Driving circuit and method for voice coil motor with spring return

A lens module comprising:

• a focusing lens;
• a voice coil motor having a return mechanism arranged such that its mover is linked to the focusing lens;
• a driving circuit configured to drive the voice coil motor,
• wherein the driving circuit comprises:
• a driving current generating unit configured to supply a driving current that corresponds to an analog control signal to a coil of the voice coil motor;
• memory configured to store digital waveform data which indicates a time waveform of the driving current, from the frequency components of which a predetermined frequency component has been removed;
• a control unit configured to read out the waveform data from the memory at a rate that corresponds to the resonance frequency of the voice coil motor, and to output the waveform data thus read out as a digital code;
• and
• a D/A converter configured to convert the digital code output from the control unit into an analog control signal, and to output the analog control signal thus converted to the driving current generating unit,
• wherein the memory is configured to store:
• first waveform data obtained by removing the predetermined frequency component from a step waveform that changes from zero to the target displacement;
• second waveform data obtained by removing the predetermined frequency component from a waveform that changes in a stepwise manner from zero to a first displacement that is greater than a target displacement, and that changes in a stepwise manner to the target displacement after the first displacement is maintained for a predetermined period of time,
• and wherein the control unit is configured to be capable of selectively reading out either the first waveform data or the second waveform data.

An electronic device comprising:

• a lens module;
• and
• an image sensing device configured to acquire an image from light that passes through the lens module,
• wherein the lens module comprises:
• a focusing lens;
• a voice coil motor having a return mechanism arranged such that its mover is linked to the focusing lens;
• a driving circuit configured to drive the voice coil motor,
• and wherein the driving circuit comprises:
• a driving current generating unit configured to supply a driving current that corresponds to an analog control signal to a coil of the voice coil motor;
• memory configured to store digital waveform data which indicates a time waveform of the driving current, from the frequency components of which a predetermined frequency component has been removed;
• a control unit configured to read out the waveform data from the memory at a rate that corresponds to the resonance frequency of the voice coil motor, and to output the waveform data thus read out as a digital code;
• and
• a D/A converter configured to convert the digital code output from the control unit into an analog control signal, and to output the analog control signal thus converted to the driving current generating unit, wherein the memory is configured to store:
• first waveform data obtained by removing the predetermined frequency component from a step waveform that changes from zero to the target displacement;
• second waveform data obtained by removing the predetermined frequency component from a waveform that changes in a stepwise manner from zero to a first displacement that is greater than a target displacement, and that changes in a stepwise manner to the target displacement after the first displacement is maintained for a predetermined period of time,
• and wherein the control unit is configured to be capable of selectively reading out either the first waveform data or the second waveform data.

A driving circuit configured to drive a voice coil motor having a spring return mechanism, the driving circuit comprising:

• a driving current generating unit configured to supply a driving current that corresponds to an analog control signal to a coil of the voice coil motor;
• memory configured to store digital waveform data which indicates a time waveform of the driving current, from the frequency components of which a predetermined frequency component has been removed;
• a control unit configured to read out the waveform data from the memory at a rate that corresponds to the resonance frequency of the voice coil motor, and to output the waveform data thus read out as a digital code;
• and
• a D/A converter configured to convert the digital code output from the control unit into an analog control signal, and to output the analog control signal thus converted to the driving current generating unit, wherein the control unit is configured such that, when the digital code that has been set is smaller than a predetermined first threshold value, it first outputs a digital code that corresponds to the first threshold value, it then increments, with a constant slope, the value of the digital code, from the first threshold value up to a second threshold value that is greater than the first threshold value, following which it generates a digital code for the displacement from the second threshold value to a target displacement.

A lens module comprising:

• a focusing lens;
• a voice coil motor having a return mechanism arranged such that its mover is linked to the focusing lens;
• a driving circuit configured to drive the voice coil motor,
• wherein the driving circuit comprises:
• a driving current generating unit configured to supply a driving current that corresponds to an analog control signal to a coil of the voice coil motor;
• memory configured to store digital waveform data which indicates a time waveform of the driving current, from the frequency components of which a predetermined frequency component has been removed;
• a control unit configured to read out the waveform data from the memory at a rate that corresponds to the resonance frequency of the voice coil motor, and to output the waveform data thus read out as a digital code;
• and
• a D/A converter configured to convert the digital code output from the control unit into an analog control signal, and to output the analog control signal thus converted to the driving current generating unit, wherein the control unit is configured such that, when the digital code that has been set is smaller than a predetermined first threshold value, it first outputs a digital code that corresponds to the first threshold value, it then increments, with a constant slope, the value of the digital code, from the first threshold value up to a second threshold value that is greater than the first threshold value, following which it generates a digital code for the displacement from the second threshold value to a target displacement.

An electronic device comprising:

• a lens module;
• and
• an image sensing device configured to acquire an image from light that passes through the lens module,
• wherein the lens module comprises:
• a focusing lens;
• a voice coil motor having a return mechanism arranged such that its mover is linked to the focusing lens;
• a driving circuit configured to drive the voice coil motor,
• and wherein the driving circuit comprises:
• a driving current generating unit configured to supply a driving current that corresponds to an analog control signal to a coil of the voice coil motor;
• memory configured to store digital waveform data which indicates a time waveform of the driving current, from the frequency components of which a predetermined frequency component has been removed;
• a control unit configured to read out the waveform data from the memory at a rate that corresponds to the resonance frequency of the voice coil motor, and to output the waveform data thus read out as a digital code;
• and
• a D/A converter configured to convert the digital code output from the control unit into an analog control signal, and to output the analog control signal thus converted to the driving current generating unit, wherein the control unit is configured such that, when the digital code that has been set is smaller than a predetermined first threshold value, it first outputs a digital code that corresponds to the first threshold value, it then increments, with a constant slope, the value of the digital code, from the first threshold value up to a second threshold value that is greater than the first threshold value, following which it generates a digital code for the displacement from the second threshold value to a target displacement.