JPH05188530A - Film unit with lens - Google Patents

Abstract

PURPOSE:To prevent faulty weld or short shot from occurring on a rear cover. CONSTITUTION:A gate is set on an upper side part than the center of a back surface part 13a and at a position being an equal distance apart from respective hinge parts 25 and 26, and melted resin is fed from the gate to mold the rear cover 13. Thus, the melted resin forcibly flows in the respective hinge parts at the time of molding, so that the faulty weld and the short shot are not caused on the rear cover 13.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens-fitted film unit, and more particularly to an improvement of a rear cover of a lens-fitted film unit.

[0001]

2. Description of the Related Art An unexposed film pulled out from a cartridge is rolled into a unit body equipped with a simple shooting mechanism, and a film unit with a lens is pre-installed in the unit (trade name: "Sharp Run Hi"). Are provided by the applicant. In this lens-fitted film unit, in order to reduce the manufacturing cost, the front cover, the main body, and the rear cover that form the unit main body are formed of resin. In the lens-fitted photo film unit, the bottom cover 72 for taking out the cartridge is provided on the rear cover 70 through a thin hinge portion 71 as shown in FIG. 6 so that the cartridge can be easily taken out from the unit main body. It is provided integrally.

By the way, when the rear cover 70 having the hinge portion 71 is molded, if the setting position of the gate for feeding the resin is improper, a weld defect occurs near the hinge portion 71 and a short shot occurs on the bottom lid 72. There was a problem that occurs. In order to solve this problem, the applicant has set the gate 73 in the specification of Japanese Patent Application No. 2-119177 away from the patrone take-out lid, for example, at the position shown by the broken line in FIG. It has been proposed that when the tip of the resin that has flowed to reach the hinge portion 71, there is no unfilled portion in the rear cover 70 except the bottom lid 72.

[0003]

When the rear cover 70 is attached to the main body portion in a factory, there is a risk that the loose roll-shaped unexposed film may be sandwiched between the rear cover 70 and the main body portion. For this reason, in addition to the above-mentioned bottom lid, a rear cover formed integrally with a hinge portion through which a bottom lid opened at the time of film loading is formed is disclosed in Japanese Patent Application No. 3-283586.
No. is proposed in the specification. When the gate is set at the above-mentioned position with respect to such a rear cover and resin is fed from there, there arises a problem that a weld defect and a short shot occur in the vicinity of a new hinge portion and the bottom lid, respectively.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a high-quality lens-fitted film unit that does not cause weld defects or short shots on the rear cover.

[0005]

In order to achieve the above object, in the lens-fitted film unit of the present invention, a gate for feeding resin is set at an equal distance from each hinge portion. Further, when the gate is located on the end side opposite to the end on which the cartridge removal lid and the bottom lid are formed,
The resin reaches the hinge portions after being filled in the respective portions of the rear cover. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0006]

FIG. 4 shows a film unit with a lens (hereinafter, simply referred to as a film unit) embodying the present invention. The film unit 2 is composed of a unit main body 3 having a photographing mechanism and a paper box 4 for accommodating the same. Photographing is performed while the photograph is taken in the paper box 4. Therefore, the paper box 4 has a taking lens 5, a viewfinder 6, a shutter button 7, a film counter 8, and a winding knob 9.
There is an opening for exposing the.

In FIG. 2, which shows the unit main body 3 in an exploded manner, the unit main body 2 includes a front cover 11 and a main body portion 1.
2, a rear cover 13, which are integrally molded of plastic. A front cover 11 is fixed to the front surface of the main body 12 by a claw, and the front cover 11 protects not only the taking lens 5 attached to the main body 12 but also a shutter unit, a film winding unit, and the like (not shown). A cartridge chamber 15 and a film roll chamber 16 are formed at both ends of the back surface of the main body 12. A cartridge 17 is loaded in the cartridge chamber 15, and an unexposed film 18 pulled out from the cartridge 17 is loaded in the film roll chamber 16. At the time of loading, the film 18 is wound around the jig 19 into a roll. An exposure frame 2 having an exposure opening 20 formed between the cartridge chamber 15 and the film roll chamber 16
1 is provided.

The rear cover 13 has locking claws 22a, 2
The film 18 is shielded from the back surface of the main body 12 via 2b to shield the film 18 from light. After this, the cover 13 has a rear surface 13a,
It is composed of a bottom surface portion 13b and a pair of rotatable bottom lids 23 and 24, and thinned hinge portions 25 and 26 are shown in FIG. 1 between the back surface portion 13a and the bottom lids 23 and 24. Is formed. The bottom lid 23 is shown in FIG.
When the rear cover 13 is fixed to the main body 12, the jig 19 does not get in the way. The bottom lid 24 is opened when the cartridge 17 is pulled out from the cartridge chamber 15 at the developing station. The bottom lids 23 and 24 are fixed to the main body 12 or the front cover 11 via the locking claws 23a and 24a.
Reference numeral 27 is a mark of the gate into which the resin is fed when the rear cover 13 is molded.

FIG. 5 shows an injection molding machine for molding the rear cover 14. The resin is put into the injection cylinder 51 from the hopper 50, and is sent leftward in the drawing by the injection plunger 52. A heater 53 is attached to the tip of the injection cylinder 51, and the resin is melted here and is pushed out of the nozzle 54 by the pressure of the injection plunger 52. Extruded resin is sprue 55, runner 5
6, through the gate 57, it is sent out to the cavity 60 formed by the molds 58, 59. In addition, in this injection molding machine, the position of the gate 57 is set not on the side end portion of the rear cover 14 but on the back surface thereof in order to thinly mold the rear cover 14.

The operation of the rear cover of the present invention will be described below. Molten resin flows from the gate 57 to the cavity 60.
1, the front end of the resin flow (hereinafter referred to as the flow front) becomes substantially concentric as shown in FIG. 1 and flows to the end of the back surface portion 13a. And the back part 1
After the resin 3a and the bottom surface portion 13b are filled with resin, the flow front reaches the hinge portions 25 and 26. Further, when resin is fed from the gate 57, the hinge portion 2
The flow front, which has only the destination 5,26, is fed to the bottom lids 23, 24 without reducing its flow velocity. The resin thus forcedly fed is filled in the locking claws 23a and 24a at the ends of the bottom lids 23 and 24.
Therefore, the flow front does not become stagnant by the time the resin sent from the gate 57 completely fills the cavity 60, and therefore no weld failure or short shot occurs in the rear cover 13.

In this embodiment, the injection molding of the rear cover 14 is carried out by the hot runner method, but the same effect can be obtained even if the rear cover 14 is manufactured by the cold runner method or the runnerless method. it can. Further, in the above embodiment, the back cover of the normal type lens-fitted photo film unit has been described. However, other lens-fitted photo film units such as a telephoto type, a panorama type, a close-up type and the like, and a disposable type with a built-in prewind shaft. The present invention can be applied to a rear cover of a single-use camera and a single-use camera including a double cartridge.

[0012]

As described above in detail, in the present invention, since the gate for feeding the resin is set to be equidistant from each hinge portion, the resin flowing pressure in each hinge portion can be made uniform. Further, since the position of the gate is arranged on the end side opposite to the end where the patrone take-out lid and the bottom lid are formed, the resin is forced to flow into each hinge part, and the patrone take-out lid and the bottom lid are The resin is surely filled up to the end. Therefore, it is possible to prevent a weld defect or a short shot from occurring on the rear cover.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing how resin fed from a gate flows when a rear cover of a lens-fitted film unit is molded.

FIG. 2 is an exploded perspective view of a unit main body.

FIG. 3 is a perspective view showing the outer appearance of a lens-fitted film unit.

FIG. 4 is a perspective view of a unit main body with a rear cover attached.

FIG. 5 is a schematic view showing a main part of an injection molding machine for molding a rear cover.

FIG. 6 is an explanatory view showing how resin fed from a gate flows when molding a conventional rear cover.

[Explanation of symbols]

 2 Film unit with lens 3 Unit body 5 Photographic lens 12 Main body 13 Rear cover 17 Patrone 18 Film 23, 24 Bottom lid 25, 26 Hinge part 27 Gate mark 57 Gate 60 Cavity

Claims (2)

[Claims] 1. A main body portion having a photographing mechanism such as a photographing lens and a shutter, for accommodating an unexposed film with a cartridge, a rectangular rear cover attached to the main body portion for shielding the photographic film, In the lens-fitted film unit, which is integrally molded with resin through the hinge part to form a cartridge, a cartridge ejecting lid for taking out the cartridge, and a bottom lid that is opened when the film is loaded, the same distance from each of the hinge portions. A film unit with a lens, characterized in that a gate is set at a certain position, resin is fed from the gate, and the rear cover is molded. 2. The position of the gate is on the side of the end opposite to the end on which the cartridge ejection lid and the bottom lid are formed so that each portion of the rear cover is filled with resin and then reaches each of the hinge portions. The film unit with lens according to claim 1, wherein the film unit with lens is arranged.