JPS5937773Y2 - Photographic film notch detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a notch detection device for detecting notches for positioning image frames on photographic film.

In the photo printing process from 35 mm photographic negative film (hereinafter simply referred to as "negative"), after the developed negative is spliced, the edges of the film corresponding to the image frames of the negative, which are generally not taken at equal intervals, are A semicircular notch is inserted, and the printer detects this notch and stops the negative image frame at the printing position for printing.

Various types of notch detection devices have already been proposed, including mechanical (using limit switches), optical (receiving transmitted or reflected light), and combinations of these; For this reason, optical systems with no moving parts are often used.

An example of an optical notch detection device is shown in FIG.

This device is configured so that a light receiver 2 receives light from a light source lamp 1 that is lit with direct current, and a comparison level is set separately to determine whether the amount of light received by the receiver 2 changes depending on the presence or absence of a notch in the negative 3. The notch is detected based on the level difference between the two.

In this device, when the light source lamp 1 is lit with alternating current, the change in the brightness of the lamp 1 may be larger than the change in the amount of transmitted light due to the presence or absence of the notch, and in such cases, the above-mentioned constant Since it is impossible to provide a comparison level for the notch itself, and therefore it is impossible to detect the notch, an expensive DC power supply 4 is required to turn on the light source lamp 1 with DC current to prevent this. There was a drawback.

Also, although it is different from the technical field of the present invention, it was published in Japanese Patent Publication No. 49-47174 as a microfilm search mark reading device.
The publication describes a technology in which light from a light source is transmitted through the film by placing receivers at positions where there is a search mark and where there is no search mark, and detecting the difference in output between the base density of the film and the density of the search mark. However, in the case of photographic film used for printing, characters and symbols are imprinted on both sides where there is no screen, that is, on the outside of the perforations, so the reference value fluctuates and a notch may be detected incorrectly. Therefore, it cannot be used as a notch detection device.

SUMMARY OF THE INVENTION The object of the present invention is to provide an improved optical notch detection device which eliminates the above-mentioned drawbacks of the conventional optical notch detection device and can reliably detect film notches.

The present invention was made in order to achieve the above-mentioned object, and it uses an AC power source for lighting, a light source lamp that is lit by the AC power source, and a photographic film provided with a notch to transmit the light from the light source lamp. a first light receiver that receives light from the light source lamp, a second light receiver that receives light from the light source lamp without passing through a photographic film, and an output of the first light receiver and an output of the second light receiver. This is a photographic film notch detection device characterized in that it is provided with a comparator for comparison.

The present invention will be explained in detail below based on the drawings.

FIG. 2 is a block diagram illustrating an optical notch detection device according to an embodiment of the present invention.

The light source lamp 1 is lit by an AC power source 5.

The first light receiver 2a is located at a position where it can receive the light that has passed through the notch of the negative 3, and the second light receiver 2b is located at a position where it can receive the light from the light source lamp 1 without passing through the negative 3. It is set in.

The light inputted to the first and second photoreceivers is output as an electrical signal, amplified by amplifiers 6a and 6b, and inputted to a comparator 7.

Since the comparator 7 uses the amplified signal from the second photoreceiver as a comparison level to judge the amplified signal from the first photoreceiver,
The signal and comparison level change in the same phase, and it is possible to eliminate the influence of so-called alternating current ripple caused by alternating current lighting of the light source lamp.

That is, as shown in FIGS. 3A to 3C, the presence or absence of a negative notch can be reliably detected based on the sign of the difference C between the output signal a of the first light receiver and the output signal S of the second light receiver.

Furthermore, in this embodiment, as can be understood from the above-mentioned stealing, there are fluctuations that cause changes in the brightness of the light source lamp, such as fluctuations in the potential of the light source and decreases in illuminance due to changes in the light source lamp over time. Even in this case, this fluctuation is also applied to the second receiver, and is canceled out by the comparator with the input from the first receiver, so the effect is that the above-mentioned fluctuation does not affect the final output. This is an extremely practical device.

The input to the second receiver drops to an arbitrary level that is higher than it would be if the first receiver were receiving light transmitted through the negative, but lower than it would be if it were receiving light transmitted through the negative notch. You can let me.

In this case, the sign of the difference with the comparison level changes before and after the first photoreceiver detects the negative notch, making the detection more reliable.

FIG. 4 is a block diagram showing another embodiment of the present invention.

In this embodiment, after the comparator 8 calculates the difference between the output signals of the two light receivers in each case of the presence or absence of a negative notch, this signal is converted to a separately set comparison level (Vo
) and a comparator 7, which is advantageous when the difference between the output signals of the first and second photodetectors is small and amplification is required.

In this invention, the light from a light source lamp that is lit with alternating current is received by a first receiver that receives the light that has passed through the notch of the negative, and a second receiver that receives the light without transmitting the negative, and then they are compared. This makes it possible to reliably detect the edges of negatives, and compared to conventional equipment, it eliminates the need for a DC stabilized power supply, and reduces illuminance reduction due to fluctuations in power supply, changes in light source lamps over time, and other problems. It has advantages such as not being affected by changes over time.

In addition, the present invention not only detects notches on 135 size film (so-called 35 mm film), but also detects notches on 126 and 135 size films.
It can also be used to detect image frame positioning holes in 10 size film.

[Brief explanation of drawings]

Figure 1 is a block diagram showing a conventional notch detection device, Figure 2 is a block diagram showing a conventional notch detection device.
The figure is a block diagram showing one embodiment of the present invention, FIG.
is a graph showing an example of the output of the light receiver, and FIG. 4 is a block diagram showing another embodiment of the present invention. 1...Light source lamp, 2... Light receiver, 3
...Negative, 5...AC power supply, 6...
...Amplifier, 7...Comparator.

Claims (1)

[Scope of utility model registration request] In an optical notch detection device for detecting a notch for positioning an image frame of photographic film, an AC power source for lighting;
a light source lamp that is lit by the AC power source; a first light receiver that receives the light from the light source lamp through a photographic film provided with a notch; and a first light receiver that receives the light from the light source lamp without passing through the photographic film. 1. A notch detection device for photographic film, comprising: a second light receiver that receives light; and a comparator that compares the output of the first light receiver and the output of the second light receiver.