Abstract:
An objective lens of an optical head is cleaned with a cartridge accommodating a cleaning disk with a brush thereon. The cleaning disk is rotated in apparatus to clean the surface of objective lens provided on the optical head. Simultaneously with causing the rotation of the cleaning disk by driving a spindle motor, the lens is moved toward and away from the disk by driving a lens actuator. Additionally, simultaneous reciprocation of a carriage carrying the optical head toward alternate inner and outer disk peripheries may be caused. Further, the operation of reciprocating the objective lens toward the inner and outer disk peripheries and the operation of moving the lens toward and away from the cleaning disk with the lens actuator may be performed in combination.

Description:
RELATED APPLICATION 
     This is a continuation of application Ser. No. 08/084,006, filed on Jun. 29, 1993 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to optical disk apparatuses used with replaceable optical disks each accommodated in a cartridge and, more particularly, to an optical disk apparatus, in which an optical head objective lens is cleaned using a cleaning disk. 
     In a usual optical disk apparatus, information is recorded by projecting a beam from a laser diode onto a rotating optical disk. The recorded information is reproduced through detection of changes in the intensity of the reflected beam from the optical disk, polarization surface and other characters. Such optical disk apparatus provides for high information recording density, and thus its applications to external memories of information processing systems are expected. 
     Normally, a laser beam emitted from the laser diode is focused by an objective lens provided on an optical head mounted on a carriage onto the optical disk. The reflected beam from the optical disk is also focused by the objective lens to be incident on a light-receiving element for conversion to an electric signal. The objective lens is driven for focus control by a lens actuator in the optical axis directions. Further, the carriage carrying the optical head is by a voice coil motor in radial directions of the disk for position control of the optical head to a desired position. The objective lens is found close to the disk surface, typically several millimeters apart. Therefore, its surface is readily contaminated by winds produced by the rotation of the optical disk. Contamination of the objective lens surface results in reduction of the laser beam intensity, scattering of the beam and disturbance of the laser beam intensity distribution, thus having significant adverse effects on the write performance, the read performance and further the servo performance such as focus servo and track servo. A method of cleaning the objective lens surface uses a cleaning disk. With the cleaning disk, the cartridge case and disk resemble those of the normal optical disk cartridge. A difference is that the cleaning disk has a brush provided on part of its surface. The cartridge accommodating the cleaning disk, like the normal optical disk cartridge, is loaded in the apparatus, and the disk is rotated, whereby the objective lens surface is cleaned by the brush on the disk. 
     However, in the cleaning of the objective lens with such a cleaning disk, the objective lens is held stationary, and its surface is rubbed by the brush of the rotating disk. This means that only part of the brush can be used for the cleaning. Therefore, the brush is liable to be deformed, and also it is contaminated only locally. Further, the rotating brush touches the stationary objective lens in a fixed fashion, and therefore the lens can not be perfectly cleaned. 
     Meanwhile, when writing data in the optical disk, the desired track is first erased by projecting a laser beam thereonto in the presence of an external magnetic field applied in the erase direction. Then, data is written by projecting a data-modulated laser beam in the presence of an external magnetic field applied in the write direction. Further, a verify read is done to confirm the written content. Therefore, with an optical head which projects a single laser beam, the optical disk has to be rotated by at least three rotations in the write operation. To permit this write operation at an increased speed, there is provided an optical disk apparatus, which has three exclusive laser diodes for erasing, writing and reading, and in which two objective lenses, one for erasing and the other for writing and reading, are mounted together with respective lens actuators on the optical head. With such a two-actuator structure optical disk apparatus, the erase, write and read operations can be performed during one rotation of the disk, and thus the write operation speed can be increased by three times compared to the case of the ordinary optical disk apparatus. However, in such a two-actuator optical disk apparatus the two lens actuators are disposed in the same radial position of the disk and considerably close to the disk in the circumferential direction thereof. Therefore, the cleaning of the succeeding objective lens with the cleaning disk with the brush is obstructed by the preceding one. Therefore, unlike the single-lens structure, the lenses can be cleaned only insufficiently. 
     SUMMARY OF THE INVENTION 
     The invention seeks to provide an optical disk apparatus, which permits sufficient cleaning of objective lenses. 
     According to the invention, when cleaning the surface of an objective lens provided on an optical head by causing rotation of a cleaning disk with a brush, a lens actuator is driven to move the lens toward and away from the cleaning disk simultaneously with the rotation thereof. Alternatively, the cleaning control may be such as to cause reciprocations of a carriage carrying the optical head toward the inner and outer peripheries of the cleaning disk simultaneously with the rotation thereof. Further, the operation of reciprocating the carriage carrying the optical head toward the inner and outer disk peripheries and the operation of moving the objective lens toward and away from the cleaning disk with a lens actuator may be performed in combination. As a further alternative of the cleaning control, the cleaning disk may be rotated alternately in the normal and reverse directions. 
     With an optical head having a two-actuator structure, simultaneously with moving one objective lens toward the disk surface with one lens actuator, the other objective lens is moved away from the disk surface with the other lens actuator, and vice versa, these operations being performed alternately. 
     The cleaning operation is performed after the cartridge accommodating a cleaning optical disk has been inserted in the apparatus and loaded on a spindle motor, and it is started in response to the issuance of a cleaning command from an upper order system. Further, the cleaning cartridge case may be provided with a peculiar physical shape, for instance recesses or holes, indicative of that the cartridge is for cleaning, and the cleaning operation may be started automatically when it is determined from the physical shape that the loaded cartridge is for cleaning. As the physical shape indicative of the cleaning cartridge, it is desirable to utilize media sensor holes provided on the case surface at specific positions thereof. 
     With such optical disk apparatus according to the invention, the objective lens surface can be cleaned sufficiently by repeatedly moving the objective lens with the lens actuator or actuators in the focus direction repeatedly to to bring the lens or lenses toward and away from the brush on the cleaning disk while causing rotation thereof. Further, by causing the optical head carried on the carriage in the radial directions of the disk with a head actuator, the entire brush can touch the objective lens or lenses to clean the same, that is, the entire brush can be used for the cleaning, and this eliminates or reduces local deformation or contamination of the brush. Further, in the case of the two-actuator structure, by alternately moving the two objective lenses in the focus direction with the two actuators, each lens can be cleaned without being obstructed by the preceding lens. Thus, the two objective lenses can be sufficiently cleaned. 
     The above and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description with when the same is read with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic representation of the invention; 
     FIG. 2 is a view showing the internal structure of the optical disk apparatus according to the invention; 
     FIG. 3 is a back side perspective view showing a carriage shown in FIG. 2; 
     FIG. 4 is a view showing lens actuators mounted on the carriage shown in FIG. 2; 
     FIG. 5 is an exploded perspective view showing a lens actuator shown in FIG. 5; 
     FIG. 6 is a a view showing a cleaning disk used according to the invention; 
     FIG. 7 is a view showing a cleaning disk cartridge used according to the invention; 
     FIG. 8 is a flow chart illustrating a routine according to the invention; 
     FIG. 9 is a flow chart illustrating a subsequent routine to that shown in FIG. 8; and 
     FIG. 10 is a flow chart illustrating an automatic cleaning routine according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows an embodiment of the optical disk apparatus with cleaning control according to the invention. A disk  10  for cleaning the objective lens, shown by the phantom circle, is loaded and then chucked on a spindle motor  18 . The spindle motor  18  is disposed in a box-like carriage. An optical head  14  is provided on one side of the carriage, and on the other side thereof is provided a voice coil motor  24  which serves as a head armature. In this embodiment, the optical head  14  has two lens actuators  20 - 1  and  20 - 2 . 
     FIG. 2 shows the internal structure of the optical disk apparatus including the optical head. The carriage  98  is disposed movably on a support frame  96  provided in a housing  94 . The carriage  98  carries an optical head movable part  14 - 1  provided on the right side and a voice coil motor  24  provided on the left side. The support frame  96  has an inner periphery and an outer periphery stopper  95  and  97  provided on the left and right sides, respectively. The carriage  98 , as shown from the back side in FIG. 3, has a central rectangular cavity with the spindle motor  18  disposed therein. The cleaning disk  10  which is accommodated in a cartridge  26 , is chucked by loading on the shaft of the spindle motor  18 . The cleaning disk  10  has a brush  12  provided on the side of the optical head movable part  14 - 1 . The cartridge  26  is chucked on the shaft of the spindle motor  18  by a loading mechanism when it is inserted into the housing  94  by pushing and opening a door  102  thereof. 
     Further, as is clearly shown in the back side view of FIG. 3, a light-emitting diode  32  is mounted on one side of the bottom of the carriage  98 , and on the stationary side a position sensor  34  is disposed such as to face the position detecting diode  32 . The position of the carriage  98 , i.e., the position of a beam in the optical head movable part  14 - 1  mounted on the carriage  98 , can be detected by the light-emitting diode  32  and position sensor  34 . The optical head movable part  14 - 1  provided on the carriage  98  has a light incidence window  104 , and an optical head stationary part  14 - 2  is disposed on the stationary side as shown in FIG. 2 such that it faces the light incidence window  104 . In the movable part  14 - 1  of the head a head optical system is mounted, which includes at least an objective lens and a lens actuator. The other components of the optical system, such as a laser diode, are provided on the side of the optical head stationary part  14 - 2  to reduce weight of the side of the optical head movable part  14 - 1  and reduce the inertia of the carriage  98 . 
     Referring to FIG. 1 again, a position control servo unit is provided for controlling the position of the optical head  14  mounted on the carriage  98  with the voice coil motor  24 . When the position sensor  34  is illuminated by light from the light-emitting diode  32 , currents corresponding to the illuminated position is obtained from opposite terminals of the position sensor  34 . These currents are converted in I-V converters  36  and  38  into voltage signals. An adder  40  takes the difference between these voltage signals to produce a carriage position signal. The carriage signal is converted in an A/D converter  42  into digital data which is input to a MPU  30  operating as a controller. The carriage position signal from the adder  40  is also differentiated in a differentiator and then converted in an A/D converter  46  into digital data which is input to the MPU  30 . The carriage position signal from the adder  40  is further coupled through an adder  48  to a phase compensator  52 , and thence through a switch  54  and an adder  56  to a power amplifier  58 . The output of the power amplifier  58  drives the voice coil motor  24 . An offset can be input to the adder  48  from a D/A converter  50 . Further, the differential signal output from the differentiator  44  is coupled through a switch  60  to the adder  56 , and the carriage position signal can be set in the adder from the MPU  30  through a D/A converter  62 . The position control servo unit as described above can effect two basic controls, i.e., 
     I, a follow control, and 
     II, a speed control. 
     When seeking an optical disk track designated from a higher order system with the optical head  14 , the speed control is effected. For this control, the switch  52  is turned off, while the switch  60  is turned on. When a desired speed signal is set in the adder  56  through the D/A converter  62 , the MPU  30  causes the power amplifier  58  to drive the voice coil motor  24  to make zero the difference between the desired speed and the actual speed of the head obtained in the differentiator  44 . When the head is moved to the desired track by this speed control seek operation, the control is switched over to the follow control. For the follow control, the switch  54  is turned off while the switch  60  is turned off, thus MPU  30  is forming a servo loop through the D/A converter  62 , whereby the voice coil motor  24  is driven to hold the positioner at a predetermined position. At this time, an offset can be coupled to the adder  18  through the D/A converter  50 . For example, it is possible to realize a positioner movement corresponding to a deviation of the optical disk by providing an offset. Further, since the track is formed spirally, a kick-back operation, i.e., kicking the head back by one track portion for every rotation of the disk, is caused by providing an offset. Further, by setting the position signal in the D/A converter  62  with both the switch  54  held “on” and the switch  60  held “off”, the MPU  30  can forcibly cause the voice coil motor  24  to drive the positioner to a desired position. 
     The MPU  30  includes a cleaning controller  24   a  under its program control. When cleaning the objective lens with the cleaning disk  10 , the cleaning controller  24   a  causes reciprocation of the positioner in the radial direction of the cleaning disk  10 . For this radial reciprocation, the cleaning controller  24   a  executes control in one of the following two modes. 
     Mode 1: 
     With the servo switches  54  and  60  held “on” and “off” respectively, an offset signal is input to the adder  48  from the D/A converter  50  to drive the voice coil motor  24 . 
     Mode 2: 
     With the servo switches  54  and  60  both held “off” a position signal is input to the D/A converter  62  to drive the voice coil motor  24 . 
     Further, two focusing systems are provided for the lens actuators  20 - 1  and  20 - 2  provided in the optical head  14 . The focusing system for the lens actuator  20 - 1  includes an amplifier  66 , a phase compensator  68 , a switch  70 , an adder  72 , a power amplifier  74  and a D/A converter  76 . The focusing system for the lens actuator  20 - 2  includes an amplifier  78 , a phase compensator  80 , a switch  82 , an adder  84 , a power amplifier  86  and a D/A converter  88 . Taking the focusing system for the lens actuator  20 - 1 , for instance, a focus error signal FES 1  obtained according to reflected light from the optical disk is amplified in the amplifier  66  and then leading phase compensated in the phase compensator  68 . At the time of focus servo, the switch  70  is turned on by the MPU  30  to couple the output of the phase compensator  68  through the switch  70  and adder  72  to the power amplifier  74  so as to drive the lens actuator  20 - 1  such as to minimize the focus error signal FES 1 . The MPU  30  can couple an offset to the adder  72  through the D/A converter  76 . This is the same with the focusing system for the lens actuator  20 - 2 . 
     When cleaning the objective lens with the cleaning disk  10 , the cleaning controller  24  causes reciprocation of the objective lens in the optical axis direction by driving the lens actuators  20 - 1  and  20 - 2 . For the reciprocation of the lens in the optical axis direction, the MPU  30  provides suitable offsets to the D/A converters  76  and  88  with the switches  70  and  82  held “off”. For the lens actuators  20 - 1  and  20 - 2 , track servo circuits  90  and  92  are provided, respectively. The track servo circuits  90  and  92  cause the track actuator to move the objective lens in the state of position control of the positioner with the voice coil motor  24  such as to minimize the track error signals TES 1  and TES 2  from the optical head  14 , thus causing the beam to follow the desired track. The spindle motor  18  is driven by a spindle motor drive circuit  28 . A load motor (not shown), having a disk load mechanism is driven by a load motor drive circuit  45 . To the MPU  30  are further connected a media hole sensor  140  for sensing a media hole formed in the cartridge and a cartridge sensor  142  for sensing the insertion of the cartridge and thereupon causing the start of the load motor. 
     Now, the two-actuator structure is driven in the optical axis direction in the cleaning control according to the invention will be described. 
     FIG. 4 shows the optical head used according to the invention. The optical head movable part which is provided on one end of the carriage  98 , has two lens actuators  20 - 1  and  20 - 2 . The lens actuators  20 - 1  and  20 - 2  are rotatable about their shafts  106  and  107 , and their opposing portions are provided with respective objective lenses  16 - 1  and  16 - 2 . Assuming that the disk  10  is rotated in the clockwise direction as shown by the arrow, the objective lens  16 - 1  at the preceding position is illuminated by an erase beam EB. On the other hand, the succeeding objective lens  16 - 2  is illuminated by two beams, i,e., a write beam WB and a read beam RB. 
     FIG. 5 shows one of the lens actuators shown in FIG. 4. A base  108  supports a magnetic circuit assembly  110  secured to it. It also supports a post  112  extending upright through the center of the magnetic circuit assembly  110 . A rotatable arm  114  is provided as a movable part with respect to the base  108  which is a stationary part. The rotatable arm  114  has a lower cylindrical portion, on which a tracking coil  118  and a focus coil  120  are wound. The rotatable arm  114  has an objective lens  16  mounted at one end and a balancer weight  116  mounted at the other end. It further has a central hole  115 , which is fitted on the post  112  of the base  108 . The rotatable arm  114  thus is rotatable about the post and simultaneously axially movable therealong. With the above lens actuator structure, in the cleaning control according to the invention the rotatable arm  114  is moved upward and downward to bring the objective lens  16  toward and away from the disk by causing a drive current through the focus coil  120 . 
     FIG. 6 shows a cleaning disk used according to the invention. A cleaning disk  10  is accommodated in a cartridge  26 . The cleaning disk  10  has a brush  12  provided on one side and extending radially. It also has a central hub  122  made of a magnetic metal for chucking it on the spindle motor shaft. 
     FIG. 7 shows a cleaning disk cartridge used according to the invention. A 5-inch optical disk cartridge conforming to ISO standards is taken as an example. The cartridge  26  has a shutter  125 , which can be opened and closed by a shutter operation member  124 . The shutter  125  has an opening  128 , which is closed as shown normally, that is, outside the apparatus. The shutter  125  has a rightward extension extending from its top portion and formed with a notch  126 . By inserting the cartridge  26  into the apparatus, a lever end is received in the notch  126 . With further pushing of the cartridge, the shutter  125  is moved to the left along the shutter operation member  124  so that the accommodated optical disk and the hub  122  thereof are exposed to the outside via the opening  128 . The cartridge  26  has two, i.e., left and right, write inhibition members  134  and  136  provided on its lower portion. With the accommodated optical disk held in its inner position as shown, the writing of data in the disk is inhibited. Beneath each of the write inhibition members  134  and  136 , four sensor holes are provided. For example, media sensor holes  130  have information about A side (or surface), and media sensor holes  132  have information about B side (or surface). The apparatus reads disk surface information according to whether the individual media sensor holes  130  and  132  are open or closed. In the ISO 5-inch optical disk cartridge, of the media sensor holes  130  and  132  only the second outermost ones as shown shaded are used, that is, no other media sensor hole is used. According to the invention, other media sensor holes than those shown shaded are used to indicate that the optical disk cartridge is for cleaning; for example, the innermost media sensor holes are utilized as open holes to indicate that the cartridge is for cleaning. 
     By utilizing the media sensor holes among those  130  and  132  that are not usually used for the purpose of indication of the cartridge as that for cleaning, the media sensor hole sensor  140  shown in FIG. 1 may be directly used to recognize the cleaning optical disk cartridge that is inserted in the apparatus. Of course, it is possible to provide the cartridge with other physical shape than the media sensor cartridges  130  and  132 , for instance holes or depressions, to be detected for automatic recognition by the apparatus that the optical disk cartridge is for cleaning. 
     Now, the operation of the cleaning controller  24  shown in FIG. 1 will be described with reference to the flow charts of FIGS. 8 and 9. Referring to FIG. 8, the cleaning cartridge is inserted in the drive, i.e., the optical disk apparatus in a step S 1 . When the cleaning cartridge is inserted, the optical disk apparatus loads and chucks the cartridge on the spindle motor. After the loading of the cleaning cartridge in the step S 1 , cleaning control is started under control of a cleaning command given from an upper order system, for instance. When the cleaning control is started under control of the cleaning command, a step S 2  is executed, in which the switches  54 ,  60 ,  70  and  82  shown in FIG. 1 are turned off, and hexadecimal data “80H-08H” is set in the D/A converter  62 . The data “80H” serves as a zero point signal, and the power amplifier provides zero drive current to the voice coil amplifier  24 , that is, the carriage is not moved. Thus, when the data “80H-08H” is set in the D/A converter  62 , the power amplifier  58  causes a slight current through the voice coil motor  24  to slowly move the carriage to the inner side. The carriage is thus slowly moved to the inner side in a step S 3 . In a subsequent step S 4 , a check is done as to whether the speed taken from the A/D converter  46  is zero, that is, a check is made as to whether the carriage has been moved up to the inner periphery stopper  95  of the support frame  96  shown in FIG. 2 when it is stopped. If the carriage has been moved to the inner periphery stopper, the speed is determined to be zero in the step S 4 . As a result, the spindle motor  18  is started in a step S 5 . In a subsequent step S 6 , the data in the D/A converter  62  is switched over to “80H+08H”. As a result, an inverse current is caused through the voice coil motor  24  to slowly move the positioner to the outer side. In a subsequent step S 7 , hexadecimal data “C0H” and “40H” are simultaneously set in the D/A converters  76  and  88 , respectively to drive the objective lenses in the optical axis direction. As a result, the lens actuators  20 - 1  and  20 - 2  simultaneously drive the objective lenses, for instance, toward and away from the disk, respectively. In a subsequent step S 8 , a predetermined wait time is provided, and the objective lens approaching the disk is cleaned with the brush. In a subsequent step S 9 , converse to the step S 7 , hexagonal data “40H” is set in the D/A converter  76  to quickly move one of the objective lenses away from the disk, while at the same time hexagonal data “C0H” is set in the D/A converter  88  to quickly move the other objective lens toward the disk. In a subsequent step S 10 , a predetermined wait time is provided, and the cleaning of the objective lens approaching the disk with the brush is caused by the output of the D/A converter  88 . In subsequent step S 11 , a check is done as to whether the speed taken from the A/D converter  46  is zero, that is, a check is done as to whether the carriage has been moved up to the outer periphery stopper  90  of the support frame  96  shown in FIG.  3 . Upon detection in the step S 11  of the contact of the carriage with the outer periphery stopper, a step S 12  is executed, in which, like the step S 3 , the hexadecimal data “80H-08H” is set in the D/A converter  62  to slowly move the carriage to the inner side again. 
     In subsequent steps S 13  through S 17 , like the steps S 7  through S 11  in FIG. 8, opposite drive data are set in the D/A converters  76  and  88  alternately, and this sequence of operations is repeated until it is found in the step S 17  that the carriage has moved up to the inner periphery stopper. If it is detected in the step S 17  that the carriage has moved up to the inner periphery stopper, a check is done in a step S 18  as to whether the number of reciprocations of the carriage has reached a preset value, for instance  4 . If the number is less than  4 , the routine is returned to the step S 6  in FIG. 8 to repeat the cleaning operation noted above. If it is detected in the step S 18  that the preset value, for instance  4 , is obtained as the number of carriage reciprocations, a step S 19  is executed, in which hexagonal data “80H” for providing zero point is set in the D/A converters  62 ,  76  and  88  used for the cleaning control, and in a subsequent step S 20  the spindle motor  18  is stopped. In a subsequent step S 21 , the load motor is driven to cause unloading of the cartridge and ejection thereof from the apparatus, thus bringing an end to the series of cleaning operations. 
     In the cleaning control shown in FIGS. 8 and 9, the the objective lenses are vertically driven quickly by switching the hexadecimal data “40H” and “C0H” set in the D/A converters  76  and  88 . However, it is possible to change the data “40H” and “C0H” in steps each of 1 to cause gradual vertical movement of the objective lenses. 
     FIG. 10 is a flow chart illustrating an automatic cleaning routine that is executed in case where a cleaning cartridge can be recognized on the side of the optical disk apparatus by utilizing the media sensor holes  130  and  132  as shown in FIG.  7 . If a cleaning cartridge inserted in the optical disk apparatus is detected by the cartridge sensor in a step S 1 , a step S 2  is executed in which the load motor is driven to cause loading of the cartridge and chucking thereof on the spindle motor. In a subsequent step S 4 , the media sensor holes of the cartridge are checked. Then, if it is determined in a step S 4  that the loaded cartridge is for cleaning, a step S 6  is executed, in which the cleaning operation in the steps S 2  to S 20  in FIGS. 8 and 9 is performed. When the cleaning is ended, the cartridge is unloaded and ejected in a step S 7 , thus bringing an end to the cleaning routine. In case when a normal cartridge, i.e., a cartridge other than that for cleaning, is inserted, this is detected in the step S 4 , whereupon a step S 5  of normal read or write operation is executed. 
     As a different example of the cleaning control according to the invention, the cleaning disk may be rotated by the spindle motor not only in the normal direction of rotation but also in the reverse direction. As a further alternative, it is possible to cause repeated rotation in alternate normal and reverse directions. To this end, a step for switching the rotational direction of the spindle motor may be provided between the steps S 17  and S 18  in the flow chart of FIG.  9 . 
     Further, while in the above embodiment the cleaning of lens is carried out by rotating the cleaning disk with the brush, since according to the invention it is possible to movement of the objective lens in the radial direction of the disk and also in the vertical directions, the invention is applicable as well to a cleaning cartridge, in which the brush is not rotatable but is secured to the optical head. 
     As has been described in the foregoing, according to the invention the brush provided on the cleaning disk touches the objective lens not in a constant fashion but in a variable fashion, and this permits a greatly enhanced cleaning effect to be obtained. In addition, since the entire brush is used to clean the lens, the brush is not locally deformed or contaminated, and thus it is possible to extend the cleaning life of the brush. Further, when the brush has become short due to fluctuations in cleaning or in long use, sufficient cleaning is obtainable because the lens can be moved vertically by the actuator.