JPS6141435B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting marks on a film.

In general, when microfilm is used to photograph objects such as documents and drawings in a reduced size, for example, as shown in FIG. A rectangular mark 3 is written on it.

If you want to automatically search for the required screen from this film, illuminate film 1 with a lamp and move film 1 to find the mark 3 on the film.
The search is performed by receiving an optical signal from a phototransistor using a photoelectric conversion element such as a phototransistor, converting it into an electrical signal, and counting this electrical signal.

Conventionally, when detecting mark 3, the mark and one photoelectric conversion element are placed opposite each other, but when detecting stains or dirt on the film, it is necessary to distinguish between these noise signals and the signal from the mark. There was a problem where incorrect searches were performed.
For example, if the film is a positive film, the base part of the film will be opaque and the mark part will be transparent. However, if there are stains or scratches on the base part, the stains or scratches will become transparent, and the photoelectric conversion element will detect these. It may be mistakenly detected as a transparent mark. On the other hand, when the film is negative, the base part of the film is transparent and the mark part is opaque.
If there is dust or dirt on the base portion, the dust or dirt becomes opaque, and the photoelectric conversion element may mistakenly detect this as an opaque mark.
For this purpose, as shown in FIG. 2, two photoelectric conversion elements 5 and 6 are arranged side by side in the direction of film movement.
The microfilm 1 is illuminated with a lamp 7, and the optical signal from the mark 3 is transmitted to two photoelectric conversion elements 5 and 6.
I try to accept it. As shown in FIG. 3, the output signals of the photoelectric conversion elements 5 and 6 are sent to the logic circuit 12 via amplifiers 8 and 9 and level converters 10 and 11, respectively, but this makes the device complicated and It has the disadvantage of being expensive.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, and to provide a mark detection device with a simple structure that can prevent malfunctions caused by stains, scratches, dust, etc. on the film and perform accurate search operations. It is in.

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 4 shows a mark detection unit, in which a lamp 9 for illuminating the film is placed on one side of the movement path of the microfilm 1, and two light guides 10, 11 and a single light guide are placed on the other side. A photoelectric conversion element 12 is arranged. The light guides 10 and 11 are composed of optical fiber bundles that guide light beams incident on one end to the other end. They are arranged side by side at a predetermined interval in the direction of the arrow), and the other end is opposed to the light receiving surface of the photoelectric conversion element 12.

Also, microfilm 1 and light guide 10,
A slit plate 13 having an opening of a size corresponding to the end of each light guide is arranged between the light guides 11.

The photoelectric conversion element includes a phototransistor, a photodiode, and the like.

When the film 1 is fed, the light beam from the lamp 9 is blocked or transmitted by the mark 3, and the optical signal from the mark passes through the light guides 10 and 11, is detected by the photoelectric conversion element 12, and is converted into an electrical signal. converted.

For example, if the mark is opaque, when the light beam from the lamp is blocked by the mark, the photoelectric conversion element will generate an electrical signal corresponding to the mark, and if the mark is transparent, the light beam from the lamp will be blocked. When the light passes through the mark, the photoelectric conversion element generates an electrical signal corresponding to the mark.

Now, assuming that mark 3 is a transparent mark, when the film 1 moves from left to right, light rays enter the light guides 10 and 11 in that order due to mark 3, and the photoelectric conversion element 12 passes through each light guide 10 and 11. It produces a predetermined output when it receives a beam of light.

FIG. 5 shows one embodiment of the detection circuit.
5 is a photoelectric conversion section, 16 is an amplification section, and 17 is a level conversion section. The photoelectric conversion unit 15 includes the photoelectric conversion element 12 described above, and a photodiode is used as the photoelectric conversion element 12. In Figure 5, 2
0 is a fixed resistor, 21 is a variable resistor, 22 is an operational amplifier, 23, 24, 25 are fixed resistors, 26 is a Zener diode, and the Zener voltage is set to 5V.

In the above configuration, the photodiode 12 generates a current depending on the intensity of light sent from the light guides 10 and 11 depending on the presence or absence of a mark, and the current change is converted into a voltage change by the load resistors 20 and 21. . If the mark 3 does not exist on the front surface of the light guides 10 and 11 when the film 1 is fed, the light from the lamp 9 will not enter the light guides 10 and 11, and no voltage change will occur in the photodiode 12. Next, when light enters either one of the light guides 10 or 11 due to the presence of the mark 3, a voltage of 300 mV is generated in the photodiode 12. Thereafter, when light enters both light guides 10 and 11, a voltage of 600 mV is generated in the photodiode 12. Generally, the output current of a photodiode is proportional to the light receiving area and changes depending on the thickness of the light guide. For example, if the thickness of the light guides 10 and 11 is doubled, when light enters one light guide 10 or 11, the light receiving area of the photodiode will be doubled and a voltage of 600 mV will be generated. In order to reliably detect a mark, the voltage generated from the photodiode when the light from one light guide is received by the photodiode must be equal to the saturation voltage of the photodiode (the voltage generated when the light is received over the entire light-receiving surface of the photodiode). (equivalent to the voltage). In the above example, the saturation voltage of the photodiode is
1V or more, and the output voltage of the photodiode when receiving light from one light guide is 300m
It is set to be V. Note that the number of light guides is not limited to two, but three or more may be provided.

In FIG. 5, when the voltage at point a is set to -450 mV by adjusting the variable resistor 21, the potential at point b is -450 mV when no light enters both light guides 10 and 11, and then When light enters one light guide 10 or 11, a voltage of 300 mV is generated in the photodiode 12, so the potential at point b becomes -150 mV, and then when light enters both light guides 10 and 11, Since a potential of 600 mV is generated at the photodiode 12, the potential at point b becomes +150 mV. When the potential at point b is -450 mV or -150 mV, the potential at point b is lower than the potential at point d, so the output voltage of the amplifier 22 becomes positive and the potential at point c becomes +5V. The potential at point b is +
When the voltage reaches 150 mV, the potential at point b becomes higher than the potential at point d, the output voltage of the amplifier 22 becomes negative, and the potential at point c becomes -0.6V. Therefore, when light enters both light guides 10 and 11, the level converter 17 -
A mark detection device with a potential of 0.6V can be obtained, and when no light enters either or both of the light guides 10 and 11, no detection signal is generated. Therefore, by counting these detection signals, accurate information retrieval can be performed. Furthermore, even if there are transparent stains or scratches on the film, these stains or scratches are smaller than the marks, so when these stains or scratches pass under both light guides 10, 11, both light guides 10, 11 Therefore, stains and scratches will not be mistakenly detected as marks, and erroneous searches will be prevented.

The present invention can use a negative film with opaque marks in addition to a positive film, and by applying the present invention, opaque dust, dirt, etc. on the negative film may be mistakenly detected as marks. Accidents can be prevented.

In the above embodiment, one end of the two light guides is placed side by side in the film movement direction, but these light guides may be placed side by side in a direction perpendicular to the film movement direction, and in any case, they are separated at the position where the mark is detected. Just place it.

As described above, according to the mark detection device of the present invention, one end of a plurality of light guides that guide a light beam from one end to the other end are arranged side by side at intervals along the movement path of the film. , the other end is placed opposite to the light receiving surface of the same photoelectric conversion element, and the light beam from the mark on the film is provided to the photoelectric conversion element through the light guide, and when each of the light guides receives the light beam from the mark. By generating a detection signal from the photoelectric conversion element, even one photoelectric conversion element can perform a search accurately without malfunctioning in counting marks. Further, there is no need to provide a large number of photoelectric conversion elements, amplifiers, etc. as in the conventional case, and the device becomes simple and inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a front view showing one embodiment of the microfilm used in the present invention, Fig. 2 is a main part configuration diagram of a conventional detection device, Fig. 3 is a detection circuit diagram of the device shown in Fig. 2, and Fig. 4 5 is a main part configuration diagram showing one embodiment of the detection device of the present invention, and FIG. 5 is a detection circuit diagram of FIG. 4. 1... Microfilm, 3... Mark, 1
0, 11...Photoelectric conversion element, 12...Photoelectric conversion element.

Claims (1)

[Scope of Claims] 1. A plurality of light guides are provided that transmit a light beam incident from one end to the other end, one end of each light guide is spaced apart and faces the mark movement path, and the other end is spaced apart and faces the mark movement path. A mark detection device characterized in that an end of the mark is faced to a light-receiving surface of one photoelectric conversion element. 2. The mark detection device according to claim 1, wherein the light guide is made of optical fiber.