JPS637071B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a recording device for improving the recording speed without increasing the power supply capacity for recording in a facsimile device, particularly a thermal recording type. be.

[Prior art]

First, the conventional method will be explained according to the drawings.

FIG. 1 is a block diagram of an example of a conventional recording device, which is a thermal recording type facsimile device, and FIG. 2 is a power output characteristic diagram thereof.

This recording device uses a diode matrix type thermal recording head. This thermal recording head consists of blocks B ₁ to B _n divided into m groups.
Each of them is provided with n micro-machined heating resistors R ₁ to _{R o} and diodes D ₁ to _{D o} for each corresponding matrix configuration, resulting in an m×n dot matrix configuration. It's becoming like that.

Each block B ₁ to _{B n} has a common terminal C ₁ to _{C n} , which is combined into one terminal, to a block selection switch SW.
The individual data terminals A ₁ -A _o are connected in common to each corresponding terminal, and are connected to the data switches D ₁ -D _o .

For example, if you want to make the heating resistors R ₁ and R ₂ of block B ₁ generate heat and record "black" on the thermal recording paper that is pressed against the main head, press the selection switch.
Set SW to common terminal C ₁ , data switch D ₁ ,
Close D ₂ for a specified period of time.

As a result, the heating resistors R ₁ and R ₂ of block B ₁
A predetermined current flows from the recording power source E to generate heat,
The heat prints (records) a "black" dot at the desired location.

Thereafter, in the same manner, the heating resistor R ₁ of each block B ₂ to _{B n} is adjusted according to the desired recording position on the thermal recording paper.
By sequentially selecting, setting and closing the selection switch SW and each of the data switches D ₁ to D _o so that ~R _o generates heat, printing (recording) for one line can be performed.

The recording power source E is a stabilized power source having output characteristics as shown in FIG.
is a constant voltage of the specified voltage V ₀ until the output current I reaches the specified value I ₀ .

The above specified output current value I ₀ is the value of each block B ₁ ~
It is selected so that the constant output voltage V ₀ is maintained even if current flows simultaneously through all the heating resistors R ₁ to _{R o} of B _n .

Note that output current I ₀ is normally taken as an overcurrent protection measure.
When the load exceeds the above, as shown by the broken line in FIG. 2, the output current of the output current value I ₀ is not output due to the zero return characteristic and drooping characteristic.

In this way, in the conventional example described above, each block B ₁
~B If there is even one dot of “black” to be recorded in _n ,
Each block _B1 to _Bn is energized for the required time,
Since this process has to be repeated for the number of blocks (m), the same amount of time is required to record one line regardless of the amount of "black".
Even if the number is small, the overall recording time cannot be particularly reduced.

Furthermore, if an attempt is made to improve the recording speed by reducing the number of blocks and the number of repetitions, if there are many "black" blocks in the block, the recording current will become excessive and the recording power supply E will be turned off as described above. Since no output can be obtained, recording becomes impossible, or in order to make recording possible, the capacity of the recording power source E must be increased, which makes the recording device not only larger but also more expensive. It ends up.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology, increase the number of heat-generating resistors that can be driven simultaneously without increasing the recording power supply capacity, increase the recording speed, and significantly reduce the recording power. The objective is to provide an economical recording device that can

[Summary of the invention]

The configuration of the recording apparatus according to the present invention is such that the recording apparatus can control recording characteristics by the relationship between recording power and recording time, and includes a recording head section that can perform predetermined recording for each pixel according to recording information; On the other hand, a drive unit for controlling the supply of the required recording power for each pixel, and a drive unit that supplies recording power to the recording head, and outputs a constant voltage until the recording power reaches a predetermined value. When the power exceeds the above predetermined value, a power supply unit having an output characteristic that reduces the output voltage or output current at a predetermined rate, and the necessary control of each of the above parts, and the number of recording pixels of the recording head unit or the required and a control unit that detects power consumption and sets the time width of the recording command to the drive unit to a required predetermined time according to the detected power consumption, and when the number of recording pixels driven simultaneously exceeds a predetermined number. Furthermore, the output voltage or power source of the power supply section is lowered.

A specific example of thermal recording in a facsimile device will be explained as follows.

This thermal recording is the same as the conventional example described above, but with the recent reduction in the cost of integrated circuits and the development of packaging technology, there are now devices that can simultaneously drive all the heating resistors of the thermal recording head (so-called driver-equipped type). things) are being developed.

This corresponds to all the blocks B ₁ to B _n of the conventional example shown in FIG.
Since this corresponds to driving the two at the same time, the recording time can be reduced to 1/m of the conventional example.

However, considering the case where one line is completely black, the capacity of the power supply needs to be m times that of the conventional example, resulting in a considerable increase in cost.

Therefore, in the present invention, when the number of black dots exceeds a predetermined number, that is, when the load exceeds the stabilization range of the power supply, the power supply voltage is lowered to prevent the power of the power supply from rising, thereby reducing the cost increase. It's something you're trying to hold onto.

Therefore, when the above-mentioned limit is exceeded, the voltage decreases, so the electric power applied to each heating resistor decreases, and the temperature rise per unit time becomes smaller.

Therefore, in this case, by increasing the time during which power is applied to each heat generating resistor, each heat generating resistor is raised to a predetermined temperature to obtain a predetermined recording density.

If you do this, the recording time will be longer than when all dots are recorded with the specified power, but since the average black rate of recorded images for facsimile communication is less than 20%, this limit can be avoided. The probability of exceeding the black record is extremely small, and as a result,
The recording time does not become long, and there is no need to increase the capacity of the power supply.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is a block diagram of an embodiment of the recording apparatus according to the present invention, and FIG. 4 is a power output characteristic diagram thereof.

Here, numeral 1 is a recording head section which consists of heating resistors R ₁ to R _p and transistor switches T ₁ to _{T p} and is capable of thermally recording p dots (pixels), for example, and 2 is a drive section thereof. gates G ₁ - corresponding to the transistor switches T ₁ -T _p
3 is a power supply unit having output characteristics as shown in FIG _. 4, 4 is a control circuit related to the control unit, and 4A is the same. counter, 4B
is the same A/D converter.

First, the control circuit 4 transfers recording information ("white" and "black" data) to each recording pixel portion of the shift register SR of the driving section 2 through the data line DATA. This transfer is performed before a recording command is issued on the control line CNT, and the data is retained during recording, which will be described below.

Next, when a recording command (for example, a logic signal of "1") is issued through the control line CNT, the gates _G1 to _Gp corresponding to "black" are opened according to the recording information of the shift register SR. In the recording head section 1, the corresponding transistor switches T ₁ to T _p
is conductive and each heating resistor connected to it
_R1 to _Rp are energized and generate heat, and "black" is recorded on the corresponding portions of the recording paper.

The recording time is determined by the time width of the recording command issued to the control line CNT, and its length can be controlled by the control circuit 4.

When the number of recording dots (pixels where "black" is recorded, i.e. heating resistors) is less than a predetermined number and the total current is smaller than the maximum rated current _I0 of the power supply section 3, the time width of the recording command is always set to the predetermined value. It is controlled to have the value t _a .

When the number of recorded dots exceeds the predetermined number, the output voltage V of the power supply section 3 drops below the rated voltage _V0 ,
The time width of the recording command is increased to reduce the required power. In this case, the power supply unit 3 will operate in region F (output voltage V<V ₀ ) in FIG. 4.

The counter 4A counts the black data of the data (chronologically serial) transferred from the control circuit 4 to the shift register SR of the drive unit 2, and transmits the total number of black data to the control circuit 4. .
The control circuit 4 may count this by itself when transferring the data.

The control circuit 4 calculates the load resistance value of the heating resistor based on the number of black data, and calculates and determines the recording time according to the output voltage and supplied power of the power supply device 3 obtained from the known power supply characteristics in advance. The recording command is sent to the control line CNT.

The recording time may be controlled as follows.

In other words, the recording command is sent from the control circuit 4 to the control line.
When the recording power is sent to the CNT and is supplied from the power supply section 3 to the recording head section 1, the output voltage V decreases below the rated value _V0 depending on the number of black data due to its output characteristics.

The control circuit 4 converts the voltage value into an A/D converter 4B.
The converted digital value is then received, and a recording command of the required time width is sent out in the same manner as described above. Note that in this case, there is no need to count the number of black data.

Finally, the output characteristics of the power supply section 3 will be explained. As shown in Fig. 4, the output characteristics of the power supply section 3 are, for example, a constant output voltage until the load current _I0 .
V ₀ , but when the load current exceeds I ₀ , the output voltage begins to decrease, and when the load current reaches KI ₀ (K>1), the output voltage becomes 0.

For example, by applying a voltage V ₀ to n heating resistors for a time t _a with a current I ₀ , a predetermined amount of heat is generated (recorded).
It is assumed that a certain density can be obtained, and that the recording energy (recording power x recording time) for obtaining a predetermined density is constant.

In this case, if K=3, the recording voltage is 0.75V ₀ when the heating resistor is driven 2n, and 0.6V ₀ when the heating resistor is driven 3n, and the required recording time is 1.78t a and 2.77t _a , respectively. It becomes t _a .

In this way, if the number of recorded dots is greater than the limit value, it will take longer to record, but the black rate will still be 20%.
By setting the above limit values, recording can be performed at a speed that does not pose a practical problem.

In Fig. 4, the characteristic of region F is shown as a straight line, but depending on other parts of the design, it may be a curved line, a broken line, etc., and in extreme cases, the limiting current value I ₀ =
It may be 0. Note that not only voltage control but also current or power control may be used.

As described above, in this embodiment, all dots are driven simultaneously, but it can also be applied to a block division type, and in either case, the number of simultaneous drives can be increased to improve the recording speed without increasing the power supply capacity. I can do it.

Although the explanation has been made using the thermal recording method as above, the present invention is also applicable to other recording methods (for example, energization, photosensitive recording method, etc.) in which recording characteristics (density) can be controlled as a function of recording power and recording time. It can also be applied to

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to increase the number of heat-generating resistors that are simultaneously driven without increasing the recording power supply capacity, thereby increasing the recording speed and significantly reducing the recording power. Therefore, a remarkable effect can be obtained in making this type of recording apparatus more economical and improving its performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of a conventional recording device, FIG. 2 is a power output characteristic diagram thereof, and FIG.
A block diagram of an embodiment of a recording device according to the present invention,
FIG. 4 is a diagram showing the power supply output characteristics. DESCRIPTION OF SYMBOLS 1... Recording head section, 2... Drive section, 3... Power supply section, 4... Control circuit, 4A... Counter, 4B
...A/D converter.

Claims (1)

[Claims] 1. In a recording device whose recording characteristics can be controlled as a function of recording power and recording time, a recording head section capable of performing predetermined recording for each pixel according to recording information;
On the other hand, a drive unit for controlling the supply of the required recording power for each pixel and the recording head unit supplies recording power to the recording head unit, and outputs a constant voltage until the recording power reaches a predetermined value. When the recording power exceeds the above predetermined value, a power supply unit having an output characteristic that reduces the output voltage or power current at a predetermined rate, and the necessary control of each of the above units, and the number of recording pixels of the recording head unit or and a control unit that detects the required power consumption and sets the time width of the recording command to the drive unit to a required predetermined time according to the required power consumption, and when the number of recording pixels driven simultaneously exceeds a predetermined number. A recording apparatus characterized in that, at times, the output voltage or power current of the power supply unit is reduced.