JPH05208592A - Lead holding failure detector in automatic drafting machine - Google Patents

Abstract

PURPOSE:To prevent a reduction of plotting efficiency caused by defective pencil by a method wherein with the occurrence of a lead-unchucked state at the first lead push-out action in a lead supply action by which a residual lead held only by a pencil lead displacing tube of a push button-type pencil is pushed out by a new lead, the displacing tube is judged as a lead holding failure. CONSTITUTION:In a plotting head 2 which relatively moves in X-Y directions in an automatic drafting machine, a raising/lowering driver 10 is fixed on a base 8, and a pen holder 22 detachably holding a push button-type pencil 20 is provided on a raising/lowering body 14. The pencil 20 is provided with a lead chuck mechanism which is brought to holding/releasing states by the vertical movement of a pushing mechanism 34a. A pencil lead holding position is changed by vertically moving a lead displacing tube 38 relatively to the mechanism. In this invention, if the occurrence of a lead-unchucked state at the first lead push-out action in a lead supply action, by which a residual lead held only by the pencil lead displacing tube 38 is pushed out by a new lead, is judged from the output of a displacing tube detection sensor 29, the use of the appropriate pencil 20 is inhibited by conducting an error processing for a failure of the lead displacing tube in holding a lead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a defective state in which a holding force of a pencil lead displacement tube (also called a center piece) holding a pencil lead is lowered in an automatic drafting machine for drawing with a knock type pencil. The present invention relates to a core holding defect detection device for an automatic drafting machine.

[0002]

2. Description of the Related Art An automatic drafting machine called an XY plotter is one in which a drawing pencil is moved based on drawing data output from a computer to sequentially perform drawing.
This pencil is a knock type that has multiple built-in pencil leads, and one of them is used in sequence while feeding.
A pencil lead displacement tube (center piece) and a lead chuck mechanism required for this operation are provided inside.

The pencil lead displacement tube has a rubber ring at the center for holding the pencil lead therethrough, and tends to move away from the lead chuck mechanism by the elasticity of the spring. The lead chuck mechanism holds and holds the pencil lead and performs an opening operation. When the displacement tube is moved away by the elasticity of the spring at the time of opening, the pencil lead is fed out from the lead chuck mechanism by that amount. This operation is "centering". When this lead chuck mechanism is holding a pencil lead,
As described above, the pencil lead is not pulled out even if the displacement tube tries to move away due to the elasticity of the spring. On the contrary, by abutting the tip of the displacement tube against the lower knock plate described later, the pencil lead cannot be displaced even when it is brought close to the lead chuck mechanism against the elasticity of the spring. However, at this time, the tip of the pencil lead projects outward from the displacement tube by the amount of movement of the displacement tube.

[0004]

The retentive force of the rubber ring at the center of the displacement tube decreases as the above-mentioned centering operation is repeated many times. This is because the elasticity of the rubber is reduced, the inner surface of the rubber ring is worn, and the core scrap is attached. In any case, if the holding force of the displacement tube becomes weak, even if the displacement tube is pushed downward by the spring, the pencil lead cannot be pulled out, so that normal "centering" cannot be performed. This phenomenon is called "middle piece slip" or "displacement tube retention failure", and the pencil having the displacement tube in this state basically cannot be used. Nevertheless, if the pencil is used continuously, the core cutting and the core feeding operations are repeated, which may cause a reduction in the drawing efficiency.

The present invention, in an automatic drafting machine for drawing with a pencil having a pencil lead displacement tube, detects a displacement tube holding defect called "Nakamoma slip" so that the drawing efficiency is not reduced by using a defective pencil. The purpose is to do so.

[0006]

To achieve the above object, in the present invention, a knock mechanism 34 containing a plurality of pencil leads 42, and a lead chuck mechanism 36 in which a gripping and releasing action is performed by the vertical movement of the knock mechanism. And a knock-type pencil 20 having a pencil lead displacement tube 38 that moves up and down relative to the lead chuck mechanism to change the holding position of the pencil lead, and a spring 64 that pushes the displacement tube downward. In an automatic drafting machine that holds a pen holder 22 and lowers the pen holder to draw an image, and raises the pen holder to perform centering, the residual core in the displacement tube is pushed out by a new core in the core chuck mechanism. Means for performing a core movement, means for determining core breakage by the displacement tube protruding when the pencil is raised, and this core breakage is the first after the core feed operation. When produced in out is the first characterized in that it comprises a means for determining a core retention failure of the displacement tube.

According to the present invention, a knock mechanism 34 having a plurality of pencil leads 42 incorporated therein, and a lead chuck mechanism 36 for performing a gripping and releasing operation by the vertical movement of the knock mechanism are provided.
A pen holder capable of vertically moving a knock type pencil 20 having a pencil lead displacement tube 38 that moves up and down relative to the lead chuck mechanism to change a holding position of a pencil lead, and a spring 64 that pushes down the displacement tube. In an automatic drafting machine that holds the object 22 and draws the pen holder to draw an image, and raises the pen holder to perform the drawing, a means for detecting the drawing distance from the previous centering to the current centering, and A second feature is that it is provided with means for determining normal if the drawing distance is longer than a predetermined value and determining core holding failure of the displacement tube if the drawing distance is shorter than the predetermined value.

[0008]

When the holding force of the pencil lead displacement tube is reduced and the middle piece is slipping, the pencil lead does not protrude much even if the "centering" operation is performed. Therefore, even after the centering and the shift to the printing, the state becomes "out of center" before the printing is performed so much.
When the core is cut off, the operation is shifted to the core feeding operation again, and eventually the core is disconnected by the first centering from the core feeding. Therefore,
According to the first feature of the present invention, it is detected whether or not the center is cut off at the first centering after the core feeding, and when the center is cut off, it is determined that the middle piece is slipped.

In the above-described middle-piece slip, the drawing distance from the centering to the center cutting is significantly shorter than that in the normal state. Therefore, the drawing distance from the centering to the center cutting is compared with a predetermined value, and if it is a predetermined value or more, it is determined as "normal", and if it is less than or equal to it, it is determined as "middle frame slip". This is due to the second feature of the present invention. The drawing distance can be measured from the time required for the down stroke of the pencil.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, an image forming head in an automatic drafting machine will be described with reference to FIGS. In these drawings, reference numeral 2 is an image forming head of an XY plotter, which is supported so as to be movable relative to the paper 6 on the paper placing member 4 in the two XY directions. An elevating and lowering drive device 10 including a moving coil is fixed to the base 8 of the drawing head 2, an elevating and lowering body 14 is fixed to an elevating and lowering output body 12 of the drive device 10, and the elevating and lowering body 14 is a guide shaft fixed to the base 8. 1
It is supported by 6 and 18 so that it can be raised and lowered.

The lifting body 14 is provided with a pen holder 22 for detachably holding the knock type pencil 20.
The upper knock plate 26 is attached to the mounting plate 24 erected on the base 8.
Is fixed. The upper knock plate 26 is disposed above the flange 28 of the pencil 20, and is placed in the U-shaped slot 26a (see FIG. 4) of the upper knock plate 26.
A knock tube 34a of the pencil 20 is loosely fitted and arranged.

On the other hand, a lower knock plate 30 is fixedly mounted on the substrate 8, and this lower knock plate 30 also serves as a guide for the pencil lead displacement tube 38 of the pencil 20 in the previous term. The lower knock plate 30 is configured so that the tip projection 38a (see FIG. 4) of the displacement pipe 38 can be slidably fitted in the slot 31 (see FIG. 3) whose front is open. The lower horizontal surface of is configured to be locked to the step horizontal surface 30a around the slot 31 of the lower knock plate 30.

A displacement tube detection sensor 29 using a photo sensor is arranged on the substrate 8 toward the pencil 20. When the pencil 20 is moved up to a predetermined position, the sensor 29 moves the pencil core displacement tube 38 of the pencil 20 from the tip of the case 40 of the pencil 20 before the flange 28 of the knock tube 34a engages with the upper knock plate 26. It is arranged at a height position for detecting whether it is protruding or retracting inward of the case 40. Reference numeral 68 denotes a stroke-detecting photosensor fixedly mounted on the substrate 8, and by interaction with a displacement plate 70 attached to the lifting body 14, converts the lifting displacement of the lifting body 14 into an electric signal and feeds it back to the controller. It is for doing.

A stocker for holding a plurality of knock type pencils is arranged on the machine body of the XY plotter, and the mutual pencils can be automatically exchanged between the stocker and the pen holder 22 of the drawing head 2. However, illustration and description of this portion are omitted.

Next, the structure of the knock type pencil 20 is shown in FIG.
Will be described. In the figure, 34 is a knock mechanism, 36 is a lead chuck mechanism, 38 is a pencil lead displacement tube, and 40 is a case. The knock mechanism 34 has a knock tube 34 a having a core passage 44 that holds a plurality of pencil leads 42, and a knock spring 46.

The lead chuck mechanism 36 includes a chuck member 48 which is cracked in advance, a ball 50 which is attached to the chuck member 48, a chuck case 52 which is fixed to an inner case 62 via a tube body 53, and two chuck springs. It has 54 and 56. The chuck member 48 holds the inner core 42 under pressure contact by the elastic force of the chuck springs 54 and 56.

The pencil lead displacement tube 38 is provided at the tip of the pencil 20, and has a rubber ring 60 at its center for holding the pencil lead 42 with an appropriate frictional force. The pencil lead displacement tube 38 is supported slidably up and down, and is biased downward by a spring 64.

Next, the operation of the knock type pencil 20 will be described. One pencil lead 42 held in the lead passage 44 is taken into the lead passage by the funnel-shaped member 66 formed on the upper portion of the lead chuck mechanism 36. Here, the pencil lead (old lead) that is taken in first is the first pencil lead 42a, and the pencil lead (new lead) that is taken in later is the second pencil lead 42b.

By moving the knock mechanism 34 up and down once or a plurality of times to open and hold the chuck member 48 by the number of times, the first pencil lead 42a falls by its own weight and the chuck of the lead chuck mechanism 36 is chucked. It is gripped by the member 48. At this time, the tip of the first pencil lead 42a generally falls until it comes into contact with the upper end of the rubber ring 60 of the pencil lead displacement tube 38. In this state, by vertically moving the pencil lead displacement tube 38, the first pencil lead 42a is gradually fed out.

This operation will be described in more detail. The lead chuck mechanism 36 of the pencil 20 has an extremely strong holding force in the direction in which the pencil lead is taken out and in the direction in which the pencil lead is pushed back, while holding the pencil lead. Is configured. Therefore, when the pencil lead displacement tube 38 moves upward, the first pencil lead 42a is not displaced because the first pencil lead 42a is held by the chuck member 48. The position changes with respect to the first pencil lead 42a.

When the chuck member 48 is opened from this state, the pencil lead displacement tube 38 returns to its original position by the elastic force of the spring 64. At this time, the first pencil lead 42a is pulled out by the vertical stroke of the displacement tube 38 due to the frictional force of the rubber ring 60. With this, when the first pencil lead 42a comes out from the tip of the pencil 20, the drawing can be performed.

Next, the drawing operation will be described. This drawing operation involves operations such as pen down, pen up, centering, centerless detection, and core feeding. When the drawing operation is started and a drawing command is input from the host computer to the controller, the controller controls the up-and-down drive device 10 to be energized and lowers the up-and-down body 14. In this state, as shown in FIG. 4, the pencil lead displacement tube 38 is in a state of being projected the longest from the case 40 by the elastic force of the spring 64. When the elevating body 14 descends, the horizontal surface of the displacement tube 38 is locked to the lower knock plate 30, and the tip of the pencil lead 42a is attached to the case 40.
The sheet is pressed against the surface of the sheet 6 of the sheet mounting member 4 by the descending force from the (pen-down state).

When the controller moves the drawing head 2 in the XY directions relative to the paper 6 by the drawing command, the pencil lead 42a on the paper 6 along the relative movement locus of the drawing head 2 with respect to the paper 6. Is drawn by.
When the pencil lead 42a is consumed during this drawing, the case 40 is
The pen pressure on the paper 6 of the pencil lead 42a is always kept constant by being lowered by the descending force from the elevating and lowering drive device 10.

When the case 40 descends, the lower knock plate 3
The displacement pipe 38, which is locked in place by 0, gradually retracts into the case 40 against the elastic force of the spring 64. The pen-up operation during drawing is performed by slightly raising the elevation output body 12 of the elevation drive device 10. When the elevating / lowering output body 12 rises, the case 40 rises slightly from its lowered position, and in conjunction with this, the pencil lead 42a
Rises from the 6th surface of the paper.

During drawing, the pencil lead 42a is consumed and the case 40
When is lowered to a predetermined lowermost position, the signal of the lowered position is supplied to the controller by the stroke detection sensor 70. The controller determines whether or not the case 40 has descended to the lowest position, and if it determines that the case 40 has descended, it drives and controls the lifting drive device 10 to raise the case 40 to a predetermined maximum position. In the process of raising the case 40 to the maximum raised position, before the flange 28 is locked by the upper knock plate 26, the controller determines whether or not the sensor 29 is on.

In the state where the displacement pipe 38 is most retracted into the case 40 (see FIG. 2), the displacement pipe 38 is the sensor 2
Not detected by 9. That is, the sensor 29 is in the off state. In this state, the pencil lead 42a is still long enough,
It is shown that it is gripped by the lead chuck mechanism 36. That is, when the pencil lead 42a is held by the lead chuck mechanism 36, even if the displacement tube 38 is disengaged from the lower knock plate 30 due to the rise of the case 40, the displacement tube 38 is rubbed with the lead 42a to cause friction. Hold the state of being pulled in. When the controller recognizes that the displacement tube 38 is retracted, it determines that there is a core and continues drawing.

When the case 40 rises, the flange 28 engages with the upper knock plate 26, and when it is pushed down by this, the lead chuck mechanism 36 is opened, and the spring 64.
Due to the elastic force of, the displacement tube 38 is displaced in the direction in which it projects from the case 40 by the maximum amount. At this time, the pencil lead 42 a is extended from the lead chuck mechanism 36 by the displacement stroke of the displacement tube 38 due to the frictional force of the rubber ring 60. This is the "centering" operation.

Next, description will be made on the case where the pencil lead 42a is worn and shortened and is disengaged from the lead chuck mechanism 36 (without lead). When the case 40 rises in a state where the pencil lead 42a is shortened and disengaged from the lead chuck mechanism 36, the displacement tube 38 is moved by the elastic force of the spring 64 with respect to the case 40, as shown in FIG. Stick out. The controller determines whether or not the sensor 29 is on before the flange 28 is locked to the upper knock plate 26. In this case, since the displacement pipe 38 is located on the detection axis of the sensor 29 as shown in FIG. 5, the sensor 29 detects the displacement pipe 38 and turns on. Therefore, the controller determines "no core" by turning on the sensor 29.

Next, the "leading" operation and the "leading completion recognition" operation after detection of no lead will be described with reference to FIGS. When the old lead 42a held by the rubber ring 60 of the pencil lead displacement tube 38 is shortened as shown in FIG. 5, the lead feeding operation is started, and the raising and lowering operation of the case 40 is repeated. First, as shown in FIG. 6, when the case 40 is lifted and the knock pipe 34a is pushed down relative to the case 40 by the upper knock plate 26, the new core 42 held by the core chuck mechanism 36 is moved.
b is released and falls by its own weight, and its lower end abuts the upper end of the old core 42a. When there is no old lead, the pencil lead displacement tube 38 is brought into contact with the upper end of the rubber ring 60.

Next, the case 40 is lowered as shown in FIG. 7, and the pencil lead displacement tube 38 is moved to the case 4 by the lower knock plate 30.
When pushed up relative to 0, the old lead 42a locked by the new lead 42b held by the lead chuck mechanism 36 moves within the pencil lead displacement tube 38 by the amount of the rising stroke of the pencil lead displacement tube 38. Is only paid out downward.

When the case 40 is raised again as shown in FIG. 6, the pressure from the lower knock plate 30 is released from the pencil lead displacement tube 38, and the elastic force of the spring 64 causes the old lead 42 to move.
While holding a, it moves in the projecting direction with respect to the case 40, and due to this movement, an interval having the same length as the projecting stroke of the pencil lead displacement tube 38 is generated between the old lead 42a and the new lead 42b. The case 40 further rises and the knock pipe 34
When a is engaged with the upper knock plate 26 and the lead chuck mechanism 36 is opened, the new lead 42b is downwardly extended to a position where it collides with the old lead 42a due to its own weight.

By repeating the above operation, the new core 42b is press-fitted into the rubber ring 60 of the pencil core displacement tube 38, and the old core 42a pushed out by this new core 42b is pushed into the pencil core displacement tube 38 as shown in FIG. And fall downward. When the new core 42b is press-fitted into the rubber ring 60 of the pencil lead displacement tube 38, the case 40 of the pencil lead displacement tube 38 rises as shown in FIG. 9, and the pushing force from the lower knock plate 30 to the pencil lead displacement tube 38 is increased. Even if the case 40 is released, the case 40 is kept retracted in the depth direction. In this retracted state, the knock pipe 34
a is engaged with the upper knock plate 26, and the lead chuck mechanism 36
Is held until is released. This is the core feeding operation.

The controller recognizes from the output of the sensor 29 whether or not the pencil lead displacement tube 38 protrudes from the tip of the case 40 by a predetermined amount before the knock tube 34a is engaged with the upper knock plate 26. Pencil lead displacement tube 3 as in 9
When the reference numeral 8 does not protrude from the case 40 by a predetermined amount, that is, when the reference numeral 8 is retracted, the "feeding is completed" is recognized.

Next, the operation of the entire centering control device of the present invention will be described with reference to the flow charts of FIGS. This control device is configured by software in a part of the controller described above.

When the centering control routine of FIG. 10 is entered,
First, in step S1, it is determined whether the down position is centerless. Here, the down position is a descending position where the pencil can be drawn. If it is determined in step S1 that there is a center, centering is not necessary, so this centerless determination process is repeated. Eventually, if it is determined in step S1 that there is no core, the displacement pipe (also referred to as a middle piece) 38 is moved to the displacement pipe detection sensor 29 position in the next step S2.
In the subsequent step S3, the output of the sensor 29 is read and stored in the memory. Further, in step S4, in order to accurately perform centering determination and the like from the read sensor output, the offset value and gain necessary to remove the influence of ambient light and the threshold required in the second sensor read (step S10) Determine the level.

In step S5, the pencil 20 in use is in use.
Determine the core diameter of. Here, it is determined whether the pencil has a built-in 0.2 mm core that is low in strength and easily breaks, or a pencil that has a thicker core and is hard to break. If it is determined in step S5 that the pencil is not 0.2 mm, the knock stroke is set to the normal 2.0 mm in step S6. However, if it is determined that the pencil is 0.2 mm, the knock stroke is shorter than normal in step S7. Set to 1.5 mm.

In step S8, centering knock is performed by the knock stroke set in step S6 or step S7. Since this centering is performed at the position where the pencil is raised, the pencil is moved down to the sensor position in order to confirm the completion of the centering at the next step S9, and the output of the sensor 29 is read at the next step S10. This sensor reading is the second time, and it becomes possible to perform a process in which the correction for the disturbance light or the like which was insufficient at the time of the first sensor reading (step S3) is added.

Based on this second sensor output, the presence or absence of a lead is determined in step S11. If it is determined that there is no center, it is determined in step S12 whether centering has occurred in the first centering after feeding. "Center-cutting" is a state in which "centering" is not possible even if the centering operation is performed, that is, a state where the old core is disengaged from the chuck and core feeding is required. If Y (yes) is determined in step S12, middle frame slip error processing is performed in step S13. On the other hand, if N (No) is determined in step S12, normal core feeding processing is performed in step S14.

The processing of steps S12 and S13 is firstly performed because the middle piece projects even though there is a core when the rubber ring 60 of the middle piece 38 reduces the frictional force and "slips the middle piece". The line segment that can be drawn by one time centering becomes short, and secondly, there is a possibility that it will be erroneously detected by the presence / absence detection of the core (there will be erroneously detected that there is a core). To do. That is, in the case where the centering is broken at the first centering after the core feeding, such a thing cannot occur if the rubber ring 60 has a normal frictional force, so the middle piece slip error processing is performed. Make the pencil unusable.

If it is determined in step S11 that there is a core,
In step S15, the pencil is moved down to the drawing position and a predetermined writing pressure is applied. Here, first, in step S16, a writing pressure (for example, 50 g) lower than that during normal drawing is applied for a certain period of time. Next, in step S17, it is determined again whether or not the pencil is a 0.2 mm pencil, and when Y, it is determined in step S18 whether or not the lead chuck is off (center cut). The core detached from the chuck is held only by the rubber ring, and there is a gap between the core and the subsequent new core. Therefore, when writing pressure is applied to the pencil, the middle piece holding the chuck-off core retreats to the inside by the gap. Therefore, this is detected by a sensor to determine whether or not the lead chuck is disengaged.

If it is determined as Y (core-cut) in step S18, normal core-feeding processing is performed in step S19.
If it is determined to be N, a process of applying a high writing pressure (for example, 200 g) necessary for normal drawing is performed in step S20. When it is determined as N in step S17, the process of step S20 is performed without passing through step S18. this is,
This is because it is not necessary to perform such a treatment on the core of 0.3 mm or more.

The processes of steps S18 and S19 improve the following points. In other words, even if the lead comes off from the chuck, the drawing is continued unless the lead-free position is reached, so that the rear end of the old lead is hit with the tip of the new lead, which causes jamming. Normally, after centering, the center piece 38 is sufficiently projected, so the down position of the center piece detected by the sensor 29 is high, but when the core is removed from the chuck, a gap is created between the core and the chuck. , The down position is slightly lower (higher than the centerless position). Therefore, this height is read to detect a core break.

When a low writing pressure is applied in step S16 and a high writing pressure is applied in step S20, both hold the same height as long as the chuck has a normal gripping force. However, if the holding power of the chuck decreases as the usage time of the chuck increases, the pencil lead slips into the chuck when the writing pressure is high, even if the writing pressure is low. Here, this chuck holding failure is called "core slip",
It is distinguished from the above-mentioned "middle piece slip (poor core retention)" caused by the rubber ring failure.

Since it takes time to detect the center slip by switching the writing pressure, if this is performed for each centering, the drawing efficiency decreases. Therefore, since the distance that can be drawn by one-time centering is generally known, the center slip detection is performed only when the distance drawn from the previous centering to the current centering is short.

Specifically, the value of the core slip flag is determined in step S21. This flag is set to "0" when the distance from the centering to the centering is long, set to "1" when the distance is short, and cleared to "0" when the pencil is replaced. If it is determined in step S21 that the flag = 1 (short), core slip detection is performed in step S22.
This core slip detection is a writing pressure switching method that uses low writing pressure and high writing pressure. Based on the result of this core slip detection processing, it is determined in the next step S23 whether or not there is core slip. here,
When it is determined that the slippage occurs, the slippage error process is performed in step S24, and when it is determined that the slippage is not performed, the normal drawing process is performed in step S25. Step S2
The lead slip error processing of No. 4 includes a pencil replacement operation or a display for prompting the operation.

On the other hand, flag = 0 in step S21.
When it is determined to be (long), it is determined in step S26 whether the down position is centerless. This determination is step S
Since it is the same as 1 and all are normal when judged as N here, normal drawing processing is performed in step S25,
When it is determined to be Y, core feeding processing is performed in step S27.

In the core feeding process of steps S14, S19 and S27, vibration is applied to surely discharge the residual core. This vibration is effective when the screen is not horizontal and the pencil is tilted at 45 °, for example. Specifically, when the core feeding operation is completed, the pencil 20 is lowered to the down position,
The tip of the displacement pipe 38 is brought into contact with the lower knock plate 30. When the pencil is slightly vibrated at a high speed in this state, the displacement tube enters the pencil each time the vibration occurs, and the tip of the new core 42b further enters the displacement tube after the completion of the normal core feeding operation.
Therefore, although the remnant core 42a is almost pushed out by the first vibration, the remnant core adhering to the displacement pipe can be surely dropped by vibrating a plurality of times just in case.

In the normal drawing process of step S25, the current of the moving coil 10 is corrected, and control is performed so that the specified writing pressure is always obtained irrespective of the descending height of the pencil. this is.
This is because the torque generated by the moving coil 10 has a characteristic that it changes according to the stroke of the pencil. Therefore, in this writing pressure correction, the stroke length-thrust force characteristic of the moving coil is grasped in advance, and a writing pressure is kept constant by applying a current having the opposite characteristic.

One of the lead holding defect detecting devices of the present invention is one of steps S11, S12 and S1 of the above-mentioned flowchart.
It consists of 3 parts. Here, the center frame slip error processing is carried out when the center is out of alignment at the first centering after feeding (steps S12 and S13). You may detect.
In the middle piece slip error processing in step S13, the pencil is replaced and an error is displayed.

[0050]

As described above, according to the present invention, a defective pencil is used in an automatic drafting machine for drawing with a pencil having a pencil lead displacement tube, by detecting a displacement tube holding defect called a middle piece slip. It is possible to prevent the drawing efficiency from being lowered.

[Brief description of drawings]

FIG. 1 is a side view of an imaging head.

FIG. 2 is a side view of the drawing head in different states.

FIG. 3 is an external view of a lower knock plate.

FIG. 4 is a cross-sectional view of a knock type pencil.

FIG. 5 is a partial cross-sectional view of a pencil without a core.

FIG. 6 is a partial cross-sectional view of the pencil at the start of core feeding.

FIG. 7 is a partial cross-sectional view of the pencil during the core feeding operation.

FIG. 8 is a partial cross-sectional view of the pencil at the completion of core feeding.

FIG. 9 is a partial cross-sectional view of the pencil when the completion of core feeding is recognized.

FIG. 10 is a flowchart of centering control of the present invention.

11 is a continuation flowchart of FIG.

FIG. 12 is a continuation flowchart of FIG. 11.

[Explanation of symbols]

2 ... Drawing head, 6 ... Screen, 20 ... Pencil, 22 ...
Pencil holder, 26 ... Upper knock plate, 28 ... Flange, 29 ... Displacement pipe detection sensor, 30 ... Lower knock plate,
34 ... Knock mechanism, 36 ... Lead chuck mechanism, 38 ... Pencil lead displacement tube, 42 ... Pencil lead, 64 ... Spring, 68 ... Stroke detection sensor.

Claims (2)

[Claims] 1. A knock mechanism 34 having a plurality of pencil leads 42 incorporated therein, a lead chuck mechanism 36 which is gripped and released by a vertical movement of the knock mechanism, and a knock mechanism 34 which moves up and down relative to the lead chuck mechanism. A knock type pencil 20 having a pencil lead displacement tube 38 that changes the holding position of the pencil lead and a spring 64 that pushes the displacement tube downward is held by a vertically movable pen holder 22, and the pen holder is lowered to draw an image. In the automatic drafting machine that raises the pen holder to perform centering, a means for performing a core feeding operation of pushing out the residual core in the displacement tube with a new core in the core chuck mechanism, and when the pencil is raised. And a means for determining core misalignment due to the displacement tube protruding, and when this core misalignment occurs during the first centering after the core feeding operation, it is determined that the displacement tube has a core misalignment. A device for detecting defective core holding of an automatic drafting machine, comprising: 2. A knock mechanism 34 having a plurality of pencil leads 42 incorporated therein, a lead chuck mechanism 36 which is gripped and released by a vertical movement of the knock mechanism, and a lead chuck mechanism 36 which moves up and down relative to the lead chuck mechanism. A knock type pencil 20 having a pencil lead displacement tube 38 that changes the holding position of the pencil lead and a spring 64 that pushes the displacement tube downward is held by a vertically movable pen holder 22, and the pen holder is lowered to draw an image. Also, in an automatic drafting machine that raises this pen holder to perform centering, a means for detecting the drawing distance from the previous centering to the current centering, and normal if this drawing distance is longer than a specified value, and short A core holding failure detection device for an automatic drafting machine, comprising: means for determining that the displacement tube has a core holding failure.