FR2613500A1 - APPARATUSES FOR READING AND FORMING IMAGE WITH MOTOR STEP BY STEP - Google Patents

Abstract

THE INVENTION RELATES TO AN IMAGE FORMING APPARATUS. IT RELATES TO A DEVICE IN WHICH AN ORIGINAL PLACED ON A TABLE 12 IS READ BY A MOBILE OPTICAL SYSTEM INCLUDING MIRRORS 22, 24, 34, 36, 38 ARRANGED IN TWO GROUPS OF WHICH ONE HAS DOUBLE THE SPEED OF THAT OF L 'OTHER. ACCORDING TO THE INVENTION, THE MOVEMENT OF THE TWO GROUPS OF MIRRORS OF THE OPTICAL SYSTEM IS PROVIDED BY A STEP-BY-STEP MOTOR OF THE PERMANENT MAGNET TYPE. THIS TYPE OF MOTOR ALLOWS SIMPLIFICATION OF THE CONTROL. APPLICATION TO ELECTRONIC COPYERS.

Description

The present invention relates to a training apparatus

  image and an image reading device,

  type having a permanent magnet stepping motor.

  It is known that in the training apparatus of ima-

  Currently available, e.g. electronic copiers, an optical reading device for exposing and reading an original is driven by a composite type stepper motor. This composite type engine can be constituted as follows. The rotor of the stepper motor is constituted by a permanent magnet which is magnetized in the axial direction of its shaft, and two iron cores having teeth which are mounted at the outer periphery of the magnet. These nuclei are

  magnetized respectively so that they possess

  N and S rites, and the teeth of a first core have a misalignment of half a step compared to those of the other core. Stators each having several coils are arranged around the rotor. Each stator

  has a predetermined number of teeth formed at its

  internal and external (eg 48 internal and 50 external). As can be appreciated from the foregoing, the composite type stepper motor has a complex structure and is therefore expensive. This naturally increases the cost of the electronic copier

having such a stepmaker.

  In addition, the composite type stepper motor

  has an angle of rotation (step angle) of 1.8 per pulse

  if we. Provided that the displacement of the motor for a step is 0.125 mm, the number of pulses transmitted to the stepping motor is 1328 at the time of reading

  of an original and 2500 at the time of the return of the

  tif optical reading to the rest position. When

  the displacement in steps is 0.1 mm, the number of

  is 1252.3 in the first mode and 2340 in the last mode. Thus, a control circuit of the stepper motor must command the latter with a pulsed signal

  of high frequency, so that it must have a

complexity.

  The invention relates to an image forming apparatus which can be manufactured with a low cost and

  which has a simplified motor drive system.

  More specifically, the invention relates to a reading apparatus which comprises a device for supporting a document, a reading device of the document, intended to read image data of the document and arranged so that it can move by report to document

  which is carried by the support device, and a device

  device intended to move the reading device by

  document, this traveling device com-

  a stepping motor of the permanent magnet type.

  The invention also relates to a training apparatus

  image which comprises a device for supporting a document

  a reading device of the document so that it reads image data from the document and arranged so that it is movable relative to the document carried by the support device, a device for forming an image according to the data read by the device

  reading device, and a device for moving the

  movement of the document, this

  displacement system comprising a stepper motor

permanent type.

  Other features and advantages of the

  will be better understood when reading the description of

  following description of embodiments, made with reference to the accompanying drawings in which:

  Figure 1 is an external perspective of a co-

  electronic device which is an example of a

  image imation according to the invention; Figure 2 is a schematic sectional side elevation of the apparatus of Figure 1; Fig. 3 is a plan view of a control panel;

  FIG. 4 is a schematic sectional view of

  side effect of a training device of an optical system; Figs. 5A and 5B show the structure of the permanent magnet stepper motor, the first being a side elevational section passing through the motor axis and the second being a front elevation of a stepper motor rotor; Figures 6A and 6B are an exploded perspective

  and a partial plan view showing the relationship

  the windings and teeth of a stepping motor of the permanent magnet type;

  FIGS. 7A, 7B, 7C and 7D are representative views.

  sensing the relation between the polarities and the rotor, during the excitation of the individual phases A, B, A and B;

  FIG. 8 is a block diagram showing

  schematically a set of command; Fig. 9 is a diagram of a motor driving circuit;

  FIGS. 10A, 10B, 10C and 10D are diagrams

  mes de temps representing signals transmitted to the bases of transistors QA, QB, QA and QB respectively; and FIG. 11 is a timing diagram for explaining the control of a stepper motor

permanent magnet.

  Figures 1 and 2 show schematically an image forming apparatus according to the invention, for

  example an electronic copier. On a body 10 of co-

  an original support table (transparent glass)

  rent) 12 is fixed, an original being intended to be placed on it. A fixed ladder 14 is placed on the table 12 so that it allows a proper adjustment of the original. A lid 16 which can be opened and intended to cover an original, is placed close to the table 12. An optical system comprising an exposure lamp 18 and mirrors 20, 22 and 24 is arranged

  under the table so that he can move in trans-

  along the bottom of Table 12,

  in the direction of arrow a in FIG.

  ginal is exposed and read when the optical system moves in translation in the direction a. The lamp

  18 exposure and the mirror 20 are placed on a

  first carriage 26 while the mirrors 22 and 24 are placed on a second carriage 28. Thus, the exposure-reading operation is performed by moving the two carriages 26 and 28 in the direction of the arrow a of Figure 2. The second carriage 28 is driven at a speed equal to half that of the first carriage

  24 so that the length of the light path remains

  aunt. The first carriage 26 is integral with a point light source 30 (hereinafter described) which is movable in a direction perpendicular to the direction of travel.

moving the first carriage 26.

  The light reflected by the original, when read by the optical system, that is to say the light

  reflected by the original from the light of irrational

  diation of the exposure lamp 18, passes through an enlargement lens block 30, after reflection by the mirrors 20, 22 and 24, and reaches a photoconductive drum 40 after having been reflected by

  mirrors 34, 36 and 38. As a result, an image of the original

  ginal is formed on the surface of the photoconductive drum 40. The drum 40, which can rotate in the direction of

  the arrow b, has its surface which is first electrically charged

  tress by a main charging member 42, and then undergoes the formation of a latent electrostatic image, on its surface, by exposure according to a slit by the image of the original, at the level of a set Ph

  exposure. The latent electrostatic image is

  greening agent applied by a first set 44 or a second set 46 of development, so that a

  visible image is formed. The first and second ensen-

  44 and 46 respectively contain

  red and black coloring agents, for example

  pie, and they are selectively trained at will.

  These sets 44 and 46 of development are mounted

  Removable way on the body or frame 10 of the copier.

  The color of the turning agents contained in the

  44 and 46 are adjusted by the state of connection of a plurality of pins of a connector (not shown) disposed on the body 10 of the copier, and is displayed on a control panel 100 which

  is described in detail later.

  Leaves, constituting media on

  the images are reported, are transmitted one from an upper cassette 481 or a lower cassette 482 sheet feed, a roll 501 or 502 in advance and a pair of rollers 521 or 522, in function of a selection. The sheet is guided by a sheet guide path 541 or 542 to two positioning rollers 56 which then guide

  the sheet to a set of image report. Cases-

  481 and 482 sheets are mounted so

  removable on the lower right side of the body 10 of the

  and can be selected by Panel 100

  control. The dimensions of the cassettes or the dimensions

  In the cassettes 481 and 482, the sheets are detected by size detection switches 581 and 582, respectively. Each of the 581 switches

  and 582 of size or format detection has several

  microswitches that are triggered by the intro-

  duction of cassettes of different sizes. A guide

  manual 483 feeding is placed at the top

  of the cassette 481. The sheet introduced manually

  This guide 483 is guided towards the pair of rou-

  521 by the feed roll 503 and then advance in the same manner as a sheet from

cassette 481.

  The sheet sent to the transfer set comes

  intimately in contact with the surface of the photo drum

  40 at a location where a transfer charge member 60 is disposed, so that an image

  turning agent is transferred to a photoconven-

  driver 40 by the carry-over member 60. The sheet

  the image on which the image has been reported is separated

  trostatically of the photoconductive drum 40 by a separating charge member 62 and is conveyed by a conveyor belt 64 to a fixing roller 60 incorporated in a fixing assembly 66 placed

  at the outer end of the conveyor belt 64.

  The image of turning agent carried on the sheet is fixed, as it passes along the roller 60, and the sheet is then discharged by a pair of output rollers 70 on a receiving tray 72 placed outside

of the body 10 of the apparatus.

  Moreover, the turning agents remaining on the surface of the photoconductive drum 40, after transfer of the image of the turning agent, are removed by a cleaning blade 76, in a cleaning member 74. After removal of the residual turning agents, the photoconductive drum 40 undergoes a remaining image erase operation performed by a discharge lamp 78

and returns to its original state.

  An erase arrangement 80 having a plurality of

  photoemissive elements arranged in the longitudinal direction

  tudinal of the photoconductive drum 40 is placed between

  the main load member 42, placed above the drum

  40, and the Ph exposure section.

  partially cementing the image of the original, the light emitting elements constituting the erasing arrangement 80

  are excited about a specified area of erase-

  for example by the point light source 30

  so that the photoconductive drum 40 is discharged.

  Even when the unloaded portion of the drum 40 is exposed

  then exposed to light by the exposure section Ph, no latent electrostatic image is formed therein

  meaning that the image of the original has been erased.

  A cooling fan 82 is arranged to prevent an increase in temperature which can be caused by the assembly 66 in

the body 10 of the apparatus.

  Figure 3 shows a control panel 100 placed at the top of the body 10 of the copier. In the figure, the reference 102 designates a copy key intended to indicate a beginning of copying, the reference 104 designates ten keys intended to adjust the number of copies to be made, etc., the reference 106 designates a section for adjusting the density of the copy, the reference 108 designates a display section of the operating state of each set, the jamming of the

  paper, etc., reference 110 designates a key of

  truction counting to cause the display section 108 to display the total number of copies

  number of copies for each color, and the reference

  reference 112 designates an interrupt key which is

  prompted by an operator during a copy operation

  to perform another copy operation.

  114 denotes a magnification key one for adjusting the magnification to the value one

  (100%), the reference 116 designates a touch of

  intended to be ordered so that the growth

  When the upper cassette or the lower cassette 481 or 482 is to be selected, the reference numeral 118 denotes a cassette selection key that is controlled.

  color change intended to be operated during

  that a copy of a different color must be formed, and reference 122 designates a mode memory key. When an editing key 128 (described below) is commanded and when an erase zone

  of the original is specified by the light source

  For example, the mode memory key 122 is commanded so that it retains data relating to the specified erasure area in a memory (not shown) or reads data stored in memory.

  advance. Reference 124 denotes a touch of information

  tions to be ordered when the information associated with each mode is to be entered; for example, when this key 124 is controlled at the time of paper jamming, the paper jam removal information is displayed on a display device 130 (hereinafter described). The reference 126

  designates a function check key which, when

  that it is ordered, causes the display, by the

  positive 130, of the function set. Reference 128 designates an edit key to be controlled to execute a partial erase function

  erasing part of the image of the original

  ginal, and then performs its copy function, its func-

  multicopy, its copy function on both

faces, or the like.

  The display device 130 which includes a liquid crystal dot matrix panel, for example, indicates the setting states of the copying apparatus as characters. When the various aforementioned keys 110, 112, 114, 116, 118 and 120 are controlled, the display device 130 has the characters associated with each key operation. By

  For example, when a paper jam occurs

  In a copy operation, the display device 130

  display indicates where the jamming took place and how to remove the jamming of the paper, using characters and symbolic drawings. Keys of

  132, 134, 136, 138, 140, 142, 144, 146,

  the individual functions displayed on the device 130 are arranged on both sides of the

display device 130.

  The reference numeral 148 is a key to

  Position marking for indicating the coordinates given by the source 130 of point light. The

  coordinates are determined by a 150 touch of

  which specifically moves the light source 30. More precisely, the movement key 150 can be inclined at the four corners as indicated by the arrows 150a, 150b, 150c and 150d, and when the movement key 150 is controlled, on the desired arrow part, the source 30 is moved in the indicated direction

by the arrow.

  FIG. 4 represents the control circuit of the

  optical system which is an essential part of

  vention. The first and the second carriage 26 and 28 can

  to be controlled by a stepping motor 84 with a magnet

  manent whose kinetic energy is transferred to a pulley 92 by a decelerating member consisting of a pulley 86, a belt 88 and a pulley 90. A wire 94 to which are fixed the first carriage 26

  and the second carriage 28 is placed on the pulley 92.

  if, when a copy operation begins, the engine

  step by step 84 is trained so that the first and the se-

  The carriage 26 and 28 move to the left in the figure under the control of the pulleys 86, 90 and 92, the belt 88 and the wire 94. At this time, as previously described, the second carriage 28 moves at a speed equal to the half of that of the first trolley

  26 so that the light path keeps its length.

  Figures 5A and 5B show the structure of a permanent magnet stepper motor 84. This stepper motor 84 comprises a rotor 842 carrying a plurality of permanent magnets placed around a shaft 840 as shown, and a stator 846 placed around the rotor 842.

  is surrounded by a winding 844. The rotor 842 is con-

  it is located by 24 permanent magnets magnetized so that the adjacent magnets have different polarities as shown in Figure 5B, and the pitch angle (pulse rotation angle) is in this case equal to 7.5. The permanent magnet stepper motor 84 may have another pitch angle, for example 12 or 18,

  this means that the stepper motor has a solid rotor

  standing with 12 or 10 permanent magnets, magnetized as previously indicated. (These two types are

not represented).

  As shown in FIG. 6A, the winding 844 comprises windings 844a for the phases A and A and windings 844b on the phases B and B. These windings 844b

  844a and 844b are formed around the cores respec-

  850a, 852a, 850b, 852b having 48 teeth 846a, 848a, 846b and 848b respectively. As shown in Fig. 6B, the teeth 846a, 848a, 846b and 848b deviate from each other by the respective pitch angle. Thus, the teeth 846a and 848a deviate from each other by 15, as do the teeth 846b and 848b, and the teeth 846a and 848a (on the winding side 844a) deviate from the teeth 846b and 848b (from the winding 844b) of an angle

equal to 7.5.

  FIGS. 7A to 7D represent the states

  In this case, the rotor 842 tends to be stable in the positions shown in Figs. 7A-7D. Consequently, the switching of the excited phase according to the phase A-phase B-phase phase-B sequence makes it possible to rotate the rotor 842 by the pitch angle of 7.5 in the direction of clockwise, following the sequence represents in FIGS. 7A - 7B

- 7C - 7D.

  Figure 8 represents the essential part of

  the control assembly of the apparatus according to the invention.

  A main processor 200 controls the overall operation of the copier. The main processor 200 is coupled to said control panel 100 and has a sensor 202

  switch, comprising various switches and

  such as switches 581 and 582 for detecting

  cassette format, so that it can detect

  the signals from the sensor 202, etc. and can

  order the necessary order. The main processor 200 is also connected to a developer sleeve (not shown), to a control electromagnet 204

2613 5 0 0

  of the cleaning blade 76, to a lamp regulator 206 for adjusting the excitation of the main charging member 42, the charge charging member 60, the discharge lamp 78 and the lamp 18 exposure, and a fixture control member 208 for controlling the assembly 66, and controls these different assemblies. The main processor 200 is further connected to a motor drive member 212 which controls a photoconductor drum drive motor 40 and a motor drive circuit 214 for controlling the drive of the stepper motor. permanent magnet, etc. The motor control circuit 212 can be realized as shown in FIG. 9. A transistor QA whose emitter is grounded (NPN type) has its collector coupled to a power supply (24 V DC) of voltage Vc via a winding LA for the phase A. A diode DA is mounted between the two ends of the winding LA, its anode being coupled to the side of the transistor QA and its cathode being coupled to the supply side Vc. A transistor QA and a winding LA, for phase A, are coupled analogously in parallel with transistor QA and winding LA. In this case, a diode DA, of polarity shown, is coupled to both ends of the winding LA. Similarly, a circuit of a transistor QB, a coil LB of phase B and a diode DB, and a circuit of a transistor QB, a coil LB for phase B and a diode DB are mounted between the two ends of a supply Vc as shown in FIG.

  transistors QA, QB, QA and QB have their bases which receive

  wind signals as shown in Figures 10A

at 10D.

  First, when transistors QA and QB conduct

  sent, a current is transmitted by the power supply Vc to

  phases A and B of the stepper motor. When the transis-

  tor QA is set to the non-conductive state and the transistor QA is turned on, the current flowing in phase A flows in the diode DA. Consequently,

  this current is reduced with a predetermined time constant

  completed which depends on the inductance and resistance of the coil. Furthermore, the conductive state of the transistor QA causes the flow of a current to the phase A through the transistor QA. When the transistor QB is set to the non-conductive state, the

  transistor QB is immediately turned on.

  As a result, the current flowing in phase B flows in the diode DB and is reduced, and a current

  flows to phase B through the trans-

tor QB.

  The rotor 842 of the stepper motor 84 rotates as shown in FIGS. 7A to 7B, by repetition of

aforementioned operations.

  In the foregoing structure, the permanent magnet stepper motor 84 during a copy operation is driven by the driver circuit 214 in the manner

next.

  As shown in Figure 11, it is assumed that

  t !, t2, t3, t4, t5 and t6 represent the acceleration time

  ration to the SC exposure-reading period of the

  ginal, the deceleration time from this period SC, the hold time to zero, the acceleration time to the RE return period, the deceleration time after the RE return period, and the decay time. waiting after the return. It is also assumed that each of these times t1 to t6 is equal to 50 ms, and that the deceleration ratio of the deceleration assembly constituted by the pulleys 86 and 90 and the belt 94 is equal to 1 / 2.0, and that the displacement per step is 0,208 mm. When the copy machine is set to make 18 A4 copies per minute in

  the previous conditions, the number of trans pulses

  permanent magnet stepper motor 84 is 480 during the exposure-reading and

726 during the return time RE.

  When the number of pulses transmitted to the stepper motor 84 is set to 500 under the above conditions, the number of pulses during the RE return period is 648. Since the step displacement is 0.219 mm and the deceleration ratio is equal to 1 / 1.9, the other conditions being the same,

  if the number of pulses during the exposure period SC

  reading is equal to 462, the number of pulses is

  equal to 664 during the RE return period.

  In this embodiment, as described above,

  Finally, as the permanent magnet stepper motor has an increased pitch angle per pulse compared to the conventional composite type stepper motor, the number

  necessary control pulses can be reduced.

  It is therefore possible to simplify the structure of the

  baked pulse oscillation for transmitting the control pulses of the stepper motor. In addition, since the stepper motor control operation, which must be executed by the main motor, becomes simpler, the main processor load can be

  reduced accordingly. This allows the main processor

  pal to ensure a more elaborate control of the panel of

  control, switch sensor, or the like.

  As the permanent magnet stepper motor has

  a simple structure and is inexpensive, the cost of manufacturing

  cation of the image forming apparatus can itself

to be reduced.

  According to the invention, the use of a motor

  step of the permanent magnet type as a training set

  of the optical system makes it possible to reduce the manufacturing cost of the image forming apparatus and

  the simplification of the structure of the control circuit.

  Of course, various modifications can be made by those skilled in the art to the devices that come

  to be described solely as non-limita-

  without departing from the scope of the invention.

Claims (2)

  1. Reading apparatus, comprising a device (12) for supporting a document, a device (18-38)   arranged so that it is mobile in relation to the   carried by the support device and for reading the document to read image data of the document, and a device (84-94) for moving the reading device relative to the document, the moving device comprising a stepping motor (84), characterized in that the stepping motor   (84) is of the permanent magnet type.   An image forming apparatus, comprising a document support device (12), a device (18-38) arranged movably with respect to the document supported by the support device and adapted for read the document so that it reads image data from the document, a device intended to form a   image according to the image data read by the   reading system, and a device (84-94) for   move the reading device in relation to the   the displacement device comprising a stepping motor, characterized in that the stepping motor   (84) is of the permanent magnet type.