JPH0395532A - Film feeder for camera - Google Patents

Abstract

PURPOSE:To always make a speed at which a film is fed constant, to simplify a circuit configuration, and to reduce costs by controlling an amount of energization to a motor, based on information from a storage means, which stores the number of film frames on which an image is produced, and from a voltage condition outputting means. CONSTITUTION:When a film winding sequence starts after film exposure, a sequence controller 1 decides whether voltage information from a power source voltage information outputting circuit 6 satisfies the feeding of a film or not. This voltage information is inputted to an arithmetic unit 8 together with information outputted from a circuit 7 which stores the number of frames on which an image is produced; data required for duty drive is outputted to the sequence controller 1 by the arithmetic unit 8 based on the information; consequently the control of energization to the film feeding motor 4 starts. The speed at which a film is fed can be easily made constant, by varying an amount of energization to the motor 4, taking an amount that a film is wound into account.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a film feeding device for a camera in which film feeding (winding and rewinding) is performed by driving a motor.

(Background of the Invention) Conventionally, in a film feeding device that winds and rewinds a film by motor drive, a method (hereinafter referred to as duty drive) in which the effective power supplied to the motor is kept constant based on information from a power supply voltage measuring means has been used. ) is well known. In this method, the period T in which the motor is energized according to the level of the power supply voltage. By changing the ratio between N and the period TOFF during which energization is stopped, the amount of energization P to the motor per unit time is made constant regardless of changes in the power supply voltage.

That is, as shown in Fig. 6, the energization cycle to the motor is T (=T ON + T OFF), and the terminal voltage and current consumption of the motor are V, A, and I M (=
K V M), it is expressed as (where K is a constant), and the motor terminal voltage v2 is, so P= (ToN/T) ・K・■cc, regardless of the power supply voltage VCCO value. , P is a constant value P0
To do this, (TON/T)=PO/K-VCC ・ (1)
It can be seen that it is sufficient to determine the ratio of ToN and T so that. Furthermore, if the energization cycle T is sufficiently small with respect to the energization response time of the motor, the rotational speed ω of the motor is P.
is approximately proportional to Therefore, if you want to keep the rotational speed ω constant, measure the power supply voltage VCC before starting energization and set T such that the above formula (1) is satisfied. N may be determined and the motor may be energized periodically as shown in FIG.

In this method, there is no need to monitor the rotational speed ω of the motor after the motor starts being energized, so there is no need for special additional circuits or mechanisms for detecting and controlling the rotational speed ω. etc., the advantage is that the burden on the software can be reduced.

However, in the above conventional example, although it is possible to control the rotational speed ω of the motor to a constant value ωC regardless of the power supply voltage, when the motor is used to feed film in a camera, the film feeding speed υf has the disadvantage that it is not necessarily constant. In other words, since the diameter of the film winding shaft increases by the amount of film being wound, even if the rotational speed ω can be controlled constant, the film feeding speed υf will decrease as the number of frames increases, as shown in Figure 7. is not constant and becomes large. However, for example, while the film is being fed, by blinking a light emitting element such as an LED placed facing the film, characters such as the shooting date can be imprinted on the film surface. In some cases, it is desirable that the film feeding speed υf be constant regardless of the power supply voltage.

Furthermore, keeping the film feeding speed υf constant reduces the burden on the entire control system regarding film feeding.

For the reasons mentioned above, the film feeding speed υf
In order to keep VCC constant, it is insufficient to perform duty drive based only on information about power supply voltage VCC.

Meanwhile, during the film feeding operation, the film feeding speed υf is detected. If a measuring means is provided and feedback control is performed, υf can be kept constant, but this requires additional circuits and configurations required for real-time processing and calculations, which can no longer be ignored in terms of manufacturing costs.

Furthermore, when performing sequence control using a microprocessor, etc., the film feeding speed υf is calculated using a timer and a means for generating an output signal corresponding to the film feeding amount, and motor energization is controlled based on the calculation result. Although it is possible to do so, the capacity load of the software program increases.

Therefore, if the capacity of the program is limited, there is a problem in that the entire program is subject to severe constraints.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems and to provide a camera that can maintain a constant film feeding speed while simplifying the circuit configuration and reducing costs. An object of the present invention is to provide a film feeding device.

(Characteristics of the Invention) In order to achieve the above object, the present invention provides a control means for controlling the amount of current applied to the motor based on information from the storage means and information from the voltage state output means. The present invention is characterized in that the amount of current applied to the motor is controlled in consideration of not only the power supply voltage state but also the diameter of the film winding shaft.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram representing a first embodiment of the present invention. In this configuration, when a sequence such as film exposure by an exposure control device (not shown) ends and a film winding sequence begins, the sequence control device 1 first outputs the power supply voltage from the power supply voltage information output circuit 6. A determination is made whether the information is of sufficient value to effect film advance. Further, the power supply voltage information is input to the arithmetic unit 8 along with the information output from the photographed frame number storage circuit 7, and the arithmetic unit 8 uses this information to calculate the necessary values when performing duty drive. Data is generated and output to the sequence control device 1. In response to this, the sequence control device 1 starts controlling the supply of electricity to the film feeding motor 4 via the motor driver 3. When the film feeding motor 4 starts rotating in this manner, feeding of the film is started accordingly. When a predetermined amount of film has been fed, a signal indicating this is output from the film feed amount detection circuit 5 to the input terminal FMEND of the sequence control device 1. As a result, the sequence control device 1 stops energizing the motor driver 3. Therefore, the film feeding motor 4 and the movement of the film are stopped. Then, the contents of the photographed frame number storage circuit 7 are incremented by "1", and the sequence ends.

Here, the motor driver 3 energizes the film feeding motor 4 according to the duty drive shown in FIG. This corresponds to N. Moreover, the oscillator 2 is
It is used as a means for generating sequence timing and a means for generating a synchronization signal that serves as a reference for the energization cycle to the motor.

FIG. 2 is a flowchart showing the operation in a second embodiment of the present invention, in which a microprocessor or the like is used in place of the sequence control device 1 and arithmetic device 8 in FIG. 1, and control by software is performed. In this case, the motor is energized by duty drive.

A description of the operation of this embodiment will be omitted since it is almost the same as that of the first embodiment.

In the first and second embodiments described above, the motor is energized by duty driving, and the motor energization period TON is determined using information on the power supply voltage and the number of frames taken, but in reality, the motor energization period is T. Rather than calculating N by calculation, it is easier to store necessary parameters in advance using a data memory or the like and refer to them. This example is shown in FIG. 3 as a third embodiment.

In this configuration, the sequence control device 1 refers to the data memory 9 based on the information output from the power supply voltage information output circuit 6 and the photographed frame number storage circuit 7, and imports the data required during duty drive. It has become. This data memory may be a ROM that can be referenced by software, or a rewritable nonvolatile memory (EEPROM).

FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In this embodiment, the drive of the film feed motor 4 is not driven by duty drive, but is variable between the motor driver 3 and the film feed motor 4. By intervening a load device 10 and making this load variable based on power supply voltage information and information on the number of frames taken, the amount of current applied to the film feed motor 4 is kept constant.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention. In this embodiment, the number of shootable frames is detected from the DX code, which is an international standard, in addition to the first embodiment.
An X-code photographable frame number detection circuit 11 is added, and if 7
When a thin film base such as a two-shot film is used, the calculation device 8 is configured to consider the number of frames to be halved and determine the amount of current applied to the motor.

According to the above embodiment, before feeding the film, information on the number of frames taken has been input in addition to power supply voltage information, and the amount of current applied to the motor can be varied by taking into account the diameter of the film winding shaft. As a result, the film feeding speed can be easily maintained constant without the need for processing such as real-time feedback control or the provision of complicated additional circuits.

Furthermore, instead of performing calculations to determine the amount of energization, data processing calculations can be further simplified by referring to a data memory or the like. In this case, data memory will be added, but this is much smaller in terms of capacity than the case where the capacity load of the program increases, as mentioned in the background of the invention, and is not a problem at all. There isn't.

(Effects of the Invention) As explained above, according to the present invention, the control means for controlling the amount of current applied to the motor based on the information from the storage means and the information from the voltage status output means is provided, and thereby the power supply The amount of current applied to the motor is controlled by taking into account not only the voltage state but also the diameter of the film winding shaft, which allows for a simplified circuit structure and lower costs while increasing the film feeding speed. It can always be kept constant.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
FIG. 3 is a flowchart showing the operation of the second embodiment of the invention, FIG. 3 is a block diagram showing the third embodiment of the invention, and FIG. 4 is a block diagram showing the fourth embodiment of the invention. FIG. 5 is a block diagram showing a fifth embodiment of the present invention, FIG. 6 is a waveform diagram showing an example of commonly performed energization control to a film feeding motor, and FIG. 7 is a waveform diagram showing an example of a conventional device. FIG. 3 is a diagram showing the relationship between the mork rotation speed, the film feeding speed, and the number of frames to be photographed. 1... Sequence control device, 2... Oscillator, 3... Motor driver, 4...
Motor, 6... Power supply voltage information output circuit, 7...
... Recorded frame number storage circuit, 8 ... Arithmetic device, 9 ... Data memory, 10 ... Variable load device, 11 ... DX Code-capable frame number detection circuit.

Claims (1)

[Claims] (1) A camera film equipped with a storage means for storing the number of film frames to be shot, a voltage state output means for outputting the voltage state of the power supply, a motor for feeding the film, and a film winding shaft for winding the film. A film feeding device for a camera, characterized in that the feeding device further comprises a control device for controlling the amount of current applied to the motor based on information from the storage device and information from the voltage status output device.