EPC635 datasheet(53/97 Pages) EPC

53 / 97 page

Table 31 shows a quality decision matrix as a summary of the validity and quality parameters for the distance measurement.

Step

Sensor status

Pixel

saturation

Maximum

signal

Noise

level

Modulated light amplitude

Ratio ambient to

modulated light

Action

XSYNC_

SAT

min. one

| DCSx |

all

| DCSx |

ATOF PP

AMR

Saturation or bright ob-

ject within scene

flag set

Repeat measurement with

decreased integration time and/or illumination

Saturation or bright ob-

ject within scene

> 2'000 LSB

Repeat measurement with

decreased integration time and/or illumination

No object detected

< 2'000 LSB

< 25 LSB

Repeat measurement with

increased integration time or illumination

Overexposure or bright

object within scene

< 2'000 LSB

> 25 LSB

> 2'000 LSB

Repeat measurement with

decreased integration time or illumination

No object detected

< 2'000 LSB

> 25 LSB

25 LSB

Repeat measurement with

increased integration time or illumination

Too much ambient-light

< 2'000 LSB

> 25 LSB

25 LSB … 2'000 LSB

> 60 db (or > 70 dB)

Repeat measurement with

increased integration time or illumination

Object detected

< 2'000 LSB

> 25 LSB

Good:

100 … 2'000 LSB

Enough:

25 … 100 LSB

< 60 db (or < 70 dB)

No action necessary

Table 31: Quality decision matrix

6.2. Grayscale mode

The grayscale mode allows using the epc635 as a grayscale imager. This mode can be used either without LED/LD illumination for ambi-

ent-light measurements or with LED/LD for active illumination of the scenery.

The grayscale measurement uses the regular DCS measurement but only with DCS0. It is performed in single-ended mode with readout of

MGA. Refer to chapter 8.6.5, MT registers. Corresponding registers settings can be found in Table 32.

There will be a one frame acquisition with the 12 bit grayscale values.

Due to the fact that distance measurement results can be influenced by ambient-light, the grayscale measurement without illumination can

thereof be used as an important quality and correction parameter for the distance measurement.

Grayscale: Quality of the measurement result

The same rules apply for data quality and validity as given in section “Sine mode: Quality of the measurement result”. The saturation flag

status is invalid in this mode.

These grayscale values can also be used for estimating quality information during sine mode for the 3D TOF distance calculations.

The irradiance EBW of the grayscale signal at the surface of a pixel can be calculate out of the DC sensitivity S BW, the used integration time

tINT-BW, the reference integration time tINT-REF-BW and the amplitude DCS0 of the grayscale signal the following way:

[8]

EBW

= SBW⋅

INT-REF-BW

INT-BW

⋅DCS0

e.g.

BW = 0.246

/mm

LSB

⋅

103

μ s

1.6

μ s

⋅1'000 LSB = 15.84μ W/mm

Characteristics subject to change without notice

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Datasheet_epc635-V1.02

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