In electronic apparatus such as electronic computers, electronic exchangers and the like, the following construction is widely adopted from the standpoint of maintenance or installation of optional circuits. Namely, an electronic apparatus is constituted by a plural number of electronic circuit units, each having a plural number of electronic devices like IC's and LSI's collectively mounted on a printed wiring board. Each of the electronic circuit units is mounted on a shelf with a backboard by the use of a plug-in type connector to facilitate replacement of the electronic circuit units or installation of additional or optional circuit units.
In an electronic apparatus constructed in the above-described manner, the respective electronic circuit units have to be inserted into correct positions on a shelf according to unit types because a misplaced unit is likely to cause troubles. Therefore, it is the general practice to provide an anti-misplacement mechanism which mechanically prevents an electronic circuit unit from being mounted in a false position.
For example, Japanese Laid-Open Patent Application 1-198098 discloses an anti-misplacement mechanism of this sort, as explained below with reference to FIG. 1.
In this figure, the reference numeral 11 denotes a shelf which is fixedly supported on a pair of posts 13. Fixed to the back side of the shelf 11 is a backboard 17 which is provided with a plural number of connectors 15 on the inner side thereof, along with a plural number of paired upper and lower guide grooves 19 on the ceiling and bottom sides of the shelf 11 to guide electronic circuit units therealong. A frame member 21 with an opening is provided on the front side of the shelf 11. The frame member 21 is provided with unit insertion grooves 23 in frame portions on the upper and lower sides of the opening correspondingly and contiguously to the guide grooves 19. Further, anti-misplacement grooves 25 are provided on the frame portion on the upper side of the opening correspondingly to the respective unit insertion grooves 23.
The reference 27 denotes an electronic circuit unit which has a plural number of electronic devices such as IC's, LSI's and the like collectively mounted on a printed wiring board. The electronic circuit unit 27 is provided with a connector 29 at one end thereof for coupling engagement with a connector 15 on the backboard 17, and with a surface plate 31 at the other end. The surface plate 31 is formed with an upwardly protruding anti-misplacement projection 33.
The electronic circuit unit 27 is inserted along the unit insertion groove 23 and guide groove 19 of a unit mounting position on the shelf until the connector 29 on the electronic circuit unit 27 is coupled with a corresponding connector 15 on the backboard 17.
The anti-misplacement grooves 25 formed in the frame member 21 of the shelf 11 and the anti-misplacement projection 33 formed on the surface plate 31 of the electronic circuit unit 27 function as follows. In this connection, it is the general practice to mount a plural number of electronic circuit units of different kinds or types on the shelf 11. Accordingly, there are possibilities of the electronic circuit units being mounted in positions other than actually intended positions. If the electronic apparatus is started in such a state, it becomes difficult to produce the intended functions of the apparatus, in addition to probabilities of troubles. The misplacement of this sort is prevented by the anti-misplacement grooves 25 on the frame member 21 in cooperation with the anti-misplacement projections 33 on the surface plates 31.
Namely, in a case where two kinds of electronic circuit units A and B are to be mounted on a shelf 11, the electronic circuit unit 27 of type A is provided with an anti-misplacement projection 33 at position A on the surface plate 31 as shown in the drawing, while the other electronic circuit unit 27 of type B is provided with an anti-misplacement projection at position B.
The spacing between the unit insertion groove 23, which corresponds to the mounting position of the electronic circuit unit 27 of type A, and the anti-misplacement groove 25 has the same dimension as the spacing between the printed wiring board of the electronic circuit unit 27 and the anti-misplacement projection 33 (at position A). Similarly, the spacing between the unit insertion groove 23, which corresponds to the mounting position of the electronic circuit unit 27 of type B, and the anti-misplacement groove 25 has the same dimension as the spacing between the printed wiring board of the type B electronic circuit unit 27 and the anti-misplacement projection 33 (at position B).
Where the dimension of the spacing between the unit insertion groove 23 and the anti-misplacement groove 25 as well as the dimension of the spacing between the printed wiring board of the electronic circuit unit 27 and the anti-misplacement projection 33 is suitably adjusted in this manner, the anti-misplacement projection 33 is allowed to pass through the anti-misplacement groove 25 as long as the electronic circuit unit 27 is of the correct type for that particular mounting position. Otherwise, namely, in case the electronic circuit unit 27 is of an incorrect type, the anti-misplacement projection 33 on the electronic circuit unit 27 is not allowed to pass through the anti-misplacement groove 25 and accordingly prevents insertion of the electronic circuit unit 27 into an incorrect mounting position.
On the other hand, with an electronic apparatus of this sort, there arises a necessity for electrically connecting the connector 29 of an electronic circuit unit 27, which is located outside the shelf 11, to a connector 15 on the backboard 17 by the use of a test connector. The test connector of this sort is known, for example, from Japanese Laid-Open Utility Model Application 61-165471, which is shown in FIG. 2.
In this figure, indicated at 34 is a test connector which has, at one end of a printed wiring board 35, a connector 37 to be coupled with the connector 15 on the backboard 17 shown in FIG. 1 and, at the other end of the printed wiring board, a connector 39 to be coupled with the connector 29 of the electronic circuit unit 27. Projectingly extended from the opposite side edges at the other end of the test connector 34, with the connector 39, are a pair of guide members 41 which are each provided with a guide groove to guide the opposite side edges of the electronic circuit unit 27.
The test connector 34 is placed in a predetermined position on the shelf 11, and then the electronic circuit unit 27 is inserted along the guide members 41 of the test connector 39 until the connector 29 is coupled with the connector 39 thereby to electrically couple the electronic circuit unit 27, which is projected from the shelf 11, with the backboard 17. In this state, tests are carried out to check the conditions of the electronic devices which are mounted on the electronic circuit unit 27.
In the direction of insertion or extraction into or out of the shelf 11, the printed wiring board 35 of the test connector 34 is so dimensioned as to prevent the guide members 41 from hitting against the frame member 21 of the shelf 11 when the test connector is mounted thereon.
However, the conventional test connectors have no measures for preventing misplacement, so that they have the possibility of damaging the electronic apparatus by connecting a test connector having an electronic circuit unit of a false type or damaging a connector by inserting a test connector of a different type which does not match the connector on the backboard.
Therefore, it is an object of the present invention to provide a test connector which can overcome the above-mentioned drawbacks of the conventional test connectors, preventing electric troubles which might be caused by incorrect connection of electronic circuit units when testing an electronic apparatus, as well as mechanical damages which might result from misplacement of a test connector.