Method of inspecting a negative film in a photographic processing apparatus

A method of inspecting a negative film in a photographic processing apparatus includes the steps of using a detector to detect location data (i.e., preforations) arranged at equal intervals on the negative film, electrically comparing the detected location data with equally distanced reference location data having a regularity and assigned to a standard negative film, and automatically stopping the advancing movement of the negative film upon finding a fault in the regularity of the detected location data.

BACKGROUND OF THE INVENTION 
The present invention relates to a method of inspecting a negative film 
(referred to as a negative hereinafter) in a photographic processing 
apparatus. 
It is known that a negative may be jammed and damaged during the advancing 
movement along a film passage in a photographic processing apparatus when 
it has a defect such as a slit adjacent to a perforation. 
For preventing such an incident, the negatives are visually inspected 
one-by-one by an operator being loaded into the photographic processing 
apparatus. If any defective negative is found, it is reclaimed or repaired 
to ease the advancing movement along the apparatus film passage. 
The visual inspection of the negatives is a troublesome task having very 
low efficiency, and misjudgment possible omission of a defect. If any 
defective film is loaded through possible omission of a defect, 
misjudgment, or fault action of a drive system in the film passage, it 
will be jammed and damaged causing cancellation of the printing process. 
It is thus essential to stop the advancing movement immediately and remove 
the defective negative from the film passage by manual action of the 
operator upon jamming of the defective negative. This obligates the 
operator to pay constant attention to the advancing movement of the 
negative film to prevent generation of a troublesome situation. In 
addition, the inspection process for identifying any defect on the 
negative is not easy and requires a level of skill. It has been much 
desired to develop a technique for elimination of such a disadvantage. 
It is an object of the present invention, in view of the foregoing, to 
provide a method of inspecting a negative for slits or cuts without visual 
checking of a service person or operator so that any defective negative 
film is exactly identified and prevented from loading into the film 
passage of a photographic processing apparatus. 
SUMMARY OF THE INVENTION 
For achievement of the object of the present invention, a method of 
inspecting a negative film in a photographic processing apparatus 
comprises the steps of using a detector to detect location data arranged 
at equal intervals on the negative film, electrically comparing the 
detected location data with equally distanced reference location data 
having a regularity and assigned to a standard negative film, and 
automatically stopping the advancing movement of the negative film upon 
finding a fault in the regularity of the detected location data. 
According to the inspection method of the present invention, the location 
data arranged at equal intervals on the negative film in the form of, for 
example, perforations are electrically measured or monitored and 
electrically compared with the equally distanced reference location data 
which have a regularity and are arranged on the standard film. If a fault 
in the regularity of the measured location data on the negative film is 
found, it is judged that there is at least a slit adjacent to one of the 
perforations or any obstruction in the same. In response such a judgment, 
the advancing movement of the negative film is systematically stopped to 
prevent any damage to the film and the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
One preferred embodiment of the present invention will be described below 
referring to the accompanying drawings. 
As shown in FIG. 1, a negative film 1 is continuously advanced by the 
action of drive rollers 2 towards a detector 3 which electrically examines 
whether or not the negative 1 has a defect such as a slit adjacent to a 
perforation. FIG. 2 is a flow chart showing a procedure of the 
examination. As reference location data arranged at equal intervals on a 
standard negative are initiated having a degree of regularity, the 
advancing movement of the negative 1 is commenced. The detector 3 includes 
two parts 3A and 3B positioned on opposite sites of the negative 1. 
Location data arranged on the negative 1 are detected by the detector 3 
and transmitted to a comparator (not shown) where it is electrically 
compared with the reference location data. More specifically, it is 
examined whether or not the location data on the negative 1 is identical 
or in regularity to the reference location data of the standard negative. 
If a fault in the regularity of the location data is found, the advancing 
movement of the negative 1 is terminated. When the regularity is 
acceptable, it is further examined whether the advancing movement of the 
negative 1 is continued or not before restarting the advancing movement. 
In more detail, the location data arranged on the negative 1 are provided 
in the form of a row of perforations which are aligned at equal intervals 
of a given distance as sized in a physical manner for detection with the 
detector 3. As the perforations pass the detector 3, the distance between 
any two adjacent perforations is detected (or measured) and examined (or 
monitored) by a computer. The distance data are then compared with the 
reference data for examining the regularity of the perforations. If any 
fault in the regularity is found, it is judged that there is a slit 
adjacent to one of the perforations in the negative 1 or an obstruction 
trapped in the perforation. Accordingly, the advancing movement of the 
negative 1 is automatically terminated to prevent any damage to the 
negative 1. The detector 3 may be a known perforation detector or the like 
which allows the negative 1 to be transferred to an appropriate location 
before canceling the advancing movement.