Motor-driven screwdriver operation information indicator and motor-driven screwdriver with operation information indicating function

A motor-driven screwdriver operation information indicator is retrofittable to a motor-driven screwdriver to indicate information related to an operation of the motor-driven screwdriver. An indicator housing of the operation information indicator is secured to a supporting and securing member configured to be secured to an outer peripheral surface of a screwdriver housing of the motor-driven screwdriver, thereby holding the indicator housing at a rear position of a rear end portion of the motor-driven screwdriver. An indication control circuit disposed in the indicator housing is connected to at least one of a motor-driven screwdriver drive control circuit and an external control circuit to receive a signal from the circuit connected thereto. The indication control circuit transmits a signal related to an operation of the motor-driven screwdriver on the basis of the received signal and indicates information related to the operation of the motor-driven screwdriver on an operation information indicating part.

TECHNICAL FIELD

The present invention relates to a motor-driven screwdriver operation information indicator indicating information related to an operation of a motor-driven screwdriver, and also relates to a motor-driven screwdriver with an operation information indicating function which has the motor-driven screwdriver operation information indicator. More specifically, the present invention relates to a motor-driven screwdriver operation information indicator retrofittable to a motor-driven screwdriver, and also relates to a motor-driven screwdriver with an operation information indicating function which has the motor-driven screwdriver operation information indicator retrofitted thereto.

BACKGROUND ART

There is known a motor-driven screwdriver having an indicating device that informs an operator about the drive status of the motor-driven screwdriver (Patent Literature 1). The known motor-driven screwdriver has a screwdriver body equipped with an LED indicating that the associated motor is being driven and another LED indicating a state where the motor has been stopped due to the generation of torque greater than a specified value, thereby enabling visual confirmation of the motor drive status.

Meanwhile, a production line for manufacturing a wide variety of products often requires using different tools for manufacturing products of different types. In such a production line, if an operator is left to make a judgment as to which tool should be used to make a particular product, he or she may mistakenly use an improper tool. To prevent such a judgment error, a tool management system has been developed in which a signal is sent to a tool to be used from a control circuit for controlling the operation in the production line (this kind of control circuit will hereinafter be referred to as an “external control circuit”) to light up an LED provided in the tool, thereby informing the operator about the tool to be used (Patent Literature 2).

Not all users using a plurality of tools, e.g. motor-driven screwdrivers, demand the above-described information representing the motor drive status of a motor-driven screwdriver and information indicating which one of the tools should be used. Even if such information is demanded, pieces of information wanted to be indicated differ for each user in most cases. Therefore, in order to meet each user's individual demand, conventional practice is to manufacture a motor-driven screwdriver having a specific indicating function as a specially ordered product. There is also a case where a user wants to add an information indicating function to an already used motor-driven screwdriver afterwards. In such a case, an indicator may be retrofitted to the motor-driven screwdriver. However, motor-driven screwdrivers are available in many specifications and shapes; therefore, it is necessary, in order to retrofit an indicator to an existing motor-driven screwdriver, to manufacture an indicator conforming in shape to each individual motor-driven screwdriver.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Utility Model Application Publication No. Hei6-83272Patent Literature 2: Japanese Patent No. 5078855

SUMMARY OF INVENTION

Technical Problem

However, a complicated, time- and labor-consuming operation is required to add an information indicating function to a motor-driven screwdriver by the above-described method. Accordingly, it has been desired that the operation of adding an information indicating function to a motor-driven screwdriver should be made capable of being performed even more easily.

Accordingly, an object of the present invention is to provide a motor-driven screwdriver operation information indicator capable of being retrofitted to various existing motor-driven screwdrivers by an easy operation, and to provide a motor-driven screwdriver with an operation information indicating function which has the motor-driven screwdriver operation information indicator retrofitted thereto.

Solution to Problem

That is, the present invention provides a motor-driven screwdriver operation information indicator retrofittable to a screwdriver housing of a motor-driven screwdriver to indicate information related to an operation of the motor-driven screwdriver. The motor-driven screwdriver operation information indicator includes: a supporting and securing member configured to be secured to an outer peripheral surface of a rear end portion of the screwdriver housing; an indicator housing having a securing part to be engagingly secured to a supporting and securing part provided on the supporting and securing member, the indicator housing being held at a rear position of a rear end portion of the motor-driven screwdriver by securing the securing part to the supporting and securing part; an indication control circuit disposed in the indicator housing, the indication control circuit being connected to at least one circuit selected from between a motor-driven screwdriver drive control circuit disposed in the screwdriver housing and an external control circuit outside the screwdriver housing to transmit a signal related to an operation of the motor-driven screwdriver on the basis of a signal received from the at least one circuit; and an operation information indicating part configured to receive the signal related to the operation of the motor-driven screwdriver, which is transmitted from the indication control circuit, and to indicate information related to the operation of the motor-driven screwdriver.

In the motor-driven screwdriver operation information indicator of the present invention, the supporting and securing member is configured to be secured to the outer peripheral surface of the screwdriver housing of the motor-driven screwdriver, and the indicator housing having the indication control circuit disposed therein is engagingly secured to the supporting and securing member. Therefore, only the supporting and securing member needs to be formed in conformity with the shape of a motor-driven screwdriver to which the supporting and securing member is to be attached, and the indicator housing can be used in common for motor-driven screwdrivers of different configurations. Accordingly, the motor-driven screwdriver operation information indicator can be retrofitted to any of various motor-driven screwdrivers, provided that a supporting and securing member is prepared which conforms in shape to various motor-driven screwdrivers.

Preferably, the supporting and securing member may have a ring-like shape covering the outer peripheral surface of the screwdriver housing.

More preferably, the supporting and securing member may have an inner peripheral surface conforming in shape to the outer peripheral surface of the screwdriver housing.

With the supporting and securing member having the above-described configuration, the motor-driven screwdriver operation information indicator can be retrofitted to the motor-driven screwdriver even more firmly, and it is also possible to prevent dust, water, etc. from entering the indicator housing through a gap between the supporting and securing member and the motor-driven screwdriver.

Preferably, the securing part of the indicator housing and the supporting and securing part of the supporting and securing member may be fitted to each other in the axial direction of the supporting and securing member.

With the above-described structure, it is possible to prevent positional misalignment of the indicator housing relative to the supporting and securing member, particularly in the radial direction of the supporting and securing member. Accordingly, the position of the indicator housing relative to the supporting and securing member can be stabilized even more.

Preferably, the arrangement may be as follows. The rear end portion of the screwdriver housing is provided with a suspension hole for suspending the motor-driven screwdriver. The indicator housing has a through-hole extending through the indicator housing from the outer peripheral surface to the inner peripheral surface thereof. The motor-driven screwdriver operation information indicator further includes a connecting member inserted into the suspension hole through the through-hole to connect together the indicator housing and the rear end portion of the screwdriver housing.

Specifically, the arrangement may be as follows. The through-hole of the indicator housing has an internal thread, and the connecting member is an externally threaded member engageable with the internal thread.

By connecting the indicator housing to the screwdriver housing of the motor-driven screwdriver as stated above, the indicator housing can be prevented from coming off the motor-driven screwdriver even if the indicator housing should be dislodged from the supporting and securing member.

Preferably, the indicator housing may have a suspension hole for securing a suspension hook.

The suspension hook is, usually, attached to the rear end portion of the motor-driven screwdriver. In this regard, even when the suspension hook becomes unable to be attached to the motor-driven screwdriver due to the fact that the motor-driven screwdriver operation information indicator is retrofitted to the rear end portion of the motor-driven screwdriver, the suspension hook can be attached to the motor-driven screwdriver operation information indicator instead; therefore, the motor-driven screwdriver can be suspended from a predetermined position by using the suspension hook.

Preferably, the operation information indicating part may have a light-emitting display element that emits light upon receiving the signal related to the operation of the motor-driven screwdriver from the indication control circuit.

Because information related to the operation of the motor-driven screwdriver can be confirmed visually, it is possible to inform the operator of the information accurately even at a noisy worksite.

Specifically, the information related to the operation of the motor-driven screwdriver may be at least one of the following information: information indicating that the motor-driven screwdriver is usable, which is based on a signal transmitted from the external control circuit; information indicating the operating status of the motor-driven screwdriver; information indicating the timing of inspection and repair of the motor-driven screwdriver; and information indicating a state where the motor-driven screwdriver has been forcibly stopped.

Preferably, the indication control circuit may have a recording device for recording the signal received, which is related to the operation of the motor-driven screwdriver, and a data output terminal for transferring data represented by the signal recorded in the recording device to the outside.

By taking out and analyzing the recorded data, it is possible to understand the operator's operating status and to supervise whether or not the operator is working efficiently.

Preferably, the arrangement may be as follows. The indication control circuit is connectable to the motor-driven screwdriver drive control circuit. The motor-driven screwdriver operation information indicator further includes internal signal transmission wiring connected at one end thereof to the indication control circuit. The other end of the internal signal transmission wiring is connectable to the motor-driven screwdriver drive control circuit.

In addition, the present invention provides a motor-driven screwdriver with an operation information indicating function. The motor-driven screwdriver includes a motor-driven screwdriver, and the above-described motor-driven screwdriver operation information indicator retrofitted to a screwdriver housing of the motor-driven screwdriver.

Embodiments of a motor-driven screwdriver operation information indicator and a motor-driven screwdriver with an operation information indicating function according to the present invention will be explained below on the basis of the accompanying drawings

DESCRIPTION OF EMBODIMENTS

A motor-driven screwdriver1with an operation information indicating function according to the present invention comprises, as shown inFIGS. 1 and 2, a motor-driven screwdriver10and a motor-driven screwdriver operation information indicator50retrofitted to a rear end portion14of the screwdriver10. The operation information indicator50is, as will be explained later, electrically connected to both the screwdriver10and an external control circuit (not shown) to receive signals output from the screwdriver10and the external control circuit and to visually indicate information related to the operation of the screwdriver10through a ring-shaped operation information indicating part (light-transmitting ring)68.

The screwdriver10, to which the operation information indicator50is attachable, has, as shown inFIGS. 3 and 4, a tubular screwdriver housing12, a motor20disposed in the screwdriver housing12, and a motor-driven screwdriver drive control circuit22. The screwdriver housing12has a front end portion16provided therein with a bit holder26driven to rotate by the motor20. The bit holder26is configured to be fitted with a screwdriver bit (not shown). The screwdriver housing12has a rear end surface15formed with a power supply cord holding hole28for holding a power supply cord32. That is, a power supply cord securing annular member34secured to the outer periphery of the power supply cord32is engagingly secured to the power supply cord holding hole28, thereby allowing the power supply cord32to be held so as not to come out of the screwdriver housing12. A part of the power supply cord32that extends from the drive control circuit22to the annular member34is folded in the screwdriver housing12and thus disposed with a sufficient margin of length. The rear end portion14of the screwdriver housing12has two suspension holes30formed at mutually opposing positions so as to extend inwardly perpendicularly to a longitudinal axis L of the screwdriver housing12. The two suspension holes30are fitted with a suspension hook36for suspending the screwdriver10. The screwdriver housing12is further provided with a selector switch38to enable the screwdriver10to be operated from the outside of the screwdriver housing12. The selector switch38is connected to the drive control circuit22to allow the driving direction of the motor20to be changed over among “forward”, “reverse”, and “neutral” by actuating the selector switch38. The screwdriver10is configured such that the motor20is driven to rotate when the screwdriver10is operated so that a screwdriver bit held by the bit holder26is pushed into a screw. When the motor20is driven forward, the bit holder26rotates in a direction for tightening a right-hand screw; when the motor20is driven reversely, the bit holder26rotates in a direction for loosening a right-hand screw. When the selector switch38is in the neutral position, the motor20is not driven.

The operation information indicator50, which is retrofitted to the rear end portion14of the screwdriver10has, as shown inFIGS. 1, 2 and 5, a ring-shaped supporting and securing member52secured to an outer peripheral surface18of the rear end portion14of the screwdriver10, an indicator housing58engagingly secured to the supporting and securing member52, and an indication control circuit78disposed in the indicator housing58. The supporting and securing member52has an inner peripheral surface54conforming in shape to the outer peripheral surface18of the rear end portion14of the screwdriver housing12(seeFIG. 10), so that no gap will be formed between the inner peripheral surface54of the supporting and securing member52and the outer peripheral surface18of the rear end portion14of the screwdriver housing12when the supporting and securing member52is secured to the screwdriver housing12, as will be explained later. The supporting and securing member52has a supporting and securing part56with a stepped configuration formed on the outer peripheral surface thereof. The indicator housing58has a securing part60with a stepped configuration formed on the inner peripheral surface thereof. The indicator housing58and the supporting and securing member52, which has a ring-like shape, are secured to each other with the securing part60of the indicator housing58and the supporting and securing part56of the supporting and securing member52fitted to each other in the axial direction of the supporting and securing member52.

The indicator housing58has a circular cylindrical indicator housing body62fitted to the supporting and securing member52, a light-transmitting ring68formed of a light-transmitting transparent material, and a cord holding member70. The indicator housing58is formed by screw-fixing the indicator housing body62and the cord holding member70to each other with the light-transmitting ring68held therebetween, as will be explained later. The indication control circuit78is provided with an LED. The LED emits light in response to a signal from the indication control circuit78. Light from the LED is visible from the outside of the operation information indicator50through the light-transmitting ring68.

When the operation information indicator50is retrofitted to the rear end portion14of the screwdriver10, as shown inFIG. 5, the power supply cord securing annular member34is detached from the power supply cord holding hole28of the screwdriver housing12and held by and secured to the cord holding member70. The cord holding member70comprises, as shown inFIG. 6, a first member70-1and a second member70-2. Between the first member70-1and the second member70-2, a power supply cord holding hole72is formed. The power supply cord32held in the power supply cord holding hole72of the cord holding member70extends, as shown inFIG. 5, from the drive control circuit22in the screwdriver housing12through the power supply cord holding hole28in the screwdriver housing12and through the indicator housing58. The drive control circuit22is provided with a signal output terminal24(FIG. 7B) for outputting a signal related to an operation of the screwdriver10. On the other hand, the indication control circuit78is provided with an internal signal input terminal80(FIG. 7G) for receiving a signal from the screwdriver10. Internal signal transmission wiring82connects between the signal output terminal24of the drive control circuit22and an internal signal input terminal80of the indication control circuit78. The internal signal transmission wiring82is wired to extend through the power supply cord holding hole28in which a gap is formed as a result of the removal of the power supply cord securing annular member34. The indication control circuit78is further provided with an external signal input terminal81(FIG. 7G), to which is connected external signal transmission wiring88for transmitting an external signal from the external control circuit. The external signal transmission wiring88has a transmission wiring securing annular member90secured to the outer periphery thereof. The annular member90is secured and held in a transmission wiring holding hole74(FIG. 6) formed between the first and second members70-1and70-2of the cord holding member70, thus the external signal transmission wiring88being held.

The motor-driven screwdriver drive control circuit22has a function of outputting from the signal output terminal24signals related to the operation of the screwdriver10, for example, signals indicating the following: the on/off status of the motor20; the driving direction of the motor20, i.e. “forward”, “reverse”, or “neutral”, set through the selector switch38; the completion of screw tightening; and the temperature of the motor20. The external control circuit has a function of outputting an external signal, for example, a signal indicating which of a plurality of motor-driven screwdrivers connected to the external control circuit should be used, or a signal indicating which motor-driven screwdriver is usable. The indication control circuit78of the motor-driven screwdriver operation information indicator50receives the above-described signals from the motor-driven screwdriver drive control circuit22and the external control circuit and indicates information related to the operation of the screwdriver10according to the received signals for the operator by emitting the LED. Examples of information related to the operation of the screwdriver10include the following: information indicating that the screwdriver10is usable; information indicating the operating status of the screwdriver10; information indicating the timing of inspection and repair of the screwdriver10; and information indicating a state where the screwdriver10has been forcibly stopped. The information indicating that the screwdriver10is usable is indicated based on a signal transmitted from the external control circuit. The information indicating the operating status specifically includes information indicating that the rotational drive of the bit holder26has been temporarily stopped due to the application of a specified torque to the bit holder26and hence screw tightening with a specified torque has been normally completed, and information indicating the status of the driving direction of the motor20, i.e. “forward”, “reverse”, or “neutral”, set on the selector switch38. The information indicating the timing of inspection and repair is indicated, for example, on the following occasions: when the number of times of completion of screw tightening integrated from the start of use of the screwdriver10reaches a value greater than a specified value; when, in a case where the motor20of the screwdriver10is a brush motor, the brush of the brush motor has worn to a value less than a specified value; and when the motor20does not stop even when a specified torque is applied to the bit holder26and hence the rotational drive of the bit holder26does not stop. The information indicating the fact that the screwdriver10has been forcibly stopped is indicated, for example, when it is judged necessary to cool the motor20due to the fact that the temperature of the motor20has risen to a level higher than a predetermined value.

In this embodiment, lighting/blinking of an LED is used as an operation information indicating method, but operation information may be indicated by using a display capable of displaying letters in place of the lighting/blinking of an LED. In the alternative case, numerical values may be used to indicate the number of times at which screw tightening is normally completed, or to indicate the integrated value of the driving time of the motor20, etc. as information related to the operation of the screwdriver10. Alternatively, the above-described information to be informed to the operator may be indicated by using letters.

It should be noted that the number of pieces of information indicatable on the motor-driven screwdriver operation information indicator50is not necessarily limited to one and that a plurality of pieces of information may be indicated simultaneously, for example, by providing the operation information indicator50with a plurality of LEDs of different colors. In addition, the operation information indicator50is configured to enable the user to select and set information to be indicated according to his or her demand.

The indication control circuit78may have not only a function of transmitting signals related to the operation of the screwdriver10but also a recording device for storing signals received from the motor-driven screwdriver drive control circuit22and the external control circuit as data and also a USB terminal or the like as a data output terminal for transferring the stored data to the outside. By taking out and analyzing the stored data, it is possible to supervise whether or not the operator is working efficiently. Specifically, when the number of times at which the motor20is driven reversely is large, the possibility is high that screw retightening has been performed many times; therefore, it is possible to judge that there have been a large number of errors in screw tightening. When the driving time of the motor20is long, it is possible to judge that the motor20has been uselessly driven for a long time. It is also possible to judge that the timing of adjustment and repair of the screwdriver10is approaching, and hence possible to prepare a motor-driven screwdriver10for replacement in advance of the timing of adjustment and repair. It should be noted that setting as to which information is to be indicated on the above-described motor-driven screwdriver operation information indicator50can be made by connecting a computer to the above-described USB terminal and changing the setting on the indication control circuit78from the computer.

The cord holding member70of the indicator housing58has two mutually facing suspension holes76(seeFIG. 7G) extending from the respective outer peripheral surfaces of the first and second members70-1and70-2inwardly perpendicularly to the longitudinal axis L. The two suspension holes76are fitted with the suspension hook36, which has been detached from the screwdriver10. The bottom surface of each of the suspension holes76, which are fitted with the suspension hook36, is provided with a threaded hole95extending toward the center of the cord holding member70to receive a screw96for connecting the first and second members70-1and70-2to each other.

Next, a procedure for retrofitting the motor-driven screwdriver operation information indicator50to the motor-driven screwdriver10will be explained with reference toFIGS. 7A to 7H. First, the suspension hook36(seeFIG. 4) attached to the rear end portion14of the screwdriver10is removed from the suspension holes30. Further, a circular cylindrical cover40and a coupling42are detached from the front end portion16of the screwdriver10, and three screws44-1,44-2and44-3connecting first and second housing members12-1and12-2(seeFIG. 1), which constitute the screwdriver housing12, are removed (seeFIG. 7A) to detach the second housing member12-2from the first housing member12-1(seeFIG. 7B). It should be noted that a threaded hole that receives the screw44-1is provided to extend from the bottom surface of each of the suspension holes30, in which the suspension hook36is fitted, toward the center of the screwdriver housing12. Next, the power supply cord securing annular member34is disengaged from the power supply cord holding hole28in the screwdriver housing12, and the part of the power supply cord32which has been folded in the screwdriver housing12is pulled out from the power supply cord holding hole28. In addition, a first end portion84of the internal signal transmission wiring82is connected to the signal output terminal24of the motor-driven screwdriver drive control circuit22, and the internal signal transmission wiring82is disposed to extend through the power supply cord holding hole28(seeFIG. 7C). The detached second housing member12-2is reattached to the first housing member12-1, and the first and second housing members12-1and12-2are connected and secured to each other with the three screws44-1,44-2and44-3(seeFIG. 7D). Next, the ring-shaped supporting and securing member52is press-fitted and secured to the outer peripheral surface18of the rear end portion14of the screwdriver housing12(seeFIG. 7E). The supporting and securing member52is secured to the screwdriver housing12with substantially no gap between the inner peripheral surface54of the supporting and securing member52and the outer peripheral surface18of the screwdriver housing12because the inner peripheral surface54of the supporting and securing member52conforms in shape to the outer peripheral surface18of the screwdriver housing12. It should be noted that the screwdriver housing12and the supporting and securing member52may be secured to each other by using an adhesive. Next, the indicator housing body62is attached to the supporting and securing member52so that securing part60of the indicator housing body62is axially fitted to the supporting and securing part56of the supporting and securing member52(seeFIG. 7F). The securing part60of the indicator housing body62is provided with two threaded holes64(seeFIG. 5) extending from the outer peripheral surface of the securing part60to the inner peripheral surface thereof. The indicator housing58and the supporting and securing member52are secured to each other by engaging setscrews92with the threaded holes64. The indicator housing body62further has two threaded holes66provided at respective positions corresponding to the suspension holes30of the screwdriver housing12such that the threaded holes66extend from the outer peripheral surface of the indicator housing body62to the inner peripheral surface thereof. Connecting members94(seeFIG. 7G) having external threads, respectively, are engaged with the threaded holes66so as to project from the inner peripheral surface of the indicator housing body62and to extend into the suspension holes30of the screwdriver housing12. With the connecting members94, the indicator housing body62is connected to and supported by the screwdriver housing12and held so as not to come off the motor-driven screwdriver10. Next, a second end portion86of the internal signal transmission wiring82extending out of the screwdriver housing12is connected to the internal signal input terminal80of the indication control circuit78(seeFIG. 7G). Further, a connecting terminal89of the external signal transmission wiring88is passed through the inside of the light-transmitting ring68and connected to the external signal input terminal81of the indication control circuit78. Next, the first and second members70-1and70-2of the cord holding member70(seeFIG. 6) are connected and secured to each other by engaging the screw96with the threaded hole95, with the power supply cord securing annular member34and the transmission wiring securing annular member90held in the power supply cord holding hole72and the transmission wiring holding hole74, respectively. The connected and secured cord holding member70is secured to the indicator housing body62by using screws98, with the indication control circuit78and the light-transmitting ring68held between the cord holding member70and the indicator housing body62. Finally, the suspension hook36is attached to the suspension holes76, thereby completing the operation of attaching the motor-driven screwdriver operation information indicator50to the motor-driven screwdriver10(seeFIG. 7H).

Thus, the motor-driven screwdriver operation information indicator50can be retrofitted to an existing motor-driven screwdriver10without applying additional work to the screwdriver10. In addition, assuming that the operation information indicator50will be attached to the screwdriver10, the power supply cord32is disposed in such a manner as to be folded in the screwdriver housing12so that, when pulled out of the screwdriver housing12, the power supply cord32has a sufficient length to allow the power supply cord securing annular member34to be moved to the power supply cord holding hole72of the indicator housing58. Accordingly, when attaching the operation information indicator50to the screwdriver10, there is no need for an operation such as replacing the power supply cord32with another or extending the length of the power supply cord32.

Existing motor-driven screwdrivers10vary in size and shape as shown, for example, inFIGS. 8ato 8c. Accordingly, the outer peripheral surface18of the rear end portion14of the screwdriver housing12also varies in size and shape as shown, for example, inFIGS. 9ato 9c. Therefore, in order to retrofit an indicator, a plurality of indicator bodies usually need to be prepared in conformity with various configurations of motor-driven screwdrivers. In the motor-driven screwdriver operation information indicator50according to the present invention, however, the supporting and securing member52, which is engagingly secured directly to the outer peripheral surface18of the motor-driven screwdriver10, is a member separate from the indicator housing58. Therefore, the indicator housing58can be used in common for motor-driven screwdrivers10of different configurations, provided that supporting and securing members52are prepared which have inner peripheral surfaces54conforming in shape to the outer peripheral surfaces18of various motor-driven screwdrivers as shown inFIGS. 10ato 10c. Thus, the motor-driven screwdriver operation information indicator50of the present invention can be retrofitted to various motor-driven screwdrivers10different in the shape of their outer peripheral surfaces18by only preparing supporting and securing members52, which are relatively simple in structure, in conformity with the motor-driven screwdrivers10.

In the above-described embodiment, an LED, which is a light-emitting display element, is used as an operation information indicating part indicating information related to the operation of the screwdriver10, thereby visually indicating the information. It should, however, be noted that the operation information indicating part may comprise other light-emitting display elements. It is also possible to use audio indications. Further, although the indication control circuit78is connected to both the motor-driven screwdriver drive control circuit22and the external control circuit, the indication control circuit78may be connected to only one of them. Further, the supporting and securing member52need not necessarily have a ring shape. The supporting and securing member52may have any shape that can securely support the indicator housing58. The supporting and securing member52may be formed as a member integrated with the screwdriver housing12. Alternatively, the supporting and securing member52may be formed as a member integrated with the indicator housing body62.

Although in the above-described embodiment the supporting and securing member52is secured to the outer peripheral surface18of the screwdriver housing12by press-fitting, the supporting and securing member52need not necessarily be firmly secured to the outer peripheral surface18of the screwdriver housing12because the indicator housing58, which is secured to the supporting and securing member52, is supported by the connecting members94so as not to come off the screwdriver housing12. The supporting and securing member52may be configured to only engage the outer peripheral surface18of the screwdriver housing12so that the indicator housing58will not tilt about an axis defined by the connecting members94.

LIST OF REFERENCE SIGNS