5B-2-2
Figure 2 - Reflection Light Amount Image
4 METHOD OF RECORDING CRACK
The vehicle where the automatic measurement device had been
installed was developed about 20 years ago. The device by which
then crack situation is understood uses the slit camera and 35mm
roll film. Roads are produced with the illumination installed in the
vehicle and the shadow of the shining on crack is produced. The
slit camera takes a picture of the shadow of the crack (The speed
fed according to the velocity of the car changes into the film). The
generation situation of the crack was understood from the film
taken a picture.
The Komatus Engineering Co., LTD developed another kind of
device by the digitalization of the measurement device. The
reflection record by a digital method uses the laser and the optical
detection sensor. The laser is scanned in the direction of the road
crossing at high speed in the spot. The change in the reflection
light amount of the spot laser is caught and the optical detection
sensor is recorded as line surface information in the direction of
the road crossing. The distance signal obtained when the vehicle
runs is recorded at the same time. Recorded surface information is
treated with a special player as one scanning lines and is
recognized by displaying it at the same time by the plural as a
respect image (pavement road).
Figure 3 - Laser Irradiation Entrance
Figure 4 - Irradiated Laser
5 CRACK IMAGE
Information acquired with the optical detection sensor is recorded
on the W-VHS tape (tape to record the high picture quality
reflection). Even the maximum at the recording time of the tape
can be recorded regardless of the running speed of the car. The
monitor as seen from sky by eyes projects the image of the road.
This digital image differs from 35mm roll film, is not damaged,
and is not torn off. Moreover, advancement, the retreat, and the
stop can be freely done with the remote control button of a video
device.
Figure 5 shows the crack image of the vertical direction (direction
of progress). Figure 6 shows a horizontal crack image. The crack
Line B
Line A
Crack
Reflection Light Amount Image
Line A
Bright
Dark
Line B
Bright
Dark