Camera voice coil motor driver circuit with variable power supply input voltage

Patent metadata

Field	Value
Publication number	US-2017019596-A1
Application number	US-201514798005-A
Country	US
Kind code	A1
Filing date	Jul 13, 2015
Priority date	Jul 13, 2015
Publication date	Jan 19, 2017
Grant date	—

Abstract

In a portable camera device, a variable voltage regulator produces a power supply voltage of a VCM driver circuit that conducts the coil current of a VCM actuator as part of an optical image stabilization (OIS) mechanism. A processor signals the variable voltage regulator to increase the power supply voltage when the camera device transitions from still capture mode or preview mode to video capture mode, where the increase causes an increase in stroke of the VCM OIS actuator. Other embodiments are also described and claimed.

First claim

What is claimed is:

1 . A method for operating a driver circuit of a camera OIS actuator, comprising:
determining an indication of a level of activity expected of a camera OIS actuator; and varying a power supply input voltage of a driver of the OIS actuator, based on said indication,
wherein when the indication is that the level of activity of the OIS actuator is to be at a high level, the power supply input voltage is raised, and
when the indication is that the level of activity of the OIS actuator is to be at a low level, the power supply input voltage is lowered.

2 . The method of claim 1 wherein determining an indication of a level of activity of an OIS actuator comprises:
accessing a stored variable that identifies a current mode of operation of a camera device of which the OIS actuator and the driver are a part,
wherein the indication of the level of activity of the OIS actuator is a low level of activity, in response to the current mode of operation being preview mode or still capture mode,
and wherein the indication is a high level of activity in response to the current mode of operation being video capture mode.

3 . The method of claim 1 further comprising:
starting a timer when a video capture session begins;
while the timer remains unexpired, maintaining the power supply input voltage of the driver at a high level, to enable a high level of activity by the OIS actuator; and
in response to expiration of the timer, lowering the power supply input voltage of the driver to limit the OIS actuator to a low level of activity, even while the video capture session continues.

4 . The method of claim 3 further comprising:
detecting user context of the camera device, wherein the user context is one of a) attached to a tripod, b) walking, c) head or helmet mounted, or d) driving; and
setting a duration of the timer in accordance with the detected user context.

5 . The method of claim 1 wherein determining an indication of a level of activity of an OIS actuator comprises:
accessing a stored variable that identifies a current mode of operation of a camera device of which the OIS actuator and the driver are a part, and
wherein the indication of the level of activity of the OIS actuator is a maximum level of activity in response to the current mode of operation being camera diagnostic mode.

6 . A portable camera device comprising:
a camera imaging path element; a voice coil motor (VCM) actuator coupled to move the camera imaging path element while drawing a coil current; an VCM driver circuit having an output to conduct the coil current, a power supply input, and a control input to set a level of the coil current; an optical image stabilization (OIS) processor that is signal the control input of the driver circuit to move the camera imaging path element for OIS; a variable voltage regulator having an output that is to produce a power supply voltage and is coupled to the power supply input of the driver circuit, and a control input to vary a level of the power supply voltage; and a processor to signal the control input of the variable voltage regulator to increase the level of the power supply voltage when the camera device transitions from still capture mode or preview mode to video capture mode, wherein an increase in the level of the power supply voltage causes an increase in stroke of the VCM actuator.

7 . The portable camera device of claim 6 wherein the processor is to decrease the level of the power supply voltage when transitioning from the video capture mode to the still capture or to the preview mode, which decreases stroke of the VCM actuator.

8 . The portable camera device of claim 6 wherein the camera imaging path element, the OIS actuator, and the driver circuit are integrated within a camera module that is separate from a main logic board on which the variable voltage regulator is installed.

9 . The portable camera device of claim 6 further comprising:
an autofocus actuator coupled to a camera imaging path element;
an autofocus driver circuit having an output to conduct current of the autofocus actuator; and
a further voltage regulator having an output that is to produce a further power supply voltage at a power supply input of the autofocus driver, wherein the power supply input of the VCM driver circuit is controlled separately from the power supply input of the autofocus driver circuit.

10 . A camera device comprising:
a camera imaging path element; an optical image stabilization (OIS) actuator having a voice coil motor (VCM) coupled to actuate the camera imaging path element while drawing a coil current; a driver circuit having an output to conduct the coil current of the VCM, a power supply input, and a control input to set a level of the coil current; a variable voltage regulator having an output to produce a power supply voltage and being coupled to the power supply input of the driver circuit, and a control input to vary a level of the power supply voltage; and a processor coupled to the control input of the variable voltage regulator to modulate the power supply voltage at the power supply input of the driver circuit, at all times while the camera device is powered up, as a function of a present performance level demanded from the OIS actuator.

11 . The device of claim 10 wherein the processor is to modulate the power supply voltage of the driver circuit in response to detecting a present user context in which the camera device is being used.

12 . The device of claim 10 wherein the processor modulates the power supply voltage such that headroom of the driver circuit is varied continuously and is kept at a lowest level that meets a current performance level demanded from the OIS actuator.

13 . The device of claim 10 wherein the processor is to modulate the power supply voltage based on a plurality of input variables that include a) an indication of the present capture mode of the camera device and b) a present user context.

14 . The device of claim 13 further comprising a sensor whose output data is used by the processor to detect the present user context in which the camera device is being used, wherein the present user context is one of walking, running, driving, or tripod.

15 . The device of claim 10 further comprising:
an autofocus actuator coupled to the camera imaging path element, or to another camera imaging path element;
an autofocus driver circuit having an output to conduct current of the autofocus actuator; and
a further voltage regulator having an output that is to produce a further power supply voltage and is coupled to a power supply input of the autofocus driver, such that the power supply input of the OIS driver circuit can be controlled separately than the power supply input of the autofocus driver circuit.

16 . The device of claim 10 wherein the present performance level demanded from the OIS actuator is one of low or high, and wherein the present performance level is low while the device is in preview mode and high while the device is in video capture mode.

17 . The device of claim 10 wherein the present performance level demanded from the OIS actuator is one of low or high, wherein the present performance level is low while the device is in still capture mode, and high while the device is in video capture mode.

Assignees

• Apple Inc

Inventors

• Dunn Ryan J
• Thivent Damien J
• Mcclure Morgan T
• Patel Parin

Classifications

• H04N23/667

  Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes · CPC title

• H04N23/685 Primary

  performed by mechanical compensation · CPC title

• H04N5/23293

  Electricity · mapped topic

• H04N5/23241 Primary

  Electricity · mapped topic

• H04N5/2328

  Electricity · mapped topic