FR2500929A1 - APPARATUS FOR DETECTING THE BLINKING RANGE OF A FILM - Google Patents

Abstract

THE INVENTION RELATES TO A DETECTOR APPARATUS OF THE DARKENING RANGE OF A FILM 10 INCLUDING A LIGHT SOURCE 20 FITTED ON ONE SIDE OF A FU FILM TRANSPORT PATH, AT LEAST ONE LIGHT RECEIVING ELEMENT D1 TO DN AVAILABLE FROM THE OPPOSITE SIDE TO PROVIDE AN ELECTRICAL OUTPUT SIGNAL. THE PROBLEM SOLVED CONSISTS OF PERFORMING AN ACCURATE DETECTION OF THE BLACKENING RANGE WITH AN INCREASED EXIT SIGNAL. THE APPARATUS IS CHARACTERIZED IN THAT THE RECEIVER ELEMENT D1 TO DN CONTAINS AT LEAST ONE PHOTO-ELECTRIC SEMICONDUCTOR FULFILLING AN ELECTRICAL CHARGE STORAGE FUNCTION, A REVERSE VOLTAGE APPLIED TO IT TO TAKE AN OUTPUT SIGNAL CORRESPONDING TO THE QUANTITY OF LIGHT RECEIVED BY THE RECEIVING ELEMENT, THAT QUANTITY OF LIGHT RECEIVED CORRESPONDING TO THE QUANTITY TRANSMITTED THROUGH THE UNDARKED RANGE OF THE FILM. THE INVENTION IS APPLICABLE TO THE DEVELOPMENT OF PHOTOGRAPHIC FILMS.

Description

"Film Blackening Detector Apparatus" This

  The subject of the invention is a device for detecting the blackening range of a film, this apparatus electrically detecting the blackening range.

  of a movie submitted to a development operation.

  In a photographic camera with

  development, it is necessary to ensure the filling of

  developer, so as to restore the activity of the developer solution that occurred during the development of the film. Since the amount of fill in developer solution acts on the result of the development, it is well known to measure by means of a photoelectric cell serving as a film blackening detector, the blackening range of the film. movie developed to control the

  filling quantity according to the measured value.

  It is also well known to use

  Such detectors of the blackening range of a film can be used to measure the film blackening range by photoelectric means. Such detecting apparatus comprises a light source mounted on one side of the film transport path, and a plurality of light receiving elements arranged in line on the opposite side of transporting the film. When the movie

  is brought between the source and these elements, the quantity of

  intercepted by the blackened film parts is detected

  as a decrease in the output signal of the receiver elements.

  However, with the detec-

  earlier in the blackening range of a film,

  has encountered the disadvantages mentioned below.

  Since the photoelectric current

  the receiver elements is too weak to be processed.

  As an output signal, an amplifier is usually

  Next, and an output signal is taken through this amplifier. When the amplification current of the photoelectric current is large enough for this current to be processed as an output signal, the amplified current is likely to make noise that interferes with the output signal. As a result, the detection errors are increased accordingly. Furthermore, it is well known that the output signal of the receiver elements can be increased by increasing the intensity of the incident light because the electric current passing when the receiving elements receive the

  incident light is proportional to its intensity. How-

  since light diodes are generally used

  In order to have high-speed modulation of the light source, there is an intrinsic limitation of the luminance of

  these diodes and it is impossible to increase the

  output signal of the light receiving elements.

  Accordingly, the present invention

  aims to-create an improved detector device from the -

  blackening range of a film, this device being able

  to eliminate the disadvantages mentioned above.

  More specifically, the object of the invention is to eliminate the detection errors caused by

  during the amplification of the photoelectric current.

  The invention also aims to

   ermet; re the increase of the output signal of the elements re-

  receivers, which makes it possible to carry out a precise detection of the

blackening beach of a movie.

  The invention relates for this purpose to an

  same type as above, characterized in that the element

  receiver comprises at least one photoelectric semiconductor having an electric charge storage function, an inverted voltage being applied thereto for taking an output signal

  corresponding to the amount of light received by the element re-

  ceptor, this quantity of light received corresponding to the

  amount transmitted through the non-blackened range of the film.

2500929 '

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  The invention will be better understood by

  the following description and the accompanying drawings represent-

  both an exemplary embodiment of the invention, drawings in the-

  which - Fig. 1 is an elevation view

  schematic front of the black range detector

  film forming according to the present invention; Fig. 2 is a circuit diagram of the film-shading range detection apparatus according to the present invention. FIG. 3 is a diagram of the circuit of a detector mechanism of a photoelectric element intended to

  explain the operation of this mechanism.

  Fig.1 shows a film to which development processing and fixing treatment have already been applied, this film being transported in the direction perpendicular to the figure plane. In a suitable location of a transport path, for example at the location of the outlet of a fixing tank (not shown) is mounted a light source 20 which sends a linear radiation on the

  film 10 crossing the full width of this parallel movie-

  to his plan. The distribution of the luminance of the light source 20 must be consistent. It is not mandatory that the light source 20 be constituted by a compact unit;

  it can be constituted by a line of light diodes.

  Light receiving elements DI to Dn for detecting the blackening range of the film

  , are constituted by photodiodes or photo-transistors

  two lines following a line corresponding to the light source

  20. These light-receiving elements D1 to Dn are dis-

  placed in the path of the film on the opposite side of the light source 20 facing this light source and being arranged parallel thereto. The light receiving elements shown in FIG. 1 are arranged to scan each of the ranges of the film, given the division into smaller ranges -4-. The present invention is not limited to such

  exemplary embodiment. It also applies when a re-

  The light receiver consists of a single receiver element on which the transmitted light is converged through the film. FIG. 2 is a diagram of a circuit representing a detection circuit comprising the receiving elements Di to Dn. The detector circuit for measuring the blackening range of the film consists of the connection in

  parallel of several rows of detection members 30, each

  that member comprising a receiver element D and a switch S.

  The switches SI to Sn are respectively

  connected to the receiving elements D1 to Dn. An inverting voltage

  is applied to these receiving elements D1 to Dn by

  intermediate switches Si to Sn. When the reverse voltage

  If the resistance is applied to the receiving elements Di to Dn, an electrical charge is stored at both terminals of the corresponding receiving element D, because the resistance between these two terminals increases. The negative potential terminals of the receiving elements D1 to Dn are respectively connected to a common wire 40 which is

  grounded through a resistor R.

  mutators Si-to Sn must convert the inverted voltage applied

  to the receiver elements in pulsed voltage according to their closing and opening actions. They consist of metal oxide type transistors (MOS)

  field effect. The control terminals C1 to Cn of the switching

  S1 to Sn are respectively connected to the output terminals Li to Ln of a shift register 50. As a function of scanning pulses Pi to Pn which are applied from the switches S to Sn one after the other at each of the output terminals Li to

  Ln, the switches Si to Sn are actuated in the order by

  termittence. The shift register 50 applies scanning pulses P1 to Pn in sequence at the output terminals Li to Ln,

  when this shift register 50 receives a clock pulse

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  CP. As indicated above, the conductive state of

  If Sn is transmitted to the next switch each time a scan pulse is generated to apply

  inverted voltage pulses to the respective receiver elements

  3 tifs Di to Dn who receive them one after the other.

  FIG. 3 is a circuit diagram of the network equivalent to the detection element 30, this diagram being

  intended to explain the operating mode of the circuit

  tection. The switch Si goes into the conductive state for a predetermined period of time when

  receives a scanning pulse P1 applied from the

  During the duration of this state, the inverted voltage E is applied to the receiver element D1 to change a connection capacitor Cc. An electric charge is then stored in this capacitor. During the charging process, the photoelectric current i1 passes into the element

  Dl receiver when the incident light 70 comes in. The result is

  that the discharge by the photoelectric current takes place at the same time as the charge. However the discharge by the photoelectric current is negligible during this period because

  that the charging power is preponderant. An electric charge

  sufficient ring is stored in the receiver element.

  When the scanning pulse P1 which actuates the switch S1 is transmitted to the next switch, the switch S1 is open, so that the discharge by the photoelectric current becomes preponderant and the stored electric charge is reduced. During this period,

  the dissipated electric charge is the integral of the photo current

  -30 electrical i1 for the duration of the opening of the switch Si.

  On the other hand, the photoelectric current i1 is proportional

  the intensity of the incident light and the value of the

  grale is proportional to the amount of light received. In

  zonsquence, the dissipated electric charge is finally pro-

  3r- proportional to the amount of light received by the element

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  receiver Dl during the duration of the opening of the switch Si.

  After the scanning pulses Pi to Pn have been respectively applied to the switches Si to Sn, a scanning pulse is again applied to the switch S1 and this switch again turns on for a predetermined time. An inverted voltage is thus

  applied to the receiving element D1 to charge it again.

  The charge made at this time is intended to compensate the

  previously dissipated electrical charge and the

  that performed is equal to the electrical charge dissipated. By taking the load current i2 at this time by means of a resistor R as an output signal, it is possible to

  take on an output line 70 an output signal proportionally

  the amount of light received by the receiver element Di when the switch Si is open. In addition, the tension

  output can be greatly increased because the

  Ge is made extremely short by setting resistance R to an appropriate value. This eliminates the need for any amplifier that was needed in prior film blackening detectors for the direct output of the photoelectric current. There is however no

  probability of spurious noise. We can thus perform a de-

  more accurate detection of the film blackening range.

When the film to be examined 10 is

  transported between the light source 20 and the receiving elements

  Since the amount of light incident on the receiving elements depends on the black part of the film 10 which intercepts the light 70. The light passing through the non-blackened area can be received by the receiving elements. Thus the receiving elements D1 to Dn receive a reduced amount of light when the light is transmitted through the blackening range of the film 10. As long as the transport speed of the film is kept constant, the cumulative value of the variation -: e The amount of light received by the receiver elements is proportional to the blackening range of the film because the reduction in light amount is proportional to the blackening range of the film. As a result, the filling quantity of the developer solution can be controlled by

  function of the variation of the output signal of the receiver

  D1 to D1 raised on the output terminal 40.

  From the description above,

  it is clear that a detector of the range of black-

  film according to the present invention can provide

  at least the following advantages. In the first place, it is pos-

  It is also possible to obtain a high output signal even with a low luminance light source, which makes it possible to perform the detection accurately. Second, it is not necessary

  to provide an amplifier such as that used in the

  such conventional detectors. Thirdly, the amount of light received, and consequently the output signal, can be increased only by increasing the number of pulses as long as the light source is sending light because the amount of light received is detected in the light.

  switch open condition.

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Claims (2)

  A detector apparatus for detecting the blackening range of a film (10), having a light source (20) mounted on one side of a film transport path (10) at a predetermined location of said path of trans-   of the film to be examined, at least one receiving element of   (Dl to Dn) mounted on the opposite side of the source   light, this receiver element converting into electrical signals   the light radiated by the light source and through   the film to be examined, the film to be examined presenting a   darkening range and non-blackened range corresponding to the image to be reproduced, the blackening range intercepting the light radiated by the light source, so that only the light transmitted through the non-blackened range is received by the element receiver, the blackening range of the film being thus detected by measuring the reduced amount of light corresponding to the amount of light intercepted by the blackening range of the film, characterized in that   the receiving element (D1 to Dn) comprises at least one semiconducting   photocontroller performing an electric charge storage function, an inverted voltage being applied thereto for taking an output signal corresponding to the amount of light received by the receiver element, the received amount of light corresponding to the amount transmitted to the receiver element; through the non-blackened beach of the film.   2) - Detector to detect the beach   for blackening a film according to claim 1, characterized   in that at least one resistor <R) is connected in series with the photoelectric semiconductor (D1, Dn), the two terminals of this resistor constituting the output terminals   for sending electrical signals.   ) - Detector to detect the beach   blackening of a film according to one or other of the claims   1 and 2, characterized in that photoelectric semiconductors (D1 to Dn) are respectively connected in series with switches (Si to Sn) by one of their terminals and with at least one resistor (R). ) by their other terminal, a control terminal (C1 to Cn) of the respective switches (Si to   Sn) being further connected to a shift register (50) followed by   In parallel mounting, the scanning pulses   by this shift register being applied in a manner consistent with   one after the other at the respective control terminals.   ves. 4) - Detector to detect the beach   for blackening a film according to claim 3, characterized   in that the switches (Si to Sn) are field-effect transistors of the metal oxide semiconductor type (MOS).