WO2008010136A1 - Lecteur optique - Google Patents

Lecteur optique Download PDF

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Publication number
WO2008010136A1
WO2008010136A1 PCT/IB2007/052672 IB2007052672W WO2008010136A1 WO 2008010136 A1 WO2008010136 A1 WO 2008010136A1 IB 2007052672 W IB2007052672 W IB 2007052672W WO 2008010136 A1 WO2008010136 A1 WO 2008010136A1
Authority
WO
WIPO (PCT)
Prior art keywords
opu
optical
unit
temperature
optical pick
Prior art date
Application number
PCT/IB2007/052672
Other languages
English (en)
Inventor
Cornelius Antonius Hezemans
Hendrikus Albertus Johanna Looijmans
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2008010136A1 publication Critical patent/WO2008010136A1/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08505—Methods for track change, selection or preliminary positioning by moving the head
    • G11B7/08529—Methods and circuits to control the velocity of the head as it traverses the tracks

Definitions

  • the present invention relates to an optical drive for reading and/or recording information from/to an associated optical carrier, processing means for controlling an optical drive, and a method for operating an optical drive.
  • optical pick-up unit which is displaceable in a radial direction of the optical carrier in a mechanical configuration with the OPU having a bearing arranged on at least one shaft, the OPU being displaceable along a shaft by a motor.
  • This motor e.g.
  • a stepper motor or a stepping motor is arranged with a spindle in the radial direction of the optical carrier and in mechanical co-operation with the OPU so that upon rotation of the spindle by the stepper motor, the OPU is radially displaced.
  • the accuracy needed in the radial displacement is dependent on the optical properties of the OPU during reading or writing.
  • the seek time i.e. the average time needed for displacing the OPU from one track to another track
  • the lifetime requirements are typically above one million random seeks.
  • stepper motors used in optical drives fulfill the above requirement as stepper motors in general have an inherent precise positioning and reliable feed forward control via the input voltage or current. External factors such as temperature and humidity, and possibly ageing, are normally taken into account via safety factors on the mechanical design of the OPU and of the motor control.
  • the temperature is expected to be a more important factor in upcoming radial displacement designs for the OPU.
  • One such example is the sliding resistance of the OPU on a radially directed shaft; the resistance is dependent on temperature.
  • the ambient temperature can in some situations have a relatively high impact on seek times and OPU radial accuracy.
  • US patent 6,954,414 discloses an optical drive, wherein a drive current or drive voltage of a stepper motor is controlled according to a load that changes when the OPU is radially moved.
  • a drive current or drive voltage of a stepper motor is controlled according to a load that changes when the OPU is radially moved.
  • One such change of the load can result from a change in temperature and thereby the drive current or drive voltage is indirectly adapted to a temperature change.
  • the motor current is already adapted to its maximum value to guarantee a fast and reliable access at higher temperatures, the current can not be increased to guarantee a fast and reliable access at lower temperatures, where the sliding resistance is higher.
  • the seeks at higher temperatures are too slow and/or not reliable.
  • an improved optical drive would be advantageous, and in particular a more efficient and/or reliable optical drive would be advantageous.
  • the invention preferably seeks to mitigate, alleviate or eliminate one or more of the above mentioned disadvantages singly or in any combination.
  • an optical drive for reading and/or recording information from/to an associated optical carrier
  • the optical drive comprising: an optical pick-up unit (OPU) being arranged in a mechanical displacement configuration for displacement relative to the optical carrier by actuation of an actuator, the optical pick-up unit (OPU) comprising a temperature sensor for measuring a temperature on the optical pick-up unit (OPU), said sensor being adapted for outputting a corresponding temperature signal (S_T) indicative of the measured temperature, and processing means for processing a seek command (SC) and outputting a corresponding control signal (C_step) to the actuator, the seek command (SC) being processed into a seek pattern (SP) in dependency of a set of mechanical restriction parameters (R) of the mechanical displacement configuration of the optical pick-up unit (OPU), wherein at least one of the mechanical restriction parameters (R) is dependent on the temperature signal (S_T) from the temperature sensor of the optical pick-up unit (OPU).
  • the invention is particularly, but not exclusively, advantageous for obtaining an optical drive that - in a direct and feasible manner - takes into account the effect of the temperature on the sliding dynamics for the mechanical displacement of the optical pick-up unit (OPU).
  • This is obtained by incorporating a measured temperature on the optical pick-up (OPU) into the mechanical restriction parameters (R) that define control limits for the seek pattern (SP) of the stepper motor.
  • R mechanical restriction parameters
  • SP seek pattern
  • the function of the temperature sensor i.e. outputting a temperature signal indicative of the measured temperature
  • the function of the temperature sensor could equivalently be performed by one or more parts of the OPU capable of performing the same function as a temperature sensor but not directly dedicated for temperature measurements.
  • the threshold voltage of an laser source by its dependency on temperature could be applied as temperature signal (S_T) within the context of the present invention.
  • the laser source may be considered as least indirectly as a temperature sensor.
  • the mechanical displacement configuration of the OPU may comprise any component and elements that have an influence or impact on the mechanical process of displacing the optical pick-up unit (OPU).
  • the displacement is preferably in a substantially radial direction of the optical carrier.
  • Such components may include, but need not be limited to, the optical pick-unit itself (and any of its sub-components), the actuator for displacing the OPU, a spindle being rotated by the actuator, a shaft for guiding the OPU during a displacement, and a bearing on or within the OPU for receiving said shaft.
  • the mechanical restriction parameters (R) may include any parameter in relation to the mechanical displacement configuration of the OPU (as defined in the above paragraph) that defines an upper limit or a lower limit for the displacement process of the OPU. Such parameters may include, but need not be limited to, values of the position, the velocity, and acceleration of the OPU.
  • the mechanical restriction parameters (R) can be the combined result of various factors restricting the mechanical displacement of the OPU, such as a maximum possible velocity of the actuator for reliable control in combination with a maximum allowed velocity for safe guarding the optical pick-up unit (OPU) during displacement, and so forth.
  • the mechanical restriction parameters (R) may comprise a maximum velocity (V_max) and/or a maximum acceleration (A_max) as such control parameters can be essential for operating the actuator and/or setting limits for OPU.
  • the seek pattern (SP) may comprise a time-dependent acceleration signal (a(t)), and the processing means may then comprise integration means for processing said seek pattern (SP).
  • the mechanical restriction parameters (R) may advantageously comprise one or more boundary conditions
  • V_max, A_max for the integration means as this provides a straightforward way of implementing the temperature dependency of the mechanical displacement configuration of the OPU. It should be noted that integration in the context of the present application may be taken to include both a mathematical integration of a time-dependent function and a mere summation of such a time-dependent function.
  • the actuator may be an electrical stepper motor.
  • a stepper motor can be operated with a substantially constant current and a variable frequency, or it can be operated with a substantially constant voltage and a variable frequency depending on the desired characteristics of the stepper motor. It should be noted that some stepper motors can operate in so-called imitated constant current mode by allowing the voltage amplitude to depend on the frequency.
  • the temperature sensor may be positioned substantially adjacent to an irradiation source in the optical pick-up unit (OPU) so as to use the temperature sensor for more than one application. This is important due to weight considerations with respect to the OPU.
  • the temperature signal (S_T) can be transmitted via a common flexible path (the "flex") connecting the optical pick-up unit (OPU) and the processing means in order to provide an easy and direct assessment of a temperature on the OPU.
  • Some prior art solutions have relied on power management assessments for estimating the temperature on the OPU (e.g. a power proportional to the square value of the current supplied to the OPU and/or laser). However, this is an indirect approach and therefore not a reliable way of controlling the seek processes performed by the OPU.
  • the invention in a second aspect, relates to processing means for controlling an associated optical drive for reading and/or recording information from/to an optical carrier, the associated optical drive comprising an optical pick-up unit (OPU) being arranged in a mechanical displacement configuration for displacement relative to the optical carrier by actuation of an actuator, the optical pick-up unit (OPU) comprising a temperature sensor for measuring a temperature on the optical pick-up unit (OPU), said sensor being adapted for outputting a corresponding temperature signal (S_T) indicative of the measured temperature, wherein the processing means is arranged for processing a seek command (SC) and outputting a corresponding control signal (C_step) to the actuator, the seek command (SC) being processed into a seek pattern (SP) in dependency of a set of mechanical restriction parameters (R) of the mechanical displacement configuration of the optical pick-up unit (OPU), wherein at least one of the mechanical restriction parameters (R) is dependent on the temperature signal (S_T) from the temperature sensor of the optical pick-up unit (OPU).
  • the invention in a third aspect, relates to a method for operating an optical drive adapted for reading and/or recording information from/to an optical carrier, the optical drive comprising an optical pick-up unit (OPU) being arranged in a mechanical displacement configuration for displacement relative to the optical carrier by actuation of an actuator, the optical pick-up unit (OPU) comprising a temperature sensor for measuring a temperature on the optical pick-up unit (OPU), the method comprising the steps of: outputting from said sensor a corresponding temperature signal (S_T) indicative of the measured temperature, processing by processing means a seek command (SC) and outputting a corresponding control signal (C_step) to the actuator, the seek command (SC) being processed into a seek pattern (SP) in dependency of a set of mechanical restriction parameters (R) of the mechanical displacement configuration of the optical pick-up unit (OPU), wherein at least one of the mechanical restriction parameters (R) is dependent on the temperature signal (S_T) from the temperature sensor of the optical pick-up unit (OPU).
  • S_T
  • the invention in a fourth aspect, relates to a computer program product being adapted to enable a computer system comprising at least one computer having data storage means associated therewith to control an optical drive according to the third aspect of the invention.
  • This aspect of the invention is particularly, but not exclusively, advantageous in that the present invention may be implemented by a computer program product enabling a computer system to perform the operations of the second aspect of the invention.
  • some known optical drive may be changed to operate according to the present invention by installing a computer program product on a computer system controlling the said optical recording apparatus.
  • Such a computer program product may be provided on any kind of computer readable medium, e.g. magnetically or optically based medium, or through a computer based network, e.g. the Internet.
  • the first, second, third and fourth aspect of the present invention may each be combined with any of the other aspects.
  • Fig. 1 schematically shows an optical recording apparatus or drive and an optical information carrier according to the present invention
  • FIG. 2 schematically shows the processing means and the optical pick-up unit (OPU) according to the invention
  • Fig. 3 shows in more detail a sub-section of the processing means
  • Fig. 4 schematically shows a seek pattern (SP) and the resulting torque of the actuator according to the present invention
  • Fig. 5 shows a graph of the damping constant of a mechanical displacement configuration for an OPU as a function of temperature
  • Fig. 6 is a flow-chart of a method according to the invention.
  • FIG. 1 shows an optical recording apparatus (or an optical drive) and an optical information carrier 1.
  • the carrier 1 is fixed and rotated by holding means 30.
  • the optical carrier 1 comprises a material suitable for recording information by means of a radiation beam 5.
  • the recording material may, for example, be of the magneto-optical type, the phase-change type, the dye type, metal alloys like Cu/Si or any other suitable material.
  • Information may be recorded in the form of optically detectable effects, also called “marks” for rewriteable media and "pits" for write-once media, on the optical carrier 1.
  • the optical apparatus i.e. the optical drive, comprises an optical head 20, sometimes called an optical pick-up (OPU), the optical head 20 being displaceable by actuation means 21, e.g. an electric stepper motor, a linear motor, or a DC motor.
  • the optical head 20 comprises a photo detection system 10, a laser driver device (LDD), a radiation source 4, a beam splitter 6, an objective lens 7, and lens displacement means 9 capable of displacing the lens 7 both in a radial direction of the carrier 1 and in the focus direction.
  • the function of the photo detection system 10 is to convert radiation 8 reflected from the carrier 1 into electrical signals.
  • the photo detection system 10 comprises several photo detectors, e.g. photodiodes, charged-coupled devices (CCD), etc., capable of generating one or more electric output signals.
  • the photo detectors are arranged spatially to one another and with a sufficient time resolution so as to enable detection of error signals, i.e. focus error FE and radial tracking error RE.
  • the focus error FE and radial tracking error RE signals are transmitted to the processing means 50 where a commonly known servomechanism operated by using PID control means (proportional-integrate- differentiate) is applied for controlling the radial position and focus position of the radiation beam 5 on the carrier 1.
  • PID control means proportional-integrate- differentiate
  • the radiation source 4 for emitting a radiation beam or a light beam 5 can for example be a semiconductor laser with a variable power, possibly also with variable wavelength of radiation. Alternatively, the radiation source 4 may comprise more than one laser.
  • the term "light” is considered to comprise any kind of electromagnetic radiation suitable for optical recording and/or reproduction, such as visible light, ultraviolet light (UV), infrared light (IR), etc.
  • the temperature of the radiation source 4 is monitored by the temperature sensor 22 placed adjacent to or in proximity to the irradiation source 4 so as to provide temperature monitoring of the irradiation source 4. Equivalently, the sensor 22 may be positioned more remotely to the irradiation source 22, but in thermal contact to the irradiation source 22 via a thermal bridge, i.e. an interconnection element made of an efficient heat conducting material such as a metal.
  • the temperature signal S_T can be transmitted to the laser driver device (LDD) (not shown) that controls the irradiation source 4 for power management purposes.
  • LDD laser driver device
  • the temperature signal S_T is transmitted to the processing means 50 through the common flexible path (the "flex") connecting the optical pick-up unit 20 (OPU) and the processing means 50.
  • the temperature sensor 22 can be used for simultaneously monitoring a temperature relevant for the power management of the irradiation source 4 and monitoring a temperature relevant for the dynamics of the radial displacement of the OPU 20, but separate temperature sensors could also be provided within the context of the present invention.
  • the temperature sensor 22 can be placed close to, preferably adjacent to, a sliding interface of the mechanical displacement configuration of the OPU 20 so a to provide a temperature signal S_T that is a better representation or indication of the actual temperature in the sliding interface.
  • the temperature sensor 22 may be a resistance temperature device (RTD) or a similar device capable of measuring a temperature and outputting a corresponding signal.
  • the processing means 50 also receives and analyses signals from the photo detection means 10.
  • the processing means 50 can also output control signals to the actuation means 21, the radiation source 4, the lens displacement means 9, and the rotating means 30, as schematically illustrated in Figure 1.
  • the processing means 50 can receive data to be written, indicated at 61, and the processing means 50 may output data from the reading process as indicated at 60. While the processing means 50 has been depicted as a single unit i.e.
  • the processing means 50 may be a plurality of interconnecting processing units positioned in the optical recording apparatus, possibly some of the units may be positioned in the optical head 20.
  • Figure 2 schematically shows the details of the processing means 50 and the optical pick-up unit 20(OPU).
  • the optical pick-up unit 20 (OPU) is arranged in a mechanical displacement configuration with a spindle 23, a shaft 25a with a corresponding bearing 25b attached to or in the optical pick-up unit 20 (OPU).
  • a gap or play can be defined between the shaft 25a and the bearing 25b.
  • the benefits of the invention may be particularly rewarding for gap values below 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 micrometers, though the invention is not limited to these maximum gap values.
  • the benefits of the invention may be particularly rewarding for a bearing sliding area below 1O x 10-9 m , 20 x 10-9 m 2 , 30 x 10-9 m 2 , 40 x 10-9 m 2 , 50 x 10-9 m 2 , 60 x 10-9 m 2 , 70 x 10-9 m 2 , 80 x
  • the mechanical displacement configuration is capable of displacing the OPU 20 - relative to the optical carrier 1 - by actuation of the actuator 21, e.g. a stepper motor arranged for rotating the spindle 23 meshing with a counter part of the OPU 20 so as to provide displacement of the OPU as indicated by the double-headed arrow
  • the optical pick-up unit 20 comprises a temperature sensor 22 for measuring a temperature on the optical pick-up unit (OPU).
  • the sensor 22 is adapted for outputting a corresponding temperature signal (S_T) indicative of the measured temperature.
  • the processing means 50 process a seek command SC i.e. a command representing a target position (track) to be reached from the present position (track) and the processing means 50 then outputs a corresponding control signal C_step to the actuator 21.
  • the seek command SC is processed into a seek pattern SP by processor 51 in dependency of a set of mechanical restriction parameters (R) of the mechanical displacement configuration of the optical pick-up unit 20 (OPU). At least one, but possibly more, of the mechanical restriction parameters (R) is dependent on the temperature signal S_T received from the temperature sensor of the optical pick-up unit 20 (OPU).
  • the seek pattern SP is processed by the processor 52 into a control signal C_step, which is transmitted to the actuator 21.
  • a current or voltage drive signal sequence e.g. a pulse sequence or a sine wave etc.
  • FIG. 3 shows in more detail the processor 51 of the processing means 50.
  • the actuator 21 could be an electric stepper motor, preferably of the permanent magnet
  • An initial set of mechanical restriction parameters (R) comprises a maximum acceleration A_max and a maximum velocity V_max that are provided from e.g. a look-up table connected to the sub-processor 51a.
  • the sub-processor 51a additionally receives the temperature signal S_T from the optical pick-up unit (OPU) 20 (not shown in Figure 3), and based on the seek command SC and a range of inputs related to the mechanical displacement configuration of the OPU, such as stepper motor parameters, mass of the OPU, damping as a function of temperature (see e.g. Figure 5 below), gear efficiency, and present current in the stepper motor coil, a modified set of mechanical restriction parameters (R) comprising a maximum acceleration A_max (T) and a maximum velocity V_max (T) (now dependent on temperature, T, through the temperature signal
  • the sub-processor 51b subsequently calculates the seek pattern SP which is represented by a time-dependent acceleration signal, a(t), in this embodiment of the invention.
  • the sub-processor 51b also receives as an input the seek command SC because the seek pattern SP should of course result in an appropriate displacement of the OPU 20 (not shown) as required by the seek command SC.
  • This can be verified by two times integration of the time-dependent acceleration signal a(t) having the boundary conditions of the maximum acceleration A_max (T) and the maximum velocity V_max (T).
  • maximum acceleration A_max (T) and a maximum velocity V_max (T) are constants of time, the integration is relatively easy to perform.
  • a maximum deceleration DEC_max (T) of the mechanical displacement configuration of the OPU 20 is introduced, which is numerically different from the maximum acceleration A_max (T) thereby creating an asymmetrical seek pattern SP in time.
  • the process of calculating a set of mechanical restriction parameters (R) (dependent on temperature, T) and the corresponding seek pattern SP is performed once per seek process.
  • Figure 4 schematically shows a seek pattern SP and the resulting torque of the actuator 21 for a high temperature shown in part A to the left, and for a low temperature shown in part B to the right.
  • the seek pattern SP is the time-dependent acceleration signal, a(t), shown in the upper graphs in part A and part B being the result of the calculations performed by the sub-processor 51a and transmitted to the other sub- processor 51b.
  • the middle graphs of part A and part B show the time-dependent velocity signal, v(t), obtained by integration of the time-dependent acceleration signal, a(t).
  • the distance S (indicated under the velocity curves) can be obtained.
  • the temperature, T is relatively higher than in part B, and accordingly the maximum allowed velocity V_Max (T) is higher in part A than in part B.
  • Figure 5 shows a graph of the measured damping constant (N x seconds /m, vertical axis) of a mechanical displacement configuration for an OPU as a function of temperature (degrees Celsius, horizontal axis).
  • the tested mechanical displacement configuration had a relatively small gap or play between the shaft 25a and the bearing. It is seen that the damping constant exhibits more than a three-time increase as the temperature is lowered from around 20 degrees Celsius to 5 degrees Celsius. This can result in a fatal read/write error of the optical drive if not compensated for.
  • optical drives intrinsically warm up due to the power dissipated e.g. by the irradiation source 4, this may nevertheless take some time, and it may not happen at all if the optical drive initially fails a seek process completely.
  • Figure 6 is a flow-chart of a method according to the invention.
  • the method operates - in a feed forward control - an optical drive adapted for reading and/or recording information from/to an optical carrier 1, the optical drive comprising an optical pick-up unit (OPU) 20 being arranged in a mechanical displacement configuration 20, 21, 23, and 25 for displacement relative to the optical carrier 1 by actuation of an actuator 21, the optical pick-up unit (OPU) 20 comprising a temperature sensor 22 for measuring a temperature on the optical pick-up unit (OPU) 20, the method comprising the steps of: Sl outputting from said sensor 22 a corresponding temperature signal S_T indicative of the measured temperature,

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  • Optical Recording Or Reproduction (AREA)
  • Moving Of Head For Track Selection And Changing (AREA)

Abstract

L'invention se rapporte à un lecteur optique pour lire et/ou enregistrer des informations depuis/sur un support (1) optique, comprenant une unité d'analyse optique (OPU ; 20). L'OPU est disposée selon une configuration (20, 21, 23, 25) à mobilité mécanique pour pouvoir être déplacée avec un actionneur (21). Une sonde (22) de température sur l'OPU mesure une température et délivre un signal (S_T) de température. Dans les moyens (50) de traitement, une commande (SC) de recherche est traitée et un signal (C_step) de commande est envoyé à l'actionneur (21). La commande (SC) de recherche est traitée dans un modèle (SP) de recherche qui dépend d'un ensemble de paramètres (R) de restriction mécanique de la configuration à mobilité mécanique. Un (ou plusieurs) des paramètres (R) de restriction mécanique dépend du signal (S_T) de température en provenance de la sonde (22) de température de l'unité d'analyse optique (OPU). En choisissant un modèle (SP) de recherche optimal en fonction de la température, il est ainsi possible d'obtenir un lecteur optique plus efficace et plus fiable avec des durées de recherche qui peuvent être nettement réduites.
PCT/IB2007/052672 2006-07-17 2007-07-09 Lecteur optique WO2008010136A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06117304.3 2006-07-17
EP06117304 2006-07-17

Publications (1)

Publication Number Publication Date
WO2008010136A1 true WO2008010136A1 (fr) 2008-01-24

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013013995A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Scheinwerferlinse für einen Fahrzeugscheinwerfer
DE102013001075A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Scheinwerferlinse für einen Fahrzeugscheinwerfer
DE102013001072A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Fahrzeugscheinwerfer

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5285431A (en) * 1987-12-02 1994-02-08 Mitsubishi Denki Kabushiki Kaisha Information storage device with head position detection outside a user utilizable region and an optical disk drive device having target velocity-controlled head actuation
US20030151997A1 (en) * 2002-02-14 2003-08-14 Hajime Nishimura Optical disk drive and method for controlling movement of optical pickup
US6657932B1 (en) * 2000-02-01 2003-12-02 Acer Communications & Multimedia Inc. Device and method of temperature control for optical storage and retrieving apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5285431A (en) * 1987-12-02 1994-02-08 Mitsubishi Denki Kabushiki Kaisha Information storage device with head position detection outside a user utilizable region and an optical disk drive device having target velocity-controlled head actuation
US6657932B1 (en) * 2000-02-01 2003-12-02 Acer Communications & Multimedia Inc. Device and method of temperature control for optical storage and retrieving apparatus
US20030151997A1 (en) * 2002-02-14 2003-08-14 Hajime Nishimura Optical disk drive and method for controlling movement of optical pickup

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013013995A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Scheinwerferlinse für einen Fahrzeugscheinwerfer
DE102013001075A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Scheinwerferlinse für einen Fahrzeugscheinwerfer
DE102013001072A1 (de) 2013-01-23 2014-07-24 Docter Optics Se Fahrzeugscheinwerfer

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