JPS6022335B2 - film counter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film counter that counts and displays the number of film frames that have been fed, and particularly to a film counter that is suitable for displaying the number of film frames that have been shot in a cine camera.

In the field of cameras, particularly cine cameras, a film counter itself is known, for example, from Japanese Patent Laid-Open No. 51-50732 (published on May 4, 1978).

However, in order to display the number of film frames sequentially and continuously as the number of film frames increases, in other words, to display the counted number of film frames in a bar shape, such a film counter has a number of memory elements corresponding to the number of display stages. For example, it required a flip-flop circuit.

For this reason, there was a drawback that the camera, which was originally required to be 4-inch, was made larger.

SUMMARY OF THE INVENTION An object of the present invention is to provide a film counter with a simple structure that can display the number of film frames in a bar shape.
Its feature lies in the use of a liquid crystal display capable of displaying a bar-shaped display as a display member, and the use of a digital-to-analog converter woven into a counter as means for controlling the voltage applied to the liquid crystal display.

The film counter of the present invention will be explained in detail below with reference to the drawings. FIG. 1 is an electrical circuit diagram of a cine camera to which the film counter of the present invention is applied, in which a cam 3 is fixed to a shaft 2 of a shutter blade 1 driven by a film drive motor (not shown) via a shaft 2. has been done.

Reference numeral 4 denotes a transfer switch having fixed contacts 4a, 4b and a movable saddle piece 4c, and the saddle piece 4c is connected to the fixed contact 4a every time a film frame is advanced by a connecting member 5 engaged with the cam 3. 4b alternately once at a time.

6 and 7 are NAND gates; one input end of the NAND gate 6 is connected to the fixed contact 4b of the switch 4 and ground via a capacitor 9, and the other end is connected to the output end of the NAND gate 7.

One input end of the NAND gate 7 is connected to the fixed point 4a of the switch 4 and the ground via a capacitor 10, and the other input terminal is connected to the output end of the NAND gate 6. Reference numeral 8 denotes a resistor connected between the ground and the movable contact piece 4c of the switch 4, and the resistance value of this resistor 8 and the values of the capacitors 9 and 10 are set so as to eliminate noise caused by mechanical contact of the switch 4. is set to a value.

11 is a BCD up/down counter that counts pulses from the pulse generation circuit formed by 4, 6 to 10; The terminal L is connected to the power supply Nc in order to increase the counter 11.
connected to c.

Further, N, R, T, and V of the counter 11 each indicate the output end, where N is the least significant digit, R is the second bit, T is the third bit, and V is the most significant digit of this counter 11. It is. 12, 13, and 14 are BCD up/down counters similar to 11, and are cascade-connected to each other as shown.

I5-30 are digital-to-analog converters (hereinafter referred to as D-A
Each of these resistances is weighted as follows: That is, 11~
The resistance value of the resistor 15 connected to the least significant digit N of the counter formed by 14 is set to R, the resistance value of the resistor 16 connected to the second bit R is set to R/2, and the resistance value of the resistor 16 connected to the second bit R is set to R/2. 3
The resistance value of the resistor 17 connected to the th bit T is R/4
resistor 18 connected to the fourth bit V
The resistance value of the resistor 19 connected to the fifth bit N is set to R/10, and the resistance value of the resistor 19 connected to the fifth bit N is set to R/10.
The resistance value of the resistor 20 connected to the bit R' is R/
20, the resistance value of the resistor 21 connected to the 7th bit T is set to R/40, and the resistance value of the resistor 22 connected to the 8th bit V is set to R/80. , the resistance value of the resistor 23 connected to the 9th bit N is set to R/100, the resistance value of the resistor 24 connected to the 1qth bit R is set to R/200, and the resistance value of the resistor 24 connected to the 1qth bit N is set to R/200.
The resistance value of the resistor 25 connected to the th bit T is R/4
00, the resistance value of the resistor 26 connected to the 12th bit V is set to R/800, and the resistance value of the resistor 27 connected to the 13th bit N' is R/100.
0, the resistance value of the resistor 28 connected to the 14th bit R is set to R/2000, and the resistance value of the resistor 29 connected to the 1Sth bit T is R/4000.
resistor 3 connected to the most significant digit V of the counter.
The resistance value of 0 is set to R/8000. 31 is a summing operational amplifier having an amplifying feedback resistor 32, the inverting input terminal (1) of which is connected to each resistor 1 which is the output device of the D-A converter.
Connected to 5-30 connection points, its non-inverting input end (10)
is grounded.

33 is an operational amplifier 33 forming an inverting gain amplifier.
The inverting input terminal (1) is connected to the output terminal of the operational amplifier 31 via a feedback resistor 35 and an input resistor 34.

36 is a liquid crystal display provided inside or outside the viewfinder of the cine camera, and includes an electrode 36a connected to the output end of the amplifier 33, transparent glass plates 36b and 36e, a flea electrode 36d connected to earth, and an electrode 36a and an electrode 36d. It has a transparent scale plate 36f that is in close contact with the liquid crystal 36c and the glass plate 36e held between them.

As shown in FIG. 2, the scale plate 36f is graduated with a plurality of numbers and letters representing the number of frames of film that have been photographed. Here, the letters (END) marked on the scale plate 36f in FIG.
0) indicates that the martyrdom of the film that has been shot is 3000 frames, and the character (START) is a scale that indicates that the film has not been shot at all. Next, in FIG.
The resistance value of this resistor 40 is set to a sufficiently smaller value than the resistance value of the resistor 38. 4
1 is a regular contact type switch linked to a release button (not shown), 42 is an R-S flip-flop circuit, and its set input terminal S is connected to a resistor 40 which is the output terminal of the pulse generation circuit indicated by 38 to 41. Connected.

In addition, a flip-flop circuit (hereinafter referred to as an FF circuit)
The output terminal 9 of is connected to one input terminal of the AND gate 43. 44 to 47 are reset pulse generation circuits having the same configuration as the pulse generation circuit formed by 38 to 41;
is a resistor, 45 is a capacitor, 46 is a regular glue set switch linked to a reset button (not shown); 47 is a resistor.

48 is an inverter for inverting the pulse from the reset pulse generating circuit; 49 is an OR gate having two input terminals connected to the output terminal of the reset pulse generating circuit and the most significant digit V of the printer; Output end is FF
It is connected to the reset input terminal R of the circuit 42. Next, the operation of the cine camera according to the above configuration will be explained.

First, when the power knob (not shown) is turned and a known power switch (not shown) is turned on, the FF circuit 42 and the counter 11 are turned on.
~14, operational amplifiers 31, 33, NAND gates 6, 7,
Power is started to be supplied to each of the AND gate 43, inverter 49, and OR gate 49, and each element becomes ready for operation. Furthermore, when the reset button is pressed only next to -, the switch 46 is instantaneously closed, so the capacitor 45
The accumulated charge is discharged to the resistor 47 via the switch 46, and a positive pulse is generated from the output terminal of the pulse generating circuit as shown in FIG. This pulse is inverted by the inverter 48 and inputted to the reset input terminal K of each counter 11-14, so that the contents of each counter 11-14 are reset. This pulse is also input to the reset input terminal R of the FF circuit 42 via the OR gate 49, so the FF circuit 4
2 is also reset, and its output terminal Q becomes ''L.'' Next, when the Lease button is pressed and the switch 41 is closed, a positive pulse is generated momentarily at the output terminal of this pulse generation circuit. Therefore, the FF circuit 42 is set, and its output terminal Q changes from "L" to "H''.

When the above-mentioned release button is pressed further, the film drive motor (not shown) starts rotating and the photographic film (
(not shown) is started. On the other hand, when the film drive motor starts rotating, the shirt wing 1 also starts rotating, and the cam 3 connects the movable twill piece 4c of the transfer switch 4 via the connecting member 5 to the fixed contacts 4a and 4b alternately.

Therefore, the pulse generating circuit continuously generates one pulse from the output device of the NAND gate 6 every time one frame of film is fed. At this time, the potential of one input terminal 43a of the AND gate 43 is held at "H", so the pulses from the pulse generation circuit are inputted to the input terminal F of the first stage counter 11 one after another via the AND gate 43. be done. Since the counters 11 to 14 count the number of input pulses in synchronization with the falling edge of the input pulse, the output terminal of the operational amplifier 31 rises stepwise. When a voltage that increases each time a film frame is fed is applied between the electrode 36a and the ground of the liquid crystal display 36 through an operational amplifier with a gain of 1, in other words, between the electrode 36a and the electrode 36d, the voltage increases. The liquid crystal 36c gradually becomes cloudy in the shape of a rod according to the applied pressure. When the number of fed frames of film reaches 3600 frames, counter 1 1~
The contents of 14 are (0011011000000000),
That is, the outputs N, R of the counter 14 and the counter 1
Since the output terminals R and T of 3 become "H'', only the characters (END) graduated on the scale plate 36f can be seen through, as shown in FIG. 2, and the other characters and numbers are visible on the liquid crystal 36c. It becomes impossible to see through the film due to turbidity.This lets the photographer know that there is no film left at all.At this time, if the photographer continues to press the release button without knowing that the shooting has ended, the shutter blade 1 continues to rotate and the counter continues counting.Then, when the film is fed 999 frames and the counter has fully counted, the output of the most significant digit V of the counter 4 becomes "H", so the FF circuit 42 outputs the most significant digit V. It is reset when the potential of becomes "L", its output terminal Q changes from "H" to "L", and the AND gate 43 blocks the pulse transferred from the pulse generation circuit.After that, keep pressing the release button. Since no pulse is applied to the input terminal F of the counter 1 at the first stage, all bits of the counter maintain the state of "H", that is, "1".
Therefore, in the liquid crystal display shown in the second figure, the characters (END
) remains visible.

When the film cartridge is replaced with a new one after all of the film contained in one film cartridge has been used as described above, the reset button is pressed again before photographing.

When this button is pressed, a reset pulse is generated from the reset pulse generation circuit as described above, and this pulse is input to the reset input device K of each counter 11 to 14 via the inverter 48, so the contents of each counter 11 to 14 are reset. and each output device of each counter 11 to 14 is “L”.
”, and the mother pressure applied between the electrodes 36a and 36d of the liquid crystal 36c becomes a support [V].For this reason, the liquid crystal display 36 shown in the second figure
The display contents of the scale plate 36f are also (START), (300
0), and (END) can all be seen through.

Next, when the release button is pressed, the switch 41 is closed, and the movable saddle piece 4c of the switch 4 alternately contacts the fixed contacts 4a and 4b, and the number of pulses corresponding to the film martyrdom sent from the pulse generation circuit is Occur. For this reason, the liquid crystal 36c shown in the second figure gradually becomes cloudy from the bottom as described above, in other words, becomes cloudy in a bar shape to display the number of frames to be fed. As described above, in the present invention, the number of film feeding frames is displayed in a zigzag manner by a combination of a DA converter and a liquid crystal display capable of displaying in a zigzag pattern, without using an FF circuit as in the case of conventional rhombuses. This not only simplifies the configuration and has the effect of making the cine camera more compact, but even if you keep pressing the release button without realizing that shooting has ended, the contents of the counter will not be cleared by the input pulse after a full count. , the camera is kept in a full count state, and the LCD continues to display the characters (END) indicating zero film remaining, so even if the photographer keeps pressing the release button by mistake, he or she can be sure that there is no film remaining. There is also the effect of being able to know things.

If you connect terminal L of each counter 11 to 14 to ground and simultaneously preset each bit of each counter 11 to 14 to "H'' before starting shooting, the counter will count down, so the display order can be completely reversed. In addition, in the above embodiment, the pulse generating circuit was configured to generate one pulse each time one frame of film was fed, but it may be configured to generate two pulses, for example. In this case, by setting the resistance value of the resistor 32 to 1/2, it is possible to display the same display as described above.

Furthermore, when replacing the film cartridge with a film cartridge of a different film sensitivity during use, another counter is provided, and counters 11 to 11 are added to this counter when the cartridge is replaced.
14 is temporarily stored, and when the film cartridge is replaced again and the original film cartridge is used, the contents stored in the second counter are stored in counters 11 to 1.
It goes without saying that if the camera is preset to 4 before starting shooting, the amount of film used at the time of interruption of use can be displayed on the liquid crystal display.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the film counter of the present invention, and FIG. 2 is a perspective view of the liquid crystal display shown in FIG. In the figure, 15 to 30... are resistors constituting a DA converter, and 36... are liquid crystal display bodies. Chart chart N *

Claims (1)

[Claims] 1. A pulse generator that generates at least one pulse for each frame of film, a counter that counts the pulses from the generator, and an analog electric machine that corresponds to the number of pulses counted by the counter. It is characterized by comprising a D-A converter that generates a signal, and a liquid crystal display device that receives the output from the D-A converter between electrodes and whose display state changes in a bar shape in response to the input signal. film counter. 2. The film counter according to claim 1, wherein the counter is formed of a BCD counter. 3 The counter has multiple BCDs connected in cascade.
2. The film counter according to claim 1, wherein the film counter is formed of a counter. 4. Claim 3, wherein the D-A converter is formed of a plurality of weighted resistors, each resistor being connected to a corresponding output terminal of the BCD counter.
Film counter described in section. 5. The film counter according to claim 1, wherein said counter is formed of an up-down counter. 6. A gate means is provided between the pulse generator and the counter to prevent pulses from the pulse generator from being transferred to the counter when the counter has counted a predetermined number of pulses. A film counter according to claim 1.