Abstract:
A heat roller control apparatus having a heat roller for hot melt coating a thin film on a member, a heater for heating the heat roller, temperature detecting member for detecting the surface temperature of the heat roller, temperature control member for controlling the heater according to a temperature detecting signal obtained from the temperature detecting means, and temperature judging member for producing a temperature judging signal for judging the state of the surface temperature of the heat roller according to the temperature detecting signal. The temperature judging member calculates a variation of the surface temperature of the heat roller from the temperature detecting signal every predetermined time and judging the stability of the hot melt coating by the variation of the surface temperature of the heat roller when the temperature detecting signal reaches into a predetermined temperature range.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a heat roller control apparatus, and more particularly relates to a control apparatus for a heat roller for use in a laminator or the like.  
           [0003]    2. Description of the Prior Art  
           [0004]    [0004]FIG. 3 shows a conventional heat roller control apparatus. In FIG. 3, a reference numeral  1  denotes a heat roller,  1 A denotes a member, such as a PVC card to be laminated with a thin film  1 B, such as a PET film,  8   a  and  8   b  denote transfer rollers for transferring the member  1 A and the thin film  1 B,  2   a  denotes an actuator, such as a motor for rotating the heat roller  1 ,  2   b  denotes an actuator, such as a motor for rotating the transfer roller  8   b ,  3   a  and  3   b  denote driving circuits for driving the actuators  2   a  and  2   b , respectively,  4  denotes a heater for heating the heat roller  1 ,  5  denotes a temperature detecting element, such as a thermistor for detecting a surface temperature of the heat roller  1 ,  6  denotes a temperature control circuit for controlling the excitation of the heater  4 ,  9  denotes a temperature judging circuit formed of a microprocessor, for example, for judging whether the surface temperature of the heat roller  1  is stable in a predetermined range lower than a first reference signal c 1  indicating the upper limit value, but higher than a second reference signal c 2  indicating the lower limit value,  10  denotes a temperature state indicator for indicating whether the surface temperature of the heat roller  1  is stable in the predetermined range, and  7   a  and  7   b  denote detecting elements, such as photosensors for detecting the presence of the member  1 A, respectively.  
           [0005]    [0005]FIG. 4 shows a diagram for explaining the surface temperature of the heat roller  1 .  
           [0006]    In FIG. 4, a reference symbol (a) denotes the first reference signal c 1  indicating the upper limit value of the predetermined range, (b) denotes the second reference signal c 2  indicating the lower limit value of the predetermined range, (c) denotes a temperature signal a outputted from the temperature sensing element  5 , and (d) denotes a temperature judging signal e outputted from the temperature judging circuit  9 . The temperature judging circuit  9  judges whether the temperature signal a outputted from the temperature detecting element  5  is in the predetermined range and maintained continuously for a predetermined setting period of time t 1 . Further, the temperature judging circuit  9  outputs the temperature judging signal e of low level “L” in case that the temperature signal a outputted from the temperature detecting element  5  is out of the predetermined range, or that the temperature signal a is in the predetermined range, but is not maintained continuously for the predetermined setting period of time t 1 . The temperature judging circuit  9  outputs the temperature judging signal e of high level “H” in case that the temperature signal a is in the predetermined range and maintained continuously for the predetermined setting period of time t 1 .  
           [0007]    The actuator  2   b  is driven by the driving circuit  3   b  when the detecting element  7   a  detects the presence of the member  1 A and the driving circuit  3   b  receives a first detecting signal b 1  outputted from the detecting element  7   a . The actuator  2   b  is not driven by the driving circuit  3   b  when the temperature judging signal e is low level “L”. The adhesive strength of the member  1 A becomes small or the member  1 A is deformed if the hot melt coating is carried out in the state that the surface temperature of the heat roller  1  is out of the predetermined range. The member  1 A and the thin film  1 B are transferred to the heat roller  1  by the rotation of the transfer roller  8   b  when the level of the temperature judging signal e is “H” and the actuator  2   b  is driven. The heat roller  1  is rotated when the actuator  2   a  is driven by the driving circuit  3   a  irrespective of the state of the temperature judging signal e or the first detecting signal b 1  outputted from the detecting element  7   a , so that the member  1 A and the thin film  1 B are held by the transfer roller  8   a  and the heat roller  1 , and the hot melt coating is carried out while they are transferred. The actuator  2   b  is deenergized when the member  1 A and the thin film  1 B are passed through the detecting element  7   b  and the driving circuit  3   b  receives a second detecting signal b 2  outputted from the detecting element  7   b.    
           [0008]    The transfer of the member  1 A is not carried out even if the presence of the member  1 A is detected and the surface temperature of the heat roller  1  is in the predetermined range because the temperature judging signal e is low level “L” until the predetermined time t 1  has been passed.  
           [0009]    Thus, the time t 1  becomes an idle time.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, it is an object of this invention to provide a heat roller control apparatus free from the above defects.  
           [0011]    It is another object of this invention to provide a heat roller control apparatus wherein a variation of a temperature signal outputted from a temperature detecting element is detected at a predetermined interval, and a temperature judging signal of high level is produced so that a member to be laminated with a thin film is transferred for hot melt coating, if the variation of the temperature signal is smaller than a predetermined value when the temperature signal reaches in a predetermined range.  
           [0012]    According to a heat roller control apparatus of this invention, the idle time after a surface temperature of a heat roller has reached to the predetermined temperature range can be shortened.  
           [0013]    A heat roller control apparatus according to the present invention is characterized by comprising a heat roller for hot melt coating a thin film on a member, a heater for heating the heat roller, temperature detecting means for detecting the surface temperature of the heat roller, temperature control means for controlling the heater according to a temperature detecting signal obtained from the temperature detecting means, and temperature judging means for producing a temperature judging signal for judging the state of the surface temperature of the heat roller according to the temperature detecting signal, wherein the temperature judging means calculates a variation of the surface temperature of the heat roller from the temperature detecting signal every predetermined time and judging the stability of the hot melt coating by the variation of the surface temperature of the heat roller when the temperature detecting signal reaches into a predetermined temperature range.  
           [0014]    A heat roller control apparatus according to the present invention is characterized by comprising a heat roller for hot melt coating a thin film on a member, a heater for heating the heat roller, temperature detecting means for detecting the surface temperature of the heat roller, temperature control means for controlling the heater according to a temperature detecting signal obtained from the temperature detecting means, and temperature judging means for producing a temperature judging signal for judging the state of the surface temperature of the heat roller according to the temperature detecting signal, wherein the member to be attached with the thin film is transferred only when the surface temperature reaches into a predetermined temperature range and a variation of the surface temperature of the heat roller is smaller than a predetermined value. The temperature judging means is a circuit comprising an A/D converter, three comparators, an AND gate, two registers, an oscillator, a subtracter, two frequency dividers, and two inverters. Other object and advantages will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a block diagram of a heat roller control apparatus in accordance with the present invention;  
         [0016]    [0016]FIG. 2 shows a diagram for explaining the heat roller control apparatus shown in FIG. 1.  
         [0017]    [0017]FIG. 3 is a block diagram of a conventional heat roller control apparatus; and  
         [0018]    [0018]FIG. 4 shows a diagram for explaining the heat roller control apparatus shown in FIG. 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    [0019]FIG. 1 shows a heat roller control apparatus having a temperature judging circuit  9 .  
         [0020]    The parts similar to those of the apparatus shown in FIG. 3 are designated by the same reference characters. The temperature judging circuit  9  has an A/D converter  11  for A/D converting a temperature signal a outputted from a temperature detecting element  5 , a comparator  12   a  for comparing the temperature signal a with a first reference signal c 1  indicating the upper limit value of a predetermined temperature range, a comparator  12   b  for comparing the temperature signal a with a second reference signal c 2  indicating the lower limit value of the predetermined temperature range, an AND gate  13  for receiving a first comparison signal d 1  outputted from the comparator  12   a  and a second comparison signal d 2  outputted from the comparator  12   b  so as to generate a third comparison signal d 3 , an oscillator  15  for generating a first clock signal f 1 , a frequency divider  17   a  for dividing the first clock signal f 1  by  2  so as to generate a third clock signal f 3 , a register  14   a  for receiving a first temperature conversion signal h 1  every time a leading edge (L→H) of the third clock signal f 3  is generated and holding the first temperature conversion signal h 1  until the next leading edge of the third clock signal f 3  is generated so as to generate a second temperature conversion signal h 2 , an inverter  18   b  for inverting the third clock signal f 3  so as to generate a fourth clock signal f 4 , a register  14   b  for receiving a second temperature conversion signal h 2  every time a leading edge of the fourth clock signal f 4  is generated and holding the second temperature conversion signal h 2  until the next leading edge of the fourth clock signal f 4  is generated so as to generate a third temperature conversion signal h 3 , an inverter  18   a  for inverting the first clock signal f 1  so as to generate a second clock signal f 2 , a frequency divider  17   b  for dividing the second clock signal f 2  by  2  so as to generate a fifth clock signal f 5 , a subtracter  16  for calculating a difference between the second temperature conversion signal h 2  and the third temperature conversion signal h 3  every time a leading edge of the fifth clock signal f 5  is generated so as to generate a temperature change signal g, and a comparator  12   c  for receiving the third comparison signal d 3 , and comparing a third reference signal c 3  indicating the maximum temperature change which is able to maintain the predetermined temperature range with the temperature change signal g so as to generate a temperature judging signal e.  
         [0021]    In the other embodiment of the present invention, a fourth reference signal c 4  is provided in case that the maximum temperature change which is able to maintain the predetermined temperature range when the surface temperature of the heat roller is increased is different from the temperature change which is able to maintain the predetermined temperature range when the surface temperature of the heat roller is decreased, and the third reference signal c 3  or the fourth reference signal c 4  is compared with the temperature change signal g according to the sign of the temperature change signal g.  
         [0022]    [0022]FIG. 2 shows a diagram for explaining heat roller control apparatus according to the present invention. In FIG. 2, a reference symbol (a) denotes a predetermined value or a predetermined level of the first reference signal c 1  showing the upper limit value of the predetermined temperature range, (b) denotes a predetermined value or a predetermined level of the temperature signal a of the second reference signal c 2  showing the lower limit value of the predetermined temperature range, (c) denotes a predetermined value or a predetermined level of the temperature signal a outputted from the temperature detecting element  5 , (d) denotes a predetermined value or a predetermined level of the first clock signal f 1 , (e) denotes a predetermined value or a predetermined level of the third clock signal f 3 , (f) denotes a value of the second temperature conversion signal h 2 , (g) denotes a predetermined value or a predetermined level of the fourth clock signal f 4 , (h) denotes a value of the third temperature conversion signal h 3 , (i) denotes a predetermined value or a predetermined level of the second clock signal f 2 , (j) denotes a predetermined value or a predetermined level of the fifth clock signal f 5 , (k) denotes a value of the temperature conversion signal g, (l) denotes a predetermined value or a predetermined level of the second comparison signal d 2 , (m) denotes a predetermined value or a predetermined level of the first comparison signal d 1 , (n) denotes a predetermined value or a predetermined level of the third comparison signal d 3 , and (o) denotes a predetermined value or a predetermined level of the temperature judging signal e.  
         [0023]    The heat roller control apparatus of the present invention will now be explained with reference to FIG. 2.  
         [0024]    As shown in (f) of FIG. 2, the register  14   a  receives the first temperature conversion signal h 1  obtained by converting the temperature signal a shown in (c) of FIG. 2 by the A/D converter  11  every time the leading edge (L→H) of the third clock signal f 3  shown in (e) of FIG. 2 is generated, maintains the first temperature conversion signal h 1  until the next leading edge of the third clock signal f 3  is generated, and then outputs the second temperature conversion signal h 2 . For example, the register  14   a  receives a value [A] of the first temperature conversion signal h 1 , maintains it until a time t 5 , and then outputs the second temperature conversion signal h 2 , if the value of the temperature signal a at a time t 2  is [A].  
         [0025]    Further, the register  14   a  receives a value [B] of the A/D converted first temperature conversion signal h 1 , maintains until a time t 8  and outputs the second temperature conversion signal h 2 , if the value of the temperature signal a at the time t 5  is [B]. The operation of the register  14   a  is repeated every time the leading edge of the third clock signal f 3  is generated.  
         [0026]    As shown in (h) of FIG. 2, the register  14   b  receives the second temperature conversion signal h 2  every time the leading edge (L H) of the fourth clock signal f 4  shown in (g) of FIG. 2 is generated, maintains the second temperature conversion signal h 2  until the leading edge of the fourth clock signal f 4  is generated, and then outputs the third temperature conversion signal h 3 . For example, the register  14   b  receives the value [A] of the second temperature conversion signal h 2  at a time t 4 , maintains it until a time t 7 , and outputs the third temperature conversion signal h 3 .  
         [0027]    Further, the register  14   b  receives the value [B] of the second temperature conversion signal h 2  at the time t 7 , maintains it until a time t 10 , and then outputs the third temperature conversion signal h 3 . The operation of the register  14   b  is repeated every time the leading edge of the fourth clock signal f 4  is generated. As shown in (k) of FIG. 2, the subtracter  16  receives the second temperature conversion signal h 2  shown in (f) of FIG. 2 and the third temperature conversion signal h 3  shown in (h) of FIG. 2 every time the leading edge (L→H) of the fifth clock signal f 5  shown in (j) of FIG. 2 is generated, and outputs the temperature change signal g obtained by subtracting the third temperature conversion signal h 3  from the second temperature conversion signal h 2 . The temperature change signal g is maintained until the next leading edge of the fifth clock signal f 5  is generated. For example, the subtracter  16  receives the value [A] of the second temperature conversion signal h 2  and a value (NONE) of the third temperature conversion signal h 3  at a time t 3  (the register  14   b  receives no reading date at the time t 3  ), calculates [A]−[NONE]=[A], and outputs [A] as the temperature change signal g until a time t 6 .  
         [0028]    Next, the subtracter  16  receives the value [B] of the second temperature conversion signal h 2  and the value [A] of the third temperature conversion signal h 3  at the time t 6 , calculates [B]−[A], and outputs the temperature change signal g until a time t 9 . The operation of the subtracter  16  is repeated every time the leading edge of the fifth clock signal f 5  is generated.  
         [0029]    The comparator  12   b  receives the temperature signal a shown in (c) of FIG. 2 and as shown in (l) of FIG. 2, outputs the second comparison signal d 2  of “L” if the temperature signal a is smaller than the second reference signal c 2  indicating the lower limit value of the predetermined temperature range, or outputs the second comparison signal d 2  of “H” if the temperature signal a is higher than the second reference signal c 2 . For example, the second comparison signal d 2  is “L” until a time  11 , because the temperature signal a is lower than the second reference signal c 2 , and is “H” after the time  11 , because the temperature signal a is larger than the second reference signal c 2 .  
         [0030]    The comparator  12   a  receives the temperature signal a shown in (c) of FIG. 2, and as shown in (m) of FIG. 2, outputs the first comparison signal d 1  of “H” if the temperature signal a is smaller than the first reference signal c 1  indicating the upper limit value of the predetermined rage, or outputs the first comparison signal d 1  of “L” if the temperature signal a is larger than the first reference signal c 1 . For example, the first comparison signal d 1  is “H” until a time tl 2 , because the temperature signal a is smaller than the first reference c 1 , and is “L” between the time tl 2  and a time tl 3 , because the temperature signal a is larger than the first reference signal c 1 . The first comparison signal d 1  is “H” after the time tl 3 , because the temperature signal a is smaller than the first reference signal c 1 . The AND gate  13  receives the second comparison signal d 2  and the first comparison signal d 1  shown in (l) and (m) of FIG. 2, respectively, and as shown in (n) of FIG. 2, outputs the third comparison signal d 3  of “H” only when the second comparison signal d 2  and the first comparison signal d 1  are “H”, respectively. That is, the temperature signal a is in the predetermined temperature range when the third comparison signal d 3  is “H”.  
         [0031]    The comparator  12   c  compares an absolute value of the temperature change signal g shown in (k) of FIG. 2 with the third reference signal c 3  showing the maximum value of temperature change for maintaining the predetermined temperature range ever time the leading edge (L→H) of the third comparison signal d 3  shown in (n) of FIG. 2 is generated, and as shown in (o) of FIG. 2, outputs the temperature judging signal e of “L” when the temperature change signal g is larger than the third reference signal c 3 , and outputs the temperature judging signal e of “H” when the temperature change signal g is smaller than the third reference signal c 3 . The fourth reference signal c 4  other than the third reference signal c 3  is provided in case that the maximum value of temperature change for maintaining the predetermined temperature range when the surface temperature of the heat roller is increased is different from that when the surface temperature is decreased. The maximum value of temperature change for maintaining the predetermined temperature range is set to the third reference signal c 3  when the surface temperature of the heat roller is increased, and set to the fourth reference signal c 4  when the surface temperature of the heat roller is decreased. The third reference signal c 3  is compared with the temperature change signal g when the temperature change signal g is “+” (the surface temperature of the heat roller is increased), and the fourth reference signal c 4  is compared with the temperature change signal g when the temperature change signal g is “−” (the surface temperature of the heat roller is decreased ). For example, the comparator  12   c  compares the value “C−B” of the temperature change signal g shown in (k) of FIG. 2 with the third reference signal c 3  at the time till, and outputs the temperature judging signal e of “L” if(C−B)&gt;the third reference signal c 3 . Further, the comparator  12   c  compares the value (L−K) of the temperature change signal g shown in (k) of FIG. 2 with the fourth reference signal c 4  at the time tl 3 , and outputs the temperature judging signal e of “H” if (L−K )&lt;the fourth reference signal c 4 .  
         [0032]    The present invention provides important advantages over the conventional heat roller control apparatus. For example, according to the heat roller control apparatus of the present invention, an interval between a time at which the surface temperature of the heat roller reaches into the predetermined temperature range and a time at which the member  1 A and the thin film  1 B are allowed to transfer can be shortened by changing the temperature judging signal from “L” to “H” quickly (within ½f, where f is the clock frequency of the oscillator ) after the surface temperature of the heat roller has reached into the predetermined temperature range.  
         [0033]    While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.