JPH0458308A - Motor controller - Google Patents

Abstract

PURPOSE:To always secure the optimum control of a motor by storing the prescribed rotational frequency of the motor and the driven variable of a member like a lens, etc., set up to its stopping position when the member is braked in the prescribed rotational frequency at starting up. CONSTITUTION:A storage means 8 stores the relation between each prescribed rotational frequency of motors 3 and 5 and the driven variable of a member in its braking state when a motor controller 5 is started. That is, an E<2>PROM 8 stores the relation between the pulses given from the encoders 4 and 6 and the ON time of a rense driving pulse as the lens driving data together with the moved variable of a lens set up to its stop when the brakes are applied to the motors in the prescribed rotational frequency. Then the lens is stopped at a target position after the lens driving data is read out. Thus the optimum motor control is always secured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor control device, and particularly to the control of a motor used in a camera.

2. Description of the Related Art In recent years, various ideas have been made to more accurately and quickly perform focus detection operations (focusing operations) of cameras.

An example of focusing drive will be explained using FIG. 3(A). First, let the target amount of movement be N, then keep the motor turned on until the amount of movement reaches N (stage I).Next, brake the motor (stage I+), this stopping position matches the target amount of movement. In this case, the driving time is the shortest. If the position stopped by this brake does not reach the target movement amount, the motor is turned on for a predetermined period of time (for example, 1m5),
Input a short brake pulse for a predetermined period of time (for example, 4m5) (hereinafter referred to as 1-pulse drive), and thereby move the lens minute by minute until it reaches the target amount of movement (Stage II+).There are no problems with this drive method. There are two important points to consider.

■ As the amount of pulse drive increases, the focusing drive time becomes longer.

(2) If the target movement amount is exceeded in the stage II brake control, driving in the opposite direction is required next, and an error factor in the system that decelerates the rotation of the motor, called so-called backlash, occurs.

Of these two problems, if (2) is given more importance, it is necessary to perform early brake control, and the focusing time (2) becomes longer.

In order to solve the above two problems, JP-A-63-1535
No. 26 describes a method in which a deceleration curve of the motor is stored in advance, and the motor is controlled along the deceleration curve to accurately stop at a target position.

Problems to be Solved by the Invention The following conditions are problematic in the above-mentioned focusing control.

(1) Load variation due to individual differences in load and its environmental conditions (2) Variation in drive torque due to motor (3) Variation in (2) due to power supply conditions These three conditions cause the target movement amount to be This may lead to overshooting or undershooting, resulting in the above problems (■) and (■).

In the case of JP-A No. 63-153526 mentioned above, the conditions (1) ~
Although (3) can be solved, since the comparison is performed during the actual photographing operation, the focusing time is long (which affects the photographing process).

tζth Means for Solving the Problems In order to achieve the above problems, the present invention provides a motor control device having a motor and a member driven by the motor. The motor controller is configured to include a storage means for storing the relationship between the drive amount of the member during braking and the drive amount of the member at the time of starting the motor control device. Furthermore, as a second configuration, the amount of drive of the above member;
The present invention is configured to include determining means for determining the relationship with the energization time of the motor at the time of starting the motor control device.

Effect With the above configuration, the present invention measures the fluctuations of the above tasks (]) to (3) before the camera's normal shooting sequence,
Based on the results, optimal motor control can be performed at all times.

Embodiment FIG. 1 is a diagram showing the overall configuration of a circuit related to a motor control I mechanism of a camera according to an embodiment of the present invention.

In the figure, a CPU 2 that controls the entire photographing operation, a distance measuring section 1, an AF motor 3 that drives a focusing lens, an encoder 4 that encodes the amount of rotation of the motor 3, and a zoom lens are shown. A zoom motor 5 for driving, an encoder 6 for encoding the rotation amount of the motor 5, a driver IC circuit 7 for driving the AF motor 3 and the zoom motor 5, and a driver IC circuit 7 for storing data for driving the lens. The circuit is composed of an E'' FROM 8, a main switch SM for starting the camera, a switch S1 for starting distance measurement, and a switch S2 for controlling exposure.

The amount of rotation of the AF motor and the zoom motor is manually input to the CPU 2 by the encoders 4 and 6, and the focal length of the photographing lens is calculated based on the amount of rotation. The AF motor 3 and zoom motor 5 are driven via the driver IC circuit 7 based on this focal length. This performs focusing and zooming operations.

In addition, E2PROM8 contains data for driving the lens as shown in Table 1, such as the relationship between the pulse PI from the encoder and the ON time of the lens (for lens driving) and the lens stopping when the motor is braked at a predetermined rotation speed. The amount of movement up to the point is memorized. By reading this data, it is possible to accurately stop the lens at the target lens stop position. In addition, in the relationship between pulse PI and motor ON time listed in Table 1, the value of PI is longer than the normal ON time (for example, 1 m5) of the motor (for example, 6 m 5lON).
This is the value when This is because the initial torque of the motor varies depending on the positional relationship between the rotor of the motor and the permanent magnet, and in order to cancel this variation, trial rotation is performed for a time longer than the ON time during actual driving. This eliminates data variation and
The optimum driving pulse for actual driving can be found.

Table 1 Next, the operation of the CPU 2 will be explained using the flow chart shown in FIG.

When a power supply battery (not shown) is installed, the CPU 2 executes step (
In step #1), wait for the camera activation switch (SM) to be turned on. When the switch (SM) is turned on, in step (#2), the focusing lens is moved once to the contact position on the infinite distance side, and then (#3) Set the focusing lens to infinite distance. (Hereinafter, the operations of steps (#2) and (#3) are referred to as infinite reset.)
During this infinite reset, the CPU 2 drives the motor at a predetermined speed (for example, 5000 rpm), and when braking is performed from that speed, the encoder 4 counts the number of pulses PI (7) from the start of braking until it stops. , is stored in E2FROM8 (step ($4)).

Next, the CPU 2 uses the pulse PI from the encoder 4 when the AF motor is turned ON for a predetermined period of time, and determines the AF motor under the current photographing conditions based on the relationship between the pulse PI stored in the E2PROM 8 and the ON time of the AF (-ta). Determine ON time (step (#5)), then step (#6)
Wait for the distance measurement start switch (Sl) to be turned on. When the switch (Sl) is turned on, step (#7
), the distance measurement data from the distance measurement unit I, the AF motor ON time data determined at the above infinite reset, the predetermined motor rotation speed stored in the E2FROM, and the lens during braking at that rotation speed are stopped. Focusing is performed based on the relationship between the amount of movement up to and the step (
At step #8), the camera waits for the exposure control switch (S2) to be turned on, and when the switch (S2) is turned on, the exposure operation is performed at step (#9) and the photographing is completed.

FIGS. 3(A) and 3(B) are diagrams showing the rotation speed of the motor and the amount of movement of the lens. (B) is a diagram when the amount of movement of the comparative lens is large in the case of (A+).

In the same figure (A), the rotation speed A is the rotation speed when the AF motor is braked, the movement amount N is the movement amount of the focusing lens when the AF motor is braked, the movement amount N2 is the movement amount of the focusing lens when the AF motor is stopped, The amount of movement N is distance measuring unit 1
This is the amount of movement for the focusing lens to be in focus, which is calculated based on distance measurement data from . The rotation speed A above and the amount of lens movement from motor braking to stop (
N2-Nl) is E'' in step (#4)
This is data stored in FROM.

Furthermore, after once stopping the focusing lens at the position of the movement amount N2, pulse drive is performed for several pulses so that the movement amount becomes N. The ON time of the pulse drive at this time is also set at the time of infinite reset (step (#5)). The determined one will be used.

FIG. 3(B) is a diagram showing the relationship between the motor rotation speed and the focusing lens movement amount when the motor rotation speed is increased to B when the movement amount N is large. In this case, once the focusing lens movement amount reaches N, the AF will start.
The motor is braked and the 0N10FF control of the motor is repeated until the number of revolutions A stored in the 6E2PROM 8 is reached. When the number of revolutions of the motor reaches A, the same control as in the case of FIG. 6A is performed.

In the above explanation, only the relationship between the focusing lens and the AF motor has been explained, but it goes without saying that this also applies to the relationship between the zoom lens and the zoom motor. Good too.

Effects As explained above, according to the present invention, in a motor control device, the rotation speed of the motor is set at a predetermined number of revolutions at the time of startup (at the time of infinite reset), and the number of rotations of members such as lenses until the motor stops when braking is performed at that number of revolutions. By storing the drive amount, motor control can be performed without affecting the actual photographing operation.

Furthermore, since the pulse drive energization time is determined at startup, it not only does not affect the actual shooting operation, but also allows pulse drive to be controlled depending on environmental conditions when the motor is temporarily stopped before the target stop position. It is possible to accurately and quickly stop at the target stop position without being affected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the camera according to the present invention, FIG. 2 is a flowchart showing the operation of the CPU 2, and FIG. 3 is a diagram showing the relationship between the rotational speed of the motor and the amount of movement of the member driven by the motor. It is a drawing. (1) ---One distance measuring section (2) ---CPU (3)
---Focusing motor (4), (6) ---One encoder (5) ---Zoom motor (7) ---Driver IC (8) ---E2FROM (SM) ---Main switch (S 1)---Focusing switch (S2)-
- Single exposure control switch

Claims (2)

[Claims] (1) In a motor control device having a motor and a member driven by the motor, the motor control device determines the relationship between a predetermined number of rotations of the motor and the amount of drive of the member during braking at the predetermined number of rotations. 1. A motor control device comprising a storage means for storing information when the motor is started. (2) In a motor control device having a motor and a member driven by the motor, a detection means for detecting the amount of drive of the member when the motor control device is started, and energization of the motor based on the result of the detection means. A motor control device comprising: determining means for determining a time.