JPS60262278A - Information retriever - Google Patents

Abstract

PURPOSE:To prevent misretrieval despite a change in lamp light quantity by using a means that detects the maximum and minimum values of the illumination light quantity and changing the threshold level of a mark detecting means in response to the output of said detecting means for illumination light quantity. CONSTITUTION:If a mark exists between a lamp (not shown in the diagram) and a light guide 41, the light quantity made incident on the guide 41 is minimum. Thus the light quantity received by a photoelectric transducer 51 is also minimum, and this quantity is stored in a minimum value detecting circuit 71. When no mark exists between the lamp and the guide 41, the light quantity is maximum and stored in a maximum value detecting circuit 70. A comparator 72 delivers a control signal so that the threshold levels of amplifier circuits 60 and 61 are set at proper values (intermediate value) according to the values of both circuits 70 and 71. When both photoelectric transducers 50A and 50B detect marks at a time, an AND gate 63 is opened. The output signals of the gate 63 are counted as mark detection signals by a counter circuit of a retrieving circuit (not shown in the diagram).

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]

Conventionally, search devices built into film readers and the like use film with search marks placed on the sides of each frame of the film, and these marks are optically detected.
By counting this, a desired frame in the Shirairum is automatically searched.

The above search device illuminates the mark on the film with a lamp,
A mark detector detects changes in the light that is blocked by the marks when the film is moved, and a counter counts the output signal of this mark detector. The comparison circuit compares the frame number of the information frame with the frame 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 projects the desired frame onto the screen. It is designed to remain stationary at a predetermined position.

However, the search device configured in this way optically detects marks on the film (using the photoelectric conversion element of the mark detector), so if the light intensity of the lamp changes significantly (for example, if the lamp burns out), When replacing the lamp (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. I was having problems finding information.

The present invention solves the above problems and provides an information retrieval device that can always search for information accurately.The invention is to provide an information retrieval device that can always accurately search for information, and is provided with a light amount detection means for detecting the amount of illumination light, and the mark detection means is detected by the output of the light amount detection means. The following is to control the threshold level.

〔Example〕

The details of the 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 invention is applied. In the same figure,
1 is a supply reel, 2 and 3 are Gaitro = 2.4 are lamps that illuminate the microfilm, 5i are condensing lenses,
6 and 7 are glass plates placed opposite each other across the film movement path;
8 is a capstan roller, 9 is a pinch roller, and 10 is a take-up reel. The supply reel 1 and take-up reel 10 are connected to a film tensioning and winding motor, and the capstan roller 8 is connected to a 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 port 28.

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

As shown in FIG. 2, the microfilm F has frames 15 on which images have been recorded and marks 16 attached to the side edges of each frame and having different densities from the periphery. The frames and marks on the film are illuminated by the light from the two frames 4 as they pass between the glass plates 6 and 7, and the images of the illuminated frames are displayed on the screen 13.
projected on top. In this embodiment, a book with a transparent film base and opaque marks 16 is used, but a film with an opaque base and transparent marks may also be used.

As shown in FIG. 2, the mark detector 11 has a movable substrate 21 having an opening 20 and first light guide members 25, 26, 27 made of optical fiber bundles. One end passes through the through hole of the block 220 and is opposed to the side edge of the opening 20.

Block 221C is shown in FIG. 3 and is provided with a mask 28 having three apertures, one end of each light guide member 25, 26, 27 being fitted into each aperture of the mask.

One end portions of the three first light guide members 25 and 26.27 are arranged side by side in the direction of film movement, and the length l between the one end surfaces of the light guide members 25.27 on both sides corresponds to the mark order of the film to be used. The marks are arranged so that the length of the marks is slightly shorter than the length of the marks in the direction of film movement.

The other ends of the first light guide members 25 , 26 , 27 are connected to the through holes 291 and 292 of the second block 29 on the substrate 21 .
．． 295) and protrudes to the opposite side through a hole in the second block 29. The mark detector 11 is configured to be removably attached to a support base 36 provided at all times in the apparatus.

A third block 37 having a through hole corresponding to the through hole of the second block 290 is fixed to the support stand 36, and a second light guide member 40 made of an optical fiber bundle is inserted into each hole of this sixth block.
- 41 and 42 are respectively inserted, and the second light guide members 40-42 protrude through each hole to the opposite side of the third block.

When the mark detector 11 is mounted at a predetermined position on the support base 36, the corresponding holes of the second block 29 and the third block 37 face each other, and the end portions 25, 25 of the first light guide member of the mark detector 11, 2627 and second light guide member 40/4
1 and 42 are optically coupled. The second block 29 is fitted into the recess of the third block 57 so that unnecessary light rays do not enter the joint between the two guide members from the outside.

The other end surface of the second light guide members 40, 41, 42 is
- They are respectively provided opposite to the light-receiving surfaces of photoelectric conversion elements, which will be described later, that receive the light transmitted by the second light guide member. Each photoelectric conversion element is connected to a control circuit described later. When the mark detector 11 is attached to a predetermined position on the support base 36 and the film is moved by driving the film drive motor in response to a search command, the two beams of light 4 that are incident on the first light guide members 25, 26, and 27 are By being interrupted by the marks, optical signals are generated in the light guide members 25, 26 and 27, respectively, and this optical signal is transmitted to the light guide members 25, 2.
6, 27 through the second light guide members 40, 41,
42, and then sent to each photoelectric conversion element where it is converted into an electrical signal.

Figure 5 shows the control circuit of the search device, so 50A-5
0B.51 is a nine photoelectric conversion element installed opposite to the second light guide member, the light from the light guide member 4o is sent to the charge conversion element 50A, the light from the optical power member 42 is sent to the photoelectric conversion element 50B,
Light from the light guide member 41 is transmitted to the photoelectric conversion element 51. The photoelectric conversion elements 50A and 50B function to detect =-16 and the photoelectric conversion element 51JI'i to detect the amount of illumination light.

Reference numerals 60, 61, and 62 are amplifier circuits that amplify and shape input signals, and the amplifier circuits 60 and 61 are photoelectric conversion elements 50A and 50.
A signal is output according to the amount of light incident on B. That is, when the output voltage of the photoelectric conversion element is below a predetermined threshold level, all high-level pulse signals are output, and when it is higher than the threshold level, low-level pulses are output. 63 is an AND gate. The amplifier circuit 62 outputs a voltage signal according to the amount of light incident on the photoelectric conversion element 51. 70 is a maximum value detection circuit for detecting the maximum value of the output of the photoelectric conversion element 51 outputted from the amplifier circuit 62 (obtained when nine lights are transmitted through the base of the film and incident on the photoelectric conversion element); 71 is a maximum value detection circuit; The minimum value in the output of the photoelectric conversion element 51 output from the amplifier circuit 62 (the opaque mark on the film compares the outputs of both the maximum value detection circuit 70 and the minimum value detection circuit 71, and based on the comparison result, the amplifier circuit 60.6
A comparison circuit that controls the threshold level of 1.
Its output is connected to an amplifier circuit 60.61.

Next, the operation of the above device will be explained. Note that the mark detector 11 shown in FIG. 2 is used when using a film F having a mark 16 in which the light beams incident on the light guide members 25, 26, and 27 are simultaneously blocked by the mark as shown in FIG. Although commonly used, the invention can also be applied to various films with different mark sizes.

When a desired frame number is input into the search device, the capstan roller 8 rotates in response to the search command, and the film F begins to move in the direction in which it is wound onto the take-up reel 10. When the mark 16 is not present between the lamp 4 and the light guide member 26, the amount of light incident on the optical kite member 26 shows the maximum value, and at this time, the amount of light received by the photoelectric conversion element 51 is the maximum,
This maximum value is stored in the maximum value detection circuit. When the mark 16 exists between the lamp 4 and the light guide member 260, the light f incident on the light guide member 26 shows the minimum value, and at this time, the amount of light received by the photoelectric conversion element 51 is the minimum, and this minimum value is stored in the minimum value detection circuit. Comparison circuit 72 outputs a threshold level adjustment signal based on the maximum and minimum values stored in detection circuit 70.71 so that the threshold level of amplifier circuit 60.61 becomes appropriate. As a result, the threshold level is changed according to the light intensity of the amplifier circuits 60 and 61#'i, and the mark can be detected correctly even if the two-band scene changes. In the embodiment, the maximum value and minimum value output from the amplifier circuits 60 and 61 and the photoelectric conversion element 51 are determined by the comparison circuit 72 so that the intermediate voltage value becomes the threshold level.
is controlled by the output of

As described above, the margin for identifying whether it is above or below the mark when detecting the mark is always kept constant, and as a result, the photoelectric conversion elements 50A, 50B (7) can reliably detect the mark 16, and the amplifier circuit 60 Pulse signals are generated sequentially from .62. When the photoelectric conversion elements 50A and 50B simultaneously detect marks, the AND gate 63 opens, and the output signal of the AND gate 63 is counted as a mark detection signal by the counter of the search circuit, and the desired signal is detected. A frame search is performed.The details of the search circuit are known in Japanese Patent Publication No. 41-260, so the explanation will be omitted.When the mark of the desired frame is detected, the drive system is stopped by the mark detection signal of the AND gate 68.
Each photoelectric conversion element 50A/50 is marked by a desired frame.
The film comes to rest when the position where the incident light beams to B.51 are simultaneously blocked, that is, the relative position of the light guide members 25, 26, 27 and the mark 16 is as shown in FIG. Even if the film is moved in the opposite direction to the above and stopped, the film frame stop position will remain as shown in Figure 4.
Regardless of the direction in which the film moves, the stopping position is one inch.

In the embodiment described above, the light output member 26 for transmitting light to the photoelectric conversion element 51 for sight detection is placed between the light output members 25 and 27 for mark detection. It may be placed in any other position as long as it is suitable. In addition, although a special light output member is placed between the light amount detection means and the film, the amount of light is measured using the output of the photoelectric conversion element for mark detection, and there is no need to provide a special photoelectric conversion element for sight detection. It's okay. Furthermore, the light from the film may be directly detected without providing a light guide member.

〔effect〕

As described above, according to the invention, the threshold level of the mark detection means is always set according to the amount of light incident on the mark detection means even if the scene of the lamp changes, so that erroneous searches can be prevented. This makes it possible to improve the reliability of the search device.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a configuration diagram of the main parts of a film reader to which the invention is applied, Fig. 2 is a perspective view of a mark detector, Fig. 3 is a sectional view of the mark detector, and Fig. 4 is a FIG. 5 is a diagram explaining the positional relationship between the photoelectric conversion element and the mark, and FIG. 5 is a diagram showing the control circuit. 4... Lamp 11... Mark detector 25.26.27... Optical kite applicant Canon Co., Ltd.

Claims (1)

[Claims] (2) A device that searches for desired information on a recording medium by optically detecting and counting marks on an information recording medium includes a mark detection means for detecting marks on an information recording medium and an illumination means. An information retrieval device comprising a light amount detection means for detecting a maximum value and a minimum value of an illumination light amount, and changing a threshold level of the mark detection means based on the maximum value and minimum value detected by the light amount detection means.