JP6670959B2 - Lamp heating device - Google Patents

Description

  The present invention relates to a heating device used for a heating process such as a firing process of a solar cell electrode, and more particularly to a lamp heating device including a visible light to a near-infrared light source such as a halogen lamp.

  A lamp heating device using a visible light to near-infrared light source such as a halogen lamp as a heat source is used for a heat treatment such as a firing treatment of an electrode of a solar cell. The lamp heating device measures the temperature of the processing object using a radiation thermometer, and drives the light source by single-loop feedback control so that the temperature of the processing object becomes an appropriate processing temperature (for example, see Patent Document 1). .).

JP 2006-147943 A

  However, the responsiveness of the light amount of the light source by the feedback control is sufficiently fast, but the responsiveness of the temperature of the processing object to the light amount is slow. Therefore, in the single loop feedback control, the temperature of the processing object quickly follows the target value. Is difficult. For this reason, when a conventional lamp heating device is used to rapidly change the temperature of an object to be processed at a speed exceeding 100 ° C./sec, for example, as in spike annealing in a firing process of an electrode of a solar cell, the control parameter Complicated work such as fine adjustment is required.

  Such a problem generally occurs not only in the firing treatment of the electrodes of the solar cell but also in the heating treatment in the lamp heating device.

  Therefore, an object of the present invention is to provide a lamp heating device that can quickly make the temperature of an object to follow a target value without requiring work such as fine adjustment of control parameters.

  A lamp heating device according to the present invention includes a light source, a temperature sensor, a light amount sensor, a temperature control unit, and a light amount control unit. The light source irradiates the object with light and heats the object. The temperature sensor detects the temperature of the processing object. The light quantity sensor detects the light quantity of the light source. The temperature control unit outputs a light amount to be irradiated by the light source as a light amount target value in order to match the temperature detected by the temperature sensor with the temperature target value. The light amount control unit drives the light source such that the light amount detected by the light amount sensor matches the light amount target value output from the temperature control unit.

  In the above-described lamp heating device, the temperature control unit performs a feedback control of a first loop (temperature control loop) for matching an object to be processed with a target temperature based on a temperature detected by the temperature sensor. The feedback control of the second loop (light amount control loop) for controlling the light amount of the light source based on the detected light amount is executed. Thereby, the lamp heating device executes the feedback control of the dual control loop including the first loop and the second loop. Then, the light amount of the light source for heating the object is directly controlled by the feedback control of the second loop, so that the temperature of the object quickly matches the target temperature.

  In the lamp heating device, the light amount sensor preferably has a detection sensitivity wavelength range that overlaps with the wavelength range of the irradiation light of the light source, and an absorption range of the light wavelength substantially coincides with the absorption range of the object. The wavelength range where the detection sensitivity of the light quantity sensor is high coincides with the wavelength range of the light for heating the processing object, and the light quantity in the wavelength range for heating the processing object can be accurately detected.

  In addition, it is preferable that the light amount sensor be disposed on the opposite side of the object to be processed with the light source interposed therebetween. The light from the light source can be reliably received, and it is difficult to receive the reflected light from the object to be processed, and the light amount of the light source can be accurately detected.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature of a to-be-processed object can be made to follow a target value quickly, without requiring work, such as fine adjustment of a control parameter.

It is an outline sectional view of a lamp heating device concerning an embodiment of the present invention. It is sectional drawing of the principal part of a lamp heating apparatus. It is a figure showing an example of the emissivity characteristic of a light quantity sensor of a lamp heating device. It is a block diagram of a control part of a lamp heating device. FIG. 4 is a diagram illustrating a temperature change of an object to be processed in the lamp control device.

  Hereinafter, a lamp heating device according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a lamp heating device 10 according to the embodiment includes a furnace body 1, a halogen lamp 2, a temperature sensor 3, a light amount sensor 4, a control unit 5, and a lamp driving unit 6, and a processing target W is predetermined. Heat to a temperature of The workpiece W is, for example, a plate-shaped solar cell electrode material made of silicon.

  The furnace body 1 is a housing having heat insulation properties, and a workpiece W is carried in and out of the furnace body 1. The halogen lamps 2 are the light source of the present invention, and are arranged inside the furnace body 1 by, for example, five lamps vertically. The workpiece W is carried in between the upper and lower halogen lamps 2. The light source of the present invention is not limited to the halogen lamp, and the number, arrangement position, and shape are not limited to the state shown in FIG.

  The temperature sensor 3 is, for example, a radiation thermometer, and measures the temperature of the workpiece W. The temperature sensor 3 is arranged outside the furnace body 1 and faces the bottom surface of the workpiece W via a through hole 11 formed in the furnace body 1. The temperature sensor 3 is not limited to a radiation thermometer, but may be one that directly measures the temperature of the workpiece W, for example.

  The light quantity sensor 4 is, for example, a silicon photodiode, is arranged outside the furnace body 1, and measures the light quantity of the halogen lamp 2 via a through hole 12 formed in the furnace body 1. The control unit 5 outputs to the lamp driving unit 6 driving data of the halogen lamp 2 created based on the detected temperature of the temperature sensor 3 and the detected light amount of the light amount sensor 4. The lamp driving section 6 drives the halogen lamp 2 based on the driving data. The control unit 5 and the lamp drive unit 6 correspond to a drive control unit of the present invention.

  The temperature sensor 3 and the light amount sensor 4 will be described in more detail with reference to FIGS. As shown in FIG. 2, the temperature sensor 3 is located between the two halogen lamps 2 arranged in the furnace body 1 in the horizontal direction, and the bottom surface of the workpiece W through the through hole 11. Directly facing. Thereby, the temperature sensor 3 can accurately measure the temperature of the workpiece W.

  The light amount sensor 4 is provided at a position facing the halogen lamp 2 at the center, for example, where the influence on the entire temperature of the workpiece W is large, among the plurality of halogen lamps 2 arranged in the furnace body 1. It is arranged at a position that is hardly affected by the reflected light from the object W and the inner wall of the furnace body 1.

  The light amount sensor 4 receives the light of the halogen lamp 2 via the neutral density filter 41 provided in the through hole 12. The light amount sensor 4 is attached to the heat radiation member 42. The light amount sensor 4 can minimize the temperature rise due to the light of the halogen lamp 2 by the neutral density filter 41 and the heat radiating member 42, and can accurately measure the light amount of the halogen lamp 2.

  In addition, the arrangement positions of the temperature sensor 3 and the light amount sensor 4 are not limited to below the furnace body 1, and one or both of them can be arranged above or to the side of the furnace body 1. However, in order to measure the temperature of the plate-shaped workpiece W with the temperature sensor 3 which is a radiation thermometer, it is desirable that the temperature sensor 3 be arranged to face the main surface of the workpiece W. Further, the light quantity sensor 4 needs to be directly opposed to the halogen lamp 2 at a position where the light quantity sensor 4 is hardly affected by the reflected light from the workpiece W and the inner wall of the furnace body 1. Furthermore, since both the temperature sensor 3 and the light amount sensor 4 are connected to the control unit 5, they are preferably arranged close to each other. For example, both can be fixed integrally via the heat radiation member 42.

  FIG. 3 shows an emissivity characteristic of the light quantity sensor 4 composed of a silicon photodiode as an example of an emissivity characteristic of the light quantity sensor 4. As shown in the figure, the emissivity characteristic of the light amount sensor 4 substantially matches the emissivity characteristic of silicon as a material of the workpiece W. Further, the detection sensitivity wavelength range of the silicon photodiode overlaps with the emission wavelength of the halogen lamp 2. The emissivity characteristic is considered to be equivalent to the light absorption characteristic. Therefore, the light amount sensor 4 can accurately detect the heating state of the workpiece W by the light of the halogen lamp 2 based on the light amount of the light of the halogen lamp 2.

  The light source of the present invention is not limited to the halogen lamp 2. Even if it is other than the halogen lamp 2, by using the light quantity sensor 4 which has a detection sensitivity wavelength range overlapping with the emission wavelength of the light source to be used and is made of a material having substantially the same emissivity characteristic, The heating state of the object W by the light from the light source can be accurately detected based on the amount of light from the light source.

The drive control of the halogen lamp 2 based on the detection values of the temperature sensor 3 and the light amount sensor 4 will be described in more detail with reference to FIG. As shown in FIG. 4, the control unit 5 includes a temperature controller 51, a light amount controller 52, and a power converter 53. Control unit 5 over time to set the target temperature T _O of the workpiece W in accordance with the sequence stored in advance in a storage unit not shown. Temperature controller 51, based on the difference between the current temperature T _R and the temperature target value T _O of the workpiece W which is a temperature sensor 3 detects a halogen lamp 2 outputs a light amount target value L _O to be irradiated . Light amount control unit 52 determines the power control value to be supplied to the halogen lamp 2 on the basis of the difference between the current light amount L _R and the light amount target value L _O of the halogen lamp 2 to the light amount sensor 4 has detected, the power converter Input to 53.

  That is, the control unit 5 controls the light amount of the halogen lamp 2 based on the light amount detected by the light amount sensor 4 in addition to the feedback control of the first loop that makes the workpiece W match the target temperature based on the temperature detected by the temperature sensor 3. Is performed in the feedback control of the second loop. The control unit 5 can directly control the light amount of the halogen lamp 2 for heating the processing target W, can quickly match the temperature of the processing target W to the target temperature, and change the temperature locus of the processing target W. Control can be performed at a high speed of 1/10 second unit.

  As shown in the control theory, when performing constant value control in which the control target value is a constant value that does not change in a time series manner, no control delay occurs if the control system has one integration pole (control deviation is 0). . On the other hand, when performing the ramping control to follow the control target value that changes in time series, it is desirable that the control system includes two integrating poles.

The transfer function C (s) of the control system in general PID control is represented by K _P , proportional gain K _I , and differential gain K _D , where K _P is the proportional gain, K _{I is} the integral gain, and K _D is the differential gain.
C (s) = K _P + K _I · 1 / s + K _D · s
It is represented by When the control target has an integration pole, the control deviation in the ramping control can be suppressed even with a single control loop control system having only one integration pole 1 / s. It is rare to have. Therefore, by forming two control loops in the control system and including two controllers each having an integrating pole, the control deviation in the ramping control can be made zero.

  For example, when a spike annealing process for maintaining the temperature of the workpiece W at a desired peak temperature is performed using a control system having only one control loop, the desired peak temperature is reached as shown in FIG. It is necessary to hold the target value for a certain period of time p later, and it is necessary to adjust the target value. In addition, a control delay occurs, and the control target cannot follow the target value.

  On the other hand, in a control system having two control poles and two integration poles, the control amount can be set to 0 when the target value reaches a desired peak value. Can be made to follow the target value that changes in time series.

  Therefore, the responsiveness of the temperature of the workpiece W to the light quantity is improved by the feedback control of the light quantity of the halogen lamp 2, and the temperature of the workpiece W can be set to the target temperature trajectory without requiring any operation such as fine adjustment of the control parameters. Can be quickly followed.

  The description of the above embodiment is illustrative in all aspects and should not be construed as limiting. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

DESCRIPTION OF SYMBOLS 1 Furnace body 2 Halogen lamp, light source 3 Temperature sensor 4 Light quantity sensor 5 Control part 6 Lamp driving part W Workpiece 10 Lamp heating device 11, 12 Through hole 41 Light reduction filter 42 Heat radiating member 51 Temperature controller 52 Light quantity controller 53 Power converter

Claims (4)

A light source for irradiating the object with light and heating the light;
A temperature sensor for detecting a temperature of the processing object,
A light amount sensor for detecting the light amount of the light source;
A temperature control unit that outputs a light amount to be irradiated by the light source as a light amount target value in order to match a temperature detected by the temperature sensor to a temperature target value,
A light amount control unit that drives the light source such that the light amount detected by the light amount sensor matches the light amount target value output from the temperature control unit;
Bei to give a,
The temperature control unit performs feedback control of a temperature control loop that matches the detected temperature to the temperature target value based on the detected temperature of the temperature sensor,
The light quantity control unit performs feedback control of a light quantity control loop that controls the light quantity of the light source based on the detected light quantity of the light quantity sensor,
Thus, to perform the feedback control of the double control loop with the temperature control loop and the light quantity control loop, ramp heating device. The lamp heating device according to claim 1 , wherein the light amount sensor has an absorption region of a wavelength of light substantially equal to an absorption region of the object to be processed . The lamp heating device according to claim 2 , wherein the light quantity sensor has a detection sensitivity wavelength range overlapping with a wavelength range of the irradiation light of the light source . The lamp heating device according to claim 1, wherein the light amount sensor is disposed on a side opposite to the object to be processed with the light source interposed therebetween .

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