■ or alternatively: use an additional, external LED driver to adjust the illumination to the needed system sensitivity level (refer to

chapter 1.3.10.: Extended operating range).

The easiest way is to adapt the exposure time to the current illumination situation (e.g. in Figure 16). With the command formats, which al-

lows adjusting of the exposure time, it is easy to do. It is simple to change the exposure time on the fly: an “INTEGRATION” command can

be sent to the chip before a capture is initiated.

range

n-1

operation

range

n

range

n+1

range

n+2

range

n-2

Distance R

Exposure time (Integration time)

R

0

2

R

0

2

R

0

R

0

R

R

2

T

0

0.5

⋅T

0

0.25

⋅T

0

4

⋅T

0

Figure 16: Operating ranges as a function of distance and exposure time

based on doubling the light power to the sensor

1.3.4. Ambient-light suppression

light sources e.g. sunlight, daylight, room illumination, etc., from the measuring signal. The user has not to take care of this, it is done by

the chip automatically. To see the capability of this function, refer to Table 3 for example values as a function of the wavelength and com-

pared to sunlight.

Similar to the system's sensitivity of the modulated light, is the ambient-light suppression a function of the integration time. The longer the

integration time, the more the measurement becomes sensitive to the ambient-light.

Notes:

■ The ambient-light suppression of the chip must not be confused ambient-light measurement command. It is a fixed built-in functionality,

which is removing the DC light component from the AC measurement signal only.

■ A DC or AC photo-signal can be generated by ambient-light (e.g. sunlight) or by cross-talk from the IR-LEDs. However, if this is above

the stated maximum value, then the sensor or the input electronics are saturated. This blocks the detection of the AC modulation signal.

1.3.5. Quality of the measurement result

The epc610 provides information on the quality and the validity of the received optical signal. This reflects the confidence level of the mea -

surement result. The better the received signal, the better and more precise the distance measurement will be.

Each distance measurement of every pixel has its own validity and quality.

After each measurement this needs to be calculated from the DCSx values delivered by the chip. This amplitude value is the feedback pa-

rameter that is used to set the integration time for the next measurement.

4

+

(DCS1−DCS3)

2

4

© 2014 ESPROS Photonics Corporation

Characteristics subject to change without notice

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Datasheet epc610 - V1.7

www.espros.ch