KR20100069131A - Apparatus and method for compensating driving of scanner - Google Patents

Abstract

Scanner drive compensation device according to an embodiment of the present invention, the rotation detection device for outputting a sensing signal for detecting the rotation of the scanner; An expected time point at which a predetermined reference sensing signal is expected to be output from the rotation detecting device when the scanner is normally rotated according to the input scanner driving signal, and a time point at which the reference sensing signal is actually output according to the actual rotation of the scanner; And a drive compensator configured to calculate a time difference between the signals and output a compensation drive signal in which an output time point of the scanner drive signal is adjusted based on the calculated time difference.

Description

Apparatus and method for compensating driving of scanner}

The present invention relates to a scanner, and more particularly, to an apparatus and method for driving compensation of a scanner.

Scanners are used in various image forming apparatuses such as laser printers, optical scanning units, projection display devices, and the like. In particular, in the use as an image display serves to implement a two-dimensional or three-dimensional image by reflecting the light beam containing the image information through the scanning mirror included in the scanner to form an image on the screen. Recently, in order to implement projection display of an image in a small display device such as a mobile device, interest in manufacturing a miniature scanner is increasing, and various studies for this are being conducted.

While the ultra-compact scanner for application to a portable imaging device has a large limitation on its size, volume and power consumption, drive linearity and repeatability within an effective range must also be satisfied for high quality images. In addition, the scanner needs to have a small moment of inertia of the device due to a driving characteristic in which the rotational direction must be reversed within a short time outside the effective section while performing constant velocity rotational movement within a certain effective section. As the moment of inertia of the scanner increases, the higher power consumption is required to generate a large drive torque in the change of rotational direction.

As such, the ultra-compact scanner for application to a portable imaging device needs to satisfy various design specifications (size, volume, power consumption, driving linearity, repeatability, moment of inertia, etc.). It needs to be manufactured according to the design specification.

That is, in the case of a micro scanner, there is no space to apply a general rotation detection device (for example, a rotation detection sensor such as a position sensor), and when the general rotation detection device is installed, the moment of inertia of the scanner itself is greatly increased. Increasingly, the driving characteristics become worse. In addition, when applying a general rotation sensor, the configuration of peripheral circuits required to process the sensing signal output from the sensor into angle information (or position information, speed information, acceleration information, etc.) is complicated, and the cost of the overall device configuration is also complicated. Will increase.

In view of the above problems, there is a configuration method using an encoder and a photo interrupter as a representative example of a conventional rotation sensing device for a compact scanner. However, such a configuration also has many problems. This will be described below with reference to FIGS. 1A to 2C.

1A and 1B, the scanner includes a rotating shaft 110, a scanning mirror 20 fixed to the rotating shaft 110 as a driven member, and an actuator 30 providing a driving force for inducing rotation of the rotating shaft 110. And an outer structure 10. At this time, the actuator 30 may be composed of a permanent magnet 31 and a coil 32 as shown in the figure, but in addition to various driving methods (for example, driving through a drive motor, driving through a piezoelectric actuator) It is obvious that a method, etc.) may be used.

The rotation detection device according to the prior art for detecting the rotation of the scanner is composed of a photo interrupter 120 and the encoder 50, the rotation detection method through this is as follows. This will be described with reference to FIGS. 2A and 2B. In FIG. 2A, reference numeral 60 denotes a buffer.

The encoder 50 is fixedly attached to the rotating shaft 110 of the scanner, thereby sequentially passing through the light receiving unit 122 of the photo interrupter 120 in conjunction with the rotation of the rotating shaft 110. Accordingly, when the light shielding area of the encoder 50 (see the black stripe pattern of the encoder 50 in FIG. 2A) passes through the light receiving part 122, the light emitted from the light emitting part 121 of the photo interrupter 120 is emitted. By being shielded by the light shielding area, the output voltage Vout output from the photo interrupter 120 has a low voltage value (see V _L in FIG. 2B). On the contrary, when the light transmission region of the encoder 50 (see the region between the black stripe patterns of the encoder 50 in FIG. 2A) passes through the light receiving portion 122, the output voltage output from the photointerrupter 120 is a high voltage value (FIG. V _{H of} 2b).

Accordingly, the rotation sensing apparatus according to the related art counts the number of times of change in the output voltage as shown in FIG. 2B for a predetermined time, and calculates a change in the rotation angle of the scanner during the corresponding time. However, the above-described conventional rotation detection method has the following problems.

First, there is a limitation that the conventional method can only detect the relative angular displacement during the corresponding time and cannot detect the absolute angle when the scanner rotates. Secondly, the conventional method further requires an analog-digital circuit for counting the change in the output voltage, and also has a problem that a separate sensing device must also be provided to detect the change in the rotational direction. Third, when the output voltage is in the V _L or V _H state, there is a problem that the angle change is not detected. Fourth, a high resolution encoder should be used for high-precision angle detection. However, due to the limitation of the precision of the encoder manufacturing, the higher the resolution, the larger the volume and the higher the price.

In addition, when the encoder is applied as a rotation detection method of the scanner, since the resolution is not good, there is a problem in that a minute driving delay occurring in the scanner cannot be detected. This is described with reference to FIG. 2C.

In general, when the diameter of the rotary shaft 110 is 1mm, and the distance (radius) from the center of the rotary shaft 100 to the encoder 50 is 3mm, each resolution of the encoder having a 50 μm pitch is 0.477 °. It is very low, only ((360 ° / (2π × 3 / 0.05))).

Therefore, if the scanner has a fine driving delay below each resolution of the encoder, it cannot be detected. That is, in order to detect the driving delay of the scanner (see the first drawing of FIG. 2C), if the driving delay degree has an angle greater than each resolution described above, a change in the number of output pulses counted from the encoder can be detected. (Refer to the second and third drawings of FIG. 2C).

Further, according to the prior art, when the value counted from the encoder according to the actual rotational drive of the scanner is smaller than the value expected to be counted during normal operation of the scanner (that is, when a driving delay occurs in the scanner), the actuator of the scanner Increase the drive voltage or current to be applied to 30 to compensate for the scanner to rotate at higher speeds. Conversely, if the value counted from the encoder according to the actual rotational drive of the scanner is greater than the value expected to be counted during normal operation of the scanner (ie, if a drive lead occurs in the scanner), then the actuator 30 of the scanner Reduce the drive voltage or current to be applied to compensate the scanner to rotate more slowly.

However, according to the conventional compensation method described above, in order to eliminate the counting error between the expected value and the actual value, a method of increasing or decreasing the magnitude of the driving voltage (or current) is used. The value itself must be changed continuously accordingly. This means that the driving circuit, the compensating circuit and the control process become complicated.

In addition, when the generation of the driving delay of the scanner is discontinuous and the delay amount exceeds 1/2 of the encoder period, it may fall into an uncontrollable state.

Accordingly, the present invention provides a simple configuration when a change in driving characteristics (driving delay or driving progression) occurs due to heat generation or mechanical wear during long time driving in a compact scanning mirror scanner having a high-speed repetitive rotational motion. The present invention provides a device and a method capable of sensing through a rotation sensing device of the present invention, and compensating for a change in scanner driving characteristics by adjusting a data output time point of a driving waveform in response to a change in driving characteristics.

Other objects of the present invention will be readily understood through the following description.

According to an aspect of the invention, the rotation detection device for outputting a sensing signal for detecting the rotation of the scanner; An expected time point at which a predetermined reference sensing signal is expected to be output from the rotation detecting device when the scanner is normally rotated according to the input scanner driving signal, and a time point at which the reference sensing signal is actually output according to the actual rotation of the scanner; There is provided a scanner drive compensation device including a drive compensation unit for calculating a time difference between and outputting a compensation drive signal in which an output time point of the scanner drive signal is adjusted based on the calculated time difference.

In one embodiment, the rotation sensing device, the photo interrupter is located on one surface, the light receiving portion is located on the other surface facing the one surface, and outputs the sensing signal proportional to the amount of light received by the light receiving portion; By interlocking with the axis of rotation of the scanner rotates on one plane across the light emitting portion and the light receiving portion, the length of the line segment from the center of rotation to the outer edge is changed linearly with increasing angle from the start end to the end It may include a light shield plate to be manufactured as.

In one embodiment, the rotation sensing device, the light emitting unit and the light receiving unit is located together on one surface, the photo interrupter for outputting the sensing signal in proportion to the amount of light emitted from the light emitting unit received by the light receiving unit, and the light emission By a fixed position on one plane in the main emission direction of the light emitted from the unit, a reflecting plate for reflecting the light emitted from the light emitting unit, and the one surface on which the light emitting unit and the light receiving unit is located in conjunction with the rotation axis of the scanner; It may include a light shield plate is rotated on one plane across the reflecting plate, the shape of the line segment from the center of rotation to the outer edge is linearly changed as the angle increases from the start end to the end. .

In one embodiment, the scanner drive signal is a signal in which the correlation of time versus output signal waveform during one drive cycle of the scanner is predefined so that the scanner can rotate repeatedly with a constant drive cycle. The profile of the output signal waveform according to time during the period may be digitalized at regular time intervals and stored in the form of a lookup table.

In one embodiment, when the time point at which the reference sensing signal is actually output is later than the expected time point, the driving compensator outputs the output signal waveform of the time point forwarded by the time difference corresponding to the time difference to the scanner driving signal. Adjust the data output time.

 In example embodiments, when the time point at which the reference sensing signal is actually output is earlier than the expected time point, the driving compensator may output the waveform of the output signal at a time point corresponding to the time difference to the scanner. Adjust the data output time.

The driving compensation unit may output the compensation driving signal every driving period of the scanner or every time corresponding to N times (N is an arbitrary natural number of two or more) times the driving period.

According to another aspect of the invention, the rotation detection device detects the rotation of the scanner; Between an expected time point at which a predetermined reference sensing signal is expected to be output from the rotation sensing device when the scanner is normally rotated according to the input scanner driving signal, and a time point at which the reference sensing signal is actually output according to the actual rotation of the scanner. Calculating a time difference; And adjusting an output time point of the scanner driving signal based on the calculated time difference.

In one embodiment, the scanner drive signal is a signal in which the correlation of time versus output signal waveform during one drive cycle of the scanner is predefined so that the scanner can rotate repeatedly with a constant drive cycle. The profile of the output signal waveform according to time during the period may be digitalized at regular time intervals and stored in the form of a lookup table.

The adjusting of the output time point of the scanner driving signal may include outputting the output signal waveform of the time point forwarded by the time difference when the reference sensing signal is actually output later than the expected time point. The data output timing of the scanner driving signal may be adjusted to be input to the scanner.

The adjusting of the output time point of the scanner driving signal may include outputting an output signal waveform at a time point corresponding to the time difference when the reference sensing signal is actually output earlier than the expected time point. The data output timing of the scanner driving signal may be adjusted to be input to the scanner.

In one embodiment, adjusting the output timing of the scanner driving signal may be performed once every driving period of the scanner or every time corresponding to N times N (N is any natural number of two or more) of the driving period. have.

According to the present invention, when a change in driving characteristics (driving delay or driving progression) occurs due to heat generation or mechanical wear during long time driving in a micro scanning mirror scanner having a high-speed repetitive rotation, it is rotated with a simple configuration. The sensing device may be sensed, and the change in the scanner driving characteristic may be compensated by adjusting the data output time point of the driving waveform in accordance with the detected driving characteristic.

The present invention may be variously modified and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail with reference to the accompanying drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, numerals (eg, first, second, etc.) used in the description process of the present specification are merely identification symbols for distinguishing one component from another component.

The scanner drive compensation device of the present invention has a rotation detection device as a configuration for detecting the rotation of the scanner, and a drive compensation as a configuration for compensating for changes in driving characteristics such as drive delay / drive progression occurring during the rotational movement of the scanner. Contains wealth.

As the rotation sensing device to be used in the scanner driving apparatus of the present invention, various devices including a known rotation sensing device can be employed without particular limitation. However, the rotation sensing device to be introduced hereinafter through the present specification has a form more suitable for applying to a compact scanning mirror scanner, thereby greatly reducing the size, volume, moment of inertia, manufacturing cost, etc. of the entire scanner, It includes the characteristic elements that are distinguished from the rotation detection device according to the prior art described above in that high precision rotation detection is possible.

In addition, the drive compensation device of the present invention includes a key feature that is distinguished from the prior art in that it uses a method of adjusting the output timing of the scanner drive signal through the drive compensation unit in compensating for the change in the drive characteristics of the scanner. Doing.

Therefore, hereinafter, a rotation sensing device applied to the present invention as a first feature of the scanner drive compensation device of the present invention will be described first with reference to FIGS. This will be described with reference to FIGS. 8 to 10B.

FIG. 3A is a view for explaining a rotation sensing apparatus applicable to the scanner driving compensation apparatus of the present invention, and FIG. 3B is a view schematically showing the rotation sensing apparatus in FIG. 3A. FIG. 3C is a view showing the shape of the light shield plate in FIGS. 3A and 3B, and FIG. 4 is a view showing the shape conditions of the light shield plate of FIG. 3C in more detail.

Referring to FIG. 3A, the configuration of the scanner itself (ie, the rotating shaft 110, the scanning mirror 20 as the driven member, the actuator 30 composed of the permanent magnet 31 and the coil 32, and the outer structure 10 of the scanner 10). ) And the like) are not different from those of FIGS. 1A and 1B described above, and the configuration of such a scanner may also be variously modified and changed. This is because the present invention does not have any feature in the configuration of the scanner itself.

The rotation sensing device applicable to the scanner drive compensation device of the present invention includes a light shield plate 130 and a photo interrupter 120 as shown in FIGS. 3A and 3B.

The photo interrupter 120 is fixedly installed at a specific position of the scanner outer structure 10. For example, the photointerrupter 120 is manufactured in a form in which the light emitter 121 is positioned on one surface and the light receiver 122 is positioned on the other surface of the photo interrupter 120, thereby being emitted from the light emitter 121 and receiving the light receiver 122. The sensing signal is output in proportion to the amount of light received. In this case, the sensing signal output from the photo interrupter 120 may be a sensing current, but in the present specification, a sensing voltage (see sensing voltage Vout output from the photo interrupter 120 through the buffer 60 in FIG. 3B). The case will be described mainly. In addition, the light emitting unit 121 may be implemented as LED, OLED, LD, etc., and the light receiving unit 122 may also be variously implemented as a photo diode, a photo decoder, a segmented photo detector, and the like. However, the configuration of the photo interrupter 120 does not have a configuration different from that of the photo interrupter described with reference to FIGS. 1B and 2A, and thus other detailed descriptions thereof will be omitted.

 The rotation sensing apparatus applied to the present invention uses the light shield plate 130 as a configuration to replace the encoder in the prior art. Hereinafter, materials, installation positions, shape conditions, and the like of the light shielding plate 130 will be described in detail.

The light shielding plate 130 is sufficient to perform a function of blocking light (that is, a function of blocking the light path in the middle so that it is no longer transmitted in the direction of travel) as the term means. Of course, there is no need to put restrictions. That is, although the entire light shield plate 130 may have an opaque material, a light reflection material, a light absorption material, and the like, only the surface corresponding to the light incident surface of the light shield plate 130 may be an opaque material, a light reflection material, and a light. Obviously, it may have an absorbent material.

In addition, the light shield plate 130 is installed to move in conjunction with the rotating shaft 110 of the scanner to detect the rotation of the scanner. To this end, the light shielding plate 130 may be directly fixed to the rotating shaft 110 of the scanner as shown in the drawings, but any installation method can be applied as long as it can move in conjunction with the rotating shaft 110 of the scanner. Of course. However, at this time, the light shielding plate 130 should act to block the path of the light emitted from the light emitting unit 121 of the photo interrupter 120 in accordance with the rotation interlocked with the scanner rotation axis 110, the photo interrupter 120 It is necessary to be installed so as to rotate on one plane across the light emitting portion 121 and the light receiving portion 122 of the.

In addition, although not necessarily, the light emitted from the light emitting unit 130 may not be blocked by the light shielding plate 130 as the vertical separation interval between the light shielding plate 130 and the light receiving unit 130 becomes larger. Since the likelihood of receiving light will be increased, it may be desirable to install the light shielding plate 130 at a position closer to the light receiving unit 130 (see the installation position of the light shielding plate 130 of FIG. 3A).

In addition, in order to achieve the objects of the present invention described above, the light shield plate 130 needs to be manufactured to satisfy a particular shape condition, and the shape condition may be expressed by Equation 1 below. Such shape conditions of the light shielding plate 130 will be described with reference to FIGS. 3C and 4.

Here, d (θ) represents the length of the line segment from the rotation center 111 to the outer edge of the light shielding plate 130, k represents a proportional constant which is any real number, θ is the start of the light shielding plate 130 The separation angle from the end to the end direction is represented, and d _ini represents the length of the line segment from the rotation center 111 of the light shielding plate 130 to the outside of the start end. In Equation 1, kθ is expressed as d _θ in FIG. 4.

That is, as shown in Equation 1, the light shielding plate 130 is linearly changed as the length of the line segment from the rotation center 111 to the outside increases with the separation angle from one end to the other. It is manufactured to have a shape to be.

At this time, the start end and the end of the light shielding plate 130 refer to both side ends of the light shielding plate 130 having an overall streamline shape (the length of d ₀ and d _max in FIG. 3A). ) And the other one. That is, when one end with line length d ₀ is viewed as the start end, the other end with line length d _max becomes the end, and when the other end with line length d _max is viewed as the start end, one side with line length d ₀ Dan will be the end. In the former, d _ini is d ₀ and the proportional constant k has a positive real value. In the latter case, d _ini is d _max and the proportional constant k has a negative real value.

However, this is only a coefficient change in the equation according to which side end of the light shielding plate 130 is assumed as the starting end, in which case the physical shape of the light shielding plate 130 itself is changed. It will be easy to understand. Therefore, hereinafter, for convenience of explanation, the shorter side of the line segment of both side ends of the light shielding plate 110 is the start end (that is, proportional to the increase of the separation angle from the start end to the end). If the length of the line segment increases linearly, it is assumed to refer to FIGS. 4 and 5B).

The rotation detection principle of the scanner using the light shield plate 130 having the above shape condition will be described with reference to FIG. 5A. In the present specification, the case of detecting the rotation angle of the scanner will be mainly described, but it is obvious that it can be processed and converted to other physical quantities (rotation position, speed, etc.).

As described above, the photo interrupter 120 outputs a sensing signal proportional to the amount of light received by the light receiver 122. In this case, the amount of received light is in proportion to the light receiving area of the light receiving unit 122. Therefore, the area where the light shielding plate 130 covers the light receiving surface of the light receiving portion 122 (that is, when viewed from above, when the light shielding plate 130 rotates), the light receiving surface of the light shielding plate 130 and the light receiving portion 122. Simplified overlapping area) will vary with a generally linear relationship in response to a change in the rotation angle of the light shielding plate 130.

For the same reason as described above, the light receiving area through which the light receiving unit 122 can receive the light emitted from the light emitting unit 121 is also changed substantially linearly in correspondence to the angle change during the rotation of the light shielding plate 130, As a result, the output voltage output from the photo interrupter 120 may have the form of FIG. 5C or 5D.

5C illustrates an output voltage from the photo interrupter 120 according to an angle change when the light shielding plate 130 rotates counterclockwise in FIG. 5A, and FIG. 5D shows the light shielding plate 130 in FIG. 5A. It is a graph which illustrates the output voltage from the photointerrupter 120 according to the change of angle in the case of rotating in the clockwise direction.

However, referring to the graphs of FIGS. 5C and 5D, the output voltage output from the photo interrupter 120 is illustrated as having a completely linear relationship (that is, a linear linear relationship with the rotation angle as a variable). Of course, may not be the same. This is because the shape condition of the light shielding plate 130 has a linear relationship according to the angle change, so that the change in the light receiving area of the light receiving unit 122 when the light shielding plate 130 is rotated must have a linear relationship. Because there is no. Of course, this will also be the case according to the deformation of its own shape of the light receiving surface of the light receiving portion 122.

However, whether or not the voltage actually output from the photo interrupter 120 is linear is not a significant problem in terms of detecting the rotation angle of the scanner. When the light shielding plate 130 is rotated, the light receiving area of the light receiving unit 122 will be continuously changed, so that the output voltage output from the photo interrupter 120 is at least in the form of a monotonic reduction or monotonic increasing function. Will be maintained, and there will be no problem in detecting the change in the rotation angle of the scanner. This is because it can be easily solved by measuring the exact relationship between the change in the rotation angle of the scanner and the actual output voltage output from the photo interrupter 120.

Referring again to FIG. 5A, FIG. 5A illustrates the case where the scanner rotates within a finite rotation angle range (ie, 0 ≦ θ ≦ θ _max ). That is, the reason why the scanner makes a finite rotational motion within a specific rotational angle range, the light shield plate 130 moving in conjunction with the scanner is also rotating in the same rotational angle range as shown in the figure. This is a case that can occur when scanning an image using a galvanometer mirror, a rotating bar, and the like.

In this case, the separation angle from the start end to the end of the light shielding plate 130 needs to be set at least equal to the maximum rotation angle (ie, θ _max ) of the scanner. If possible, the separation angle from the start end to the end of the light shielding plate 130 may be preferably set equal to the maximum rotation angle of the scanner. In this case, since there is no problem in the angle detection in the entire rotation range of the scanner, the moment of inertia of the entire device can be reduced by reducing the size, volume, and weight of the light shielding plate 130 itself.

From a similar point of view, the length of the starting line segment of the light shielding plate 130 (see d _{0 in} FIG. 3C) is greater than the starting end of the light receiving unit 122 from the rotation center 111 of the light shielding plate 130. It may be precisely set to be at least equal to the distance to the start end of the light receiving surface, which will be described below, and may be set to be smaller than the distance to the end of the light receiving unit 130 (see the first drawing of FIG. 5A).

Similarly, the length of the line segment at the position spaced apart from the start end of the light shield plate 130 by the same angle as the maximum rotation angle θ _max of the scanner (in the third view of FIG. 5C, the end segment of the light shield plate 130). The length d _max ) may be set not to exceed the distance from the rotation center 111 of the light shielding plate 130 to the end of the light receiving portion 122.

The waveform of the sensing signal (i.e., the sensed voltage) output from the above-described rotation sensing device is a device design condition (shape condition of the light shielding plate 130, area of the light receiving portion 122 of the photo interrupter 120, shape, etc.) and a scanner. It may have various forms depending on the change in the driving method (drive (rotation) range of the scanner, the direction of the rotational motion, etc.). This will be described with reference to FIGS. 6A and 6B.

6A is a diagram illustrating a positional relationship between a light shield plate and a photo interrupter when the scanner rotates bidirectionally within a predetermined rotation angle range, and FIG. 6B is a graph illustrating an output voltage output from the photo interrupter in FIG. 6A.

Referring to FIG. 6A, the scanner rotates in both directions within a finite rotation angle range (ie, 0 ≦ θ ≦ θ _max ), and the shape condition of the light shield plate 130 is designed differently from that of FIG. 5A. Therefore, when the light shielding plate 130 shown in FIG. 6A rotates clockwise and then rotates counterclockwise again, the output shown in FIG. 6B is output according to the time sequence of the scanner rotation.

Of course, in addition to using the above-described light quantity control principle according to the change in the light receiving area, it is possible to produce a variety of output signals of different types as shown in the graphs of FIGS. 5C, 5D, and 6B according to specific purposes and needs. It will be readily apparent to those skilled in the art that this will be possible.

In the above, the rotation sensing apparatus according to the exemplary embodiment applicable to the present invention has been described. Hereinafter, other modifications related to the rotation sensing apparatus will be introduced based on the above description. However, overlapping descriptions of the technical contents (particularly, all of the contents relating to the shape conditions of the light shielding plate) that can be applied in the same manner as in the foregoing embodiments will be omitted, and only other new features will be described in detail.

7A is a view for explaining another example of a rotation sensing device applicable to the scanner drive compensation device of the present invention, and FIG. 7B is a view for explaining another example of the rotation detection device applicable to the scanner drive compensation device of the present invention. Drawing. Here, FIG. 7B is a partial modification of FIG. 7A.

8A and 8B, the configuration of the scanner itself (i.e., the rotary shaft 110, the scanning mirror 20 as the driven member, the actuator 30 composed of the permanent magnet 31 and the coil 32, and the outline of the scanner) The structure 10 is the same as in the previous embodiment.

The rotation sensing device according to another embodiment includes a photo interrupter 120, a light shielding plate 130, and a reflecting plate 140. At this time, a different feature point from the above embodiment is that both the light emitting portion 121 and the light receiving portion 122 of the photo interrupter 120 are located on the same surface. Therefore, there is an advantage that the volume of the photo interrupter 120 itself can be reduced compared to the previous embodiment. Instead, the reflection plate 140 is further provided in order to allow the light emitted from the light emitting portion 121 to be received by the light receiving portion 122 located on the same surface.

The reflector 140 may be installed without particular limitation as long as it can reflect light emitted from the light emitter 121 of the photo interrupter 120, but the light emitter 121 may be viewed in terms of reflection efficiency. It may be desirable to be fixed on one plane present in the main exit direction of light emitted from.

In another embodiment, the light shielding plate 130 is positioned between the surface on which the light emitting unit 121 and the light receiving unit 122 are positioned in the photo interrupter 120 and the reflecting plate 140, thereby interlocking with the rotation of the scanner therebetween. It will rotate across the plane.

When the light shielding plate 130 is disposed as described above, the light emitted from the light emitting unit 121 is reflected by the reflecting plate 140 to linearly control the amount of light to be received in the process of being received by the light receiving unit 122. It becomes possible. The adjustment of the amount of light is a method of adjusting the amount of light itself emitted from the light emitting unit 121 and reflected by the reflecting plate 140 by covering the light emitting unit 121 itself with the light shielding plate 130 (see FIG. 8A) or light shielding A method of directly controlling the amount of light received according to the change in the light receiving area by covering the light receiving unit 122 itself with the plate 130 may be used (see FIG. 8B).

In the above, the rotation sensing apparatus applicable to the scanner driving compensation device of the present invention has been described with reference to FIGS. 3A to 7B. Hereinafter, another embodiment of the scanner driving compensation device of the present invention will be described with reference to FIGS. 8 to 10B. The role and function of the drive compensation unit, which is a core configuration, will be described in detail.

FIG. 8 is a diagram illustrating a scanner driving compensation device according to an embodiment of the present invention, and FIG. 9 is a flowchart illustrating a scanner driving compensation method using a scanner driving compensation device according to an embodiment of the present invention. FIG. 10A is a diagram for describing a method of compensating for a driving delay when a driving delay occurs in a scanner, and FIG. 10B is a diagram for describing a method for compensating for a driving phase when a driving phase occurs in a scanner. to be.

As briefly described above, the driving compensation unit in the scanner driving compensation device of the present invention compensates for the change in the driving characteristics of the scanner by using a method of adjusting the output time of the scanner driving signal input for rotational driving of the scanner. Has key features that distinguish it from the prior art. In the prior art, a method of increasing or decreasing the magnitude of the driving signal (driving voltage, etc.) as much as the driving error of the scanner is used.

To this end, the driving compensator according to the present invention, when the scanner is normally rotated according to the scanner driving signal input to the scanner, when the predetermined reference sensing signal of the sensing signal to be output from the above-described rotation sensing device is expected to be output And a time difference between the time points at which the reference sensing signal is actually output according to the actual rotation of the scanner, and adjusts the output time point of the scanner driving signal based on the calculated time difference.

Hereinafter, for convenience of classification, the scanner driving signal output after the output time is adjusted as described above to compensate for the change in driving characteristics of the scanner is referred to as a compensation driving signal.

In order to perform the above function, the driving compensator 150 has a port (refer to "sensing signal input terminal" of FIG. 8) for receiving a sensing signal output from the rotation sensing device, A port for outputting a scanner driving signal to be input to the actuator 30 may be provided (see “scanner driving signal output stage” in FIG. 8).

In addition, the scanner drive compensation device of the present invention includes an amplifier for amplifying the sensing signal output from the rotation sensing device and inputting it to the sensing signal input terminal of the drive compensation unit 150 and an output from the drive compensation unit 150. DAC for converting the scanner driving signal in the form of a driver or digital signal to amplify the weak waveform of the scanner driving signal into a waveform large enough for the actuator 30 to operate. (Digital to Analog Converter) and the like may further be included (see FIG. 8).

Although FIG. 8 illustrates a case in which the driving compensator 150 is implemented by only one microprocessor, the driving compensator 150 may be implemented by various implementation methods in addition to the present invention. Even if it is not described in detail, those skilled in the art will clearly understand.

In order to understand the scanner drive compensation method according to the present invention, first, an understanding of the scanner drive signal is required. In the present invention, the scanner drive signal is a signal whose correlation of time versus output signal waveform during one drive period of the scanner is predefined so that the scanner can rotate repeatedly with a constant drive period.

That is, the scanner driving signal is continuously input to the scanner with the same sequence in every driving period of the scanner, thereby causing the scanner to repeat the same rotational movement for each driving period.

The scanner driving signal as described above may include, in one embodiment, the profile of the output signal waveform according to the time change during the one driving period. It may be stored in advance in the driving compensation unit 150 in the form of a lookup table (LUT) digitally datad as T _d2 '.

Hereinafter, a scanner driving compensation method performed by the driving compensation unit 150 according to the present invention will be described with reference to FIGS. 10A and 10B with reference to the flowchart of FIG. 9. However, the flowchart of FIG. 9 is only a flowchart according to an embodiment of the scanner driving compensation method of the present invention. In addition, various implementation algorithms may be apparent.

The scanner drive compensation method of the present invention includes two steps when largely classified. Computing a time difference between the expected output time of the reference sensing signal and the actual output time of the reference sensing signal according to the actual rotation, assuming that the scanner rotates normally according to the input scanner driving signal. The step of actually adjusting the output time point of the scanner driving signal on the basis of this is another. This is illustrated through FIG. 9 as different functions.

T _sw0 means an expected output time point at which the predetermined reference sensing signal is expected to be output from the rotation detecting device when the scanner is normally rotated according to the input scanner driving signal. This may be a pre-measured time value (or counting number based on a predetermined time interval as follows).

Shift_Index means an index for output data to be output first from a predefined lookup table (LUT) as described above when outputting a driving waveform (that is, a scanner driving signal) every cycle. If there is no change in driving characteristics in the scanner, Shift_Index will maintain the index value of the first data of the lookup table.However, if a change in driving characteristics causes driving delay or driving progress, Shift_Index The value will also change.

Referring to S900 of FIG. 9, in a state in which T _sw0 and Shift_Index values are stored as specific initial values, the scanner performs initial rotation in response to the input scanner driving signal. In this case, since the driving characteristic does not change in the scanner, the scanner is driven according to the sequence of the profile of the driving waveform predefined in the lookup table. To monitor the future change in scanner drive characteristics, count the time from the initial output of the scanner drive signal. This counting of time may be simplified by using a timer or counter provided in the driving compensation unit 150 or using a system clock.

The above-described time difference calculating step will be described below with reference to Function 1 of FIG. 9.

When a certain time point (see T _{p0 in} FIGS. 9, 10A and 10B) of the drive waveform output by the scanner drive signal is reached (S911 in FIG. 9), every time interval (see T _{d1 in} FIG. 9) from that time point is reached. The counting count (see T _sw of FIG. 9) is increased by one (S912 of FIG. 9). If the sensing signal output from the rotation sensing device is equal to the reference sensing signal of a predetermined value during the counting process (S913 of FIG. 9), the counting is stopped and the number of times counted up to that time T _sw is determined. The data is stored at an output time point (see T _swE of FIGS. 9, 10A, and 10B) (S914 of FIG. 9).

At this time, when the difference between the phase output time point T _sw0 and the measured actual output time point T _swE does not deviate from a predetermined tolerance range, the actual driving of the scanner according to the input scanner driving signal is in a normal driving state. Since it is judged to be, the separate driving characteristic compensation is not necessary, but in the opposite case, since the actual driving of the scanner is judged to be out of the normal driving state, the driving characteristic compensation is necessary (S915 in FIG. 9). . However, S915 of FIG. 9 may be omitted in this flowchart.

When compensation of the scanner driving characteristic is required, the difference between the expected output point T _sw0 and the actual output point T _swE is _multiplied by a predetermined scale factor (see 'C' in FIG. 9) as the Shift_Index value. It stores (S916 of FIG. 9). Thereafter, the previous counting number T _sw is reset for later recounting (S917 of FIG. 9).

Here, the scale factor C is only for correcting when the counting time interval T _d1 in function 1 and the unit output interval T _d2 in function 2 are inconsistent with each other. If set to 1, it will be determined as 1.

In addition, the shift_Index value having a positive value may mean that a driving delay occurs when the scanner is driven, and having a value of − will mean that driving progress has occurred.

Then, when the scanner completes the rotational motion according to one driving period (see T _{scan_period in} FIG. 9) (S918 in FIG. 9), the time is reset again to monitor the change in driving characteristics in the next driving period (FIG. 9). S919).

Next, the output time adjustment step will be described with reference to Function 1 of FIG. 9.

When the Shift_Index value is determined in S916 of function 1, it is designated as an index value (S921 in FIG. 9), and the output of the scanner driving signal is started from the output data corresponding to the index value in the lookup table (LUT) (FIG. 9). S922).

For example, if the determined Shift_Index value is +2, the output data to be first output from the lookup table (LUT) is assumed to be the data defined as the index value 2 in the lookup table (LUT) (the index value starts from 0, In normal operation, the data to be output in the third order will be used.

Thereafter, the index value is increased by one (S923 in FIG. 9), and a driving waveform corresponding to the increased index value is output for each unit output interval T _d2 (S926 in FIG. 9). This loop is repeated until the increased index value is smaller than the Index_max value (S924 in FIG. 9), and when the value is larger than the Index_max value, the loop value is initialized again (S925 in FIG. 9).

Here, Index_max corresponds to the number of output data to be output during one driving period stored in the lookup table LUT, and corresponds to a value obtained by dividing one driving period T _{scan_period} by a unit output interval T _d2 .

The adjustment of the output timing of the scanner driving signal through the above process is _stopped when the scanner completes the rotational motion according to one driving period T _{scan_period} (S927 of FIG. 9). Thereafter, the time is reset again (S928 in Fig. 9) to compensate for the drive characteristic change in the next drive period.

The scanner driving compensation method of the present invention has been described with reference to the flowchart of FIG. 9. However, this is merely an example as described above. In FIG. 9, the time difference between the expected output time point and the actual output time point is calculated as a count number, but may be a time interval itself. 10A and 10B, it is assumed that the reference sensing signal is a time point at which the sensing signal output from the rotation sensing device is alternated from high to low. However, the reference sensing signal may be arbitrarily selected as long as the reference sensing signal exists at one point among the monotonically increasing or decreasing portions of the sensing signal. 9, 10A, and 10B, it is assumed that the compensation of the driving characteristics is performed every driving period and at the time when a new driving period starts. However, compensation of the scanner driving characteristic may be performed only once every few cycles, or may be executed immediately within the corresponding driving cycle before a new driving cycle is started.

As described above, the scanner drive compensation method according to the present invention calculates the time difference between the scanner drive when it is normally driven and when it is actually driven, and based on the output time of the scanner drive signal (that is, the order of outputting data) By adjusting, the change in driving characteristics generated in the scanner is compensated.

That is, when a driving delay occurs at a later point than the time originally expected when the predetermined reference sensing signal is actually output, the driving compensator may input the output signal waveform at the time point advanced by the corresponding time difference to the scanner. Adjust the data output time point (order) of the drive signal.

On the contrary, when the driving progress occurs when the reference sensing signal is actually output earlier than the expected timing, the driving compensator outputs the data of the scanner driving signal so that the output signal waveform at the time delayed by the corresponding time difference can be input to the scanner. Adjust the viewpoint.

This is described in detail with reference to FIGS. 10A and 10B. Here, the left side of each first drawing of FIGS. 10A and 10B shows a scanner drive signal output according to the output order as it is stored in the lookup table LUT, and the right side shows a compensation drive signal whose output order is adjusted.

Each second view in FIGS. 10A and 10B shows the actual drive of the scanner when the scanner drive signal as input in each first view of FIGS. 10A and 10B is input. 10A and 10B respectively show waveforms of sensing signals output from the rotation sensing device assuming normal driving of the scanner, and each fourth diagram shows waveforms of sensing signals according to actual driving of the scanner. Indicates.

According to the scanner drive compensation method and apparatus for performing the same according to the present invention described above, there are advantages as compared to the drive compensation method and device according to the prior art. The conventional technology is a method of compensating for a change in driving characteristics generated in a scanner, and employs a method of continuously increasing or decreasing the size of a scanner driving voltage or current by a corresponding amount corresponding to the driving error, and thus driving circuit / compensation circuit / control. The configuration of the circuit had a complicated problem.

However, according to the present invention, the compensation circuit / control circuit has a simple advantage since the scanner driving signal in a predefined state is used as it is, and only the output timing (data output order) of the driving signal is adjusted. In addition, in the present invention, when the counting time interval T _d1 described above is synchronized with the system clock, the resolution can be increased to a value corresponding to the clock frequency of the maximum microprocessor, thereby providing more accurate driving compensation.

Although the above has been described with reference to embodiments of the present invention, those skilled in the art may variously modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. And can be changed easily.

1A is a perspective view of a scanner schematically showing a rotation axis and a scanning mirror fixed to the rotation axis;

1B is a vertical sectional view schematically showing a scanner including a rotation sensing device according to the prior art;

Figure 2a schematically shows a rotation sensing device consisting of an encoder and a photo interrupter according to the prior art.

2B is a waveform diagram of an output voltage output from the photo interrupter in FIG. 2A.

FIG. 2C is a view comparing the output voltage output from the rotation sensing device of FIG. 2A during normal driving of the scanner and when a drive delay occurs. FIG.

3A is a view for explaining a rotation detection device applicable to the scanner drive compensation device of the present invention.

FIG. 3B schematically illustrates the rotation sensing device in FIG. 3A.

3C is a view showing the shape of the light shield plate in FIGS. 3A and 3B.

Figure 4 is a view showing in more detail the shape conditions of the light shield plate of Figure 3c.

5A is a view illustrating the rotation of the light shield plate of FIG. 4 according to the change of the rotation angle.

FIG. 5B is a graph showing the correlation between the shape of the light shield plate of FIG. 4 and the change in rotation angle. FIG.

5C and 5D are graphs showing the correlation between the change in the rotation angle during rotation of the light shield plate of FIG. 4 and the output voltage output from the photo interrupter.

6A is a view showing a positional relationship between a light shield plate and a photo interrupter when the scanner rotates bidirectionally within a certain rotation angle range.

6B is a graph illustrating an output voltage output from a photo interrupter in the case of FIG. 6A.

7A is a view for explaining another example of the rotation detection device applicable to the scanner drive compensation device of the present invention.

7B is a view for explaining another example of the rotation detection device applicable to the scanner drive compensation device of the present invention.

8 is a view for explaining a scanner drive compensation device according to an embodiment of the present invention.

9 is a flowchart illustrating a scanner drive compensation method using a scanner drive compensation device according to an embodiment of the present invention.

10A is a diagram for explaining a method of compensating for a driving delay when a driving delay occurs in the scanner.

10B is a diagram for explaining a method for compensating for driving progress when driving progress occurs in the scanner;

<Description of the symbols for the main parts of the drawings>

10: outer structure 20: scanning mirror

30: actuator 110: rotation axis

120: photo interrupter 121: light emitting unit

122: light receiving unit 130: light shielding plate

140: reflector 150: drive compensation unit

Claims (12)

In the scanner drive compensation device, A rotation sensing device for outputting a sensing signal sensing the rotation of the scanner; And Between an expected time point at which a predetermined reference sensing signal is expected to be output from the rotation sensing device when the scanner is normally rotated according to the input scanner driving signal, and a time point at which the reference sensing signal is actually output according to the actual rotation of the scanner. A drive compensator for calculating a time difference and outputting a compensation drive signal in which an output time point of the scanner drive signal is adjusted based on the calculated time difference Scanner driven compensation device comprising a. The method of claim 1, The rotation detection device, A photo interrupter positioned on one surface thereof, a light receiver positioned on the other surface facing the one surface, and outputting the sensing signal proportional to the amount of light received by the receiver; By interlocking with the axis of rotation of the scanner rotates on one plane across the light emitting portion and the light receiving portion, the length of the line segment from the center of rotation to the outer edge is changed linearly with increasing angle from the start end to the end Scanner drive compensation device comprising a light shield plate is made of. The method of claim 1, The rotation detection device, A photo interrupter which is located together on one surface of the light emitting unit and the light receiving unit and outputs the sensing signal which is emitted from the light emitting unit and is proportional to the amount of light received by the light receiving unit; A reflection plate for reflecting the light emitted from the light emitting part by being fixedly positioned on a plane present in the main emission direction of the light emitted from the light emitting part; By interlocking with the axis of rotation of the scanner, the light emitting unit and the light receiving unit are rotated on a plane intersecting between the one surface and the reflecting plate, and the length of the line segment from the center of rotation to the outer edge is increased by the angle from the beginning to the end. Scanner drive compensation device comprising a light shield plate is produced in a linearly changing shape according to. The method of claim 1, The scanner drive signal is a signal in which the correlation of time versus output signal waveform during one drive cycle of the scanner is predefined so that the scanner can rotate repeatedly with a constant drive cycle. And a profile of the output signal waveform according to time during the one driving period is digitalized at predetermined time intervals and stored in the form of a lookup table. The method of claim 4, wherein When the time point at which the reference sensing signal is actually output is later than the expected time point, the driving compensator selects a data output time point of the scanner driving signal so that an output signal waveform at a time point advanced by the time difference can be input to the scanner. Scanner drive compensation device characterized in that the adjustment. The method of claim 4, wherein When the time point at which the reference sensing signal is actually output is earlier than the expected time point, the driving compensator selects a data output time point of the scanner driving signal so that an output signal waveform at a time point corresponding to the time difference may be input to the scanner. Scanner drive compensation device characterized in that the adjustment. The method of claim 1, And the drive compensator outputs the compensation drive signal at every driving period of the scanner or at a time corresponding to N times (N is an arbitrary natural number of two or more) times the driving period. A method of compensating a driving of a scanner by a scanner driving compensator, wherein the scanner driving compensating apparatus includes a rotation sensing device that outputs a sensing signal sensing a rotation of the scanner; Detecting rotation of the scanner by the rotation detecting device; Between an expected time point at which a predetermined reference sensing signal is expected to be output from the rotation sensing device when the scanner is normally rotated according to the input scanner driving signal, and a time point at which the reference sensing signal is actually output according to the actual rotation of the scanner. Calculating a time difference; And Adjusting an output time point of the scanner driving signal based on the calculated time difference Scanner driven compensation method comprising a. The method of claim 8, The scanner drive signal is a signal in which the correlation of time versus output signal waveform during one drive cycle of the scanner is predefined so that the scanner can rotate repeatedly with a constant drive cycle. And the profile of the output signal waveform according to time during the one driving period is digitalized at predetermined time intervals and stored in a lookup table. 10. The method of claim 9, Adjusting the output time of the scanner drive signal, Adjusting the data output time of the scanner driving signal so that the output signal waveform of the time forwarded by the time difference corresponding to the time difference may be input to the scanner when the time when the reference sensing signal is actually output is later than the expected time; Scanner drive compensation method characterized in that. 10. The method of claim 9, Adjusting the output time of the scanner drive signal, Adjusting the data output time of the scanner driving signal so that the output signal waveform of the time delayed by the corresponding time difference is input to the scanner when the time when the reference sensing signal is actually output is earlier than the expected time; Scanner drive compensation method characterized in that. The method of claim 8, The step of adjusting the output time of the scanner driving signal is performed once every driving period of the scanner or every time corresponding to N times (N is an arbitrary natural number of two or more) times the driving period. Compensation method.

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