阅读说明：本技术 电子装置、驱动方法和存储介质 (Electronic device, driving method, and storage medium ) 是由 丁庆 阿尔珀·埃尔坎 于 2019-07-09 设计创作，主要内容包括：提供了电子装置、驱动方法和存储介质。该电子装置,包括被配置为根据多电平混合时钟方案驱动飞行时间相机的单位像素的电路。(An electronic apparatus, a driving method, and a storage medium are provided. The electronic device includes circuitry configured to drive a unit pixel of a time-of-flight camera according to a multi-level hybrid clock scheme.)

1. An electronic device includes circuitry configured to drive a unit pixel of a time-of-flight camera according to a multi-level hybrid clock scheme.

2. The electronic device of claim 1, wherein the unit pixel comprises a first trace and a second trace, and wherein the multilevel blending scheme comprises providing an active first trace modulation signal to the first trace of the unit pixel and providing an active second trace modulation signal to the second trace of the unit pixel.

3. The electronic device of claim 1, wherein the multi-level hybrid clock scheme is an N-level hybrid clock scheme, wherein an active modulation signal has N +1 voltage levels, where N is an integer greater than 1.

4. The electronic device of claim 3, wherein in the N-level hybrid clock scheme, the N +1 voltage levels of the active modulation signal define N voltage steps.

5. The electronic device of claim 2, wherein the multi-level hybrid clock scheme is a two-level hybrid clock scheme, wherein the active modulation signal provides three voltage levels.

6. The electronic device of claim 1, wherein the multi-level mixing scheme is an active multi-level mixing scheme.

7. The electronic device of claim 6, wherein the active multi-level mixing scheme comprises generating an active first trace modulation signal and an active second trace modulation signal from a predetermined voltage level.

8. The electronic device of claim 6, wherein the circuit comprises a switch driven according to a multilevel hybrid scheme to generate an active first trace modulation signal and an active second trace modulation signal.

9. The electronic device according to claim 3 or 4, wherein the voltage level is provided to the unit pixel by an analog buffer.

10. The electronic device of claim 1, wherein the multi-level mixing scheme is a passive multi-level mixing scheme.

11. The electronic device of claim 10, wherein the passive multilevel hybrid scheme includes passively redistributing charge between a first trace and a second trace of the unit pixel to generate an active first trace modulation signal and an active second trace modulation signal.

12. The electronic device of claim 10, wherein the circuit comprises a switch configured to connect the first trace of the unit pixel with the second trace of the unit pixel to passively redistribute charge between the first and second traces of the unit pixel.

13. The electronic device of claim 10, wherein the circuit comprises a first digital buffer to drive a first trace of the unit pixel and a second digital buffer to drive a second trace of the unit pixel, and wherein a first trace modulation signal is provided to the first digital buffer, and wherein a second trace modulation signal is provided to the second digital buffer.

14. The electronic device of claim 13, wherein the first and second digital buffers are enabled and/or disabled according to the multi-level mixing scheme to generate an active first trace modulation signal and an active second trace modulation signal.

15. A time-of-flight system comprising the circuit of claim 1, a light source (2) and an image sensor (6).

16. A driving method includes driving a unit pixel of a time-of-flight camera according to a multi-level hybrid clock scheme.

17. A storage medium having stored thereon a computer program comprising instructions which, when executed on a processor, control a driver of a unit pixel of a time-of-flight camera according to a multilevel hybrid clock scheme.

Technical Field

The present disclosure relates generally to the field of electronic devices, and more particularly to an imaging device and a method for an imaging device.

Background

A time-of-flight camera is a distance imaging camera system for determining the distance of an object, the time-of-flight (ToF) of the light signal between the camera and the object being measured for each point of the image. The time-of-flight camera thus receives a depth map of the scene. In general, a time-of-flight camera has an illumination unit that illuminates a region of interest with modulated light and an array of pixels that collect light reflected from the same region of interest. When individual pixels collect light from certain parts of the scene, the time-of-flight camera may include lenses for imaging while maintaining a reasonable light collection area.

A typical ToF camera pixel generates a (develop) charge that represents the correlation between the illuminating light and the backscattered light. To achieve correlation between the illumination light and the backscattered light, each pixel is controlled by a common modulation input from one or more hybrid drivers. The modulation input of the pixels is synchronized with the illumination block modulation.

The load of the hybrid driver is typically capacitive. Power consumption is well known to the publicKnown equation CV²F, where C is the total load capacitance, V is the supply voltage, and F is the switching speed (or modulation frequency) of the hybrid driver. Hybrid drivers consume large amounts of power, especially when the load capacitance is large or the modulation frequency is high.

In general, power consumption is reduced by reducing the load capacitance, especially by reducing the lightgate/passgate capacitance.

Disclosure of Invention

According to a first aspect, the present disclosure provides an electronic device comprising circuitry configured to drive a unit pixel of a time-of-flight camera according to a multi-level hybrid clock scheme.

According to a second aspect, the present disclosure provides a method comprising: the unit pixels of the time-of-flight camera are driven according to a multi-level hybrid clock scheme.

According to a third aspect, the present disclosure provides a time-of-flight system comprising the circuit of the first aspect, a light source and an image sensor.

According to a fourth aspect, the present disclosure provides a computer program comprising instructions which, when executed on a processor, control a driver of a unit pixel of a time-of-flight camera according to a multilevel hybrid clock scheme.

Further aspects are set out in the dependent claims, the following description and the drawings.

Drawings

Embodiments are explained by way of example with reference to the accompanying drawings, in which:

fig. 1 schematically illustrates the basic operating principle of indirect time-of-flight (iToF);

fig. 2 shows a circuit of a conventional hybrid driver of a ToF camera with an array of columns of pixels;

FIG. 3 shows a modulated signal provided to the input of the hybrid drive of FIG. 2;

fig. 4 shows a first embodiment of a circuit of a hybrid driver of a ToF camera with an active two-level hybrid clock scheme;

FIG. 5 shows a multi-level clocking scheme for driving the six switches of the hybrid driver of FIG. 4 to effectively modulate signal waveforms in the time domain;

fig. 6 shows a second embodiment of a circuit for a hybrid driver for a ToF camera with an active N-level hybrid clocking scheme;

FIG. 7 illustrates a multi-level clocking scheme for driving the switches of the hybrid driver of FIG. 6;

fig. 8 shows a third embodiment of a circuit of a hybrid driver of a ToF camera with a passive two-level hybrid clock scheme; and

fig. 9 shows a multi-level clocking scheme for controlling the switches and digital buffers of the hybrid driver of fig. 8 to effectively modulate signal clock waveforms in the time domain.

Detailed Description

Before a detailed description of a first embodiment of the present disclosure is given with reference to fig. 3, a general explanation is made.

As mentioned at the outset, known time-of-flight (ToF) cameras include a variety of methods for measuring the time required for light to travel a distance in a medium so that the distance can be determined. In indirect time-of-flight (iToF), a camera calculates the phase shift between the illuminating light and the backscattered light by sampling a correlation wave (e.g., a correlation wave between modulation signals used to drive the light source, pixel array, etc.) with a signal obtained based on the backscattered light to obtain a depth measurement.

The embodiments described below provide an electronic device including a circuit configured to drive a unit pixel of a time-of-flight camera according to a multi-level hybrid clock scheme.

The electronic device may for example be an image sensor, e.g. an image sensor of a direct time-of-flight camera (ToF). An indirect time-of-flight camera can resolve distance by measuring the phase shift of the emitted light and the backscattered light.

The circuitry may include any electronic components, semiconductor components, switches, amplifiers, transistors, processing components, and the like.

The circuit may be, inter alia, a driver of ToF unit pixels, which provides a modulation signal to the signal input of one or more unit pixels. Driving the unit pixels of the time-of-flight camera with the multi-level mixed clock signal may, for example, comprise using the multi-level mixed clock signal as a modulation signal for the unit pixels. The modulation signal may be a signal related to a signal collected in the unit pixel.

The time-of-flight camera may be a distance imaging camera system that determines the distance of an object by measuring the time-of-flight (ToF) of the light signal between the camera and the object for each point of the image.

A unit pixel of a ToF camera typically includes one or more photosensitive elements (e.g., photodiodes). The photosensitive element converts incident light into electrical current. A switch (e.g., a transfer gate) connected to the photodiode can direct current to one or more storage elements (e.g., capacitors) that act as accumulation elements that accumulate and/or store charge. For a time-of-flight camera, the unit pixels may be lock-in pixels, for example, FDGS-type pixels or Photonic Mixer Devices (PMD). All unit pixels in the ToF sensor may be controlled by a modulation signal based on a multi-level mixed clock signal.

A multi-level hybrid clock scheme may be used to generate one or more (active) modulation signals that drive the unit pixels. These (effective) modulation signals may be step functions comprising a plurality of voltage levels.

In some embodiments, the unit pixel includes a first trace and a second trace, and wherein the multilevel mixing scheme includes providing an active first trace modulation signal to the first trace of the unit pixel and providing an active second trace modulation signal to the second trace of the unit pixel.

For example, the first and second traces may include respective storage capacitors of the unit pixel that are charged and discharged by the active modulation signal.

Typically, the effective first trace modulation signal and the effective second trace modulation signal are phase shifted by 180 °.

The effective modulation signal may have a frequency in the range of, for example, 10 to 100 MHz.

In some embodiments, the multi-level hybrid clock scheme is an N-level hybrid clock scheme, wherein the active modulation signal has N +1 voltage levels, where N is an integer greater than 1.

The effective modulation signal may be, for example, at a high state V_DDAnd a low state GND, where N is an integer greater than 1, where the voltage step is a voltage transition from one voltage level to another.

The active modulation signal may be a periodic signal, wherein the period comprises a charging phase and a discharging phase, wherein each phase comprises N voltage steps.

In some embodiments, in an N-level hybrid clock scheme, N +1 voltage levels of the active modulation signal define N voltage steps.

In some embodiments, the multi-level hybrid clock scheme is a two-level hybrid clock scheme, wherein the active modulation signal provides three voltage levels.

The effective modulation signal may be, for example, a signal having an intermediate voltage level V_DDOf/2 at GND and V_DDOf the signal oscillating in between. At three voltage levels (GND, V)_DD/2、V_DD) Has two voltage steps, namely GND to V_DDV and 2_DD2 to V_DD. The active modulation signal of three voltage levels according to this embodiment may be a periodic signal, wherein the period comprises a charging phase and a discharging phase, wherein each phase comprises two voltage steps.

In some embodiments, the multi-level mixing scheme is an active multi-level mixing scheme.

An active multi-level mixing scheme may include providing several predefined voltage levels and generating an active modulation signal from these predefined voltage levels.

In some embodiments, the active multilevel mixing scheme includes generating an active first trace modulation signal and an active second trace modulation signal from a predetermined voltage level.

In some embodiments, the circuit includes a switch driven according to a multilevel mixing scheme to generate an active first trace modulation signal and an active second trace modulation signal.

In some embodiments, the voltage levels are provided to the unit pixels by analog buffers.

The analog buffer may transfer a voltage of a multi-level mixing scheme to the unit pixel.

In some embodiments, the multi-level hybrid scheme is a passive multi-level hybrid scheme.

In some embodiments, a passive multilevel hybrid scheme includes passively redistributing charge between a first trace and a second trace of a unit pixel to generate an active first trace modulation signal and an active second trace modulation signal.

For example, a passive multilevel hybrid scheme may include passively redistributing charge between one or more first storage capacitors of a first trace and one or more second storage capacitors of a second trace of a unit pixel to generate an active first trace modulation signal and an active second trace modulation signal.

In some embodiments, the circuit includes a switch configured to connect the first trace of the unit pixel with the second trace of the unit pixel for passively redistributing charge between the first trace and the second trace of the unit pixel.

For example, the circuit may include a switch configured to connect one or more first capacitors of a first trace of a unit pixel with one or more second capacitors of a second trace of the unit pixel for passively redistributing charge between the first trace and the second trace of the unit pixel.

By controlling the switches, the circuit can control and manage the timing between the multilevel mixing signal and the voltage/current (active modulation signal), as shown by the unit pixel.

In some embodiments, the circuit includes a first digital buffer to drive a first trace of a unit pixel and a second digital buffer to drive a second trace of the unit pixel, and wherein the first trace modulation signal is provided to the first buffer, and wherein the second trace modulation signal is provided to the second buffer.

For example, the first trace modulation signal and the second trace modulation signal are phase shifted by 180 °. The modulation signal may be a square wave with a frequency in the range of 10 to 100MHz, although more complex arrangements may be used.

In some embodiments, the first digital buffer and the second digital buffer are enabled/disabled according to a multi-level mixing scheme to generate an active first trace modulation signal and an active second trace modulation signal.

The digital buffer may be a tri-state buffer, i.e. an input controlled switch comprising an input, an output and a control input. The output may be electronically "turned on" or "turned off" by an external enable/disable control input. The control signal input may be a logic "0" or a logic "1".