JPH0244279Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a document size detection mechanism for a copying machine.

Generally, in a copying machine, a document is placed on a document table at a predetermined position according to the size of the document, a paper size is selected, and a copying operation is performed. Nowadays, copying machines have become increasingly automated and have a paper feed mechanism that selectively feeds paper of a desired size from among multiple sizes of paper preset in the paper feed section. There are also copying machines, but even in such copying machines, when starting copying as described above, the operator must select and operate a paper size button according to the original. When the originals prepared to be copied have different sizes, the above-mentioned paper size selection button has to be operated frequently, which can be cumbersome, and may cause mistakes in copying due to incorrect operation of the paper size selection button. There was a problem.

This idea was created in view of the above problems.
The purpose of this document is to provide a document size detection mechanism that automatically selects paper of the size appropriate for the document simply by placing the document in a predetermined position on the document table, and its features include: However, when a document table is provided with at least one pair of transparent electrodes, and a document is placed on the document table, the capacitance between the electrodes is increased depending on whether the edge of the document covers one of the electrodes. The reason is that the document size is configured to be detected based on the change in document size.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.A document holder 2 is arranged to be openable and closable with respect to a document table 1 made of a transparent glass plate provided at the upper part of the main body of a copying machine. On the stand 1, standard size lines 3 and 4 of the original corresponding to B5 size and A4 size, respectively, are set as the placement position of the original.
Assume that That is, each of the reference size lines 3 and 4 is associated with a size index displayed on the periphery of the document table 1, and corresponds to the vertical and horizontal edges of the document of the reference size placed at the relevant position, respectively. In other words, so as to sandwich the vertical and horizontal portions of each of the reference size lines 3 and 4,
A pair of transparent electrodes 3A, 3 are placed in a state where one side is covered by the edge of a document of a predetermined size.
B, 3C, 3D, and 4A, 4B, 4C, 4D
are provided so that each pair forms an air condenser, so to speak. These electrodes are drawn in the form of a thin film on the document table 1 using, for example, transparent conductive ink, and are connected to an amplifier or the like via lead wires (not shown).

In this way, as shown in FIG. 2, for example, when a B5-sized original 5 is placed at a predetermined position on the original table 1, that is, at a position defined by the reference size line 3,
Each vertical and horizontal edge of the original 5 is located as a dielectric between the pair of electrodes 3A, 3B and between 3C, 3D, so that
Each capacitance between C and 3D changes compared to before placing the document 5. When the document 5A is A4 size, in addition to the electrodes 3A to 3D for B5 size detection, the capacitance of the other electrodes 4A to 4D also changes. Therefore, if these changes are amplified by an amplifier or the like and used as a command signal to the paper feed system, the paper of the size corresponding to the original 5 will be selected among the multiple sizes of paper set in the paper feed section in advance. It is selected and fed toward a predetermined location such as the photosensitive drum side. In addition,
If you place the original 5 incorrectly when making a copy or use an original of a different size than the predetermined size, the capacitance of the electrodes 3A to 4D will change differently from the preset conditions. Automatic paper selection operation is not performed. Also, electrodes 3A to 4D
Since it is transparent, it will not be copied together with the contents of the original 5 during copying. Furthermore, manuscript 5
Detection as described above is naturally possible even if the object is thick such as a book or magazine.

As mentioned above, according to the present invention, at least one pair of transparent electrodes are provided on the document table to form a capacitor for each type of document of a predetermined size, and the edge of the document can be detected by the electrodes. , it becomes possible to automatically select paper according to the original size, and therefore it can contribute to further automation in copying machines.

[Brief explanation of drawings]

FIG. 1 is a perspective view conceptually showing an embodiment of a document size detection mechanism of a copying machine according to the present invention, and FIG. 2 is a sectional view conceptually showing the detection principle of the detection mechanism. 1... Original table, 3A, 3B, 3C, 3D, 4
A, 4B, 4C, 4D...electrode, 5...manuscript.

Claims (1)

[Scope of utility model registration request] At least a pair of transparent electrodes are provided on the document table to form a capacitor, and the static between the electrodes is generated depending on whether or not the edge of the document covers one of the electrodes when the document is placed on the document table. A document size detection mechanism for a copying machine, characterized in that the document size is detected based on a change in capacitance.