FR2962358A1 - Optical glasses i.e. eyeglasses, machining device, has control unit controlling secondary noise and/or vibration source based on information measured by reference and error sensors to attenuate primary noise and/or primary vibration - Google Patents

Abstract

The device (10) has an antivibration and/or antinoise system (14) comprising reference sensors (60, 64, 66) and error sensors (62, 68) to measure representative information of noise and/or vibration resulting from primary noise and/or primary vibration. A control unit (80) controls a secondary noise and/or vibration source based on the information measured by the reference and error sensors to attenuate the primary noise and/or the primary vibration generated by a machining unit (12), where the secondary noise and/or vibration source comprises a loudspeaker (70) and/or an actuator (72). An independent claim is also included for a method for attenuating primary noise and/or primary vibration generated by a machining unit of an optical glasses machining device.

Description

The present invention relates to a device for machining optical glasses, of the type comprising means for machining an optical glass capable of generating noise, and / or a primary vibration. Such a device is for example intended to machine glasses intended to be mounted on eyeglasses, from a lens blank of standard shape, in order to adapt them to the shape of the frame. Devices of the aforementioned type are known. FR 2,871,400 describes one of them.

The machining means of the glass comprise in particular a grinding wheel or a bur and a support shaft of the lens. During the machining of the lens, the lens, rotated on its support, is applied to the machining means to remove material. Therefore, the machining means vibrate and generate noises and vibrations that can be inconvenient for the user and may have a negative impact on the life of the device and / or the quality of glass processing. To overcome this problem, it is known to isolate the machine using foams or other absorbent materials. These foams increase the weight, the size and the cost of the machine, for a result that can be unsatisfactory. An object of the invention is therefore to provide an optical glass machining device adapted to attenuate the noise and / or vibrations generated by the machining means, which is efficient and compact. For this purpose, the subject of the invention is a device for machining optical glasses of the aforementioned type, characterized in that the device further comprises an anti-noise and / or anti-vibration system comprising: at least one sensor capable of measuring representative information a noise and / or measured vibration resulting from noise and / or primary vibration; at least one source of noise and / or secondary vibration; and at least one control unit, connected to the or each sensor and the or each source of noise and / or secondary vibration, the or each unit being adapted to control the or each source of noise and / or secondary vibration on the basis of at least one piece of information measured by the or each sensor to attenuate the noise and / or primary vibration generated by the machining means.

The optical lens machining device according to the invention may comprise one or more of the following characteristics, taken alone or in any combination (s) technically possible (s): - at least one sensor is a reference sensor, capable of measuring a first information representative mainly of the noise and / or the primary vibration; the machining device comprises a lens support and a grinding assembly carrying at least one optical glass machining tool, the or each reference sensor being fixed on one of the lens supports and grinding assembly; at least one sensor is an error sensor capable of measuring a second piece of information representative of the noise and / or of the vibration resulting from the sum of the noise and / or the primary vibration with the noise and / or the secondary vibration; at least one noise and / or vibration sensor comprises a microphone and / or an accelerometer; at least one source of noise and / or secondary vibration comprises a loudspeaker and / or an actuator; the control unit comprises at least one input filter for filtering at least one piece of information measured by at least one sensor, as a function of its frequency; and the control unit comprises at least one low-frequency filter with, advantageously, a cut-off frequency at greater than or equal to I kHz and at least one high-frequency filter with advantageously a cut-off frequency of less than or equal to I kHz. The subject of the invention is also a process for attenuating noise and / or primary vibration generated by machining means of an optical glass machining device, said machining device comprising a system noise-canceling and / or anti-vibration device comprising: at least one sensor capable of measuring information representative of a noise and / or a measured vibration; at least one source of noise and / or secondary vibration; and at least one control unit, connected to the or each sensor and to the or each source of noise and / or secondary vibration; characterized in that said method comprises the steps of: measuring, by the or each sensor, information representative of noise and / or measured vibration resulting from the noise and / or primary vibration; processing the or each piece of information by the control unit; controlling the source of noise and / or secondary vibration by the control unit on the basis of the or each information measured by at least one sensor so that the source emits a noise and / or a secondary vibration capable of attenuating the noise and / or primary vibration generated by the machining means. The method according to the invention may further comprise the following characteristic: the or each information is filtered at the input of the control unit, as a function of its frequency. The present invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 represents a schematic view, in partial section along a plane vertical part of a device according to the invention; Figure 2 is a schematic representation of a control unit of an anti-noise and / or anti-vibration system of the device of Figure 1; Figure 3 is an operating diagram of said noise canceling and / or anti-vibration system, for attenuation of a primary noise; and Figure 4 is an operating diagram of the same noise and / or vibration control system, for attenuation of a primary vibration. In all that follows, we will distinguish vibrations, mechanical, being transmitted in solid materials, noises, acoustic, diffusing in the air.

The machining device 10 shown in FIG. 1 is intended to produce an optical lens from a lens blank 11. This machining device 10 comprises machining means 12 capable of generating a primary noise B1 and a primary vibration V1, an anti-noise and anti-vibration system 14 and a frame 20. The machining means 12 comprise a grinding assembly 22, a lens holder 24 and means 28 for adjusting the relative position of the lens holder 24 relative to to the grinding assembly 22. The frame 20 defines a grinding chamber 30 for containing the lens blank 11, the lens holder 24, and the grinding assembly 22. The grinding assembly 22 includes a grinding assembly 22. grinding wheels 32 rotatably mounted about a first horizontal axis AA 'in a grinding wheel support 34 and rotated by a grinding motor (not shown). The wheel train 32 is composed of several wheels 32A to 32D juxtaposed. Each wheel is associated with a type of glass to grind and a step of the grinding process. For example, the grinding wheel 32A is associated with the roughing of mineral glasses, the grinding wheel 32B with the roughing of synthetic glasses, the grinding wheel 32C with the bevelled finishing, and the grinding wheel 32D with beveling polishing. Optionally or alternatively, the wheel set 32 is equipped with non-beveling finishing and / or polishing wheels. The wheel set 32 is integrally mounted on a grinding wheel shaft 36, itself rotatably mounted in the grinding wheel carrier 34 about the first axis A-A '.

In this example, a lower portion 38 of the wheel support 34 is slidably mounted in an axial direction parallel to the first axis AA 'on a sliding bar 40, in order to be able to place the lens blank 11 successively opposite the various wheels 32A to 32D. The lens support 24 comprises a carriage 42 pivotally mounted on the frame 20 and provided with two half-shafts 44A and 44B adapted to grip the lens blank 11, and a motor 46 for rotating the lens blank 11. The half-shafts 44A and 44B are arranged along a second axis BB 'horizontal, parallel to the first axis A-A'. They are provided with free ends 48A and 48B facing one another, adapted to grip the lens blank 11.

The drive motor 46 drives in rotation about the second axis B-B 'the half-shaft 44A and the half-shaft 44B by a transmission mechanism (not shown). The adjustment means 28 comprise a mechanism 50 for driving a guide rod, or key, 52, mounted movably along a third axis D-D 'substantially perpendicular to the first A-A' and second B-B 'axes. In the example shown, the drive mechanism 50 comprises a worm 53 driving in cooperation with a nut 54. The screw 52 is rotatably mounted on the frame 20 and is arranged in a direction substantially parallel to the axis DD '. This drive screw 53 is rotated by a motor 56 integral with the frame 20. Furthermore, the lower end of the key 52 is fixed to the nut 54 and the upper end of the key 52 bears against the carriage 42 of the lens support 24. The key 52 is thus able to adjust the maximum distance between the first axis A-A 'and the second axis B-B', depending on the rotation angle of the blank of lens 11. The grinding assembly 22 and the lens holder 24 form primary sources 58 of primary noise B1 and primary vibration V1. The anti-noise and anti-vibration system 14 is intended to attenuate these primary noise B1 and vibration V1. For this purpose, the anti-noise and anti-vibration system 14 comprises sensors 60, 62, 64, 66, 68, secondary sources 70, 72 of a secondary noise B2 and a secondary vibration V2, and a control unit 80.

Each sensor 60, 62, 64, 66, 68 is able to measure an information 11, 12 representative of a noise and / or a measured vibration resulting from the primary noise B1 and / or the primary vibration V1. The sensors 60, 62, 64, 66, 68 thus comprise microphones 60, 62 for measuring noises and accelerometers 64, 66, 68 for measuring vibrations. Among these sensors, the sensors 60, 64 and 66 are reference sensors and are suitable for measuring a first piece of information 11, mainly representative of the primary noise B1 for the sensor 60 and of the primary vibration V1 for the sensors 64 and 66. other sensors 62 and 68 are error sensors and are capable of measuring a second piece of information 12, mainly representing the sum of the primary noise B1 and the secondary noise B2 for the sensor 62 and the sum of the primary vibration V1 and the secondary vibration V2 for the sensor 68. The reference sensors 60, 64, 66 are fixed on or near the primary sources 58, that is to say on or near the grinding assembly 22 and the lens support 24. The error sensors 62, 66 are attached remotely from the primary sources 58, on the frame 20. In the example shown, the reference microphone 60 is fixed on the lens holder 24, the error microphone 62 is fix on the frame 20, inside the grinding chamber 30, the reference accelerometer 64 is fixed on the carriage 42 of the lens holder 24, the reference accelerometer 66 is fixed on the lower part 38 of the support of grinding wheels 34 and the error accelerometer 68 is fixed on the frame 20, inside the grinding chamber 30. In a variant, the system 14 comprises only error or reference sensors. In another variant, the same sensor is both an error sensor and a reference sensor. Secondary sources 70, 72 comprise a loudspeaker 70 for emitting secondary noise B2 and an actuator 72 for emitting secondary vibration V2. Each secondary source 70, 72 is controlled by the control unit 80. In the example shown, the speaker 70 and the actuator 72 are fixed on the frame 20, respectively inside and outside the grinding chamber 30. The control unit 80 is connected to each sensor 60, 62, 64, 68 and to each secondary source 70, 72. It is adapted to drive the secondary sources 70, 72 on the basis of the information 11, 12 measured by the sensors 60, 62, 64, 68 so as to attenuate the primary noise B1 and the primary vibration V1.

Preferably, the control unit 80 comprises analog processors of the DSP type. This allows it to have a sufficiently fast response time, for example less than 1 ms. Figure 2 gives a detailed representation of the control unit 80.

The control unit 80 comprises two inputs E1 and E2 and two outputs S1 and S2. The first input E1 is connected to the reference sensors 60, 64, 66. The second input E2 is connected to the error sensors 62, 68. The first output S1 is connected to the secondary secondary noise source 70 B2. The second output S2 is connected to the secondary source 72 of secondary vibration V2.

The control unit 80 comprises two first filters 82 and 84 connected to the first input E1, two second filters 86 and 88 connected to the second input E2 and a data processing unit 90. The first filters 82, 84 are arranged in parallel. The second filters 86, 88 are also arranged in parallel. Filters 82 and 86 are low-pass filters with a cut-off frequency greater than or equal to 1 kHz. The filters 84 and 88 are high-pass filters with a cut-off frequency of less than or equal to I kHz. The data processing unit 90 comprises two calculation units 92 and 94. The first calculation unit 92 is connected to the first high-pass filter 84, to the second high-pass filter 88 and to the first output S1. It is able to amplify a first control signal C1 coming from the first high-pass filter 84 and to phase shift it by 180 ° so as to generate a first control signal P1 sent to the first output S1. It is also adapted to adapt the first control signal P1 as a function of a first feedback signal R1 coming from the second high-pass filter 88. The second calculation unit 94 is connected to the first low-pass filter 82, to the second filter low pass 86 and at the second output S2. It is able to amplify a second control signal C2 coming from the first low-pass filter 82 and phase shift it by 180 ° so as to generate a second control signal P2 sent to the second output S2. It is also adapted to adapt the second control signal P2 as a function of a second feedback signal R2 coming from the second low-pass filter 86.

When machining an ophthalmic lens, the lens blank 11, placed on the lens support 24, is rotated about the second axis BB 'of the support 24 by the drive motor 46 so as to be oriented in different angular positions. For each angular position, it is placed in contact with the grinding wheel 32 so as to be machined.

The rotation of the lens blank 11 about the second axis B-B 'and the machining of the lens blank 11 by the wheels 32A to 32D of the wheel train 32 generate a noise and a primary vibration B1, V1. The method of attenuation of the primary noise B1 by the system 14 will now be described, with reference to FIG. 3. The reference microphone 60 measures a first piece of information 11 representative mainly of the primary noise B1. This first information 11 is transferred to the control unit 80 for processing. The first information 11 is filtered by the first high-pass filter 84. This results in the first control signal C1, which is transmitted to the first calculation unit 92. The first calculation unit 92 amplifies the control signal C1 and the 180 ° out of phase, so as to produce the first driving signal P1 to drive the speaker 70.

In response to the first driving signal P1, the speaker 70 generates a secondary noise B2 substantially in phase opposition with the primary noise B1, so as to attenuate the primary noise B1. The error microphone 62 measures a second piece of information 12 representative of the noise resulting from the sum of the primary noise B1 and the secondary noise B2. This second piece of information 12 is transferred to the control unit 80, where it is filtered by the second high-pass filter 88. This results in the first feedback signal R1, which is transmitted to the first calculation unit 92. of the first feedback signal R1 that it receives, the first calculation unit 92 adapts the first control signal P1 by modifying the amplification and / or the phase shift it applies to the first control signal C1. The method of attenuation of the primary vibration V1 by the system 14 will now be described, with reference to FIG. 4. The reference accelerometers 64, 66 measure a first piece of information 11 representative mainly of the primary vibration V1. This first information 11 is transferred to the control unit 80 for processing. The first information 11 is filtered by the first low-pass filter 82. This results in the second control signal C2, which is transmitted to the second calculation unit 94. The second calculation unit 94 amplifies the control signal C2 and the 180 ° out of phase, so as to produce the second control signal P2 to drive the actuator 72.

In response to the second control signal P2, the actuator 72 generates a secondary vibration V2 substantially in phase opposition with the primary vibration V1, so as to attenuate the primary vibration V1. The error accelerometer 68 measures a second piece of information 12 representative of the vibration resulting from the sum of the primary V1 and secondary V2 vibrations. This second piece of information 12 is transferred to the control unit 80, where it is filtered by the second low-pass filter 86. This results in the second return signal R2, which is transmitted to the second calculation unit 94. of the second feedback signal R2 that it receives, the second calculation unit 94 adapts the second control signal P2 by modifying the amplification and / or the phase shift it applies to the second control signal C2. The machining device that has been described is a preferred embodiment of the invention. However, the control unit can be adapted to control the secondary sources in open loop, that is to say without second information provided by the error sensors. In a variant, the control unit can be adapted to control the secondary sources from the only second information provided by the error sensors, without first information representative of the primary noise and vibration. In addition, it is possible to provide the machining device with a simple noise control system that is not designed to mitigate the primary vibration, or conversely to provide it with a simple anti-vibration system that is not designed to mitigate the vibration. primary noise. Thanks to the invention, the noise and vibrations generated by the optical glass machining means are attenuated, which makes it possible to increase the service life of the elements of the device and makes the use of the device more comfortable for the users.

In addition, the system used to reduce noise is efficient and compact. Finally, the fact of using reference sensors and error sensors and of separately processing the low frequency signals and the high frequency signals makes it possible to improve the attenuation.

Claims (1)

CLAIMS1.- Apparatus (10) for machining optical glasses comprising machining means (12) for an optical glass (11) capable of generating a noise and / or a primary vibration (B1, V1), characterized in that the device (10) further comprises an anti-noise and / or anti-vibration system (14) comprising: at least one sensor (60, 62, 64, 66, 68) capable of measuring information (11, 12) representative of a noise and / or measured vibration resulting from noise and / or primary vibration (B1, V1); at least one source (70, 72) of noise and / or secondary vibration (B2, V2); and at least one control unit (80), connected to the or each sensor (60, 62, 64, 66, 68) and to the or each source (70, 72) of secondary noise and / or vibration (B2 , V2), the or each unit (80) being adapted to drive the or each source (70, 72) of noise and / or secondary vibration (B2, V2) on the basis of at least one piece of information (11, 12 ) measured by the or each sensor (60, 62, 64, 66, 68) to attenuate the noise and / or primary vibration (B1, V1) generated by the machining means (12). 2. A machining device (10) according to claim 1, characterized in that at least one sensor (60, 64, 66) is a reference sensor, able to measure a first information (11) representative mainly of the noise and / or primary vibration (B1, V1). 3. A machining device (10) according to claim 2, characterized in that it comprises a lens support (24) and a grinding assembly (22) carrying at least one machining tool (32). optical glass (11), the or each reference sensor (60, 64, 66) being attached to one of the lens holders (24) and grinding assembly (22). 4. A machining device (10) according to any one of the preceding claims, characterized in that at least one sensor (62, 68) is an error sensor adapted to measure a second representative information (12). noise and / or vibration resulting from the sum of the noise and / or the primary vibration (B1, V1) with the noise and / or the secondary vibration (B2, V2). 15 5. A machining device (10) according to any one of the preceding claims, characterized in that at least one noise and / or vibration sensor (60, 62, 64, 66, 68) comprises a microphone ( 60, 62) and / or an accelerometer (64, 66, 68). 6. Machining device (10) according to any one of the preceding claims, characterized in that at least one source (70, 72) of noise and / or secondary vibration (B2, V2) comprises a speaker (70) and / or an actuator (72). 7. Machining device (10) according to any one of the preceding claims, characterized in that the control unit (80) comprises at least one input filter (82, 84, 86, 88) for filtering at least one piece of information (11, 12) measured by at least one sensor (60, 62, 64, 66, 68), as a function of its frequency. 8. A machining device (10) according to claim 7, characterized in that the control unit (80) comprises at least one low frequency filter (82, 86) with advantageously a cutoff frequency greater than or equal to I kHz and at least one high frequency filter (84, 88) with advantageously a cut-off frequency less than or equal to I kHz. 9. A method for attenuating a noise and / or a primary vibration (B1, V1) generated by machining means (12) of an optical glass machining device (10), said device machining unit (10) comprising an anti-noise and / or anti-vibration system (14) comprising: at least one sensor (60, 62, 64, 66, 68) capable of measuring an information (11, 12) representative of a noise and / or a measured vibration; at least one source (70, 72) of noise and / or secondary vibration (B2, V2); and at least one control unit (80), connected to the or each sensor (60, 62, 64, 66, 68) and to the or each source (70, 72) of secondary noise and / or vibration (B2 , V2); characterized in that said method comprises the steps of: measuring, by the or each sensor (60, 62, 64, 66, 68), information (11, 12) representative of noise and / or measured vibration resulting from noise and / or primary vibration (B1, V1); processing the or each information (11, 12) by the control unit (80); controlling the source (70, 72) of noise and / or secondary vibration (B2, V2) by the control unit (80) on the basis of the or each information (11, 12) measured by at least one sensor (60, 62, 64, 66, 68) so that the source (70, 72) emits a noise and / or secondary vibration (B2, V2) adapted to attenuate the noise and / or primary vibration (B1, V1) generated by the machining means (12). 10.- Method according to claim 9, characterized in that the or each information (11, 12) is filtered at the input of the control unit (80), depending on its frequency.