JP2005242037A - Light deflector, detection unit and method for detecting deflection timing of deflecting means in the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unit or a method capable of detecting the deflection timing of the deflecting means without giving constrains to the driving method of the deflecting means which deflects light. <P>SOLUTION: In the unit, the deflection timing of the deflecting means 202 in a light deflector having the deflecting means 202 which performs oscillation deflection of light from a light source 201 and scans the deflected light is detected. A light receiving device 101 is arranged at a position where the deflected light which is made to perform the oscillation deflection can be received and when the light source 201 is modulated in a first modulation timing, the positional distribution of a light quantity to be formed on the light receiving device 101 in a going path along which the deflected light is moved to one direction is measured, and also when the light source 201 is modulated in a second timing, the positional distribution of a light quantity to be formed on the light receiving device 101 in a returning path along which the deflected light is moved to a direction being roughly opposite to that of the one direction is measured, and the deflection timing of the deflecting means 202 to the driving signal of the deflecting means 202 is detected based on the modulation timing and data of the positional distribution of the light quantity corresponding to the modulation timing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an apparatus or method for detecting a deflection timing of a deflecting means for deflecting light with respect to a drive signal thereto, an optical deflector using the same.

As an example of a conventional optical deflector, there is a galvanometer mirror shown in FIG. 17 (see Patent Document 1). This is a galvanometer mirror that drives a movable part with electromagnetic force. A mirror is disposed on the movable portion, and the movable portion is configured to be supported from the main body portion by the torsion bar so as to swing around the axis. In FIG. 17, reference numeral 50 denotes a silicon substrate, reference numeral 51 denotes an upper glass substrate, and reference numeral 52 denotes a lower glass substrate. Reference numeral 53 is a movable plate, reference numeral 54 is a torsion bar, reference numeral 55 is a planar coil, reference numeral 56 is a total reflection mirror, reference numeral 57 is an electrode terminal, and reference numerals 60 to 63 are permanent magnets. This optical deflector is of an electromagnetic type that is driven using a Lorentz force with the permanent magnets 60 to 63 by passing a driving current through the planar coil 55. However, the example of Patent Document 1 does not pay attention to the point that the resonance period of the movable plate 53 drifts due to temperature or the like.

On the other hand, there is an electromagnetic actuator that focuses on this point (see Patent Document 2). The resonance cycle of an electromagnetic actuator (movable part) usually drifts with temperature or with age. If a current with a preset resonance frequency is continuously supplied to a planar coil, it can move according to temperature changes and time. The example of Patent Document 2 pays attention to the problem that the deflection angle of the part is not controlled to be constant. This means that the movable part swings due to electromagnetic force, and is the same as the example of Patent Document 1 described above. The electromagnetic actuator of the example of Patent Document 2 also has a total reflection mirror in the movable part. The example of Patent Document 2 provides an electromagnetic actuator or the like that can reciprocally drive an electromagnetic actuator at a resonance period and can control the deflection angle without providing a separate detection means. As a solution to this problem, the coil is used not only for exciting the movable part but also for detecting. For this detection, an induced electromotive voltage or induced electromotive current generated in the coil is used.
JP 07-175005 (page 3-4, FIG. 1) JP 2001-305471 A (page 3-4, FIG. 1)

However, in the example of Patent Document 2, since the coil as the detection means is always used for excitation, the application period of the drive signal of the electromagnetic actuator (movable part) is limited.

  In view of the above problems, the detection apparatus of the present invention is a detection apparatus for detecting the deflection timing of the deflection means in an optical deflector having deflection means for reciprocally deflecting light from a light source and scanning the deflected light. When a light receiving element (an image sensor such as a linear sensor or an area sensor) is disposed at a position where the deflected light can be received, and the light source is modulated at the first modulation timing, the forward light travels in one direction. And measuring the positional distribution of the amount of light formed on the light receiving element in the optical path, and when the light source is modulated at the second modulation timing, the light receiving element in the return path in which the deflected light moves in a direction almost opposite to the one direction. Measuring means for measuring the positional distribution of the amount of light formed on the basis of the modulation timing and the data of the positional distribution of the amount of light corresponding to the modulation timing; Characterized in that it has a detection means for detecting the deflection timing of deflecting means. In this specification, the time lag of the movement (deflection) of the deflection unit with respect to the drive signal to the deflection unit is referred to as deflection timing or movement timing. Further, the modulation of the light source is used in a broad sense including a change in the amount of light emission such as turning on and off.

In the present invention, when the light source is modulated at a desired modulation timing, the light from the light source is deflected and scanned by the deflecting means and reaches the light receiving element, and the modulation spot position is detected on the light receiving element. Since the timing (time) of the modulation signal portion of the light source corresponding to this modulation spot position is known, the light source is modulated so that at least one modulation spot position is obtained in each of the forward path and the return path of the deflection scanning, and this correspondence is achieved. Measure multiple sets of relationships. Based on the modulation spot position thus obtained and the timing (time) data of the modulation signal portion of the light source corresponding thereto, the deflection timing of the deflection means with respect to the drive signal (more specifically, the deflection means with respect to the drive signal) The turn-back time during which the direction of reciprocating motion changes) is detected.

  Further, in view of the above problems, the detection method of the present invention is a detection method for detecting the deflection timing of the deflecting means in the optical deflector having the deflecting means for reciprocally deflecting the light from the light source and scanning the deflected light, When the light receiving element is arranged at a position where the deflected light deflected back and forth can be received, and the light source is modulated at the first modulation timing, the amount of light formed on the light receiving element in the forward path in which the deflected light moves in one direction When the light source is modulated at the second modulation timing while measuring the positional distribution, the positional distribution of the light amount formed on the light receiving element in the return path in which the deflected light moves in the direction almost opposite to the one direction. , And the deflection timing of the deflection means with respect to the drive signal of the deflection means is detected based on the data of the modulation timing and the positional distribution of the light quantity corresponding thereto.

Thus, for example, in controlling the movement state of the deflecting unit, the present invention focuses on using the deflected light that is deflected by the reciprocating motion (oscillating motion) of the deflecting unit and reciprocally scanned on the light receiving element. did.

Further, in view of the above problems, an optical deflector of the present invention includes the above-described detection device and a control unit that controls the deflection unit so that the deflection unit is deflected at a desired deflection timing based on the deflection timing detected thereby. Features.

In view of the above problems, a one-dimensional or two-dimensional image forming apparatus (used in a broad sense including image display) of the present invention includes the optical deflector described above, and controls the deflection means during a non-image forming period. It is characterized by performing.

According to the present invention as described above, the concept is different from that of Patent Document 2, and the detection unit is separated from the actuator drive unit, thereby limiting the driving method of the deflection unit that is an actuator. The deflection timing of the deflection means can be detected without giving. Therefore, even when the characteristics of the deflecting means are deviated due to the environment or the like, the deflecting means can be appropriately controlled by observing the operation of the deflecting means. Also, the deflection light modulated in the forward and return paths is detected by the light receiving element, and the change in the reciprocating scanning timing (deflection timing) is used as the scanning position information on the light receiving element of the modulation spot whose modulation timing (generation time) is known. Since measurement is performed, a change in scanning state (deflection timing) can be detected with high accuracy without causing a decrease in detection accuracy due to the influence of delay or the like of the light detection circuit.

(First embodiment)
The present invention detects the deflection timing of the deflecting means and controls the deflecting means, for example, as described above, the deflected light deflected by the deflecting means by the reciprocating motion (oscillating motion) of the deflecting means and reciprocally scanned. Focused on using. In the present embodiment, specifically, the deflection light in the forward path and the return path is detected by the light receiving element by changing the timing of turning on and off the light source, and the deflection light of the forward path and the return path at the same position on the light receiving element is detected. Based on the information on the deflection timing calculated from the times, for example, the deflection means is controlled via the control means so as to be deflected at a desired deflection timing.

FIG. 1 is a cross-sectional view of the optical deflector according to the first embodiment of the present invention in a plane including deflected light deflected by deflecting means. In FIG. 1, 201 is a light source, 202 is a deflecting means, 203 is a light beam emitted from the light source 201, 204 and 205 are light beams at a maximum deflection angle deflected by the deflecting means 202, and 206 is a light deflection center of the deflecting means 202. An axis 207 is a scanning locus of the deflected light on a plane P (a plane perpendicular to the optical deflection center axis 206) at a distance L from the deflecting means 202. The light beam 203 emitted from the light source 201 is incident on the deflecting means 202, where it is deflected and scanned on the plane P. As the light source 201, a light source that can be modulated such as a semiconductor laser is used.

The deflecting means 202 is provided with a reflecting surface (see the configuration of FIG. 17), and the light means 203 is deflected in the range of the light rays 204 and 205 at the maximum deflection angle by the reciprocating swing of the deflecting means 202. The magnitude of this maximum deflection angle is θ. Hereinafter, for the sake of explanation, it is assumed that the reflected light beam when the deflecting means 202 is not oscillated (neutral state) coincides with the optical deflection central axis 206. A periodic drive waveform is applied to the drive means of the deflecting means 202 that reciprocates around the rotation axis.

FIG. 2 is a schematic diagram showing a state in which the deflected light deflected (reflected) from the deflecting unit 202 of the optical deflector according to the present embodiment moves on the light receiving element 101 together with its trajectory. In FIG. 2, 102 and 103 are deflected light, 104 is a scanning locus of the deflected light, and 105 is a plurality of light receiving regions of the light receiving element (line sensor) 101. For simplification of explanation, it is assumed here that the deflected light 102 is scanned one-dimensionally, and moves along the locus 104 in the direction A as shown in FIG. As shown by 2 (b), it moves along the locus 104 in the direction B (the reverse direction of the direction A). It is assumed that the movement in the direction A and the movement in the direction B are periodically repeated (the deflecting unit 202 is reciprocating periodically).

The light receiving element 101 is disposed at a position where the deflected light can be detected (received) at a predetermined position X on the light receiving element 101. As shown in FIG. 2A, the time during which the deflected light 102 is located at a predetermined position X in the forward path is referred to as TA. Further, as shown in FIG. 2B, the time during which the deflected light 103 is located at a certain predetermined position X in the return path is referred to as TB. By detecting TA and TB, it is possible to calculate the reciprocating motion timing (deflection timing) of the deflecting unit with respect to the modulation timing of the drive signal (periodic repetitive signal) of the deflecting unit 202.

In this embodiment, in order to detect TA and TB, the light amount of the light source 201 is changed (modulated), and the light receiving element 101 detects the distribution of the light amount, thereby detecting the position of the deflected light. If the position of this deflected light is detected, the timing for modulating the amount of light is known, so that the times TA and TB at which the deflected light is located at a certain predetermined position X can be detected.

Details will be described below. First, the deflection timing of light deflection by the deflection means 202 of the present embodiment and the calculation method thereof will be described.

  First, the deflection timing will be described. FIG. 3 shows an example of a drive signal waveform (current waveform) applied to the drive unit of the deflection unit 202. The horizontal axis represents the application time (t), and the vertical axis represents the magnitude of the applied signal. (A) is a triangular waveform, (b) is a sine waveform. The deflection angle of the deflecting means 202 changes in the same manner as the waveforms of these applied signals. When the deflection means 202 is reciprocally swung by a periodic application signal as shown in FIG. 3, scanning of the deflection light on the plane P at a distance L from the deflection means 202 (the deflection light on the plane is detected). The position is referred to as scanning) and reciprocates on a scanning locus as indicated by reference numeral 207 in FIG.

This scanning position h (distance from the optical deflection central axis 206 on the plane P at a distance L from the deflecting means 202) is:
h = L × tan (θ (t)) (1)
It can be expressed by the following formula. Here, θ (t) is a deflection angle at which a light beam is deflected from the optical deflection central axis 206 by the deflecting means 202 at a certain time.

The deflecting means 202 has different scanning (deflection) characteristics due to changes in constituent members due to temperature changes, delays in the driving means, and the like. For this reason, even when the same applied drive waveform is used, the deflection timing (delay time with respect to the applied waveform) of the deflecting means is not constant. FIG. 4 shows an example of a waveform applied to the deflection unit and a deflection timing of the deflection unit. In FIG. 4A, the horizontal axis represents the application time, and the vertical axis represents the magnitude of the applied signal. The horizontal axis of FIG. 4B shows the same application time t as in FIG. 4A, and the vertical axis shows the deflection angle θ (t). A time delay (deviation) of the deflection timing with respect to the applied waveform is defined as a delay time Dc. As described above, the delay time Dc varies depending on the environment.

  Next, a method for detecting this deflection timing (deviation) will be described. In order to measure this delay time Dc, for example, a method of measuring the time when the deflection means reaches the maximum deflection angle (oscillation angle), a zero cross point (a point where the deflection means does not oscillate, or the maximum amplitude). It is conceivable to detect the time at which the rocking angle at (midpoint) is reached. However, when optical detection is performed, it is necessary to use an optical sensor that largely shields (covers) all scanning light in order to detect all scanning, or when a part of scanning is detected, the optical deflection axis. It is necessary to accurately align the optical sensor.

Here, as shown in FIG. 4B, the change in the deflection angle by the deflection means is a mode in which a waveform symmetrical with respect to the maximum deflection angle is periodically repeated (reciprocating motion. For example, sinusoidal waveform, triangular waveform Waveform). With this premise, the midpoint between the times TA and TB at which a certain deflection angle θX is reached coincides with the turnaround time during which the direction of reciprocation changes. Using this, the time TA and TB at which a certain deflection angle θX is detected in each of the reciprocating directions are detected, and the time TC at the midpoint between TA and TB is calculated as in equation (2), and the applied drive waveform The delay time Dc can be calculated by calculating the difference from the synchronization time (time at the reference point).

ここで、遅延時間Ｄｃは、印加波形の基準点の定義の仕方により変わる。勿論、偏向手段による偏向角の変化が、最大偏向角に対して線対称な波形が繰り返される態様ではなくて、非対称であってその非対称の比率が分かっていれば、上記式は比率による重みを付けた平均を取ることになる。

Here, the delay time Dc changes depending on how the reference point of the applied waveform is defined. Of course, if the change in the deflection angle by the deflecting means is not an aspect in which a waveform that is line-symmetric with respect to the maximum deflection angle is repeated, but is asymmetric and the ratio of the asymmetry is known, the above formula weights the ratio. I will take the average I gave.

In this method, the delay time Dc can be calculated without depending on a certain deflection angle θX, and thus there is no restriction on the placement accuracy of the optical sensor. Further, since it is only necessary to detect deflected light at a certain deflection angle θX (that is, deflected light at a certain position on the light receiving element), the deflected light at other portions can be used for purposes other than detection. According to the present embodiment, by detecting only the deflected light at an arbitrary deflection angle (if this is detected, the modulation timing of the light source is known, so the time (timing) of the deflected light at that deflection angle is It is possible to detect the delay time (deflection of deflection timing) of the deflection means with respect to the drive signal.

Next, a method for detecting times TA and TB at which a certain deflection angle θX is obtained will be described. First, a method for detecting the time TA at which a certain deflection angle θX is obtained will be described. In the present embodiment, a time TA at which a certain deflection angle θX is obtained is detected from the relationship between the deflection angles θ (tn) and θ (tn + 1) at a plurality of certain times tn and tn + 1.

FIG. 5 is a graph showing changes in the deflection angle by the deflection means during a certain period. In FIG. 5, the horizontal axis represents time t, and the vertical axis represents the deflection angle θ (t). As shown in FIG. 5, it is assumed that there is a certain deflection angle θX (time TA) between the deflection angles θ (tn) and θ (tn + 1). The relationship between these three deflection angles and time is a waveform obtained by extracting a part of the waveform applied to the deflection means (strictly, it is a part of the waveform of the change in the deflection angle by the deflection means, Is different, but it can be thought of as a similar shape. Therefore, when the applied waveform is a triangular waveform, the relationship between the three points is linear. In addition, when the applied waveform is a sinusoidal waveform, the relationship between the three points may be different from linear. However, considering the case where the time interval between time tn and tn + 1 is sufficiently small with respect to the period of the deflection means, the relationship between the three points can be regarded as linear. If the relationship between the three points satisfies these conditions, even if there is a certain deflection angle θX (time TA) outside the deflection angles θ (tn) and θ (tn + 1), the same applies. Can handle.

In the present embodiment, as shown in FIG. 5A, the times tn and tn + 1 are set such that the relationship between the three points can be regarded as linear. Utilizing the fact that these three points are in a linear relationship, a time TA at which a certain deflection angle θX is obtained can be calculated by the following equation.

Similarly, as shown in FIG. 5B, when there is a certain deflection angle θX (time TB) between the deflection angles θ (tm) and θ (tm + 1), a similar method is used. Is used to calculate a time TB at which a certain deflection angle θX is obtained.

By using the expressions (3) and (4) described above, the times TA and TB at which a certain deflection angle θX is obtained can be detected. However, in the method for optically detecting deflected light according to the present invention, the deflection is performed. The angle is not detected directly, but is detected by detecting the scanning position h of the deflected light described below.

The relationship between the deflection angle θ and the position of the deflected light on the light receiving element will be described. The relationship between the deflection angle θ and the scanning position h can be expressed by the following equation (5). Here, the scanning direction on the light receiving element is taken as a coordinate axis, and the position of the deflected light at the light receiving element at a certain deflection angle θ is P. Assuming that the origin of coordinates on the light receiving element is at the position of L = L ′, the position P on the light receiving element of the deflected light having a certain deflection angle θ can be expressed by the following equation.
P = L × tan (θ (t)) − L ′ (5)

Here, the positions of the deflection angles θn and θm on the light receiving element are Pn and Pm. Similarly, the positions at θn + 1 and θm + 1 are Pn + 1 and Pm + 1, and the positions at θX are PX. The relationship between the three points is a tan relational expression. If the deflection angle θn and θn + 1 are sufficiently small, it can be said that the three points are in a linear relationship. In the present embodiment, the deflection angles θn and θn + 1 are set so that these three points can be regarded as linear. Utilizing the fact that these three points are in a linear relationship, a time TA at which the position P on the light receiving element at a certain deflection angle θX is obtained can be calculated by the following equation.

Similarly, the time TB can be calculated by the following equation.

Eventually, as described above, when the time interval between the times tn and tn + 1 is sufficiently small with respect to the deflection cycle, the deflection angle θn and θn + 1 are sufficiently small, and the relationship between the three points. Can be regarded as linear, and by using the equations (6) and (7), it is possible to detect the times TA and TB when the deflected light of a certain deflection angle θX becomes the position PX on the light receiving element. Even when three or more modulation spots are formed around the same position X, by repeating the above calculation, the times TA and TB at which the deflected light with a certain deflection angle θX becomes the position PX on the light receiving element are obtained. It can be detected.

A method for not directly detecting the deflection angle will be described next. A method for detecting the position P of the deflected light on the light receiving element at a certain time t will be described. First, generation of a modulation spot by a light source for detecting the position of deflected light by a light receiving element will be described. The light receiving element 101 is disposed on a scanning locus 207 on the plane P at a distance L from the deflecting means 202. The arrangement position may be within the scanning locus 207. Here, for the sake of simplicity of explanation, it is assumed that they are arranged almost at the scanning center.

In order to detect the position of the deflected light on the light receiving element on the forward path and the return path in the predetermined time range, the modulated light formed by turning on and off the light source at a desired modulation timing is deflected, and the light receiving element 101 transmits the light. A method is used in which a luminance (light quantity) distribution forms a certain region (modulation spot) and position information of the modulation spot is measured. Specifically, as shown in FIG. 5, the light source is turned on at a predetermined time (timing) in each of the scanning period on the light receiving element 101 in the forward direction and the scanning period in the backward direction. The spots (high luminance portions generated by the scanning light) 102 and 103 corresponding to these times in the forward path and the backward path are formed on the light receiving element 101.

Thus, by observing the distribution of the total amount of charges induced by light on the light receiving element 101, the time of the deflected light at a predetermined position can be detected on the light receiving element, and the above formula is used from these data. Thus, the times TA and TB at which the position PX on the light receiving element is reached can be detected. Therefore, by using the light receiving element 101 that outputs a signal that can measure the positions of the spots 102 and 103 on the light receiving element 101, the delay time (deflection timing deviation) of the deflecting means with respect to the drive signal can be measured. .

  Next, a light receiving element that outputs a signal that can measure the interval on the light receiving element 101 will be described. The light receiving element 101 used in this embodiment needs to be a light receiving element 101 that can detect the position of the modulated deflected light as position information and detect the position interval. In the present embodiment, a line sensor (image sensor) composed of a plurality of light receiving regions 105 is used as the light receiving element 101. In such a configuration, it is necessary to include a light receiving element that is a photoelectric conversion unit, an accumulation unit for photoelectrically converted charges, and a transfer unit for accumulated charges.

In this case, since the light quantity of the deflected light (modulated spot) can be detected for each of the plurality of light receiving areas, the position of the deflected light on the light receiving element can be specified with high accuracy. At this time, it is not necessary to transfer the accumulated charges at a high speed in accordance with the scanning speed, and after the reciprocating modulation spots are generated on the light receiving element 101 (they do not overlap these modulation spots), A low-speed transfer can be performed. Therefore, even if the scanning speed v on the light receiving element 101 is increased (for example, even if one cycle of the applied drive waveform is shortened), the position of the modulation spot on the light receiving element can be detected, which is preferable. .

If this light receiving element is used, the light amount distribution of the modulation spot on the light receiving element 101 is accumulated as electric charges, and is output as position information for each of the plurality of light receiving regions 105. For this reason, the detection accuracy is not lowered due to a change in the delay of the detection circuit, which is a problem in the method of directly detecting the scanning (deflection) timing, and the position of the modulation spot can be detected with high accuracy. Further, the deflection timing of the deflection means for the drive signal can be detected with high accuracy from the data of the modulation timing of the light source.

Next, a method for controlling the deflection means to operate at a desired deflection timing will be described. FIG. 6 is a diagram schematically showing the control unit of the optical deflector according to the present embodiment. In FIG. 6, 208 is a deflected light beam from the deflecting means 202, 301 is a modulation signal generating means for the light source 201, 305 is a modulation signal for the light source 201, 306 is a detection signal from the light receiving element 101, 302 is a signal converting means, 307 is a deflection timing detection signal, 303 is a control signal generating unit, 308 is a control signal of the deflecting unit 202, 304 is a driving unit of the deflecting unit 202, and 309 is a driving signal of the deflecting unit 202.

The light source 201 is turned on and off repeatedly (modulated at a desired modulation timing) by a modulation signal 305 that is a signal of turning on and off from the modulation signal generating unit 301. The light beam 203 modulated by the modulation signal 305 is deflected and scanned by the deflecting means 202, and the modulated deflected light 208 is detected by the light receiving element 101. The modulation signal 305 is generated so that a plurality of modulation spots 102 and 103 are detected around the same position X in both the forward and backward scans shown in FIG. Information on a plurality of modulation spots on the forward path and the return path detected by the light receiving element 101 is sent to the signal conversion means 302 as an output signal 306.

The signal conversion means 302 is based on the detection signal 306 from the light receiving element, the modulation timing of the modulation signal 305 from the modulation signal generation means 301, and the timing data of the drive signal 309 from the drive means 304, and the deflection timing of the deflection means 202. And a scanning position shift signal 307 is output as a deflection timing signal. Based on the deflection timing signal 307, the control signal generation unit 303 changes the control signal 308 of the deflection unit 202 so that the deflection timing of the deflection unit 202 becomes a desired deflection timing. The control signal 308 of the deflection unit 202 is set so as to change the number of oscillations (frequency), phase, etc. of the movable plate in order to change the deflection timing of the mirror (movable plate) included in the deflection unit 202.

The driving unit 304 sets the period, phase, and the like of the driving signal 309 based on the control signal 308 and applies the driving signal to the deflecting unit 202. As described above, the optical deflector according to the present embodiment can control the deflection timing to be desired by detecting the modulated deflected light 208 by the light receiving element 101. Such a control method is, for example, a program for executing the above-described procedure in the signal converter 302 or the control signal generator 303 of an optical deflector having a deflector that reciprocally deflects light from a light source and scans the deflected light. It can be realized in software by implementing.

In the present embodiment, the following forms are also possible.
For example, after generating a forward modulation spot on the light receiving element 101, the accumulated charge is transferred, and after this transfer, a return modulation spot is generated, and then the charge is transferred. In that case, the scanning state of the deflecting means needs to be stable within a short period (a period of twice or more the charge transfer time). As a result, it is possible to detect the modulation spot of the forward path and the backward path separately, so that the algorithm for detecting the deflection timing can be simplified.

In the present embodiment, the light receiving element 101 is arranged on the scanning locus. However, the deflecting light of the scanning locus may be reflected and extracted by using a reflection mirror or the like and guided to the light receiving element for detection. . As a result, restrictions on the arrangement of the light receiving elements 101 are reduced, and a device using an optical deflector can be made compact. In the present embodiment, one light source is illustrated, but the present invention can also be applied to an optical deflector having a plurality of light sources, for example. At this time, if light rays from a plurality of light sources are deflected by a common deflecting means, the above-described detection may be performed using one of the plurality of light sources. In the present embodiment, the light source can be any light source capable of modulating the emitted light, such as a solid-state laser or gas laser having an external modulation means such as an LED or an AOM (acousto-optic modulator) in addition to a semiconductor laser. Anything can be used.

In this embodiment, the one-dimensional optical scanning in which the deflected light passes on the same path in the forward path and the return path has been described as an example. However, in the present invention, in addition, the path of the return path is the path of the forward path and the scanning direction. The present invention can also be applied to so-called two-dimensional optical scanning that passes through a slightly different portion in the direction perpendicular to the direction and in which the trajectory of the forward path and the backward path differ in the position in the perpendicular direction. In the present embodiment, the deflected light is scanned one-dimensionally. In that case, the deflected light is scanned in the longitudinal direction of the rotating cylindrical photoconductor, so that 2 on the surface of the photoconductor. The present invention can be applied as an exposure device for a photoreceptor of a so-called electrophotographic image forming apparatus that obtains an electrostatic latent image by scanning deflected light dimensionally. The present embodiment can also be applied to an image display device (projection device) such as a projector by scanning the deflected light two-dimensionally (see the later-described embodiment).

In these image forming apparatuses or image display apparatuses, light is turned on or off so as to correspond to the pixels constituting the image. The size of one pixel is not particularly specified, and is determined by an image to be formed. Although depending on the scanning speed, since the light emitting point moves in one direction during the lighting period, the shape of one pixel is changed by the scanning distance in addition to the actual scanning spot diameter. When using a light source with a different light quantity at the center and the peripheral part of the light emitting point (for example, different ways such as Gaussian distribution), even if the light source moves in one direction during the lighting period, the substantial pixel size is the light quantity. Only a large area (for example, a half value of the maximum light amount or a 1 / e ² area) may be considered. For example, in the case of a projector that can directly see an image with the human eye, the size of the pixel that moves during the lighting period may be defined as appropriate according to the human vision.

In the optical deflector according to the present embodiment, the deflection timing of the deflecting means 202 is changed by controlling the scanning timing of the forward and backward deflection light that moves in the reciprocating direction on the light receiving element to be constant. Thus, the positional deviation between the modulation pattern in the forward direction and the modulation pattern in the backward direction on the projection (ray scanning) plane can be eliminated. Therefore, in an exposure device for a photosensitive member of an electrophotographic image forming apparatus and an image display device that displays an image in a two-dimensional manner, a desired image can be displayed using scanning light in both directions. The exposure speed and display speed can be improved.

Further, the following deflection timing detection method is also possible.
For example, the light source may be modulated at a modulation timing for forming at least one modulation spot on the light receiving element in the scanning forward path, and the light source may be modulated at the modulation timing for forming at least one modulation spot on the light receiving element in the scanning backward path. . In this case, the on / off timing of the light source with respect to the drive signal to the deflecting means is little by little so that each modulation timing is a modulation timing for forming a modulation spot at the same position in the scanning direction on the light receiving element in the forward path and the return path. It is gradually changed (for example, two lighting timings with a constant time interval are shifted little by little as a whole and continued until the modulation timing at which a modulation spot is formed at the same position). Thus, the deflection timing of the deflection means relative to the drive signal to the deflection means is calculated according to the above formula, and the deflection means is controlled via the control means so that the deflection timing is deflected based on the information on the deflection timing. .

Also, the modulation timing of the light source in one of the scanning forward path and the backward path is a modulation timing for forming at least two modulation spots on the light receiving element, and the other modulation timing is a modulation timing for forming one modulation spot on the light receiving element. It is good. Also in this case, it is possible to detect the timing at which the modulation spot is formed at the same position in the scanning direction on the light receiving element (the position on the light receiving element where one modulation spot is formed at the other modulation timing) in the forward path and the return path. . Thus, similarly, the deflection timing of the deflection means with respect to the drive signal to the deflection means is calculated according to the above formula, and the deflection means is controlled via the control means so as to be deflected at a desired deflection timing based on this deflection timing information. Control.

A form in which one modulation spot is formed in each of the forward path and the return path is also possible if the following conditions are satisfied. In other words, even if the modulation spot formation positions are deviated, if the speed of the deflected light on the light receiving element is known, the timing of the modulation spot in the forward and return paths at the same position in the scanning direction on the light receiving element can be calculated. This is possible because the deflection timing of the deflection means can be detected by the above method. When the distance between the deflecting means and the light receiving element is fixed and the movement state of the deflecting means is obtained from the applied drive signal, such a form can be adopted.

(Second Embodiment)
The present embodiment relates to a method for specifying the position (center position) of modulated deflected light (modulated spot) on a light receiving element (line sensor) 101 composed of a plurality of light receiving regions 105. Others are the same as in the first embodiment.

  FIG. 7 is a diagram for explaining the present embodiment. FIG. 7A is a diagram showing a positional relationship between a position where one modulation spot 102 is formed on the light receiving element 101 and a plurality of light receiving regions 105. The deflected light is scanned in the left (right) direction with respect to the paper surface. Hereinafter, for the sake of explanation, a single modulation spot on the light receiving element 101 will be described. Of course, the present embodiment can be configured by performing a plurality of similar processes on a plurality of spots.

  FIG. 7B is a diagram showing the distribution of the amount of light irradiated on the light receiving element 101 in the positional relationship shown in FIG. The horizontal axis is the position on the light receiving element 101, and the vertical axis is the amount of light. As described above, the modulation spot has a symmetrical distribution (as an example, a so-called Gaussian distribution type whose center is bright and whose periphery is dark) with respect to the position where the light quantity is the largest.

  FIG. 7C shows signals detected from each of the plurality of light receiving areas 105 in the positional relationship shown in FIG. The horizontal axis indicates the position of the plurality of light receiving regions 105 shown so as to correspond to the position on the light receiving element 101, and the vertical axis indicates the magnitude of the detected signal. Hereinafter, in FIG. 7, the width of the plurality of light receiving regions 105 in the scanning direction is referred to as “n” light receiving region in order from the left, and the amount of light detected in the n th light receiving region is referred to as “Pn”.

Two position specifying methods in the present embodiment will be described with reference to FIG.
In the first position specifying method, the position of the light receiving area 105 that obtains the maximum amount of light received in a plurality of light receiving areas is regarded as the position coordinate of the modulation spot 102. For example, in FIG. 7C, the fifth light receiving region 105 is regarded as the position coordinates, and it is detected that the modulation spot center is at a position “(5-0.5) × w” from the left end of the light receiving element 101. . Here, the detection accuracy is determined by the relationship between the scanning speed v on the light receiving element 101 and the width w of the plurality of light receiving regions 105 of the light receiving element 101 in the scanning direction. When the scanning speed v is constant, the detection accuracy improves as the width w in the scanning direction of the plurality of light receiving regions 105 decreases.

  According to the first position specifying method, the process of specifying the spot position on the light receiving element 101 can be simplified, and the time required for the process and the load on the part to be processed can be reduced. Further, the detection accuracy can be improved by shortening the width w of the plurality of light receiving regions 105 in the scanning direction.

  The second position specifying method is a method for specifying the spot position from the distribution of detection signals in the plurality of light receiving regions 105. It can be considered that the light distribution of the modulation spot detected by the light receiving element 101 is a symmetrical distribution with respect to the position C having the largest light amount. Therefore, when the position C with the largest light quantity does not coincide with the center of the light receiving area 105 or the boundary of the light receiving area 105, the detection signals from the respective light receiving areas 105 are asymmetrical (for example, FIG. ) Detection signal). Using this, the position coordinates “(n−1) × w” of each light receiving area and the received light amount Pn are integrated, and the integrated value “Σ (n−1)” is applied to the light receiving area 105 where the spot 102 exists. Xw x Pn "is summed. Then, the position coordinate is specified by dividing the sum by the total received light amount “ΣPn” in the light receiving region where the spot exists ((Σ (n−1) × w × Pn) / ΣPn). As a result, the spot center can be detected with a position resolution of a plurality of light receiving area widths w or less. This method is preferable for specifying the position of the deflected light spot in a configuration in which the deflected light spans the plurality of light receiving regions 105. Of course, this method is used even when the position C where the light quantity is the largest coincides with the center of the plurality of light receiving areas 105 or the boundaries of the light receiving areas 105.

  According to the second position specifying method, since the position resolution equal to or less than the width w of the plurality of light receiving regions 105 can be realized, the light receiving element 101 having the wide width w (smaller than the detected spot width) of the plurality of light receiving regions 105 is provided. Even if it is used, the position can be specified with high accuracy.

(Third embodiment)
This embodiment is an example using a light receiving element (area sensor) 101 in which a plurality of light receiving regions 105 are two-dimensionally arranged. The rest is the same as in the first or second embodiment.

  FIG. 8 is a schematic diagram for explaining a plurality of light receiving regions 105 included in the light receiving element according to the present embodiment. In FIG. 8, the light receiving element 101 has a plurality of light receiving regions 105 that are arranged in two dimensions at equal intervals in the vertical and horizontal directions (the trajectory direction 104 and the direction orthogonal thereto).

  As in the present embodiment, by arranging a plurality of light receiving regions 105 in a two-dimensional manner, the light quantity distribution of the modulation spot 102 can be detected in a two-dimensional manner, so that the shape of the modulation spot can be grasped more accurately. In addition, the number of target data increases when the position specifying method of the second embodiment is used. Therefore, the use of this embodiment makes it possible to specify the position of the modulation spot with higher accuracy.

  The light receiving element 101 of the present embodiment can use a general-purpose CCD area sensor or a CMOS area sensor used for image capturing, so there is no need to design a special sensor, and this is realized at a low cost. it can.

In the present embodiment, the light receiving areas arranged in the vertical and horizontal directions are given as the light receiving areas arranged two-dimensionally. However, in addition to the configuration in which the light receiving areas are arranged in a honeycomb shape, the scanning locus direction or the locus It is also possible to use a configuration in which the columns and rows of the light receiving areas are nested in the intersecting direction, or a structure in which the light receiving areas have a circular shape, a parallelogram shape, a triangular shape, a rhombus shape, a trapezoidal shape, and other polygonal shapes. .

(Fourth embodiment)
In the present embodiment, the deflected light entering the light receiving element is collected by a lens. The rest is the same as any one of the first to third embodiments. FIG. 9 is a cross-sectional view of a plane including the deflected light deflected from the deflecting means of the optical deflector according to the present embodiment. In FIG. 9, reference numeral 209 denotes a lens.

The lens 209 is disposed at a distance L. The light receiving element 101 is disposed at the focal length f of the lens 209. The light deflected by the deflecting means 202 is condensed by the lens 209 and the width of the modulation spot is reduced. In addition, since the light is further deflected by the lens 209, the center position of the modulation spot changes as compared with the first embodiment.

The scanning position h on the light receiving element 101 and the deflection angle θt at a certain point in time are:
h = f × tan (θt) (8)
It can be expressed by the following formula. From equation (8), the scanning speed v on the light receiving element 101 can be increased by increasing the focal length f of the lens 209 regardless of the distance of L. For this reason, the position change of the modulation spot in the round trip scanning becomes large, and the position detection accuracy is improved.

  In addition, since the spot position does not depend on the distance L, the use of the lens 209 having a shorter focal length f and a shorter focal length f facilitates the arrangement of the respective elements and enables miniaturization. A lens may be used as a component of the optical deflector of the present embodiment. That is, a lens may be installed at a light passage portion such as a housing of an optical deflector. Alternatively, the lens may be integrally provided on the light receiving element. If the deflected light is collected on the light receiving element 101 using the lens 209 as in the present embodiment, the light receiving element 101 can accurately specify the position of the deflected light as described above. Furthermore, the entire deflector can be reduced in size.

(Fifth embodiment)
The present embodiment relates to an optical deflector using a deflecting means 202 using a resonance phenomenon. Others are the same as those in the first embodiment.

  When a resonance type deflector is used for the deflecting means 202, a wide deflection angle can be obtained with the same drive energy by matching the mechanical resonance frequency fc of the resonance type deflector with the drive frequency fd. However, the mechanical resonance frequency fc of the deflector changes greatly due to changes in the deflector environment such as temperature, and the scanning (deflection) timing of the deflector 202 changes. Therefore, in order to keep the scanning state constant, it is necessary to perform control to make the resonance frequency fc of the resonance type optical deflector coincide with the drive frequency fd.

  FIG. 10 is a graph showing the frequency characteristics of the resonant deflector. In FIG. 10A, the horizontal axis represents the frequency fd of the drive signal for oscillating the resonant deflector, and the vertical axis represents the deflection width (maximum deflection angle) of the deflection angle (oscillation angle) of the resonant deflector. In this figure, the frequency at which the maximum deflection angle takes the maximum value is the resonance frequency fc (an ideal case where no delay in the drive circuit of the deflecting means 202 is considered).

  In FIG. 10B, the horizontal axis is the frequency fd of the drive signal for oscillating the resonant deflector (corresponding to the horizontal axis in FIG. 10A), and the vertical axis is the phase of the phase from the synchronizing signal of the drive frequency fd. It is a delay. Note that the origin (0 deg) on the horizontal axis of this phase delay varies depending on how the synchronization signal of the drive frequency fd is generated. Thus, in the resonance type optical deflector, when the drive frequency fd and the resonance frequency fc are different, the phase changes and the scanning (deflection) timing changes.

  The relationship between both figures is maintained when the resonance frequency fc of the deflector is constant. Even when the resonance frequency fc changes due to environmental changes such as temperature, the respective relationships in FIG. 10 are substantially maintained (that is, the similar shapes of curves such as the slope and width of each curve and the height of the peak are With little change), only the parameter of the driving frequency fd on the horizontal axis in FIG. 10 changes. When this is used, the resonance type deflector is driven at a drive frequency fd such that the scanning timing (phase) is always constant (the deflection timing for the drive signal is detected by the method of the present invention, and the drive signal is based on the detected timing). The drive frequency fd and the resonance frequency fc can be made to coincide with each other.

  Here, the greater the value representing the driving efficiency (resonance Q value), the greater the influence on the phase (scanning timing), even with the same frequency difference, so the frequency must be changed in finer increments. Thus, in the present embodiment, by detecting the deflection timing of the reciprocating scan, it is possible to control the drive frequency fd to follow the resonance frequency fc of the resonance type optical deflector, and to keep the scanning timing constant.

  FIG. 11 is a diagram showing the change over time of the drive signal 309 of the deflecting means 202 of the resonance type optical deflector and the deflection angle of the resonance type optical deflector corresponding to the drive signal 309. In FIG. 11A, the horizontal axis represents time, and the vertical axis represents the magnitude (for example, voltage) of the drive signal 309 of the deflecting means 202. FIG. 11B is a graph showing the deflection angle θt at each time of the deflecting means 202 on the vertical axis with the horizontal axis corresponding to the time axis corresponding to the horizontal axis in FIG.

  As shown in FIG. 11A, when the drive waveform is a sine wave, if the drive frequency fd and the resonance frequency fc coincide with each other, as shown in FIG. A phase delay of 90 deg occurs with respect to the drive waveform. At this time, a phase offset of 180 deg may occur depending on how the deflection angle of the deflecting means 202 is determined (depending on which direction the tilt is made with respect to the rotation axis is positive or negative). Using this characteristic, the control of following the drive frequency fd to the resonance frequency fc is performed by controlling the frequency of the drive waveform so that the deflection timing with respect to the drive waveform detected by the above method maintains such a phase delay. It will be.

  In the case of using a resonance type optical deflector, the deflection angle θt changes to a sine wave shape with respect to time even in the case of a triangular, rectangular, or sawtooth drive waveform other than a sine wave shape. Therefore, since the scanning (deflection) time in the forward path and the backward path becomes equal, if only the scanning light on one side of the forward path and the backward path is used, the time that can be used for modulation of the light source 201 is shortened (less than half), and the light utilization efficiency is improved. descend. In order to solve this, the resonance type optical deflector needs to perform modulation using reciprocating scanning light.

  When this embodiment is used, when a resonance type deflector is used as the deflecting means 202, it is possible to perform control for making the forward / return scan timing constant. As a result, the resonance type deflector capable of obtaining a large deflection angle with low power can be used for applications using reciprocating scanning light. As a result, an optical deflector with low power consumption and high light utilization efficiency can be provided.

  In the present embodiment, control for making the drive frequency fd coincide with the resonance frequency fc has been described. However, control for keeping the difference between the drive frequency and the resonance frequency at a constant value can be performed so as to have an arbitrary relationship. In this case, since the rate of change in scanning timing with respect to the frequency deviation from the desired frequency is small (the portion outside the peak in FIG. 10A is used, the rate of change in the maximum deflection angle with respect to the frequency deviation is Frequency follow-up control becomes easier.

(Sixth embodiment)
The present embodiment relates to a method for generating a modulation spot for detecting the position of deflected light on a light receiving element and a method for detecting it. The rest is the same as any one of the first to fifth embodiments. FIG. 12 is a diagram for explaining a modulation spot generation method according to this embodiment.

  FIG. 12A shows the waveform of the drive signal 309 applied to the deflecting means 202. The horizontal axis represents time, and the vertical axis represents the magnitude of the applied signal. Here, a drive waveform having a triangular wave shape will be described as an example. FIG. 12B shows a modulation signal 305 for modulating the light source 201 (turning on or turning on, turning off or turning off). The horizontal axis represents time corresponding to the horizontal axis in FIG. 12A, and the vertical axis represents the pattern of the modulation signal 305. Here, the modulation signal 305 is an OFF signal in a steady state, and becomes an ON signal when modulation is performed to generate a modulation spot on the light receiving element 101.

  The modulation signal 305 is generated once for each period in which the deflecting means 202 is deflected in both directions on the plane including the light receiving element 101, and the modulation spots 102 and 103 are separated on the light receiving element 101. (See FIG. 2). In this case, the ON signal timing is shifted little by little to find the timing at which the modulation spot comes to the same predetermined position on the light receiving element 101, and the deflection timing is detected using the above equation (2). do it.

In the above method, the drive signal is a triangular wave, but other drive waveforms are also used. FIGS. 13A and 13B show an example of the modulation signal 305 with the sinusoidal drive signal 309 (the vertical and horizontal axes are the same as those in FIG. 12).

  Further, although the number of modulation spots generated on the light receiving element 101 in each of the forward path and the return path is described as one, a plurality of modulation spots may be used for each reciprocating scanning direction. When a plurality of modulation spots are detected by the light receiving element 101, a plurality of positions can be measured and used at a time. Therefore, the detection speed is improved. In this case, a deflection timing detection method as described in detail in the first embodiment may be used.

  When the optical deflector of the present embodiment is used for an exposure apparatus or a display apparatus of an image forming apparatus, it is set so that reciprocal exposure or display is correctly performed when the deflection timing is a predetermined value. Thereby, high-quality image formation using reciprocating scanning light can be performed.

(Seventh embodiment)
The optical deflector according to the present embodiment relates to an optical deflector that projects deflected light onto a projection surface in a two-dimensional manner. Others are the same as any one of the first to sixth embodiments.

  FIG. 14 is a diagram schematically showing an optical deflector according to the present embodiment. In FIG. 14, 211 is a second deflecting unit, 210 is a scanning locus formed on the reflection plane of the second deflecting unit 211 by the deflecting unit 202, 212 is light deflected by the second deflecting unit 211, Reference numeral 213 denotes a certain plane, 214 denotes a range scanned by the deflected light 212 on the certain plane 213, and 215 schematically represents the trajectory of the scanning line on the certain plane 213. The configuration used for the control shown in FIG. 6 is not shown in FIG.

  The deflecting unit 202 and the second deflecting unit 210 deflect light in the horizontal direction and the vertical direction, respectively. Therefore, the range in which the deflected light 212 spreads becomes a two-dimensional area. The deflection means 202 and the second deflection means 210 have different deflection (swinging) speeds. Specifically, in FIG. 14, when comparing two deflection means, the deflection means 202 deflects at a relatively high speed (at a high frequency), and the second deflection means 210 deflects at a relatively low speed (at a low frequency). I do. The relationship between the two may be reversed.

  Further, a high-definition image can be displayed by using a resonance type deflector as a deflecting means for performing relatively high-speed deflection. This is because the resonant deflector can perform high-speed deflection. The light beam 203 modulated and emitted by the light source 201 is deflected by the deflecting means 202 between the light beams 204 and 205 having the maximum deflection angle (at the maximum deflection angle). The second deflecting unit 211 deflects the trajectory 210 scanned on the reflecting surface of the second deflecting unit 211 by the deflecting unit 202 as indicated by the light beam 212, and on the plane 213 arranged at an arbitrary position, A scanning range extending in a range indicated by reference numeral 214 is generated. Here, the locus of the scanning light within the scanning range 214 of a certain plane 213 is schematically shown as 215. The light receiving element 101 is arranged at a desired position in the scanning range 214. Specifically, it may be arranged on a certain horizontal scanning locus.

FIG. 15 is a diagram schematically showing the light receiving element 101 arranged in the scanning range 214 and the display area 220 used for image formation in the present embodiment. The scanning range 214 includes a display area 220 and an area where the light receiving element 101 is disposed. When the scanning is started from the scanning point S1, the deflected light 212 moves in the horizontal scanning direction X from the forward path to the backward path, and is gradually scanned from the upper part to the lower part in the vertical scanning direction Y. The deflected light scanned up to the scanning point S2 is returned again to the scanning point S1, and the same scanning is repeated. The light receiving element 101 arranged on the scanning line 215 is arranged so that the deflected light 212 passes.

  From the above, the optical deflector according to the present embodiment is a two-dimensional image forming apparatus using a resonant deflector, and the modulated light modulated by the light receiving element 101 at a desired modulation timing while forming an image. The positional distribution of the light quantity is detected, and the deflection timing of the resonance type deflector is detected based on this data. Based on this, the drive frequency of the resonant deflector can be appropriately controlled to maintain the deflection timing in a desired state, so that a high-quality image can be obtained using the reciprocating scan of the resonant deflector. Can be displayed.

  In this embodiment, the light receiving element 101 is disposed in the scanning range 214. However, using a reflecting mirror or the like, scanning light (deflected light) in a certain scanning range 214 is taken out and used as the light receiving element. You may guide and detect. Alternatively, the deflection light between the deflection unit 202 and the second deflection unit 210 may be guided to the light receiving element and detected. In this embodiment, the area where the light receiving element 101 is provided and the display area 220 are separate areas. However, the presence of the light receiving element 101 or a reflection mirror for detection of the light receiving element 101 visually affects the image. If not given above, an area in which the light receiving element 101 and the detection mirror are provided may be provided in the display area 220.

  Further, in a region other than the display region 220, the deflected light 212 may be light that is emitted only when passing over the light receiving element 101. That is, the deflected light 212 only needs to be emitted at least on the scanning locus on the light receiving element 101.

(Eighth embodiment)
The optical deflector according to the present embodiment has a light receiving element 101 therein. The rest is the same as any one of the first to seventh embodiments.

  This embodiment has the two deflecting means shown in the seventh embodiment, and an optical deflector is used as an image forming apparatus for displaying a two-dimensional image by horizontally scanning and vertically scanning the deflected light. It is the form used. Hereinafter, only differences from the seventh embodiment will be mainly described.

  FIG. 16 schematically shows an optical deflector according to the present embodiment. In FIG. 16, 213 is a frame of the optical deflector, 214 is a scanning area when the frame is a certain plane, 220 is a display area, and 215 is a scanning locus in the display area 220. The light receiving element 101 is disposed on the frame body 213 in the scanning region 214. Thereby, the plane including the display region 220 and the plane including the light receiving element 101 can be made different planes.

  Further, since the distance L from the light receiving element 101 and the deflecting means 202 and the distance from the light deflection central axis 206 at the position where the light receiving element 101 is arranged can be fixed, the speed of the deflected light on the light receiving element 101 can be calculated. The timing at which the modulation pattern is generated on the light receiving element 101 can be easily calculated from the arrangement. That is, since the speed of the deflected light on the light receiving element can be known, if the light source is modulated at such a modulation timing that one modulation spot is formed on the light receiving element in the forward path and the return path, the same on the light receiving element. The spot timing on the forward path and the return path at the position can be calculated, and the deflection timing of the deflection means with respect to the drive signal can be detected.

  According to the present embodiment, the optical deflector according to the present embodiment is mounted on the front if the observer can observe the image formed in the display region 220 while being positioned between the frame 213 and the image. It can be applied as an image display device such as a projector of a type.

  In addition, according to the present embodiment, since display area 220 can be projected onto an arbitrary plane, the display area can be arbitrarily selected. Therefore, this projector is used as an apparatus that can select an arbitrary plane without restricting the projection plane on which image display is performed. If the observer can observe the image formed in the display area 220 from the side opposite to the display surface of the display area 220, the light deflector of the present embodiment can be used as an image display device such as a rear projector. it can.

  Further, it can be applied to an image display device such as a retina direct-drawing display device or a head-mounted display. Although the optical deflector of the present embodiment does not have the frame body 213 as an essential configuration, the light receiving element 101 can be positioned if the light receiving element 101 is fixedly disposed on the frame body 213. Preferred for reasons.

  In addition, the frame body 213 is preferable in order to favorably limit the display area 220 by blocking unnecessary light for display. Therefore, it is preferable to use the frame body 213 in which the light receiving element 101 is arranged as a component of the optical deflector of the present embodiment.

It is sectional drawing in the plane containing the deflection | deviation light deflected by the deflection | deviation means 202 of the optical deflector concerning embodiment of this invention. It is a schematic diagram showing a state where the deflected light deflected (reflected) by the deflecting unit of the optical deflector according to the embodiment of the present invention reciprocates on the light receiving element together with its scanning locus. It is a figure which shows the example of the drive waveform (drive signal) applied to a deflection | deviation means. It is a figure which shows the example of the drive waveform applied to a deflection | deviation means, and the deflection | deviation timing (deviation) of the deflection | deviation means with respect to this drive waveform. FIG. 6 is a graph showing an example of a change in the deflection angle of the deflection means during a certain period. It is a figure which represents typically the control system of the optical deflector concerning 1st Embodiment. It is a figure explaining the some light receiving element which the light receiving element concerning 2nd Embodiment has. It is a schematic diagram explaining the some light receiving element which the light receiving element concerning 3rd Embodiment has. It is sectional drawing in the plane containing the deflection | deviation light deflected from the deflection | deviation means of the optical deflector concerning 4th Embodiment. It is a graph which shows the frequency characteristic of the resonance type | mold deflector of the optical deflector concerning 5th Embodiment. It is a figure which shows the time change of the deflection | deviation angle of the resonance type optical deflector corresponding to the drive signal 309 of the resonance type optical deflector of the optical deflector concerning the 5th Embodiment corresponding to the drive signal 309. It is a figure explaining the production | generation method of the modulation spot on the light receiving element in the optical deflector concerning 6th Embodiment. It is a figure explaining the production | generation method of another modulation spot on the light receiving element in the optical deflector concerning 6th Embodiment. It is a figure which shows typically the optical deflector concerning 7th Embodiment. It is a figure which represents typically the light receiving element 101 and the display area 220 which are arrange | positioned at the scanning range 214 of the optical deflector concerning 7th Embodiment. It is a figure which shows typically the optical deflector concerning 8th Embodiment. It is a figure which shows the conventional optical deflector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light receiving element 102, 103 Deflection light 201 Light source 202 Deflection means 203 Emitted light beam 208 Deflection light 301 Modulation signal generation means (light source modulation means)
302 Signal conversion means (detection means)
303 Control signal generating means (control means for deflection means)
304 Deflection means drive means 305 Modulation signal 306 to light source Positional distribution detection signal 307 formed on light receiving element 307 Deflection timing signal 308 Control signal 309 for deflection means drive means Deflection means drive signal

Claims (13)

A detection device for detecting a deflection timing of a deflecting means in an optical deflector having a deflecting means for reciprocally deflecting light from a light source and scanning the deflected light. When the light source is arranged and modulated at the first modulation timing, the positional distribution of the light amount formed on the light receiving element in the forward path in which the deflected light moves in one direction is measured, and at the second modulation timing. Measuring means for measuring the positional distribution of the amount of light formed on the light receiving element in the return path in which the deflected light moves in a direction almost opposite to the one direction when the light source is modulated, the modulation timing and the corresponding timing A detection apparatus comprising: a detection unit configured to detect a deflection timing of the deflection unit with respect to a drive signal of the deflection unit based on data on a positional distribution of the light amount. The first modulation timing is a modulation timing for forming at least one modulation spot on the light receiving element in the forward path, and the second modulation timing is for forming at least one modulation spot on the light receiving element in the return path. The detection device according to claim 1, wherein the modulation timing is a modulation timing. 3. The detection device according to claim 2, wherein the first and second modulation timings are modulation timings for forming modulation spots at the same position in the scanning direction on the light receiving element in the forward path and the backward path, respectively. 4. The detection apparatus according to claim 3, wherein the first and second modulation timings are modulation timings that are achieved by gradually changing the light on / off timing of the light source with respect to the drive signal to the deflecting means. The detection means detects the deflection timing of the deflection means by averaging the time during which the modulation spot is formed at the same position in the scanning direction on the light receiving element in the forward path and the return path based on the measurement data of the measurement means. The detection device according to claim 3 or 4. The first and second modulation timings are modulation timings for forming at least two modulation spots on the light receiving element, and the other modulation timings are modulation timings for forming at least one modulation spot on the light receiving element. The detection device according to claim 1. The detection means calculates a time for forming a modulation spot at the same position in the scanning direction on the light receiving element in the forward path and the return path based on measurement data of the measurement means, and averages the calculated values. The detection device according to claim 6, wherein a deflection timing of the deflection unit is detected. The light receiving element is composed of a plurality of light receiving regions, means for converting light incident on the light receiving region into electric charges, means for accumulating the generated charges for each region for a certain period, and the accumulated electric charges in the regions. The detection device according to claim 1, wherein the detection device is a light receiving element having means for transferring each time. 9. The optical deflector comprising: the detecting device according to claim 1; and a control unit that controls the deflecting unit so that the deflecting unit is deflected at a desired deflection timing based on the detected deflection timing. 10. The optical deflector according to claim 9, wherein the control means controls the deflection timing of the deflection means from the synchronizing signal of the drive signal to the deflection means to be held at a desired constant value. The optical deflector according to claim 9, wherein the deflecting unit is a resonant optical deflector, and the control unit controls the deflecting unit to be held in a desired resonance state. 12. An image forming apparatus comprising the optical deflector according to claim 9, wherein the deflecting unit is controlled during a non-image forming period. A detection method for detecting a deflection timing of a deflecting means in an optical deflector having a deflecting means for reciprocally deflecting light from a light source and scanning the deflected light. When the light source is modulated at the first modulation timing, the positional distribution of the amount of light formed on the light receiving element in the forward path in which the deflected light moves in one direction is measured, and at the second modulation timing When the light source is modulated, the positional distribution of the amount of light formed on the light receiving element in the return path in which the deflected light moves in the direction almost opposite to the one direction is measured, and the modulation timing and the position of the corresponding amount of light are measured. A detection method comprising: detecting a deflection timing of a deflection unit with respect to a driving signal of the deflection unit based on data of a spatial distribution.

Images