JPS6340195Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a toaster, and particularly relates to a structure for turning on and off a heater.

[Technical background of the invention]

Generally, when toasting bread continuously in a toaster,
The firing time is shorter for the first time and the second time. This is because while it is necessary to preheat the firing chamber for the first time, the firing chamber is already warmed from the second time onward and does not require time for preheating.

For this reason, toasters have already been developed and put on the market that have different baking times for the first and second baking to achieve the same brown color.

This has the circuit shown in FIG. In this circuit, first, when the power switch 1 is set, the heater 3 is heated to red heat by power supplied from the AC power source 2, and the firing chamber begins to be heated.

Further, the output of the AC power supply 2 is rectified by a diode 4, smoothed to a constant voltage by a resistor 5, a Zener diode 6, and a capacitor 7, and then supplied to the following.

Due to this power supply, the capacitor 10 is charged via the resistor 8 and the browning adjustment volume 9. When the terminal voltage of this capacitor 10 exceeds a predetermined value, the voltage detection circuit 11 operates and triggers the SCR 12. Then, SCR12 becomes conductive,
As a result, the electromagnet 13 is energized. As described later, this electromagnet 13 opens the power switch 1 when energized, so that the power supply is stopped. Then,
The heating operation of the heater 3 is stopped, and the charge in the capacitor 10 is discharged all at once to the Zener voltage via the resistor 14, the Zener diode 15, the diode 16, and the resistor 17.

After this, if you want to continue baking bread, set the power switch 1 again and the capacitor 10 will be switched to the first
Since charging is started from the Zener voltage instead of from OV as in the previous case, the time until the charging voltage reaches the predetermined voltage and the voltage detection circuit 11 operates is shortened. Note that 18 is a resistor.

Therefore, if the operating voltage of the voltage detection circuit 11 and the Zener voltage of the Zener diode 15 are selected so as to be related to the heat capacity of the toaster, that is, if the times for the first and subsequent times are set in advance. , the color of the bread will be the same the first time and the second time.

Next, the lock mechanism of the power switch 1 and the electromagnet 1
3, this has the structure shown in FIGS. 2 to 4.

A switch fixing part 20 fixed to a toaster main body (not shown) has a fixed contact plate 22 having a fixed contact 21 and a movable contact plate 24 having a movable contact 23 spaced apart from each other. An arm bar 26 is attached to the tip of the movable contact plate 24 via a presser plate 25, and a knob 27 serving as an operating portion projecting to the outside of the toaster is attached to the tip of the arm bar 26.

Below this arm bar 26, a movable iron piece 29 having a hook 28 at its upper end for locking the arm bar 26 is rotatable and biased to stand upright by a spring 30, and is attached to one side of the electromagnet 13. It is set in.

When the knob 27 is pressed down, the movable contact 23 comes into contact with the fixed contact 21, shorting the switch 1, and the arm bar 26 rotates the movable iron piece 29 as shown by the dotted line in FIG. 28 is pushed open and positioned below this hook portion 28. The movable iron piece 29 returns to the upright state by the spring 30 at the same time as the arm bar 26 is positioned below the hook 28, and locks the arm bar 26 with the hook 28.

As described above, when the electromagnet 13 is energized, the electromagnet 13 attracts the lower end of the movable iron piece 29, resulting in the state shown by the dotted line in FIG. Then, the arm rod 26 that was locked to the hook 28 of the movable iron piece 29 is released and rises, and the movable contact 23 is separated from the fixed contact 21.
Power supply is stopped.

[Problems with background technology]

However, in such a configuration, the electromagnet 13
is used to release the lock mechanism, the movable iron piece 29 must be attracted by the electromagnet 13, and the electromagnet 13 requires a large torque, making it large and expensive. , the lock mechanism itself has become larger and more complex,
The disadvantages were that it was difficult to manufacture and was expensive.

Also, in a toaster, especially an oven toaster,
The drawback is that if the number of breads baked at one time is different, the baked color will vary dramatically even with the same setting value.
For this reason, as shown in Fig. 5, a baking color adjustment setting name plate 31 for single-sheet printing and a baking color adjustment setting name plate 32 for double-sheet printing are provided separately. In accordance with this, the volume 9 was adjusted using the browning adjustment knob 33.

Furthermore, since the temperature in the baking chamber increases little by little each time, the color of the baked goods tends to become darker little by little. For this reason, a configuration is adopted in which a thermistor is connected in series to the baking color adjustment volume 9, and the baking time becomes shorter as the temperature increases. However, in reality, since the toaster itself is almost entirely made of metal, it has good heat conduction, and the resistance value of the thermistor becomes very low during the first firing, so the resistance value of the thermistor becomes very low for the second and subsequent firing times. The drawback was that it almost ceased to play a role.

[Purpose of invention]

The present invention was devised in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a toaster that is inexpensive, has good manufacturability, and has less variation in browning color.

[Summary of the idea]

The toaster of the present invention includes a timer circuit consisting of a power switch, an electromagnet that is energized by the setting operation of the power switch and holds the power switch in the set state, a resistor, and a capacitor connected to the power supply through the resistor. a timer operation unit that switches the time constant of the timer circuit in response to an external operation; a voltage detection circuit that cuts off energization to the electromagnet when the charging voltage of the capacitor exceeds a set value; and a voltage detection circuit that cuts off energization to the electromagnet. and a discharge circuit for discharging the charging voltage of the capacitor, and the power switch set by the setting operation of the power switch is held by the attraction force of the electromagnet.

[Embodiment of the invention] Next, an embodiment of the invention will be described based on FIGS. 6 to 9.

FIG. 6 is a front view of the toaster 41. Most of the front surface of this toaster 41 is occupied by a door body 42 that opens and closes the baking chamber, and a set knob 44 for turning on a power switch 43, which will be described later, is located above one side. A browning adjustment setting nameplate 45 and a browning adjustment knob 46 are provided at the lower part of 44.

FIG. 7 shows a control circuit for the toaster 41.

47 is an AC power supply, to which a heater 48 is connected via a power switch 43, a rectifying and smoothing circuit consisting of a diode 49, a resistor 50, a Zener diode 51, and capacitors 52, 53 is connected, and a terminal a , b.

Between these terminals a and b, a diode 54, a resistor 55, a color adjustment adjuster 56, and a capacitor 5 are connected.
7 series circuits and a resistor 58 are connected. Further, a series circuit of a diode 59 and a resistor 60 is connected between the terminal a and the intermediate tap of the volume 56, and the diode 59, the resistor 60, the volume 56, and the capacitor 57 constitute a timer circuit 61. A discharge circuit 67 consisting of a Zener diode 62, a resistor 63, an SCR constituted by transistors 64 and 65, and a resistor 66 is connected in parallel to the capacitor 57. This discharge circuit 67 is connected to the collector of a transistor 69, which will be described later, via a resistor 68, and becomes conductive when the transistor 69 is turned off.

70 is a comparator as a voltage detection circuit,
Field effect transistor (hereinafter referred to as FET) 71,
Transistor 72, semi-fixed resistor 73 and resistor 7
4, 75, 76, 77, 78, and 79, and changes the voltage at the output terminal according to the voltage across the capacitor 57. The base of a transistor 81 is connected to this output terminal via a resistor 80. The emitter of this transistor 81 is connected to terminal a, and the collector is connected to terminal b via resistors 82 and 83.

Numeral 84 denotes an electromagnet for holding the set knob, one end of which is connected to terminal a and the other end of which is connected to terminal b via transistor 69.
The base of 9 is connected to the junction between resistors 82 and 83. Reference numeral 85 denotes a diode for absorbing counter electromotive force.

FIGS. 8 and 9 are mechanical diagrams of the power switch 43, the set knob 44, and the electromagnet 84. In this figure, 86 is a switch fixing part;
It is fixed to a mounting board (not shown). A movable contact plate 87 and a fixed contact plate 88 are attached to the switch fixing portion 86 so as to face each other and be spaced apart from each other. At the tip of this movable contact plate 87 is a presser plate 8.
9 is attached, and an arm bar 91 having a metal suction plate 90 on the underside is attached to the center of this presser plate 89, and the set knob 44 is provided at the tip of this arm bar 91.

An electromagnet 84 is provided below the suction plate 90, and when the set knob 44 is pulled down and the electromagnet 84 operates with the suction plate 90 in contact with the electromagnet 84, this state is maintained.

Further, the movable contact plate 87 is provided with a movable contact 92, and the fixed contact plate 88 is provided with a fixed contact 93. When the set knob 44 is pulled down between these contacts 92 and 93, the movable contact plate 87 is lowered. The switch 43 shown in FIG. 7 is thereby closed. Both contact plates 87, 88
The electromagnets 84 and 84 are each connected to the circuit shown in FIG. 7 by lead wires 94.

Next, the operation of this embodiment will be explained.

First, when the set knob 44 is pulled down, the contact 9
2 and 93 are brought into contact and the switch 43 is closed. Then, the heater 48 is energized to heat the firing chamber and a constant voltage is supplied between terminals a and b.

Initially, when voltage is supplied between terminals a and b, the charging voltage of capacitor 57 is OV, so in comparator 70, the set voltage is applied to the base of transistor 72, and transistor 72
turns on and FET71 turns off. Then, the output of the converter 70 turns on the transistor 81 via the resistor 80, so that the transistor 69 also turns on, and the electromagnet 84 is operated to generate an attraction torque. For this reason, the arm rod 91
The suction plate 90 provided on the electromagnet 84 is attracted to the electromagnet 84, and the switch 43 is held in the closed state.

Therefore, a constant voltage continues to be supplied between the terminals a and b, and this supply voltage causes a voltage to flow through the diode 59, the resistor 60 and the volume 56 to the capacitor 57.
After a certain time, the capacitor 57
When the charging voltage reaches the set value, the FET 71 turns on.
The transistor 72 is turned off and the comparator 70
Then, the output of the comparator 70 turns off the transistor 81 and also the transistor 69, so that the electromagnet 84 is no longer energized and the attraction of the attraction plate 90 is released. As a result, the switch 43 is turned off and the heater 48 is turned off.
Heating by the heater is stopped.

Furthermore, when the transistor 69 is turned off, the collector voltage of this transistor 69 increases, and the transistors 64 and 65 are connected via the resistor 68.
Trigger the SCR circuit. Then, the discharge circuit 6
7 is made conductive, and the charge in the capacitor 57 is discharged all at once to the Zener voltage of the Zener diode 62 via this discharge circuit 67.

From the second time onward, charging of the capacitor 57 is started from the Zener voltage instead of from OV, so the time required to reach the set voltage is shortened by the amount that the firing chamber has already been preheated.

As described above, in this embodiment, when the switch 43 is closed, that is, when the set knob 44 is pulled down, the electromagnet 84 operates to attract and hold the suction plate 90 for a predetermined period of time determined by the timer circuit 61. The operation of the rear electromagnet 84 is stopped, and the suction plate 9
The suction plate 90 is configured to release the suction of the electromagnet 4 and open the switch 43.
4, it is sufficient to maintain this state, and a smaller suction torque is required compared to the conventional configuration in which the movable iron piece 29 must be attracted only by the suction torque of the electromagnet 13. A small and inexpensive device can be used.

Also, operate the browning adjustment knob 46 to adjust the volume to 5.
By moving the intermediate tap 6 and changing the resistance value of the timer circuit 61, the baking time can be changed to achieve the desired coloring of the bread.

In the above embodiment, the timer circuit 61 was formed of a diode 59, a resistor 60, a regulator 61, and a capacitor 57, but as shown in FIG. Then resistance 96 and volume 5
6 is connected in parallel to the resistor 60, and a thermistor 97 is connected between the resistor 60 and the intermediate terminal of the volume 56. 98 is resistance.

Note that this thermistor 97 is connected to the heat dissipation fin 9.
9 and is housed in a box body 100 made of a heat-resistant material, and this box body 100 is located at the part of the toaster where the temperature rise is the lowest, for example, at the bottom of the toaster.
It is attached at the farthest corner from the heater 48, and in such a way that the outer wall of the box body 100 does not come into contact with the steel plate of the toaster case. Further, as shown in FIG. 6, the operating knob 101 of the changeover switch 95 is provided on the upper part of the browning adjustment setting plate 45 and can be operated from the outside.

When the switch 95 is turned on by operating the operation knob 101, a resistor 96 and a potentiometer 56 are connected in parallel to the resistor 60 and thermistor 97.
Since a part of the resistor 96 and the regulator 56 connected in parallel are connected, the resistance value of the timer circuit 61 becomes small and the firing time becomes short. Since it is separated, the resistance value increases and the firing time becomes longer. Therefore, without operating the browning color adjustment knob 46, the browning color can be changed by simply operating the operation knob 101 if the load in the baking chamber is the same;
When the loads are different, especially when there is one piece of bread and when there are two pieces of bread, the same browning can be achieved by appropriately selecting the value of the resistor 96.

In addition, a thermistor 97 was connected between the resistor 60 and the middle tap of the volume control 56, and since this thermistor 97 was housed in the box 100 and installed at the location where the temperature rise was lowest, it was repeated two and three times. As the temperature in the firing chamber gradually increases as the layers are baked,
The thermistor 97 is connected via the box 100 with poor thermal conductivity.
Since the ambient temperature also gradually rises, as the temperature of the firing chamber rises, the resistance value of the thermistor 97 also decreases, and the time set by the timer circuit 61, that is, the firing time, becomes shorter. For this reason, even when baking repeatedly, it is possible to always bake the same color.

[Effects of the invention] According to the invention, when the power switch is set, the electromagnet holds it, and after the time set by the timer circuit, the power to the electromagnet is cut off to release the holding of the power switch. The electromagnet only needs to hold the set power switch in the set state, and therefore the attraction force is smaller than that required for attracting and moving movable iron pieces, and it is possible to use small, lightweight, and inexpensive electromagnets. This makes it possible to reduce the size, weight, and cost of toasters.

In addition, the timer operation section is equipped with a switch for changing the number of pieces of bread to be baked, which changes the baking time.
By setting the color to be the same for single-sheet printing and double-sheet printing, there is no need to provide two setting nameplates for adjusting the baking color, one for single-sheet printing and one for double-sheet printing.
There is no need to operate the browning adjustment knob, and it is possible to switch between single-cooked and double-cooked grills.

Furthermore, since a thermistor housed in a box made of heat-resistant material is used as the resistor for the timer circuit, the baking time can be changed according to changes in the temperature in the baking chamber, and by baking two or three times, the baking can always be done in the same way even if the temperature in the baking chamber gradually rises.

[Brief explanation of drawings]

Fig. 1 is a conventional baking time control circuit diagram of a toaster, Figs. 2 to 4 are diagrams showing a conventional power switch mechanism, Fig. 5 is a front view showing a baking color adjustment section,
Fig. 6 is a front view showing the toaster of the present invention, Fig. 7 is a baking time control circuit diagram of the same, Fig. 8 is a perspective view showing the power switch mechanism of the present invention, Fig. 9 is a side view of the same, Fig. 10. 11 is a firing time control circuit diagram showing another embodiment of the present invention, FIG. 11 is a sectional view showing the thermistor in a stored state, and FIG. 12 is a perspective view of the same. 43... Power switch, 46... Browning adjustment knob as a timer operation section, 56... Volume operated by the browning adjustment knob, 57... Capacitor,
60...Resistor, 61...Timer circuit, 67...
Discharge circuit, 70... Voltage detection circuit, 84... Electromagnet, 97... Thermistor, 101... Changeover switch.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) From a power switch, an electromagnet that is energized by the setting operation of the power switch and holds the power switch in the set state, a resistor, and a capacitor connected to the power supply through the resistor. a timer circuit that switches the time constant of the timer circuit in response to an external operation; a voltage detection circuit that cuts off energization to the electromagnet when the charging voltage of the capacitor exceeds a set value; A toaster comprising: a discharge circuit that discharges the charging voltage of the capacitor when electricity is interrupted. (2) The toaster according to claim 1, wherein the timer operation section is provided with a changeover switch for changing the number of toasted sheets, and by switching the changeover switch, the set time is changed according to the operation. (3) Utility model registration claim 1 or 2, characterized in that a thermistor housed in a box made of heat-resistant material is used as a resistor in a timer circuit.
Toaster mentioned in section.