JPS6252537A - End detecting method for roll film - Google Patents

Abstract

PURPOSE:To detect the end of a film without providing any sensor which detects the feed quantity of the film such as an expensive encoder by detecting whether take-up operation is completed or not on the basis the counter electromotive voltage of the driving motor for a payoff reel and the counter electromotive voltage of the driving motor for a take-up reel. CONSTITUTION:When the 1st computing element A1 outputs a voltage drop IRM and a roll film F is taken up around a take-up reel 1 completely, its take-up motor M1 stops, its counter electromotive voltage VR1 is not generated any more, and a voltage Vs developed across a current detection resistance Rs becomes maximum, so the value of the voltage drop IRM when the voltage Vs becomes maximum is compared with a set threshold value Vref to detect the complete end. Then a CPU 13 receives a near end signal S1 and a complete end signal S2 and controls the supply of the driving voltage V to the take-up motor M1 to control the switching of the driving speed of the motor and its stop.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for detecting the end of a roll film in the feeding direction of the roll film when winding or rewinding the roll film used in a reader printer or the like. Relating to a method for detecting.

[Conventional technology]

Generally, regardless of whether each frame of a roll film is searched automatically or visually, if the feeding operation is performed by a drive means such as a motor, the roll film may be damaged due to user's carelessness or erroneous operation. It may be sent to the end. In particular, when the end of the roll film is fixed to the rotation shaft of the reel, excessive conveyance that causes it to be wound up to the end may cause damage to the roll film or its drive system, or abnormal heat generation of the drive motor. This may cause an accident.

Therefore, various means for detecting the end of a roll film have been proposed.

For example, a mark indicating the end of the film is provided near the end of the roll film itself, and when this mark is detected, the film advance operation is forcibly stopped, or a mark for counting the number of frames is provided on each frame of the roll film. There have been proposed means for determining the end of a mark when the next mark is not detected even after a set time has elapsed, and for counting the number of passing marks.

However, with the above-mentioned method of providing marks on the roll film itself, it is necessary to separately provide means for detecting the mark, which has the disadvantage of complicating the device configuration. If you perform editing such as removing or adding pieces, you will need to take other actions such as changing the mark position indicating the end or changing the number of set marks in addition to this editing work, which is not practical. There is an inconvenience.

Therefore, in order to detect the end of the roll film without providing any marks for detecting the end of the roll film,
A method has been proposed that includes an encoder that outputs a pulse signal in response to film advance, counts the number of output pulses from the encoder, and detects the end of the film based on the counting result. (Refer to Japanese Unexamined Patent Publication No. 57-177135.) [Problems to be Solved by the Invention] However, in the means for detecting the end by counting the number of output pulses of the encoder, it is difficult to detect the film feed amount. It is necessary to separately provide an encoder and its counting means, which has the disadvantage of making the device configuration complicated and expensive.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to detect the end of the film without providing a sensor for detecting the film feed amount such as an encoder, which makes the device configuration complicated and expensive. It's about doing.

[Means for solving problems]

The method of the present invention is characterized in that the ratio of the back electromotive force of the drive motor of the supply reel around which the roll film is wound and the back electromotive force of the drive motor of the take-up reel that winds the roll film is: It is detected whether or not the winding on the take-up reel side is completed based on whether or not the rotation ratio of each reel is equal to or higher than a set ratio corresponding to the rotation ratio of each reel at the end of winding of the roll film onto the take-up reel. The function is as follows.

[For production]

In other words, the number of reel rotations required to wind the roll film onto the take-up reel to the end of the film corresponds to the length of the roll film wound on the supply reel, that is, the winding diameter, so the feed amount of the roll film is It is proportional to the ratio of the number of rotations of the reel to the number of rotations of the take-up reel. Therefore, if the ratio of the rotational speeds of the supply reel and the take-up reel can be detected, it can be determined whether the winding has been completed to or near the end. Since the rotation speed of each reel is proportional to the back electromotive force of the drive motor that drives each reel, the back electromotive force of the drive motor of the supply reel and take-up reel is By detecting this and determining whether the ratio is greater than or equal to the set ratio, it is possible to detect whether the roll film has been wound to the end.

〔Example〕

Embodiments of the method of the present invention will be described below based on the drawings.

FIG. 4 is a perspective view showing a schematic configuration of a film carrier of a reader printer to which the method of the present invention is applied, showing a take-up reel (1) pivotally supported on the film carrier, and a supply reel that is detachable from the film carrier. (2), a pair of upper and lower glass plates (3a) constituting the light irradiation part (3),
(3b), three guide rollers (6a), (6b), (6) that guide the roll film (F) wound on the supply reel (2) to the take-up reel (1).
c), a light source (7) that illuminates the light irradiation section (3), a condenser lens system (8) that guides the light from this light source (7) to the light irradiation section (3), and the light irradiation section (3). a projection lens (9) for projecting the image on the roll film (F) illuminated by the light transmitted through the screen onto a screen (not shown), and a take-up for rotationally driving the take-up reel (1). A motor (M+) and a rewind motor (M2) for rotationally driving the supply reel (2) when rewinding the roll film (F) are provided.

Then, while operating one of the take-up motor (Ml) or the rewind motor (M2) to send the roll film (F) in either the forward or reverse direction,
) The image illuminated by the light from (7) is projected onto the screen.

The three guide rollers (6a), (6b),
Two of (6c), (6a) and (6b), are provided on the supply reel (1) side, and are designed to sandwich and guide the roll film (F) from above and below.

and a disc (10) formed with a plurality of slits that rotates integrally with the upper roller (6a), and a pair of light emitting elements (lla) disposed opposite to each other on both sides of the slit portion.
A photo ink sensor (11) consisting of a light receiving element (llb) and a light receiving element (llb) is provided.
By sensing the light that is transmitted and blocked as the disc (10) rotates, a pulse signal is output in synchronization with the rotation of the disc (10), that is, with the feeding of the roll film (F). It's Nishide. With this, the disk (10
) and a pulse encoder (12) that detects the film feed amount using an optical sensor (11). Incidentally, this pulse encoder is used to detect the amount of film feed during film retrieval.

By the way, the core diameter (rl) of the take-up reel (1)
The core diameter (r2) of the supply reel and the supply reel (2) are known values, and those having the same diameter are usually used. Further, the initial diameter (R) of the roll film (F) wound around the supply reel (1) is also a known value.

Therefore, the number of rotations (ωI) of the take-up reel (1) and the number of rotations (ωI) of the supply reel (2) near the end of winding (
The ratio of ω2) is determined by the core diameter (rI) of the take-up reel (1) and the roll film (F
) to the initial diameter (R).

ωl/ωz=rt/R--(i) Therefore, as shown in equation (i) above, both reels (1)
, (2), it will be possible to determine whether or not the roll film (F) has been wound onto the take-up reel (1).

The back electromotive force (Vll), (VRI2) corresponding to the back electromotive force of each motor (Ml), (M2) is the rotational speed (ωI), (ω2) of the respective reel (1), (2).
), this back electromotive force (VRI)
, (νRZ) is the ratio of the core diameter (rI) of the take-up reel (1) shown in equation (i) above to the initial diameter (R) of the roll film (F), that is, as shown in FIG. Thus, it corresponds to the amount of winding of the roll film (F).

As shown in FIG. 1, the film end detection device detects the back electromotive force (vi+) of each of the motors (MO, (M2)).

(vR□) is configured to detect the end of the roll film (F) based on the ratio of A D/A converter (14) that converts the drive voltage (-Vin) into an analog voltage, this D/A converter (
14) Analog value drive voltage (-Vin
) is inverted and amplified and outputs the motor drive voltage (V) (80), the output (ν) of this power amplifier (80)
The winding motor (M1) and the rewinding motor (M2)
), a current detection resistor (Rs) that detects the current (I) flowing through the winding motor (Ml), and
a first computing unit (IRM) that calculates the voltage drop (IRM) due to the winding motor (Ml) based on the voltage (Vs) generated across the winding motor (Fl) and the internal resistance (R14) of the winding motor (Fl, ); A, ), a second back electromotive force calculator (82) that detects the second back electromotive force (Vll2) generated by the rewinding motor (M2), an output (V) of the power amplifier (80); The voltage drop detected by the first computing unit (A,) (
a first back electromotive voltage calculator (A3) that calculates the first back electromotive voltage (V□) of the winding motor (M, ) based on the IRM);
, the first back electromotive voltage (VRI) and the second back electromotive voltage (VR2
), and compares the first back electromotive voltage (VRI) with a set dark value (Vref). The roll film (F) is transferred to the take-up reel (
1) A comparator (A) that outputs a complete termination detection signal (S2) that inverts from “H” to
, ). In addition, in FIG. 1, (LPFI).

(LPF2) is a filter for removing noise from the back electromotive voltages (V□) and (VR□) output from each of the motors (Ml) and (M2). Similarly, (CI), (C
2) is also a capacitor for noise removal.

~ Also, the gain of the first computing unit (A,) is determined by the internal resistance (RM) of the winding motor (Ml) and the current detection resistor (R).
s), and the detection voltage (Vs) by the current detection resistor (Rs) is set to correspond to the ratio of RM/R3
The structure is such that the voltage drop (IR, ) is output by multiplying the voltage. and the current detection resistor (Rs)
is a resistance value so small that it can be ignored with respect to the internal resistance (R8) of the winding motor (Ml), and the voltage drop (Vs) due to this current detection resistor (Rs) is the first back electromotive voltage. This is to prevent it from becoming a cause of calculation error in the first back electromotive force calculation unit (A,) that calculates (Vat).

Next, the operation of the film end detection device having the above configuration is as follows.
This will be explained based on FIG. 2, which shows voltage changes at various parts.

That is, the motor applied voltage (V) supplied from the power amplifier (80) is as shown in equation (ii) below:
It is the sum of the voltage drop (IR, ) caused by the winding motor (Ml) and its back electromotive force (Vat).

V ” IRM + VRI ”' ”・(li)
Therefore, when the voltage drop (IRM) output from the first amplifier (AI) is subtracted from the motor applied voltage (V), the first back electromotive force (VR
I) will be obtained. On the other hand, when the take-up motor (Ml) is driven, the rewind motor (M2) is indirectly operated by the take-up motor (Ml) through the supply reel (2) by winding the roll film (F). Therefore, the output voltage becomes the second back electromotive voltage (VR2) itself.

Therefore, the first back electromotive voltage (VR,), which is the output of the first back electromotive voltage calculator (A3), gradually decreases as the amount of winding of the roll film increases, and the rewinding motor (
Conversely, the second back electromotive force (Vat) of M2) increases. Therefore, the first back electromotive voltage (VRI) and the second back electromotive voltage (VR
At the time when each voltage value of t) is reversed, the first back electromotive voltage (
The output signal (Sl) of the approximate termination calculator (A4) that calculates the ratio between VRI) and the second back electromotive voltage (VR□) changes from "H" to "
It is possible to detect that the roll film (F) has been wound up to the vicinity of its end, that is, to its approximate end.

By the way, if the end of the roll film (F) is determined when it is wound up to its end, there is a risk of damaging the roll film (F) if the roll film (F) is wound at high speed. 1).

(2) and the motor (+'11) and (M2), the output signal (Sl) of the approximate termination calculator (A4) is used to wind the roll film (F) to the vicinity of the termination end. This is so that the signal corresponds to the approximate termination when That is, based on the above equation (ii), the second back electromotive force (V
, □) are divided at a predetermined ratio (β) as shown in equation (iii) below and manually inputted to the second back electromotive force calculator (A2).

R++Rz R Further, to explain in detail the detection of complete termination by the comparator (A4), the voltage drop (I RM) output from the first arithmetic unit (A1) is caused when the roll film (F) ), this winding motor (M, ) stops and its back electromotive force (V+t+
) is no longer generated, and the voltage (Vs) generated across the current detection resistor (Rs) reaches its maximum.The value of the voltage drop (IR, 4) at the time of reaching this maximum is set as the dark value (Vre).
By comparing with f), complete termination can be detected.

Then, the CPU (13) receives the approximate termination signal (S, ) and the complete termination signal (S2), controls the supply of drive voltage (V) to the winding motor (Ml), and drives the winding motor (Ml). It controls speed switching and stopping.

The operation of the CPU (13) that controls the motor drive speed in response to the approximate termination signal (S+) and complete termination signal (S2) will be described below based on the flowchart shown in FIG.

First, it is determined whether the approximate termination signal (S+) is in the ON state (step #1).

If the motor is not in the ON state, the process ends; if the motor is in the ON state, the voltage (V) applied to the motor is set to a high voltage (V
O), it is determined whether the motor drive mode is the high speed mode (step 12).

When the motor drive mode is a high speed mode, the voltage (V) applied to the motor is set to an intermediate voltage (V) corresponding to a medium speed.
vL) and set to medium speed mode (Step #3).

On the other hand, if the motor drive mode is not the high speed mode, it is determined whether the complete termination signal (S2) is in the ON state (step 114).

If the complete termination signal (S2) is not in the ON state, the process is ended and the complete termination signal (S2) is turned ON.
Wait until the condition is reached. On the other hand, the complete termination signal (S2) is O
If it is in the N state, the voltage (V) applied to the motor is made zero, the winding motor (M) is stopped (step 'j #5), and the process is ended.

Therefore, the roll film (F) is wound at high speed up to the vicinity of its end, and then at medium speed until the roll film (F) is completely wound up, taking care not to generate excessive tension on the roll film (F). When the roll film (F) is completely wound up on the take-up reel (1), the motor (Ml) is automatically stopped.

In the present invention, the approximate termination and complete termination in this embodiment described above are collectively referred to as the termination of the roll film.

[Effects of the Invention] Therefore, according to the method of the present invention, the end of the roll film can be detected without providing a sensor, a mark, etc. for detecting the end of the roll film.

[Brief explanation of drawings]

The drawings show an embodiment of a film end detection device to which the roll film end detection method according to the present invention is applied, FIG. 1 is a circuit diagram showing the configuration of the film end detection device, and FIG. 2 is a drawing explaining its operation. , FIG. 3 is a flow chart showing the operation of the control device, and FIG. 4 is a perspective view showing the schematic structure of the film carrier of the reader printer. (1)...Take-up reel, (2)...
・Supply reel, (Ml)... Winding motor,
(M2)... Rewind motor, (F)...
...Roll film, (vRI)...Back electromotive force of the winding motor, (V*□)...Counter electromotive force of the rewinding motor.

Claims (1)

[Claims] The ratio of the back electromotive force of the drive motor of the supply reel around which the roll film is wound and the back electromotive force of the drive motor of the take-up reel that winds the roll film is determined by A method for detecting the end of a roll film, which detects whether or not winding to the take-up reel side has ended based on whether or not the rotation ratio of each reel at the time of winding end is greater than or equal to a set ratio corresponding to the rotation ratio of each reel.