanning device having a scanning line bending measurement function at many points at low cost.
The transparent member (optical window) 18 described above is a parallel plate, and the surface treatment (coating) conditions are appropriately set so that the reflectance of the incident surface is larger than the reflectance of the exit surface.
Therefore, the influence of the multiple reflection of the transparent member (optical window) 18 can be reduced, the reflectance therefrom can be set to a predetermined value, and the amount of light necessary for the scanning line bending measuring device can be reflected. Therefore, it is possible to provide an optical scanning device having a function of measuring the scanning line bending and the like more stably.
The optical scanning device mechanically adjusts the optical components of the scanning optical system on the basis of the measurement result of the scanning line bending output from the computing unit 21, thereby adjusting the scanning line bending to make the scanning line bending substantially linear. Means 23 are provided.
Since there are few constituent elements, it is possible to provide an optical scanning device that can measure and correct scanning line bending at a large number of points because the sub-scanning position shift amount at a large number of scanning lines can be measured at low cost. .
The optical scanning device further corrects the spot position by performing resampling for correcting the image data to be output so as to cancel the scanning line curve, based on the measurement result of the scanning line curve output from the computing unit 21. It is configured.
This makes it possible to provide an optical scanning device that can measure and correct scanning line bending with a high spatial frequency because it can measure the amount of sub-scanning misalignment at many points on the scanning line at low cost because it has few components. It becomes.

Further, in summary, the present invention measures the positional deviation of the spot light at all points on the scanning line in principle. This is the direction in which the electrophotographic device measures the scanning line bending of the optical scanning device and corrects it by digital data processing to enable high-quality printing without image distortion or color misregistration. In this case, if the number of scanning line bending measurement points is increased, more accurate correction can be performed.
Since the designer can freely set the spot light position displacement measurement and correction at the actual point, the same parts can be used from the high end (highest grade) to the low end (low price). We can expect cost reduction by common use.
In the present invention, scanning line bending when spot light is scanned by the optical scanning device is output in real time as an analog signal. Therefore, it is free to convert this into digital data as a position shift at this point. Therefore, this can be achieved without any increase in cost, particularly when it is desired to detect misalignment at a large number of points and measure the scan line bending.
Furthermore, in the present invention, high accuracy is required only for the straightness of the convex portion of the support member and the attachment of the two light guide members, and a large number of detection units are arranged with high accuracy as in the conventional example. There is no assembly process, and high accuracy can be achieved relatively easily.

1 is a schematic perspective view showing a first embodiment of a scanning line bending measuring apparatus. Schematic explaining the measurement operation | movement of the scanning line bending of the main scanning cross section of an optical scanning device. Schematic explaining the measurement operation | movement of the scanning line bending of the subscanning cross section of an optical scanning device. The functional block diagram corresponding to description of a calculating means. The schematic diagram explaining the output of the 1st and 2nd electric signal U1, U2. The schematic perspective view which shows 2nd Embodiment of a scanning line bending measuring apparatus. The schematic perspective view which shows 3rd Embodiment of a scanning line bending measuring apparatus. Schematic explaining embodiment of the optical scanning apparatus which added the scanning line bending measurement function. Schematic which shows the state which looked at the lens and the scanning line curve adjustment means from the optical axis direction. 6 is a flowchart showing an operation for adjusting a scanning line curve.

Explanation of symbols

2 1st light guide means 3 2nd light guide means 4 1st light receiving means 5 2nd light receiving means 6 3rd light receiving means 7 4th light receiving means 8 Spatial light modulation means (mask)
11 Light source 15 Deflection means (polygon mirror)
16 Imaging optical system (lens)
18 Transparent member (optical window)
21 calculating means 22 scanning line bending control means 23 scanning line bending adjusting means

Claims (10)

  In a scanning line bending measuring apparatus for measuring a scanning line bending at each image height, a first light guiding unit having a long incident surface in the main scanning direction, and a sub-scanning direction in the vicinity of the first light guiding unit A first light guide unit disposed at a position shifted from the first light guide unit, a first light receiving unit configured to receive light emitted from each end of the first and second light guide units, and to convert the received light amount into an electrical signal; And a second light receiving means, and a calculation means for calculating the amount of bending of the scanning line at each image height based on outputs from the first and second light receiving means. Bend measuring device.   2. The scanning line bending measuring apparatus according to claim 1, wherein the first and second light guiding means have at least an exit surface that is a surface having a large number of minute irregularities on a mirror surface.   3. The scanning according to claim 1, wherein the first and second light guide means have high reflectance at an end portion other than the end portion where the first and second light receiving means are installed. Line bending measuring device.   In a scanning line bending measuring apparatus for measuring a scanning line bending at each image height, a bar-shaped first light guide means long in the main scanning direction and a shift in the sub-scanning direction in the vicinity of the first light guiding means. A second light guide unit disposed at a predetermined position, and first and third light receiver units that receive light emitted from both ends of the first light guide unit and convert the amount of received light into an electrical signal; The second and fourth light receiving means for receiving light emitted from both ends of the second light guiding means and converting the amount of received light into an electrical signal, and outputs from the first to fourth light receiving means And a calculating means for calculating a scanning line bending amount at each of the image heights.   Spatial light modulation means having a plurality of openings provided at equal pitches in the main scanning direction is disposed in the vicinity of the incident surfaces of the first and second light guide means, and the arithmetic means is adapted to scan line bending and magnification error. 5. The scanning line bending measuring apparatus according to claim 1, wherein the scanning line bending measuring apparatus according to claim 1 is obtained.   A low-pass filter that performs low-pass filter processing on the output from each light-receiving unit, and the arithmetic unit performs low-pass filter processing on the output from each light-receiving unit using the low-pass filter, and then scan line bending 5. The scanning line bending measuring apparatus according to claim 1, wherein the scanning line bending measuring apparatus according to claim 1 is obtained.   7. An optical scanning device including the scanning line bending measuring device according to claim 1, wherein the light source, a deflecting unit that deflects a light beam emitted from the light source, and a deflection by the deflecting unit. An imaging optical system for condensing the luminous flux on the image plane, and a transparent member. A part of the light is reflected by the transparent member, and the reflected light beam is incident on the scanning line bending measuring device.   8. The optical scanning device according to claim 7, wherein the transparent member is a parallel plate, and surface treatment conditions are set so that the reflectance of the incident surface is larger than the reflectance of the exit surface.   Based on the measurement result of the scanning line bending output from the arithmetic unit, the scanning line bending adjusting unit is provided to make the scanning line bending substantially linear by mechanically adjusting the optical components of the scanning optical system. 9. The optical scanning device according to claim 7, wherein the optical scanning device is characterized in that:   8. The spot position is corrected by performing resampling for correcting image data to be output so as to cancel the scanning line curve, based on the measurement result of the scanning line curve output from the arithmetic means. Or the optical scanning device of 8.

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