JPS6191767A - Information retrieving device - Google Patents

Abstract

PURPOSE:To detect the 1st mark surely and remove the influence of variation in the quantity of lamp light by providing the 1st setting means which sets a specific threshold level previously and the 2nd setting means which sets a threshold level according to the maximum value output of a detecting means. CONSTITUTION:A mark is detected during automatic loading or power-on opera tion by using the 1st threshold value set previously by the 1st level setting circuit 26 before the start of retrieval. The 2nd threshold value set by the 2nd threshold level setting circuit 27 according to the maximum output value of a photoelectric converting element 21 is used after the 1st mark is detected to perform mark detection Consequently, the mark detection is secured even if the quantity of lamp light varies and the 1st mark is detected surely at the start of retrieval.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information retrieval device that automatically retrieves desired information on an information recording medium such as a film by counting marks on the recording medium.

[Background and purpose of the invention]

Conventionally, search devices built into film readers, etc., use film with search marks attached to the sides of each frame of the film, optically detect these marks, and count them. The desired frame is automatically searched.

The above search device illuminates the mark on the film with a lamp,
When transporting film! A mark detector detects the change in the light blocked by the mark detector, the output signal of this mark detector is counted by a counter, and the counted content of this counter and the desired information frame input from a keyboard etc. The comparison circuit compares the number with the number, and when the two match, the comparison circuit issues a stop signal to the drive control circuit, which stops the drive system that transports the film and places the desired frame in a predetermined position where it will be projected on the screen. It is designed to stand still.

However, since the search device configured in this way optically detects the mark on the film using the photoelectric conversion element of the mark detector, if the light intensity of the lamp changes significantly (for example, the lamp burns out and needs to be replaced). (when the lamp deteriorates, or when the power supply voltage fluctuates greatly), the margin of light intensity change for mark detection changes, and in some cases marks may not be detected correctly. This caused the problem of searching for incorrect information.

The present invention aims to solve the above problem, and includes: a photoelectric conversion means that receives light from a mark and a base of an information recording medium; a detection means that detects the maximum value or minimum value of the output from the photoelectric conversion means; a first setting means for setting a predetermined threshold level in advance; a second setting means for setting a threshold level according to the output of the detection means; The present invention is characterized by further comprising a comparison means for comparing the output of the photoelectric conversion means with the threshold level determined by the photoelectric conversion means.

[Embodiments of the invention]

The details of the present invention will be described below with reference to the drawings.

FIG. 1 shows a microfilm reader equipped with an information retrieval device to which the present invention is applied. In the same figure,
1 is a supply reel, 2 and 3 are guide rollers, 4 is a lamp that illuminates the microfilm, 5 is a condensing lens, 6 and 7 are glass plates placed opposite each other across the film transport path, 8 is a capstan roller, and 9 1 is a pinch roller, and 10 is a take-up reel. The supply reel 1 and the take-up reel 10 are connected to a film tensioning and winding motor, and are connected to a capstan roller 8 film drive motor.

The microfilm F is stretched between the supply reel 1 and the take-up reel 10, and is wound onto the take-up reel or rewound onto the supply reel by driving the capstan roller 8.

11 is a mark detector, 12 is a projection lens, and 13 is a screen.

As shown in FIG. 2, the microfilm 7 has frames 15 on which images are recorded and marks 16 attached to the side edges of each frame, which have a different a degree from the periphery (base part). The frames and marks on the film are illuminated by the light from the rung 4 as they pass between the glass plates 6 and 7, and the images of the illuminated frames are projected onto the screen 15. In this embodiment, a film in which the base portion B is transparent and the i-ri 16 is opaque is used, but a film with an opaque base portion and transparent marks may also be used.

The mark detector (photoelectric conversion means) 11 is an optical fiber 20
and a photoelectric conversion element (hereinafter referred to as sensor) 21, the tip of the optical fiber 20 is placed opposite to the path through which the i-ri 16 and the base part B pass, and the rear end is connected to the sensor 2.
It is set opposite to 1. The sensor 21 receives the light from the lamp 4 that has passed through the film via the optical fiber 20.

When the film F is transported in the direction of the arrow, the light incident on the sensor 21 is interrupted by the base portion B and the mark 16. Note that the mark detector may be configured so that the sensor directly receives light from the film without providing an optical fiber.

FIG. 6 shows the mark detection circuit of the above search device.
22 is an amplifier circuit that amplifies the output of the sensor 21, 25 is a maximum value detection circuit that detects the maximum value of the output of the amplifier circuit 22, and 26 is a first threshold value that sets a predetermined threshold level in advance. A level setting circuit 27 is a second threshold level setting circuit that sets a threshold level according to the maximum value detected by the maximum value detection circuit 23. The second threshold level setting circuit 27 outputs a threshold voltage according to the detected maximum value. 28 is a first Ua value level setting circuit 26
Alternatively, it is a comparison circuit that compares the threshold voltage output from the second threshold level setting circuit 27 and the output of the amplifier circuit 22 and outputs a counting mark detection signal. 50 and 51 are parent circuits, the differentiating circuit 50 outputs a pulse signal at the fall of the output signal of the amplifier circuit 22, and the differentiating circuit 31 outputs a pulse signal when the output signal of the amplifier circuit 22 falls.
A pulse signal is output when the output signal falls at 9 o'clock. 35
is a control circuit that controls the operation of each circuit, and the differential circuit 3'o
, sl outputs control signals for operating each circuit at predetermined timings based on pulse signals sent from , sl.

The threshold of the first threshold level setting circuit 26 is set to a predetermined value in advance before starting the search. Second threshold level setting circuit 27
The threshold value is set to one of three threshold values according to the maximum value detected by the maximum value detection circuit 23.

Figure d shows the relationship between the amount of illumination light to the film and the output voltage of the amplifier circuit, where the horizontal axis represents the amount of illumination light and the vertical axis I11
] represents the output voltage of the amplifier circuit.

When a film of a certain density is illuminated by varying the amount of illumination light,
When the sensor detects the base of the film (low concentration), the output voltage becomes a straight line LB, and the mark (high concentration)
When detected, the output voltage becomes a straight line LM.

In this embodiment, when the output voltage of the amplifier circuit is X7 or more, that is, when the maximum voltage detected by the maximum value detection circuit 23 is X1 or more, the threshold level is set to voltage a, and the output voltage is When the output voltage is between X and x2, the threshold level is set to voltage a2, and when the output voltage is equal to or higher than X2, the threshold level is set to voltage a3.

In the above embodiment, the second threshold level setting circuit sets three thresholds according to the detected maximum voltage, but it is possible to set two or more thresholds. Further, it is desirable to set this threshold value to a value of about 30% to 70% of the detected maximum voltage.

FIG. 5 shows the output waveforms of each part of the mark detection circuit.

゛ Next, the operation of the above device will be explained. When the film F is transferred in the direction of the arrow by the search start command, if the base part B of the film is transparent (low density) and the mark 16 is opaque (high density), the base part B will be the same as the original fiber 20. When located at the tip, a high level signal a is output from the amplifier circuit 22.
', and when the mark 16 is located at the tip of the optical fiber 20, the amplifier circuit 22 outputs a low level signal a' (see waveform C in FIG. 5). That is, when the sensor 21 is receiving an optical signal from the mark 16, the output voltage of the amplifier circuit 22 is at a low level.

First, a case will be described in which the counting mark detection signal is generated using the output of the second threshold level setting circuit 27.

When the sensor 21 is receiving the optical signal from the base B, the maximum value detection circuit 23 operates to detect the maximum value of the output of the amplifier circuit 22 based on the control signal output from the control circuit 33. When the output of the amplifier circuit 22 falls, that is, when the sensor 21 detects the mark 16, a pulse signal b' (waveform shown in FIG. 5) is output from the differentiating circuit 5o.

When the control circuit 33 receives the pulse signal b', the control circuit 33 outputs the running value voltage from the second threshold level setting circuit 27 according to the maximum value detected by the maximum value detection circuit 23, and outputs the voltage from the amplifier circuit 22 using the comparison circuit 28. and the threshold voltage output from the circuit 27. When the cent-21 detects a mark, the voltage of the signal a' output from the amplification port N522 becomes lower than the threshold voltage output from the second threshold level setting circuit 27,
At this time, the comparison circuit 28 outputs a counting mark detection signal c/
(waveform C in Figure 5) is output. This mark detection signal is counted by a counting section of the search device. The Buyeo device uses the count value of the counter to search for a desired frame, but since the details are well known, the explanation will be omitted.

After the comparison circuit 28 outputs the mark detection signal, the pulse signal d' is output from the differentiating circuit 31 at the falling edge of the mark detection signal.
(Waveform C in Figure 5) appears. The control circuit 33 receives a pulse signal d
′ is sent, the maximum value detection circuit 23 is reset to the initial state, starts the detection operation again, and at the same time the comparison circuit 2
8 stops the comparison operation.

Thereafter, the circuit 25 detects the maximum value in the same way as described above, and after the differentiating circuit 30 outputs a pulse signal, the ig2 threshold-level setting circuit 27 outputs a threshold voltage corresponding to the detected maximum value, and the comparison circuit 28 outputs a threshold voltage corresponding to the detected maximum value. The two input values are compared, and when the output voltage of the amplifier circuit 22 is smaller than the threshold voltage, the comparison circuit 28 outputs a mark detection signal.

Thereafter, the above operation is repeated every time a mark detection signal is output.

As described above, even if the amount of illumination light changes during the search operation, the mark can be reliably detected and the correct search operation can be performed.

The detection of the maximum value, the setting of the threshold level, and the comparison operations are performed during the time period in FIG. 5, and are performed for each period in which a mark is detected.

Next, a case will be described in which the output of the first threshold level setting circuit 26 is used to generate a counting mark detection signal. Usually, a p-leader tape is connected to the tip of the microfilm using adhesive tape, and by automatically transferring this leader tape from supply reel 1 to the take-up reel, the tip of the film is automatically loaded to the take-up reel. However, the autoloading is completed after the leader tape is wound around the take-up reel 10.

This leader tape or adhesive tape may have a different density from the base part of the microfilm, and if a mark is detected using the output of the second threshold level setting circuit 27 during autoloading, the mark detector detects a lower density than the mark. There is a risk that the leader tape or adhesive tape may be mistakenly detected as a mark.

Also, with the selected frame on the microfilm placed at the projection position, turn on the power switch and turn on the lamp 4.
If you turn on the mark and issue a command to start a search from this state, depending on the relative positional relationship between the rung and the film, it may not be possible to detect the mark that first passes the mark detection position when film transport begins. In order to be able to reliably detect the first mark even during autoloading or power-on, Kinei Meikan provided a first threshold level setting circuit. That is, at the start of autoloading or when the power switch is turned on, an initial setting signal is sent to the input terminal 33a of the control circuit 35, and when the control circuit 35 receives the initial setting signal, it changes the output of the first threshold level setting circuit 26. Send to comparison circuit 28, M
2. The output of the threshold level setting circuit 27 is switched not to be sent to the comparison circuit 28.

The threshold level of the first threshold level setting circuit 26 is preset before the start of the search, and can be manually preset according to the density of the leader tape or adhesive tape, or the displacement of the film position from the illumination optical path. be done. When replacing and using multiple films using the same leader tape and adhesive tape, once the threshold of the first threshold level setting circuit 26 is set to a predetermined value, the circuit 26 is changed each time the film is replaced. There is no need to change the threshold value.

When the first threshold level setting circuit 26 is selected at the start of film transport, the threshold voltage outputted from the first threshold level setting circuit 26 is sent to the comparator circuit 28. When the voltage becomes smaller than the threshold voltage output from the level setting circuit 26, a mark detection signal is output, and this mark detection signal is counted by the above-mentioned counting section.

Comparison circuit 2
When the first mark detection signal is output from 8, a pulse signal is output from the differentiating circuit 31, and this pulse signal is sent to the control circuit 551.
1C will be sent.

When the control circuit 33 receives this pulse signal, it switches to select the second threshold level setting circuit 27. That is, the output of the second threshold setting circuit 27 is sent to the comparison circuit 28, and the output of the first threshold setting circuit 26 is switched not to be sent to the comparison circuit 28. Thereafter, the output of the second threshold value setting circuit 27 is used to generate a mark detection signal, but the details have been described above and will therefore be omitted.

Therefore, when autoloading or when power is turned on, the first threshold level setting circuit 26 sets the first threshold level in advance.
After the first mark is detected, the mark is detected using the second threshold level set by the second threshold level setting circuit 27 according to the output of the photoelectric conversion element. This makes it possible to reliably detect all marks on the film.

In the above embodiment, the mark is detected by one sensor, but it can also be detected by a plurality of sensors. In this case, the output of each sensor is compared with the threshold voltage set by the detection circuit of the above embodiment connected to only one sensor to output a mark detection signal, and each sensor simultaneously outputs a mark detection signal. When output, K is applied to obtain a counting signal.

The base is opaque (high density) and the mark is transparent (low density)
When using a film, the minimum value of the output of the amplifier circuit 22, that is, the minimum value of the voltage output when the base of the film is detected, is detected, and the second threshold value is set according to this detected value. In this case, the second threshold value is desirably set to a value of approximately 150% to 300% of the detected minimum voltage.

Note that as a sensor for detecting the maximum value, a maximum photoelectric detection sensor may be specially provided separately from the mark detection sensor 21. In addition, the rise of the output of the amplifier circuit differentiates the pulse signal to generate a pulse signal, and this signal is sent to the differentiating circuit 3.
It may be replaced with the pulse signal d' output from 1.

〔Effect of the invention〕

As described above, according to the present invention, marks can be reliably detected even when the lamp deteriorates, the lamp light intensity changes due to fluctuations in the power supply voltage, and the density of the FC or information recording medium differs. However, the first mark can be reliably detected at the start of the search. As a result, erroneous searches can be prevented and the reliability of the search device is improved.

[Brief explanation of drawings]

Part 1: A schematic drawing of the main parts of a film reader to which the present invention is applied, Fig. 2 is a perspective view of a mark detector, Fig. 3 is a block diagram of a mark detection circuit, and Fig. 4 shows illumination light intensity and output voltage. FIG. 5 is a signal waveform diagram of each output terminal of the mark detection circuit. 4...Lamp 11...Mark detector 21...Photoelectric conversion element

Claims (1)

[Claims] (1) In a device that searches for desired information in an information recording medium by detecting and counting marks on the information recording medium, the photoelectric conversion means receives light from the marks and the base of the information recording medium; a detection means for detecting the maximum value or minimum value of the output of the conversion means; a first setting means for setting a predetermined threshold level in advance; and a second setting means for setting the threshold level in accordance with the output of the detection means. and a comparison means for comparing the output of the photoelectric conversion means with the threshold level set by the first setting means or the second setting means.